Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: TheBoy on 03 April 2007, 20:29:15

Title: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 03 April 2007, 20:29:15
Right, since replacing the stat which had holes drilled in it, the temp on the TD is more stable.  It sits at 92/93ish, rising to 96ish when pushed.  Never goes outside of this range.

However, when it does get hot, the cap seems to give, losing coolant in the process.

Assuming the dash gauge is accurate (and the correct one - it shows 1/4 as 90, 1/2 as 95, and 3/4 as 100??), and ideas?  Can't check ECU's view on temp, as the coolant temp sensor is fubar...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 03 April 2007, 20:36:29
and, no, I don't think the HG has gone.
Title: Re: 2.5TD Overheating or overpressurising?
Post by: JamesV6CDX on 03 April 2007, 20:37:00
CTS is fubar'd? Surely then, if the ECU isn't getting the right temp feedback, it won't run right, which could be contributing to the performance issues?

I would say change the Coolant Temp Sensor, and then read the ECU's thoughts on engine temp with your magic Tech2.

If temp appears normal.. then maybe the pressure cap is knackered? Or.. another Air leak causing the pressure ? Does the TD have an HBV?

When the cap starts blowing off.. are the rad hoses rock hard?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Taxi_Driver on 03 April 2007, 20:40:14
Well assuming the guage is ok.....i would have said 95 is normal temp as its in the middle.....tho 95 sounds a bit hot for a diesel, they usually run a tad colder than petrols.
My merc has a normal operating temp of 80, 80 being in the centre of the guage.

I assume it has the correct instrument cluster in it? ie not one from a petrol?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 03 April 2007, 20:41:38
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CTS is fubar'd? Surely then, if the ECU isn't getting the right temp feedback, it won't run right, which could be contributing to the performance issues?

I would say change the Coolant Temp Sensor, and then read the ECU's thoughts on engine temp with your magic Tech2.

If temp appears normal.. then maybe the pressure cap is knackered? Or.. another Air leak causing the pressure ? Does the TD have an HBV?
Waiting for the intake gaskets to turn up before I change sensor.  I agree, it may affect performance. Certainly buggering up g/box, as that is moaning that the engine is moaning about coolant temp.

Tried 3 coolant caps now.

TD does have a HBV (different to v6), but I am fairly sure there are no leaks....
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Marks DTM Calib on 04 April 2007, 08:00:24
I still say your rad is blocked......perhaps I need to borrow the infra red temp probe or thermal camera from work one weekend.....
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 08:11:36
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I still say your rad is blocked......perhaps I need to borrow the infra red temp probe or thermal camera from work one weekend.....
Blocked rad was something Omegatoy suspected.

However, the right side (looking from front) is hot, and gets progressively cooler towards the left.  I have checked top and bottom, though can't reach middle.  Is this right?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Andy B on 04 April 2007, 08:13:21
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......perhaps I need to borrow the infra red temp probe or thermal camera from work one weekend.....

What's your job when you have a TIC camera at work? The last time I used a thermal imaging camera was fire fighting in the RN.  :y
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Marks DTM Calib on 04 April 2007, 08:23:39
We use it for looking at complex circuit boards during the eval phase to look for hot spots......nice bit of kit.....about 25K's worth...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 08:25:23
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We use it for looking at complex circuit boards during the eval phase to look for hot spots......nice bit of kit.....about 25K's worth...
Will it work through the a/c condensor?

Do you still think its rad, despite my comments that it seems to get evenly cooler right to left?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Marks DTM Calib on 04 April 2007, 08:49:51
Its the middle section thats important....on end is likely to warm up jut via conduction....
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 08:52:00
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Its the middle section thats important....on end is likely to warm up jut via conduction....
Is it possible to get it checked somewhere before I blow £200 on new rad?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Auto Addict on 04 April 2007, 11:50:28
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I still say your rad is blocked......perhaps I need to borrow the infra red temp probe or thermal camera from work one weekend.....
Blocked rad was something Omegatoy suspected.

However, the right side (looking from front) is hot, and gets progressively cooler towards the left.  I have checked top and bottom, though can't reach middle.  Is this right?

No, middle is centre ::)
Title: Re: 2.5TD Overheating or overpressurising?
Post by: JamesV6CDX on 04 April 2007, 13:22:26
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Its the middle section thats important....on end is likely to warm up jut via conduction....
Is it possible to get it checked somewhere before I blow £200 on new rad?

