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[fcc-pt]

So, today I was able to remove all the pulleys, timing belt cover, head cover and plugs! Based on what I have seen I wouldn't say that head gasket has failed me but I'm in doubt and before I go ahead I need opinions. It took me a paper roll to clean the oily soaked plugs pots. Plugs have 15K Km no more...
Also not detected cloged intake plenum... tomorrow I will remove the ventilation crankcase.

Click on image for better quality please.



FALSE - Mayo like substance on the dip stick
TRUE  - Mayo on oil filler cap
TRUE  - Oily deposits in the expansion tank
FALSE - Water signs on spark plugs
FALSE - Vapour coming from the exhaust
TRUE  - Water hose builds pressure
FALSE - Sign of water in the oil
TRUE  - Spark plugs pot were dripping with oil
TRUE  - Water missing
TRUE  - Bad Oil cooler
TRUE  - Leak at the back of the heads
TRUE  - Engine started to misfire for about +/- 2 seconds
FALSE - Temp gauge shot into red
FALSE - Emissions warning light

[Nick W]

As removing the heads is quite a long job, Some fairly involved diagnosis is required:


Water loss - it's going somewhere. Radiator, heater core, plumbing fault, gasket failure, oil cooler. Jetwash the engine bay, add some dye to the coolant, drive the car and investigate


Compression test - can show certain gasket failures


Leakdown test - a lot more useful, as the pressure can be heard leaking past valves, rings or the head gasket.


Pressurising the cooling system - this is good with an inspection camera into the bore, as it will show coolant leaking into the combustion chamber. That was the fault with mine, both head gaskets were rotten at their end cylinders and leaking into the engine especially once the cooling system was pressurised and the engine not running.

[Doctor Gollum]

The 2.5/3.0 head gaskets tend to leak externally. Usually at the rear of the 246 head.

Sounds like you do have:

1. Failed oil cooler. Later ones are stainless and last better, although regular coolant changes are essential preventative maintenance.

2. Failed head gasket. Replace both.

3. You are either doing a lot of short journeys and/or using crap oil. Both will guarantee mayo on the oil cap/filler neck. Castrol is particularly bad for this, GM genuine rarely produces any.

Either way, you've a couple of days work ahead of you. 

[fcc-pt]

The 2.5/3.0 head gaskets tend to leak externally. Usually at the rear of the 246 head.

Sounds like you do have:

1. Failed oil cooler. Later ones are stainless and last better, although regular coolant changes are essential preventative maintenance.

2. Failed head gasket. Replace both.

3. You are either doing a lot of short journeys and/or using crap oil. Both will guarantee mayo on the oil cap/filler neck. Castrol is particularly bad for this, GM genuine rarely produces any.

Either way, you've a couple of days work ahead of you. 

I do have a failed oil cooler, no doubts! Removed it, rusted all over completely ruined.
The new one is not stainless steel, unfortunatly I was unable to find one.
I'm doing a lot of short runs and not that good oil... I could agree with that yes.

I could spot a coolant leak at the back of the engine near the rubber hose perhaps due to abnormal pressure?!?

A new link to plugs:



 

[Doctor Gollum]

The 2.5/3.0 head gaskets tend to leak externally. Usually at the rear of the 246 head.

Sounds like you do have:

1. Failed oil cooler. Later ones are stainless and last better, although regular coolant changes are essential preventative maintenance.

2. Failed head gasket. Replace both.

3. You are either doing a lot of short journeys and/or using crap oil. Both will guarantee mayo on the oil cap/filler neck. Castrol is particularly bad for this, GM genuine rarely produces any.

Either way, you've a couple of days work ahead of you. 

I do have a failed oil cooler, no doubts! Removed it, rusted all over completely ruined.
The new one is not stainless steel, unfortunatly I was unable to find one.
I'm doing a lot of short runs and not that good oil... I could agree with that yes.

I could spot a coolant leak at the back of the engine near the rubber hose perhaps due to abnormal pressure?!?

A new link to plugs:



 

The gasket fails and coolant weeps out, it isn't a particularly high pressure leak as it an external leak rather than an internal one and doesn't usually get pressurised by the cylinders.

