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[feeutfo]

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?

[Marks DTM Calib]

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?

[3.2omegaestate]

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

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.

[tunnie]

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

[Marks DTM Calib]

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

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

[feeutfo]

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.

[Marks DTM Calib]

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.

[3.2omegaestate]

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......

[tigers_gonads]

get a sniff test done on your water bottle 

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

[/highlight]


realy 

noted 

[nemo]

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