Take it out for a really good reverse flush?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 13:24:17
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Its the middle section thats important....on end is likely to warm up jut via conduction....
Is it possible to get it checked somewhere before I blow £200 on new rad?

Take it out for a really good reverse flush?
From what I've heard, the tractors are prone to rad silting, and no amount of normal flushing affects it. Caustic Soda may shift it, but will probably knacker the rad...

I would have though that the silt would have silted up the bottom of the rad, yet that seems (heat wise) normal...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: JamesV6CDX on 04 April 2007, 13:27:13
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Its the middle section thats important....on end is likely to warm up jut via conduction....
Is it possible to get it checked somewhere before I blow £200 on new rad?

Take it out for a really good reverse flush?
From what I've heard, the tractors are prone to rad silting, and no amount of normal flushing affects it.

I would have though that the silt would have silted up the bottom of the rad, yet that seems (heat wise) normal...

Bleh... flush it with petrol ;D
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 15:41:31
Quick update.  On a gentle 60/70mph trip up A43 to Silverstone and back (about 15m round trip), it was flawless.  No coolant seeping from cap.  Temp never really went 94/95.

Went on a shorter trip, giving it a good thrashing, temp went up to just over 95.  It then seeped coolant from cap.

 :-/
Title: Re: 2.5TD Overheating or overpressurising?
Post by: MaxV6 on 04 April 2007, 16:18:48
have you checked to see if the TD has a differently rated expansion tank cap to the V6 and 4 pot???    not sure about today, but back in the good old days, (Sennie A & B and earlier....)  you could get a range of Cap ratings to deal with different temperature and pressure conditions.

it's just a thought....

also, last time i looked, Serck would do a re-core for a a LOT less than a new Rad.  they're based here in oxford as well./...


Max

Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 16:40:18
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have you checked to see if the TD has a differently rated expansion tank cap to the V6 and 4 pot???    not sure about today, but back in the good old days, (Sennie A & B and earlier....)  you could get a range of Cap ratings to deal with different temperature and pressure conditions.

it's just a thought....

also, last time i looked, Serck would do a re-core for a a LOT less than a new Rad.  they're based here in oxford as well./...


Max

EPC shows the diesel caps to be different. Q&H catalogue shows them to be the same.  Either way, would I be right in thinking petrol and diesel cooling systems would be under similar pressure for same temperature?

It would appear the cap begins to go at 95ish...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Marks DTM Calib on 04 April 2007, 16:43:22
Yes, the coolant pressures should be about the same.....

The cap should not be leaking at 95deg if the system is not over pressurised somewhere.....
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 16:44:36
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Yes, the coolant pressures should be about the same.....

The cap should not be leaking at 95deg if the system is not over pressurised somewhere.....
I am making a huge assumption that the dash gauge is accurate of course.....
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Matchless on 04 April 2007, 20:15:01
Swap caps with the MV6?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 20:17:23
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Swap caps with the MV6?
I have tried the original cap, a new Q&H cap, and a cap from a TD at scrappy. The Q&H is the best.  I will try the MV6 one if you thing worthwhile...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Omegatoy on 04 April 2007, 20:21:31
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Quick update.  On a gentle 60/70mph trip up A43 to Silverstone and back (about 15m round trip), it was flawless.  No coolant seeping from cap.  Temp never really went 94/95.

Went on a shorter trip, giving it a good thrashing, temp went up to just over 95.  It then seeped coolant from cap.

 :-/

That just aboput confirms it then , if its fine cruising and only overheats when boosting hard hence producing lots more heat, it has to be a silted up radiator as i first suspected!!!
IT HAS TO BE!!!!

Or just cruise everywhere and enjoy the economy!!! ;D
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 20:22:50
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Quick update.  On a gentle 60/70mph trip up A43 to Silverstone and back (about 15m round trip), it was flawless.  No coolant seeping from cap.  Temp never really went 94/95.

Went on a shorter trip, giving it a good thrashing, temp went up to just over 95.  It then seeped coolant from cap.

 :-/

That just aboput confirms it then , if its fine cruising and only overheats when boosting hard hence producing lots more heat, it has to be a silted up radiator as i first suspected!!!
IT HAS TO BE!!!!
But why is cap letting go at only 95 degrees? As far as dash gauge is concerned, its not overheating....
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Omegatoy on 04 April 2007, 20:35:36
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Quick update.  On a gentle 60/70mph trip up A43 to Silverstone and back (about 15m round trip), it was flawless.  No coolant seeping from cap.  Temp never really went 94/95.

