Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: brian36 on 29 October 2013, 13:06:43
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hi, need help to fix my 2.6 mv6 it's been throwing up faults and today managed to find out why.
short story,
misfire no 5 knock sensor fault, replaced coil packs both sides and spark plugs also changed crankshaft sensor.
so today mechanic checked compression in no 5 found to be about 75 and low, so then he took out spark plug and sent camera down to have a look and after saying oh a few times the stating won't be cheap he told me that I had a burnt valve in no 5. he told me engine would need to be stripped down etc. now after picking myself up from the floor I am now in a awkward position of what to do?. I do not have a lot of finances and need a car I am open to good suggestions and hope there are members out there that fancy doing this job for me. I live in fife but in next 2-4 weeks will be moving hopefully to Milton Keynes,i don't mind leaving car for someone to fix in own time, will just use bus. is there any chaps out there that can help? :'(
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Changing what you have, does it still misfire :-\
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Has the knock sensor been over tightened.
also never known a omega to burn a valve, bend them yes.
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Never heard of a burnt valve in a v6 either. Anythings possible though. I would get hold of a compression tester and check it for myself.
If hes right,then Darth Loo-knee is the man for the job imo. Hes in Stoke. :y
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I'm not far from MK (half hour or so) if you can get the thing down here?
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Serek only 45mins from mk in Huntingdon,give him a pm. :y
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thanks for replies,
regarding misfire yip still there after changing all things.
as said today had car down garage he tested compression said low no 5.
any ideas cost involved in doing this? I guess head gasket kit,do belts same time and valve of course thanks
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The investigation will cost you nothing.
Parts wise, new gaskets recommended for hg, cam cover, exh manifold, coolant bridge, etc
So not nearly as expensive as you'd think
You could do both banks, but on a v6 the multi layer head gaskets never fail
The most important thing in this situation is finding out why the valve burnt (eg why that pot was running lean to cause it).
Doing the work is very basic, just a little time consuming to clean things up etc.
If you don't find our WHY it failed though, and remedy that, it will probably fail again...
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Assuming it is a pitted Valve and not bent from its previous life, could be a failing injector causing it to miss fire and run lean or hot. :-\
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Assuming it is a pitted Valve and not bent from its previous life, could be a failing injector causing it to miss fire and run lean or hot. :-\
Yep. I'd suggest when it's running on all 6 again, live data is closely looked at for some time after...
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My experience of burnt valves is that they actualy result in close to zero compression, and the compression test hints at a bit more than this. Never seen one on a V6, what year is it?, any sign of stem seal issues?
Also, having used endoscopes in the past, not sure how he got a view of the valve seat when poked in through the spark plug hole (small entry hole and having to view something behind the entry hole in a very small and confined space).
As already said, get it to Nottingham and leave it on the drive and I will have a fiddle.
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ok will be in touch thanks to all :y
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My experience of burnt valves is that they actualy result in close to zero compression, and the compression test hints at a bit more than this. Never seen one on a V6, what year is it?, any sign of stem seal issues?
Also, having used endoscopes in the past, not sure how he got a view of the valve seat when poked in through the spark plug hole (small entry hole and having to view something behind the entry hole in a very small and confined space).
As already said, get it to Nottingham and leave it on the drive and I will have a fiddle.
Brian - that's an offer you really shouldn't refuse. ;)
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My experience of burnt valves is that they actualy result in close to zero compression, and the compression test hints at a bit more than this. Never seen one on a V6, what year is it?, any sign of stem seal issues?
Also, having used endoscopes in the past, not sure how he got a view of the valve seat when poked in through the spark plug hole (small entry hole and having to view something behind the entry hole in a very small and confined space).
As already said, get it to Nottingham and leave it on the drive and I will have a fiddle.
Brian - that's an offer you really shouldn't refuse. ;)
Agreed :y
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will do ,be in touch thanks to all :y
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things only get worse my car in trouble wife just comes in and says a guy just ran into her, bumper gone front wing gone headlight and fog light gone,aah the joys of motoring,guess I won't get to borrow wifes :'(
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If valve is bad, compression is usually 0.
Wet compression test should be done and I would flush engine by ATF to clean possibly stuck rings.
Mechanic cannot see anything if compression is 75. If valve is bent pretty bad, he would see it.
Usually all good exhaust valves have pitting.
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My experience of burnt valves is that they actualy result in close to zero compression, and the compression test hints at a bit more than this. Never seen one on a V6, what year is it?, any sign of stem seal issues?
