Oil in Expansion tank

mark230678 · Post by **mark230678** » 04 Mar 2010, 18:40

Hi i have oil in expansion tank of 1.9td xantia.
Starts and runs fine. no leaks.
Expansion tank becomes pressureised when running.

Have taken oil cooler pipes off thinking it could be a faulty oil cooler.
But no oil emerges when running.

Could it still be a faulty cooler.
Could it be air in the system
Or is it the head?

quai_de_javel · Post by **quai_de_javel** » 04 Mar 2010, 19:01

Sounds like headgasket to me.

Post by **CitroJim** » 04 Mar 2010, 21:50

It's unusual that head gasket failure results in oil contaminated coolant as the oilways are so well separated from the coolant passages.

Unless the car is showing any of the classic signs of head gasket failure, you can assume the gasket itself is OK. However, there may be a crack in the head that allows coolant and oil to mix or the cooler may still be faulty. It takes only a tiny spot of oil in water to make a big impression and the cooler may only be leaking when it has hot water under pressure flowing.

Bypass the cooler to prove but don't run for long or under heavy load with the cooler bypassed. It is essential on a TD to keep oil temperature under control.

Mu betting is the cooler as head problems leading to water and oil mixing are comparatively rare.

mark230678 · Post by **mark230678** » 04 Mar 2010, 21:56

When i say oil.
I mean thick black oil, and not just a few spots.
Complete contamination

vince · Post by **vince** » 05 Mar 2010, 06:40

If its that bad then like Jim says it doesnt sound like head gasket issues as you wouldnt get that much oil in it.

My head gasket let go in a bad way on my TD a while back and i didnt see any oil contamination to that degree

boristhespie · Post by **boristhespie** » 05 Mar 2010, 07:12

JUst had my headgasket repaired. Picke car up last night. They skimmed it but this morning just got out of car and found black oil in coolant reserviour where it had never been previously.

Advice?

xmexclusive · Post by **xmexclusive** » 05 Mar 2010, 09:46

Once you start to deal with an oil in the coolant problem it gets very difficult to tell new leakage from the old contamination not fully cleared from the cooling system. Because oil floats on water the bulk of the oil will be as a layer in the top of the header tank. The rest of the oil will be trapped around the system in those locations where air would lodge on refilling with coolant.
If you drain down to try to clear the oil the coolant usually drains while the oil clings to the inside of the system pipe work. On refilling much of the oil returns to the header tank. My experience is with 2.5 XM's where oil cooler failure is a regular problem. I have taken to overfilling to float the oil out the top of the header tank. Messy but clears much more oil each time. The coolant needs pumping out down to the correct level before you put the pressure cap back on. Clearing the oil caught around the system can need quite a few system flushes. As the coolant will need changing once the system is cleaned I add some washing up liquid to help free the oil. With one particularly persistant case it took a dishwasher tablet into the header to finally clear the oil.
I am sure that someone more experienced will identify a suitable proprietry product for cooling system cleaning. The point I was trying to make is that with oil in the coolant it is very difficult to tell quickly if the problem is ongoing or just heavy residual contamination.

John

mark230678 · Post by **mark230678** » 05 Mar 2010, 10:24

The problem is though i have taken the oil cooler pipes off and expected to see oil pour out of them if it was a faulty cooler.
Would this be the case, how did you identify the fault on the XM

Xaccers · Post by **Xaccers** » 05 Mar 2010, 10:33

Well the question is; has your oil level been dropping suggesting it's leaking into the coolant system?

If not, could this be from a previous owner, as said above, and old oil in the cooling system working it's way out?

How pessurised does your header tank get?
If you run the engine for a few minutes and then remove the cap, do you get a fountain?

mark230678 · Post by **mark230678** » 05 Mar 2010, 11:11

Yes, i can run it and leave it off and after about a minute get a nice grey trickle coming out of the top of the coolant tank

xmexclusive · Post by **xmexclusive** » 05 Mar 2010, 11:18

Because the oil floats on the coolant in the header tank it will look as though the system is heavily contaminated. It can still be a very little oil in terms of total coolant volume and just the results of a very small leak. If you visualise a 1mm thick layer of oil in the top of the header tank we are probably talking about a total oil volume of around 100cc, difficult to notice as a variation on the dip stick. In the header tank that volume will look pretty extreme, black rather that grey and be very difficult to clear from the system. It will also fairly quickly destroy the rubber seal on the header cap.
On the XM's while running with the oil cooler disconnected only in one case did enough oil leak to fill the cooler and cause it to overflow and that took months to happen.

John

mark230678 · Post by **mark230678** » 05 Mar 2010, 11:41

Just drained rad, clear water and then a good 100-200 ml of grey slime.
If car is started with dipstick out nothing comes out of the dipstick spout.
Also the red light is on on the oil temp gauge, with the temp gauge showing zero

mark230678 · Post by **mark230678** » 06 Mar 2010, 08:33

Is there anybody else with any ideas??

nginmu · Post by **nginmu** » 06 Mar 2010, 09:02

Are you sure it's oil? Is it possible it could be a previous owner's attempt at curing a water leak by adding 'radweld' or similar to the coolant.

My Dispatch van has thick black goo in the coolant that looks like oil contamination, but I know it isn't, because I put it there myself.. radweld..

Is it worth dumping out all the coolant, giving the cooling system a really good flush out, several times, maybe with some kind of proprietary flushing compound, and then refilling with clean coolant & seeing if the contamination returns?

Post by **Peter.N.** » 06 Mar 2010, 09:26

I had an XM with this problem, changed the head gasket but it didn't cure it, never did find the problem but I used to periodically remove the filler cap and slowly run water into it with the engine running, the oil would come to the top and overflow, a few minutes of that would make it much cleaner. I went on to do a fair mileage with it in that condition as it still ran OK.

Peter

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Oil in Expansion tank

Oil in Expansion tank

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