Went on a shorter trip, giving it a good thrashing, temp went up to just over 95.  It then seeped coolant from cap.

 :-/

That just aboput confirms it then , if its fine cruising and only overheats when boosting hard hence producing lots more heat, it has to be a silted up radiator as i first suspected!!!
IT HAS TO BE!!!!
But why is cap letting go at only 95 degrees? As far as dash gauge is concerned, its not overheating....

you keep saying *Assuming the gauge is reading correctly* till you change the cts and confirm it with the tech2 I would guess the gauge is a bit lazy mate!!!
but the fact remains when boosting hard it produces a hell of a lot more heat for the cooling system to cope with and if the rad is slightly suspect there is nowhere for the extra heat to disapait disapate dissiapate  drat cant spell that  :-[ the heat to be gotten rid of!!!
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 20:44:45
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Quick update.  On a gentle 60/70mph trip up A43 to Silverstone and back (about 15m round trip), it was flawless.  No coolant seeping from cap.  Temp never really went 94/95.

Went on a shorter trip, giving it a good thrashing, temp went up to just over 95.  It then seeped coolant from cap.

 :-/

That just aboput confirms it then , if its fine cruising and only overheats when boosting hard hence producing lots more heat, it has to be a silted up radiator as i first suspected!!!
IT HAS TO BE!!!!
But why is cap letting go at only 95 degrees? As far as dash gauge is concerned, its not overheating....

you keep saying *Assuming the gauge is reading correctly* till you change the cts and confirm it with the tech2 I would guess the gauge is a bit lazy mate!!!
but the fact remains when boosting hard it produces a hell of a lot more heat for the cooling system to cope with and if the rad is slightly suspect there is nowhere for the extra heat to disapait disapate dissiapate  drat cant spell that  :-[ the heat to be gotten rid of!!!
I'm picking up a new CTS tomorrow, about £15 from Motorserv, and they have one. Considered getting one from scrappy, but can't get there for a few days...

Best price on rad so far is £185 + VAT from Vx  :'(
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Omegatoy on 04 April 2007, 21:02:16
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Quick update.  On a gentle 60/70mph trip up A43 to Silverstone and back (about 15m round trip), it was flawless.  No coolant seeping from cap.  Temp never really went 94/95.

Went on a shorter trip, giving it a good thrashing, temp went up to just over 95.  It then seeped coolant from cap.

 :-/

That just aboput confirms it then , if its fine cruising and only overheats when boosting hard hence producing lots more heat, it has to be a silted up radiator as i first suspected!!!
IT HAS TO BE!!!!
But why is cap letting go at only 95 degrees? As far as dash gauge is concerned, its not overheating....

you keep saying *Assuming the gauge is reading correctly* till you change the cts and confirm it with the tech2 I would guess the gauge is a bit lazy mate!!!
but the fact remains when boosting hard it produces a hell of a lot more heat for the cooling system to cope with and if the rad is slightly suspect there is nowhere for the extra heat to disapait disapate dissiapate  drat cant spell that  :-[ the heat to be gotten rid of!!!
I'm picking up a new CTS tomorrow, about £15 from Motorserv, and they have one. Considered getting one from scrappy, but can't get there for a few days...

Best price on rad so far is £185 + VAT from Vx  :'(

HEY thats great mate, have you enquired about having your rad rebuilt?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 04 April 2007, 21:04:03
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Quick update.  On a gentle 60/70mph trip up A43 to Silverstone and back (about 15m round trip), it was flawless.  No coolant seeping from cap.  Temp never really went 94/95.

Went on a shorter trip, giving it a good thrashing, temp went up to just over 95.  It then seeped coolant from cap.

 :-/

That just aboput confirms it then , if its fine cruising and only overheats when boosting hard hence producing lots more heat, it has to be a silted up radiator as i first suspected!!!
IT HAS TO BE!!!!
But why is cap letting go at only 95 degrees? As far as dash gauge is concerned, its not overheating....

you keep saying *Assuming the gauge is reading correctly* till you change the cts and confirm it with the tech2 I would guess the gauge is a bit lazy mate!!!
but the fact remains when boosting hard it produces a hell of a lot more heat for the cooling system to cope with and if the rad is slightly suspect there is nowhere for the extra heat to disapait disapate dissiapate  drat cant spell that  :-[ the heat to be gotten rid of!!!
I'm picking up a new CTS tomorrow, about £15 from Motorserv, and they have one. Considered getting one from scrappy, but can't get there for a few days...