Also, having used endoscopes in the past, not sure how he got a view of the valve seat when poked in through the spark plug hole (small entry hole and having to view something behind the entry hole in a very small and confined space).
As already said, get it to Nottingham and leave it on the drive and I will have a fiddle.
Brian - that's an offer you really shouldn't refuse. ;)
Agreed :y
plus infinity, Mark really is the guru and master on these motors :y
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My experience of burnt valves is that they actualy result in close to zero compression, and the compression test hints at a bit more than this. Never seen one on a V6, what year is it?, any sign of stem seal issues?
Also, having used endoscopes in the past, not sure how he got a view of the valve seat when poked in through the spark plug hole (small entry hole and having to view something behind the entry hole in a very small and confined space).
As already said, get it to Nottingham and leave it on the drive and I will have a fiddle.
Brian - that's an offer you really shouldn't refuse. ;)
Agreed :y
plus infinity, Mark really is the guru and master on these motors :y
+1 :y
Camera down in the cylinder. I've never even heard of that.
Anyways, the cost to rebuild is pretty low in terms of parts and I saw it as a good opportunity to renew lots of gaskets and seals. and now shes running sweet!
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thanks to all,mark will have a dabble when we can arrange thanks to all :y
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My experience of burnt valves is that they actualy result in close to zero compression, and the compression test hints at a bit more than this. Never seen one on a V6, what year is it?, any sign of stem seal issues?
Also, having used endoscopes in the past, not sure how he got a view of the valve seat when poked in through the spark plug hole (small entry hole and having to view something behind the entry hole in a very small and confined space).
As already said, get it to Nottingham and leave it on the drive and I will have a fiddle.
Brian - that's an offer you really shouldn't refuse. ;)
Agreed :y
plus infinity, Mark really is the guru and master on these motors :y
+1 :y
Camera down in the cylinder. I've never even heard of that.
Anyways, the cost to rebuild is pretty low in terms of parts and I saw it as a good opportunity to renew lots of gaskets and seals. and now shes running sweet!
Its a bore scope Webby,very usefull bit of kit for some applicazione but as usefull as tits on a boar for checking valve damage through the plughole :D ;)
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So this car is now on my drive and the drivers head an hour or so away from removal.
This has been a challenge, the previous cambelt change must have been done by a gorilla as the fixings are rounded and hugely overtightened plus some threads buggered.
On top of this the cam timing is a tooth out.
And to just do and things off, the heads have been off before and some brackets are missing, some cam caps fitted the wrong way round and the can seals not fitted correctly so were leaking.
Head finally off tomorrow hopefully!
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Nothing like a challenge eh :o Amazing how some of them even run :-\
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Enthralling thread, gentlemen. I take off my hat to all you learned engineers with your experience and wisdom. I haven't taken a head off a car since my Ford Escort days, that was a simple push rod job. Nowadays modern materials and rotating valves make it rarely necessary.
Good luck to all, and keep the story coming
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will be good to see a correct diagnosis! if its a tooth out.... bent valve perhaps?
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I do not think one tooth out would cause damage. Two teeth out cause clattering, engine still runs, but no lasting damage. I imagine three teeth out stop the engine.
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I do not think one tooth out would cause damage. Two teeth out cause clattering, engine still runs, but no lasting damage. I imagine three teeth out stop the engine.
Ralf (my old PFL 2.5 v6 mig) was 5 teeth out. and still ran ;)
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I do not think one tooth out would cause damage. Two teeth out cause clattering, engine still runs, but no lasting damage. I imagine three teeth out stop the engine.
Ralf (my old PFL 2.5 v6 mig) was 5 teeth out. and still ran ;)
For a while :D ;D
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Also thinking about it.... I think it's perfectly reasonable for a valve to be bent if a tooth out. thinking about how close they are together (pistons and valves).
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But a single valve on a single cylinder with a tooth out?
In reality a single tooth wont cause valve impact, and the heads still not off, some arse has used standard nuts on the front pipe to manifold connection and rounded them off, got one off but the other needs cutting.
Getting quite a list of bits needed here, thankfully I have some already
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Is the lifter sitting low on the affected cylinder? Could it even be a pumped up lifter? Well worth checking before the head comes off.
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Way ahead of you on that, and no, lifters all good and even force bled them down on that cylinder
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Way ahead of you on that, and no, lifters all good and even force bled them down on that cylinder
Didn't think you would've missed it to be honest. Interested to hear the outcome of this one. Some of the borescope kits have a tiny mirror attachment to enable the viewing of valves.
