Hi folks.
Looking for a bit of advice.  This all happened when it was really cold and I fear more than one problem.

Omega 2.5V6 1998~140k.
Has been using a bit of water for a while- nees about a litre a month.  In December I was in down out and cheked the water and there was oil in the expansion tank, list a little on the cap and floating - smelled like warm fresh engine oil.  Topped up the water and drove home~350miles ran a bit hot 97-100+ ut behaved fine.

Just before Christmas drove up to Moray and back in the very cold -15C and no problems.  Since then ...

If I start an run the car temp rises quickly to top, warning light on!  Seems to cool quickly when turned off but quickly rises again if driven.

Running the car without driving see temperature rise to 97-100 but no overheat.  Running the case with the top off the header tank and it goes through a slow cycle of ejecting about 1.5litres then dropping down again - usually with some air.  Radiator did eventually get hot and taking a pipe off the header tank was able to confirm thermostat opening and water pumping. 

From what I have read on here I guess that either there is a head gasket away or a blocked oil cooler.  I am planning to do a compression test at the weekend but have a couple of questions.

The Haynes manual says that there should be no more than 15psi difference between any two clyinders, that's about 5%.  Is it really that critical?

How do I test for a blockage in the oil cooler?

Any other advice or comments would be greatfully received.

Thanks in advance!

John

I would say it is one of the head gaskets!

Unfortunately the symptoms do sound like a head gasket failed... Could still be oil cooler with sludge stopping the coolant flow properly, but I doubt it :( :(

Thanks guys - rather what I thought.

Any thoughts of the limit of 15psi between any two cylinders?

John

Interesting thoughts by some on here....I personaly am very interested to hear the explanation on how oil gets into the coolant with a failed head gasket.

Discuss.  :y (note, treat it as a learning exercise  ;))

Leaking oil cooler mate  ;)

Marks DTM Calib wrote on 15. Jan 2010 at 07:30:

Interesting thoughts by some on here....I personaly am very interested to hear the explanation on how oil gets into the coolant with a failed head gasket. Discuss.  :y (note, treat it as a learning exercise  ;))

Guessing its not possible, hence you fishing for answers. BUT... it could fail around one of the fire rings? Allowing oil to get into the coolant jacket bit.... BUT not sure how the 2 pressures would react  :-/

The coolant system is under pressure, but so is the cylinder, guessing there is more in there so that would win, pushing some oil into the jacket  :-/

Cylinder pressures are huge, coolant system pressure is just large.

The floor in your thoughts is...where does the oil in the cylinder come from?

failed oil cooler in my mind, and thats before seeing Marks post.

Basic rule, and is quoted somewhere on here i believe,
oil in water, oil cooler failed.
water in oil, head gaskit failed.

Take the water tank cap off when hot and it will boil over, the pressureised system prevents boiling.

I wonder if the the boiling and the fact its a 98 has had an influence on replies maybe?

Another suggestion into the mix.......and I'm sorry that it is not going to be good news. :'( :'( :( :(

What about a cracked block or head between the oilways and coolant channels running inside the block head which has occurred as a result of a blown headgasket causing the excessive temperature you describe and then the temperature causing the block or head to crack  :'( :'(

The explanation of oil in coolant

When the engine starts the oil system reaches pressure almost immediately and will overcome the  reduced pressure of the cooling system at cold. This will allow oil into the coolant as the two systems try to equalise their pressures.

I think whatever the theory, you almost certainly have a serious engine issue headgasket failure, cracked head / block and or failed oil cooler. The symptons you describe regards temperature (not oil in coolant) are exactly what I had a work with an Astra, and the diagnosis was ..........blown headgasket.