Best price on rad so far is £185 + VAT from Vx  :'(

HEY thats great mate, have you enquired about having your rad rebuilt?
Not yet.  How long does it take for rad to be refurbished?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Kevin Wood on 04 April 2007, 22:19:41
Another angle on this is that if coolant flow is poor due to (for example) a blocked radiator, under heavy load you may get coolant boiling in the engine itself and overpressurising the system before there is any indication on the gauge, if accurate.

This is why a pressurised system will generally boil over if you take the pressure cap off, even below boiling point on the gauge. There are local hot spots in the engine that will boil the coolant if it's not under pressure and / or being circulated quickly.

Alternatively, there's not an air lock in the system, i suppose?

Kevin
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Markjay on 16 April 2007, 20:59:23
Sorry, just got around to check the header tank cap...

It is P/N 90 467 473, and it is actually stamped '140' which I understand to be KPa.

According to EPC, there are three types of caps:

All engines Petrol and Diesel except 2.5TD - 90 467 473

U25TD & X25TD - 90 467 694

Y25TD - 9266953

It would be interesting to hear from owners of 2.5TD what P/N is their header tank cap and if it is stamped with the pressure value.








Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 16 April 2007, 21:03:03
My TD doesn't have any details other than part no....

Seen a number of Astras with 140 stamped on top.
Title: Re: 2.5TD Overheating or overpressurising?
Post by: osealy on 16 April 2007, 22:21:29
mine current one runs much hotter than previous two 95-97 & 100 while towing up an incline.
Water under pressure boils at over 100c. The water pumps in these are renowned for losing their plastic vanes.
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 17 April 2007, 17:53:04
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mine current one runs much hotter than previous two 95-97 & 100 while towing up an incline.
Water under pressure boils at over 100c. The water pumps in these are renowned for losing their plastic vanes.
Mine currently sits at 94 - 96, thats without pushing it too hard.
Title: Re: 2.5TD Overheating or overpressurising?
Post by: osealy on 17 April 2007, 22:50:03
I haven't lost any water yet though even after hitting 100c. done about 8k in it. I would say that the viscous fan (if it works) is much quieter than my previous two TD's . The first one never got over 90c . Pain in the bollix in winter.
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 17 April 2007, 22:51:52
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I haven't lost any water yet though even after hitting 100c. done about 8k in it. I would say that the viscous fan (if it works) is much quieter than my previous two TD's . The first one never got over 90c . Pain in the bollix in winter.
I seem to lose coolant out of cap when I hit 96 degrees :(
Title: Re: 2.5TD Overheating or overpressurising?
Post by: osealy on 17 April 2007, 23:12:27
I'll check the cap & how hard the hoses are tomorrow, 450ml drive.
Title: Re: 2.5TD Overheating or overpressurising?
Post by: tunnie on 17 April 2007, 23:16:00
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I haven't lost any water yet though even after hitting 100c. done about 8k in it. I would say that the viscous fan (if it works) is much quieter than my previous two TD's . The first one never got over 90c . Pain in the bollix in winter.
I seem to lose coolant out of cap when I hit 96 degrees :(

Is that with the 'bodge' V6 coolant tank?

Maybe thats the weak link now, as the pressure builds to keep the engine cold. The cap and tank can't hold it!

If there was a blockage it should have been cleared by now, plus it should affect it even when cooler.

You put any bleach in the coolant yet, and given it a damn good thrashing?
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Markjay on 18 April 2007, 00:06:31
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I haven't lost any water yet though even after hitting 100c. done about 8k in it. I would say that the viscous fan (if it works) is much quieter than my previous two TD's . The first one never got over 90c . Pain in the bollix in winter.
I seem to lose coolant out of cap when I hit 96 degrees :(


What's the Vx P/N of the cap you are currently using?


Title: Re: 2.5TD Overheating or overpressurising?
Post by: Pitchfork on 18 April 2007, 19:55:19
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I haven't lost any water yet though even after hitting 100c. done about 8k in it. I would say that the viscous fan (if it works) is much quieter than my previous two TD's . The first one never got over 90c . Pain in the bollix in winter.
I seem to lose coolant out of cap when I hit 96 degrees :(

Is that with the 'bodge' V6 coolant tank?

Maybe thats the weak link now, as the pressure builds to keep the engine cold. The cap and tank can't hold it!

If there was a blockage it should have been cleared by now, plus it should affect it even when cooler.

