760 GLE (B280E) oil in coolant reservoir.

[A-D-H]

Hi all,

Just bought a V6 (89 B280E 141,000mls ) estate - before you ask why - because I always wanted one and yes I am aware of the reputation of these engines .

So impressed with smoothness and comfort of these (bearing in mind my other day to day car is a T5-R) I couldn’t ressist.

However I am faced with the not uncomon problem of oil in the coolant.

Is it possible to diagnose which oil is in the coolant as it just looks brown and mushy and I cant tell whether it is ATF or Engine oil.?
Why would there be no cross contamination of coolant in engine oil or coolant in the ATF, is there such a difference in pressure ?
Any other symptoms to look for ?
I would say there is no misfires and no overheating but maybe it’s a bit smokey on cold start ( or are they all like that ?)
I feel lots of people would dismiss the V6 as a bit of a duffer but there must be fans of these somewhere on the forum ?


Cheers!
Adh

[Peter Milnes]

You will probably need a new radiator as it combines coolant with automatic gearbox oil cooler. When this fails it is usually between the two portions hence the "chocolate sauce" appearance. The engine oil does not normally come into contact with coolant unless the engine has been overheated causing head(s) to warp which allows coolant to get into the cylinders and will cause the engine to suffer a hydraulic lock. Make sure that it is radiator failure by undoing one of the oil cooler nipples on the radiator (rhs near top). If coolant emerges mixed with the ATF then the radiator has gone. If no coolant appears in the oil lines then yopu will probably need two new heads and gasket and a head skim to ensure perfect mating. As the engiune is a "wet liner" type it is best to get someone experienced in this type to do the work.

The B280 is very much more reliable than the earlier B28 and B27 engines. In the B280 the lack of camshaft lubrication has been solved with the consequence that the B280 is the only V6 to use if utter reliability is needed.

When replacing the radiator it will be necessary to flush and refill the gearbox with fresh ATF, run it for about 250 miles then reflush and fill again with fresh ATF. This refreshing of the ATF should also be carried out every 30,000 miles. The coolant must be 50% anti-freeze mix. Check the thermostat for correct operation at same time.

It is possible to fit one of the Renault or Peugeot versions which can be fitted with turbos. Why? because the engine was produced by Peugeot/Renault/Volvo in consortium.

Re your query about coolant in engine oil or gearbox oil it does and you do get coolant in either oil. This is why you need to flush/ replace the gearbox oil if the radiator fails.

All the best, Peter.

[TheJoyOfSix]

Another way of testing what oil/coolant mix it suffers from is to check the auto trans dipstick. if that too suffers from a sludgy mix then it is definately the radiator that has failed.

I agree with Peter that this is the most likely cause of your problem. Juat be aware that the gearbox clutch material is held onto the plates with a water based glue, so the sooner you flush the transmission fluid out the better. The recommended way is to drain the sump on the gearbox and refill with fluid, this takes care of the gearbox, but the torque converter and transmission cooler/pipes will still have contaminated fluid in them. To deal with this unbolt the join in the cooler lines that is level with the radiator (fluid flows box - rad - cooler - box so this join is in the cooler back to box line). Attach a piece of hose to the line coming from the cooler, put the other end in a container and then start the engine. When approx 1.5-2 litres of fluid hasbeen pumped out switch off and and refill the box with fluid. repeat twice. re-connect the lines and refill, job done!

Regarding the smoking on a cold start, mine tends to do that for a bit as have others I've owned so I'm inclined to believe that it's just one of their foibles.Before anyone jumps in and says it's due to high mileage and bore wear, it is unburnt fuel and mine did it when it had a mere 120k on it when I got it 5 years ago and it does it exactly the same now it has 195k on it!

[A-D-H]

Thanks for your posts,
Am confused as there is no slime on engine oil dipstick or on ATF oil dipstck and I expected to see some.

Can the radiator only leak one way - ATF into coolant ?
and wouldnt Head gasket failure show some coolant in engine oil ?

Cheers
Adh

[A-D-H]

Have removed radiator and will take for a pressure test to make sure, but have a nasty feeling the heads are going to come off.
Will update with results.

[niloc]

There is a diffenence in pressure between the auto box and engine coolant.
To put it into perspective - I just fitted a radiator into my car to replace the bent (ahem) one. Started the enine, seemes fine for a few seconds, then the water level rose quickly and started spewing ATF and water out of the coolant bottle. Extremely quickly. And that was with the engine just idling. Needless to say, I hastily removed that rad!

Maybe a compression test on each cylinder may throw a result.

Point for Peter - these heads cannot be skimmed due to the way they are mounted.

Head change isn't a really serious job. I purchased a good used head for £50 (delivered) from Swedish Car Parts.

[Peter Milnes]

Small point for Colin, your old 760 had both heads skimmed and is now running absolutely perfectly. Done by the garage owner who now owns your old 760.

All the best, Peter.

[niloc]

He must've skimmed the head very little. Either that, or he elongated the bolt holes slightly where the front cover bolts to the head.

so the only reason for the no skim on the v6 heads is the front cover bolts not aligning.
I presumed it was more to do with head design,certainly the first time Ive come across a head that cant be skimmed......