Check the compression of each cylinder but also get a sniff test done on the coolant to determine if hydrocarbons (combustion gases) are present in it. If they are then it is a very good indicator that the head gasket has failed. The test is easy to carry out with a dramatic almost instant colour change to indicate failed headgasket. See hear for details http://www.justoffbase.co.uk/Combustion-Leak-Detector-Sealey-VS0061

If you do find it is the head gasket, get the heads skimmed or replacement true (level) heads before refitting to remove any distortion, as you dont want to do this job again in the near future. It goes without saying as well do both head gaskets even if only one has failed, and whilst the engine is stripped down this far consider a cam belt kit and new water pump, to save you time in the long run.

Sorry it is not positive news but good luck.

HTH

Again, still sadly a floored thought.

There is but 1 very small high pressure oil channel in the head, this is some distance from any coolant channels....when heads crack it is more often than not between adjacent combustion bowls and by this stage it would be running like a dog. Thankfuly, craked heads on V6's are unheard of.

It cant come from the oil return channels (of which there are more and they are both large and close to the coolant channels) as these run at a vaccum thanks to the breather system.

Good thought though

get a sniff test done on your water bottle  :y

if its just oil then i'd go for the oil cooler

if there is hydrocarbons in there then there is a good chance it's a head gasket  :(


edit ............ is there any mayo on the dipstick ?

Received and understood :y :y

Perhaps then as the OP suggests he has more than one problem. Blown oil cooler hence oil in water (well documented) and blown headgasket hence the high temp, etc but at this stage not sufficiently advanced to get the water into the oil (the dipstick test) but would be proven by snif and compression test, or snif test alone but not compression test alone.

Reasoning: poor compresion can be caused by other things as well e.g. piston rings etc, the snif test is for testing h.g. failure, cracked block alone and when used with compression test hopefully will identify which bank and cylinders the breach has occurred at.

Still change both headgaskets though.
One of the most common reasons for h.g. failure is poor maintenance i.e. not replacing antifreeze on a regular basis. Anti freeze has corrosion inhibitors in it that deteriorate after time hence the change interval (2 years ? am I correct please advise) to maintain the corrosion and antifreeze properties.

HTH


Must type faster than tigers gonads....... ;D ;D ;D

The answer is ....do nothing and assume nothing....until the diag is complete.

talk of headgaskets and even oil cooler at this stage is premature...

tigers_gonads wrote on 15. Jan 2010 at 09:45:

get a sniff test done on your water bottle  :y if its just oil then i'd go for the oil cooler if there is hydrocarbons in there then there is a good chance it's a head gasket  :( edit ............ is there any mayo on the dipstick ?

Sady, not nearly as conculsive as it used to be...this test can give some very eronius results

would the oil in water account for the high temp? both from high temp of the oil itself and poor water circulation caused by emullsification?

chrisgixer wrote on 15. Jan 2010 at 10:13:

would the oil in water account for the high temp? both from high temp of the oil itself and poor water circulation caused by emullsification?

Poor water circulation is a possible....the tests done with the header tank cap off are a red herring as the lack of system pressure lowers the boiling point of the coolant and hence the flash boiling seen.

So, as we are not jumping to conclusions in this case (as its an unusual one) then....what questions should we be asking?

Quote:

Sady, not nearly as conculsive as it used to be...this test can give some very eronius results

:o :o

Mark, I don't doubt what you're saying however please can you elaborate, since I am interested as to why (not that in your experience they just have) erroneous results occur since all the workshops that I have been in appear to use this as a good indicator of a failed headgasket cracked head/block. 8-) 8-)

I would also agree with you that it is a pointless exercise to change things on a whim and a prayer and that they only correct method to repair a car is to diagnose fully and correctly, looking at all the symptons.  :) :) :)

A thing that is very hard to do when it is being done remotley with what appear to be multiple symtons without the vehicle infront of you however my posts are suggestions as to what maybe wrong and how to diagnose the faults. ;) ;) ;)

Marks DTM Calib wrote on 15. Jan 2010 at 08:47:

Cylinder pressures are huge, coolant system pressure is just large. The floor in your thoughts is...where does the oil in the cylinder come from?