You put any bleach in the coolant yet, and given it a damn good thrashing?

BLEACH???
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Paul M on 18 April 2007, 21:10:28
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I haven't lost any water yet though even after hitting 100c. done about 8k in it. I would say that the viscous fan (if it works) is much quieter than my previous two TD's . The first one never got over 90c . Pain in the bollix in winter.
I seem to lose coolant out of cap when I hit 96 degrees :(

Is that with the 'bodge' V6 coolant tank?

Maybe thats the weak link now, as the pressure builds to keep the engine cold. The cap and tank can't hold it!

If there was a blockage it should have been cleared by now, plus it should affect it even when cooler.

You put any bleach in the coolant yet, and given it a damn good thrashing?

BLEACH???

(http://ec1.images-amazon.com/images/P/B0000035E7.01._SCLZZZZZZZ_AA240_.jpg)
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 18 April 2007, 22:11:04
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I haven't lost any water yet though even after hitting 100c. done about 8k in it. I would say that the viscous fan (if it works) is much quieter than my previous two TD's . The first one never got over 90c . Pain in the bollix in winter.
I seem to lose coolant out of cap when I hit 96 degrees :(

Is that with the 'bodge' V6 coolant tank?

Maybe thats the weak link now, as the pressure builds to keep the engine cold. The cap and tank can't hold it!

If there was a blockage it should have been cleared by now, plus it should affect it even when cooler.

You put any bleach in the coolant yet, and given it a damn good thrashing?
LOL, I won't be putting bleach in the cooling system...   ...I don't mind running it through an old knackered rad though ;)
Title: Re: 2.5TD Overheating or overpressurising?
Post by: osealy on 18 April 2007, 23:37:19
sorry 420 mls later, never went over 95 stayed mostly at 92, I suggest if yours gets too hot maybe a lot of the vanes have fallen/broken off, & the coolant isn't circulating.
Mine got up to 100c towing 19ft skiboat with 5.7 chev 200mls.
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 19 April 2007, 08:14:20
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sorry 420 mls later, never went over 95 stayed mostly at 92, I suggest if yours gets too hot maybe a lot of the vanes have fallen/broken off, & the coolant isn't circulating.
Mine got up to 100c towing 19ft skiboat with 5.7 chev 200mls.
New water pump.  Old one was in tact as well...

94 seems to be lowest it will go. Ever so easy to push it to 96, don't like to see it go higher, so tend to ease off then...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Pitchfork on 19 April 2007, 19:44:03
Is the fan on the Intercooler working?
Mine had seized (and blown the 20A fuse in the aux Fuse-box)
As a result when under strain, the engine had to work harder (more hot air needed than cooler) resulting in the temperature rising
As soon as the engine was allowed to work less hard the temp dropped back
Replacement Fan is £100 ish from VX, & rarely seen (if ever) in scrap yards because the Intercooler is hidden behind o/s wheel arch & goes with the remains of th ecar into the crusher
They seize because they are exposed to the elements at the end of the duct on the bumper
This could be your problem also
IW
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 19 April 2007, 19:46:50
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Is the fan on the Intercooler working?
Mine had seized (and blown the 20A fuse in the aux Fuse-box)
As a result when under strain, the engine had to work harder (more hot air needed than cooler) resulting in the temperature rising
As soon as the engine was allowed to work less hard the temp dropped back
Replacement Fan is £100 ish from VX, & rarely seen (if ever) in scrap yards because the Intercooler is hidden behind o/s wheel arch & goes with the remains of th ecar into the crusher
They seize because they are exposed to the elements at the end of the duct on the bumper
This could be your problem also
IW
I think they seize because they are exposed to heavy water (spray etc) through the cooler duct, and the fact that the fan is rarely on.  The way it is set up is that the intercooler fan only comes on with the slow speed rad fans.