A failed knock sensor would be a bad start in this situation as it could be a contributing factor to a hot cylinder, that said in my experience they usually drop into limp at the slightest hint of KS issues.
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Motronic setup retards valve timing (by 12 degrees I seem to recall) under knock sensor fault detection
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Must end up firing ATDC in some situations at -12 degrees. No wonder they feel flat. Never had any of my vehicles in a forced limp mode, but have experienced it on a friends x25.
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Yep, they are hopelessly slow, unplug one and you will see :y
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can I just say I didn't think it would cause you so much agro but then again its a challenge and hope that you like such a challenge I appreciate all your doing to help me and await the outcome :)
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can I just say I didn't think it would cause you so much agro but then again its a challenge and hope that you like such a challenge I appreciate all your doing to help me and await the outcome :)
Did he tell you he's keeping the car after?!? :-\ ::) ;D
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But a single valve on a single cylinder with a tooth out?
In reality a single tooth wont cause valve impact, and the heads still not off, some arse has used standard nuts on the front pipe to manifold connection and rounded them off, got one off but the other needs cutting.
Getting quite a list of bits needed here, thankfully I have some already
Fair enough :)
Can't wait for strip down and conclusion
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can I just say I didn't think it would cause you so much agro but then again its a challenge and hope that you like such a challenge I appreciate all your doing to help me and await the outcome :)
Did he tell you he's keeping the car after?!? :-\ ::) ;D
to be honest I wouldn't blame him but I reckon he knows how desperate I am to get my miggy back but I am glad I have a expert on the case!! :y
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can I just say I didn't think it would cause you so much agro but then again its a challenge and hope that you like such a challenge I appreciate all your doing to help me and await the outcome :)
Did he tell you he's keeping the car after?!? :-\ ::) ;D
to be honest I wouldn't blame him but I reckon he knows how desperate I am to get my miggy back but I am glad I have a expert on the case!! :y
he is that mate ;)
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Got a pair of complete 2.6 heads in the shed if any bits needed
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Head is off....!
The culprit:
(http://i23.photobucket.com/albums/b394/Marks_DTM_Calib/Head_Burnt_Valve_zps14877134.jpg)
Removed and good valve fitted and lapped to check the seat:
(http://i23.photobucket.com/albums/b394/Marks_DTM_Calib/Head_Valves_Removed_zpscf395062.jpg)
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they look like gauges.... any idea how that's happened? debris in the cylinder?
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Once you get a point that does not seal, the gas erodes the valve and creates the gouges.
Thankfully the seats are hardened so they get away with it.
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Once you get a point that does not seal, the gas erodes the valve and creates the gouges.
Thankfully the seats are hardened so they get away with it.
got ya :) :) :)
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Original mechanic bang on with his diagnosis then. Credit where its due. Well made heads on the v6 aren't they. Very little room for improvement, there is virtually no unmasking to be had and just a tickle on the porting with a bit if texturing afterwards. Was quite dissapointed not to do more fettling on mine.
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I wonder if aforementioned gorilla dropped something down an inlet tract when the plenum was off and eventually it left the engine via that exhaust valve, damaging it in the process.
In 1968 I had a saddle mounting nut fall off its bolt and dive into the open carburretor throat of my Velocette Venom motorcycle. I took off the head and found it trapped under the exhaust valve.
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These heads have been re-worked at some point, the valves are pattern items (the replacement one in the pic is a GM sodium filled 3.0 exhaust valve). The question will be was the re-build done well and was there a mark/damage on the valve when it was installed?
I have further concerns with the head as the stems feel, at first impression, a little loose in the guides. This in reality is not such a major issue given the valve actuation setup (would be a big issue on push rod units with rockers) but, I need to check further.
With the age of the car, you would expect the usual 2.6 stem seal issues but, there also not originaly and all ok.
It is nice to see a good original diag, never ever seen a burnt valve on one of these in the 18-19 years the engine type has been produced.
And your tright Andy, not to much can be done on the heads with respect to porting/flowing (although more can be done on a 2.5/2.6 with opening the throat out to match the 3.0/3.2 inlet bridge)
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Dread to think what the pot 6 valves look like on mine after the spark plug saga :o though the bulk of the problem was electrical...
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Al, in my experience you find witness marks on the crowns and head combustion chambers but no evidence on the valves and seats.
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Reassuring :y
Given that it still works 100k later, I won't be taking the heads of to look...