Would have replied sooner, but its patch Friday here  >:(

Like a muppet i was thinking the cylinders are full of oil sloshing around to lube to cylinder heads, but that can't be... as i now remember when taking the head off and seeing the pots.

Short answer is, i guess no oil can get into the coolant from HG, only the oil cooler.

Water can get into the pots, and cause lumpy starts when cold, but soon burnt off, and once pressure is up, it smoothes out

3.2omegaestate wrote on 15. Jan 2010 at 10:29:

Quote: Sady, not nearly as conculsive as it used to be...this test can give some very eronius results :o :o Mark, I don't doubt what you're saying however please can you elaborate, since I am interested as to why (not that in your experience they just have) erroneous results occur since all the workshops that I have been in appear to use this as a good indicator of a failed headgasket cracked head/block. 8-) 8-) I would also agree with you that it is a pointless exercise to change things on a whim and a prayer and that they only correct method to repair a car is to diagnose fully and correctly, looking at all the symptons.  :) :) :) A thing that is very hard to do when it is being done remotley with what appear to be multiple symtons without the vehicle infront of you however my posts are suggestions as to what maybe wrong and how to diagnose the faults. ;) ;) ;)

Simples....the method used tries to detect small quantities of hydrocarbons.....and many modern antifreeze additives also give off similar substances....plus if the engine is a V6 and has ever had any form of oil cooler failure or is suffering one then the oil also gives off traces of hydrocarbons.

There is NO single conclusive test for head gasket failure.....you can only infer it once you have gathered more evidence

Marks DTM Calib wrote on 15. Jan 2010 at 10:25:

chrisgixer wrote on 15. Jan 2010 at 10:13: would the oil in water account for the high temp? both from high temp of the oil itself and poor water circulation caused by emullsification? Poor water circulation is a possible....the tests done with the header tank cap off are a red herring as the lack of system pressure lowers the boiling point of the coolant and hence the flash boiling seen. So, as we are not jumping to conclusions in this case (as its an unusual one) then....what questions should we be asking?

only outstaning question is where is the water leaking from? are you thinking external hg failure?


oil cooler seems a defo to me unless residue is left over from previuos oil cooler repair? as you say, where else would oil in header tank come from?

ps oil in header tank would fail a hydrocarbon test.

Thoughts

1) How long has the car been owned and what is the history of repairs (if known).

2) Is the amount of oil in the header tank just a trace or loads?

3) And visable signs of coolant loss?

No1 is a key one really....2 pretty crucial.....3 less so.

I have a suspicion that air is getting into the system....and we know there was a leak and any point where water can get out can let air in once the unit starts to call.

Quote:

Simples....the method used tries to detect small quantities of hydrocarbons.....and many modern antifreeze additives also give off similar substances....plus if the engine is a V6 and has ever had any form of oil cooler failure or is suffering one then the oil also gives off traces of hydrocarbons. There is NO single conclusive test for head gasket failure.....you can only infer it once you have gathered more evidence

Yep, see your point and how the 'snif' test could give those erroneous results and quite agree that h.g. failure diagnosis is the culmination of a number of tests and exploratory work.  ;) ;)

Thanks for explanation, I'm off to write a 2000 word essay now......

Marks DTM Calib wrote on 15. Jan 2010 at 09:57:

tigers_gonads wrote on 15. Jan 2010 at 09:45: get a sniff test done on your water bottle  :y if its just oil then i'd go for the oil cooler if there is hydrocarbons in there then there is a good chance it's a head gasket  :( edit ............ is there any mayo on the dipstick ? Sady, not nearly as conculsive as it used to be...this test can give some very eronius results

realy  :o

noted  :y

sounds very much like mine. Results were new oil cooler which was leaking both oil inside and coolant outside followed by a new radiator which was blocked by sludge and would not flush clean hope this helps Adrian :)