I unseized mine and replaced the fuse about 3 weeks ago...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Omegatoy on 19 April 2007, 19:46:56
apparently the engine is safe up to 110 degrees!!!!! :o which is why the full fan power isnt switched on till 105 degrees!!! the new Omega estate goes up to top of the temp gauge and just as i get  really worried and am looking for steam coming outr of the bonnet the fans cut in on full power including the intercooler fan, and it cools down very quickly!! dont like to see it get that high but apparently its designed that way, BUT it doesent chuck water out!! even when the gauge is nudging the red!! maybe it is just the coolant bottle and cap on yours>>
Omegatoy
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 19 April 2007, 19:49:52
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apparently the engine is safe up to 110 degrees!!!!! :o which is why the full fan power isnt switched on till 105 degrees!!! the new Omega estate goes up to top of the temp gauge and just as i get  really worried and am looking for steam coming outr of the bonnet the fans cut in on full power including the intercooler fan, and it cools down very quickly!! dont like to see it get that high but apparently its designed that way, BUT it doesent chuck water out!! even when the gauge is nudging the red!! maybe it is just the coolant bottle and cap on yours>>
Omegatoy
Tried yet another coolant cap from scrappy, off an astra petrol. This one holds the pressure much, much better.  However, still seeping a bit from cap when hot (96 ish on the gauge). Unless gauge is wrong of course, but won't know until the CTS is fixed.
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Kevin Wood on 19 April 2007, 19:56:33
I don't suppose the cap is not sealing properly on the top of the expansion tank, is it? Maybe the top of the thread is a bit rough and allowing it to weep. Loss of pressure then causes it to boil?

Kevin
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 19 April 2007, 20:03:38
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I don't suppose the cap is not sealing properly on the top of the expansion tank, is it? Maybe the top of the thread is a bit rough and allowing it to weep. Loss of pressure then causes it to boil?

Kevin
This cap really does seal - If I remove cap in morning to top up, I get a hiss as I undo, despite it being used since evening before...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Pitchfork on 19 April 2007, 20:10:37
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Is the fan on the Intercooler working?
Mine had seized (and blown the 20A fuse in the aux Fuse-box)
As a result when under strain, the engine had to work harder (more hot air needed than cooler) resulting in the temperature rising
As soon as the engine was allowed to work less hard the temp dropped back
Replacement Fan is £100 ish from VX, & rarely seen (if ever) in scrap yards because the Intercooler is hidden behind o/s wheel arch & goes with the remains of th ecar into the crusher
They seize because they are exposed to the elements at the end of the duct on the bumper
This could be your problem also
IW
I think they seize because they are exposed to heavy water (spray etc) through the cooler duct, and the fact that the fan is rarely on.  The way it is set up is that the intercooler fan only comes on with the slow speed rad fans.

I unseized mine and replaced the fuse about 3 weeks ago...

That's interesting because both of my electic fans (the ones in front of the radiator) were working despite the intercooler being seized & the fuse blown!
Are you sure that they are on the same circuit?
IW
Title: Re: 2.5TD Overheating or overpressurising?
Post by: TheBoy on 19 April 2007, 20:18:23
Quote
Quote
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Is the fan on the Intercooler working?
Mine had seized (and blown the 20A fuse in the aux Fuse-box)
As a result when under strain, the engine had to work harder (more hot air needed than cooler) resulting in the temperature rising
As soon as the engine was allowed to work less hard the temp dropped back
Replacement Fan is £100 ish from VX, & rarely seen (if ever) in scrap yards because the Intercooler is hidden behind o/s wheel arch & goes with the remains of th ecar into the crusher
They seize because they are exposed to the elements at the end of the duct on the bumper
This could be your problem also
IW
I think they seize because they are exposed to heavy water (spray etc) through the cooler duct, and the fact that the fan is rarely on.  The way it is set up is that the intercooler fan only comes on with the slow speed rad fans.

I unseized mine and replaced the fuse about 3 weeks ago...

That's interesting because both of my electic fans (the ones in front of the radiator) were working despite the intercooler being seized & the fuse blown!
Are you sure that they are on the same circuit?
IW
Not on same circuit, but powered by the same DPST relay.  The intercooler fan is seperately fused.  Try turning intercooler fan by hand to free up, then connect it to a 12v battery for an hour to really free it up...
Title: Re: 2.5TD Overheating or overpressurising?
Post by: Pitchfork on 20 April 2007, 20:04:17
It was so seized that it took a hammer & copious amounts of WD40 to get it turning once it was off the car
Even now once the WD40 has evaporated, it's extremely stiff & would probably blow the fuse again, hence it was replaced with a new one At just over £100!
I fear that in reality there is little choice in the matter
IW
Title: Re: 2.5TD Overheating or overpressurising?
Post by: wombatcurry on 20 April 2007, 20:18:30
My "new" 2000 2.5TD cap is marked as 90 467 964.
It's interesting that the new car runs at an indicated 80C climbing occasionally to 85C if I give it some welly. The old car (97 2.5TD) ALWAYS runs between 92 and 95.
I'll check the cap on the old car when I get home on Tuesday.