MarkDTM did a detailed explanation of the difference between oil cooler and head gasket failure on the V6 Omega, in particular why you get oil in the coolant and not coolant in the oil. 

[fcc-pt]

This is for sure a gasket failure right?
What we can infer from the plugs carbon build around the metal case and the burning core state?

[Doctor Gollum]

They don't look too horrible... The tan cores look about normal, but again short journeys means a lot of rich running, especially if the cooling system isn't working correctly, so you'll get some build up from the cumulative over fuelling.

Put another way, they would benefit from a clean/decent fuel and a work out. But they aren't fouled or covered in oil

[Nick W]

This is for sure a gasket failure right?
What we can infer from the plugs carbon build around the metal case and the burning core state?

The only thing I would infer from those plugs is that they were new when fitted recently.


This isn't a cast iron OHV 4 cylinder engine where the gasket set costs £15 and changing it is 60 minutes work running to running.





Slow down, and work your way through all of the diagnostic procedures and think about the documented results rather than just guessing.

[fcc-pt]

This is for sure a gasket failure right?
What we can infer from the plugs carbon build around the metal case and the burning core state?

The only thing I would infer from those plugs is that they were new when fitted recently.

This isn't a cast iron OHV 4 cylinder engine where the gasket set costs £15 and changing it is 60 minutes work running to running.

Slow down, and work your way through all of the diagnostic procedures and think about the documented results rather than just guessing.

Right, the only thing I know is that the water pressure goes up the roof leading to leak at the back of the engine. I guess that could be due to oil temperature since the oil coller is broken but not necessarly.

So I'm goign with a leak test and lets see the results.

[fcc-pt]

They don't look too horrible... The tan cores look about normal, but again short journeys means a lot of rich running, especially if the cooling system isn't working correctly, so you'll get some build up from the cumulative over fuelling.

Put another way, they would benefit from a clean/decent fuel and a work out. But they aren't fouled or covered in oil

I was a bit worried about oil consumption but than I realized that most of the added oil was accumulated on the plug pots and dripping from the heads to the exhaust manifold.

[Doctor Gollum]

They don't look too horrible... The tan cores look about normal, but again short journeys means a lot of rich running, especially if the cooling system isn't working correctly, so you'll get some build up from the cumulative over fuelling.

Put another way, they would benefit from a clean/decent fuel and a work out. But they aren't fouled or covered in oil

I was a bit worried about oil consumption but than I realized that most of the added oil was accumulated on the plug pots and dripping from the heads to the exhaust manifold.

That'll do it

Breathers and Camcover gaskets will soon solve that

Re plugs...

I used to change mine every 20k (from memory) and then only with genuine. But then I was only paying a couple of quid a plug...

[Enceladus]

I do have a failed oil cooler, no doubts! Removed it, rusted all over completely ruined.
The new one is not stainless steel, unfortunatly I was unable to find one.
I'm doing a lot of short runs and not that good oil... I could agree with that yes.

I could spot a coolant leak at the back of the engine near the rubber hose perhaps due to abnormal pressure?!?

A new link to plugs:

The coolant leak at the back of the engine might be from the HBV (Heater Bypass Valve). This is a common failure. The valve is behind the offside cylinder head.
It could also be the pigtail hose that connects the spigot of the coolant bridge to the inlet of the HBV. The hose splits underneath the hose clip at the bridge end.

If you have removed the oil cooler it should be a lot easier to check the condition of the HBV and it's inlet hose.

[fcc-pt]

The hose that connects the valve to the back of the head has been changed about 3 years ago. As for the valve it self has been changed 7 years ago. Both where original GM.
As far as I can tell the water drops from the back of the head exactly where the ruber hose connects!
Has I said earlier, I think that is due to ecessive pressure.

The larger hose that links the thermostat to the radiator gets a bit hard I think it's not normal...
Today I've checked for air leaks, only three cylinders but till now can only ear a small leak about 10% or even less is escaping throught out the dipstick.
I'm not sure but I think it's pretty normal.