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Reassuring :y
Given that it still works 100k later, I won't be taking the heads of to look...
Ahh go on ;D
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Er...
No ;D
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So, further inspection shows a very poorly refurbed set of heads where the guides are reamed to the wrong size and the valve seats cut badly, anybody got a set of late 2.5 or 2.6 heads?
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So, further inspection shows a very poorly refurbed set of heads where the guides are reamed to the wrong size and the valve seats cut badly, anybody got a set of late 2.5 or 2.6 heads?
Reply #41 Mark
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Hello James!
Somehow I haven't come across you for a very long time on here. My Mig's still going lovely since the bent valve scenario a few years back. Your assistance was invaluable during the surgery!
I know you'd return a superb motor if offered to you to sort. ;D
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So, further inspection shows a very poorly refurbed set of heads where the guides are reamed to the wrong size and the valve seats cut badly, anybody got a set of late 2.5 or 2.6 heads?
3.2 head different ? :-\
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So, further inspection shows a very poorly refurbed set of heads where the guides are reamed to the wrong size and the valve seats cut badly, anybody got a set of late 2.5 or 2.6 heads?
3.2 head different ? :-\
Sadly yes, larger combustion chamberr
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3.0l. ?
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Sadly 3.0 are the same as 3.2 :o (I have some 3.0 heads)
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Got a pair of y26 heads. Would need a skim though as engine got cooked. Free if someone wants to pick them up. Full set of valves and camshaft caps, but no lifters or shafts.
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So, thanks to the good weather, I managed to get everything re-assembled over the weekend with the final bits going on last night.
Work has included.
Full re-furb of a second hand set of heads (thanks Twiglet) including valves cleaned, polished and lapped in, new stem seals fitted, heads fully cleaned (they were filthy!) and de-greased, reassembled and leak test carried out on the combustion chambers.
Heads fitted with new gaskets and bolts.
Oil cooler plate and thermostat housing re-sealed, thermostat tested.
Thermostat link pipe replaced as the mounting bracket had been snapped off.
Exhaust manifolds cleaned up and front pipe stud threads run over with a die to clean them up then re-fitted with new metal gaskets.
1-3-5 bank engine lifting eye fitted to support transfer pipe from rear of the V (missing from engine).
Timing cover repaired (plastic weld) following previous damage
Brake servo pipe repaired due to tee for vaccum hoses being snapped off
Two connectors repaired (locking clips had been snapped off)
Crankshaft sensor cable re-routed as per the guide to lessen the effects of heat on the cable and make replacement MUCH easier.
Having finished that, battery is on charge and it should be good for a first start on Wednesday evening.
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Nice one , back breaking work at times :y
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can i just say thanks mark you have stuck with it through some crap weather and i appreciate your help i hope all goes well on start up and i can get my wee car back as i kind of missed it,legs now 3 inches shorter but as you know i have some to spare, anyway let me know what flavour you want this time and will nip! up with it etc when you feel its ready to go,and can i add my thanks to the fellow members who helped mark help me again its much appreciated. :y
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Started fine so warmed it up and then changed the oil.
Re-started and after a few minutes of the usual post head swap tappet chatter, all was quiet and happy. Plenty of smoke from various components where my grubby mits have been!
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excuse my lack of understanding is this good? does it still live
thanks :y
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excuse my lack of understanding is this good? does it still live
thanks :y
Yes, running smoothly on six cylinders, no noisy lifters just the usual smoke from the cleaning agents and oily hand prints which will soon burn off. Need to do a final pressure test on the coolant system to confirm that it is water tight (it appears to be as everything is dry and no sign of drips)
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Wow, well done. :y
I need to think about moving to Nottingham
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thanks mark glad all looking good will await you all ok :y
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Fancy doing an oil burner? ::)
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so great stuff got car back today from marks dtm calib done a great job he has and car drove great so just wanted to say a huge thanks to mark for all he has done :y :y
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Nice one :y
There isn't much Mark can't fix...
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your right although much was over my head he fixed every wee bit he could and i'm glad there are people like mark around. :)
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your right although much was over my head he fixed every wee bit he could and i'm glad there are people like mark around. :)
Hi Brian
Glad your happy and it dove well, the gunk should have burnt off on that run.
Hopefully its pulling well.
Enjoy!
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hi mark took it easy sat at 70-80 was fine thanks :y
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Nice one :y
There isn't much Mark can't fix...
:y :y
Handy with a Plasma Cutter too :D ;D