HG or oil cooler - how to tell?

[chinkostu]

Went to check coolant today in the usual fluid check to find the coolant black and very oily. Checked the dipstick and no emulsion and is still oil so clearly oils getting into the coolant somehow.

Question is, am I looking at a headgasket replacement or is it likely to be the oil cooler? Neither are a cheap option (lots of labour in a HG but oil coolers arent cheap) so don't fancy heading the wrong way.

As an aside, the cooler lines still have the original crimps but last time I tried removing some I ended up damaging hoses, so whats the best way of removing them?

[RichardW]

Lots of black oil in the water is usually the cooler - if the HG goes you usually get a smaller amount of brown emulsion type gunk in the header tank. You can fairly easily check for the cooler leaking by clamping the hoses, and then removing them from the cooler and starting the engine - if it ejects oil out of the cooler pipes you know where the fault lies!!

The clips are probably Clic type - easiest way to remove them is with a proper set of Clic pliers.

[chinkostu]

Removed lines and theres a lot of oil spotting on the coolant thats sat in there, but with the engine running its not putting anything out of either stub! So unless its leaking when warm (which means I need to refill the coolant and connect the hoses!) I'm looking at HG aren't i?

As an aside, looking into the tank you can see nice clean coolant from what I assume is the return line, but oily water already in there. Plus the coolant that escaped when removing the hoses had minimal oil in.

[white exec]

It still may be a slow oil leak (pinhole) in the oil cooler, which is easier and cheaper to sort than the HG. If a very slow weep, it could be the reason you're not seeing oil gushing from the stubs.
Try joining the two water pipes with a length of ?15mm pipe, and running the car for a while like that. Stopper one of the stubs, and rig up a small bottle/container under the other one to collect any gradual leak.

Oil in the coolant will accumulate at the surface/highest point, which is why there is a layer of it in the header tank, but clear coolant (from lower down) being being returned to the tank.

A HG leak is usually peristent and gradual, and not suddenly catastrophic; an oil cooler rupture can deliver huge quantities of oil into the cooling system if it really lets go, so best sorted urgently. A new cooler is not expensive, so maybe worth doing right away.

[chinkostu]

Thanks guys, I think I might run a hose from the thermo connector to the stub on the rad that the cooler normally runs through, would running it this way with some water in there be safe? I'm sure running sans cooler isn't a big issue but i'd rather be sure!

Can't have been long ago I last checked the coolant tbh so both your diagnosis seem spot on

[white exec]

Stu,
Running without an engine oil cooler will be fine.
Safe method is to bypass it with a short length of pipe or hose.
On some vehicles, the cooler can just be blocked off, as it then obliges all coolant to pass through the main radiator; not sure if this is the case on Xantia, hence advice to bypass it, not block it off.

[chinkostu]

Cheers guys. Heres hoping doing that and flushing the system stays clean!!

[white exec]

Recommend LiquiMoly Radiator Cleaner (art.no.2506), 300ml can, if you can get some.
Specifically for removing oil/grease from the system, as well as calc etc.
One can will be enough, but might be worth buying two in case the problem reappears.
Good instructions on the can, and on the LM website.

[kenbw2]

I had an oil cooler leak with exactly your symptoms. My original post is here: viewtopic.php?f=3&t=58012

Mine was on a DW8 which has the same block as the XUD9 in yours, was a very easy job once I got the part from a scrapper. I posted how I did it here: viewtopic.php?t=58040

[chinkostu]

Ken, did it end up being the cooler in the end? Thread is inconclusive hahaha!

I've been and aquired some hose and ran it from the stub on the thermo to the radiator stub, bypassing the cooler. Refilled the system and ran it up and trying the method of overfilling to flush the oil out! Might end up just dumping the contents as they're contaminated anyway then take thermostat out and run hot water through see if I can get any bigger amounts out before refilling with water and seeing if it returns.

The oil doesn't seem to be frothed up so it's almost like it's never reaching the pump. Level looks fine still so not losing enough to make me think it was pouring into the system!

[white exec]

A relatively small amount of oil in the coolant will just float to the top (ie to the header tank) and not get emulsified by the pump. The pump will almost certainly be operating in 'clean' coolant.

[chinkostu]

Excellent, thought so. Fingers crossed its clean as a whistle come flushing on sunday!

[kenbw2]

Yes mine ended up being oil cooler, much to my relief. All of what you describe is exactly what I had. Fingers crossed yours is the same.

Try not to run it for longer than needed - my heater matrix was clogged with oil and the heater's never been the same since. I did give it plenty of flushes with degreaser, and mechanically it;s been just fine. Just it's a little chilly in winter.

[chinkostu]

I might unplumb the matrix and flush it separately as well. Glad to hear i'm in the ballpark with ideas. Thanks all! Sunday will be the real test when I flush it out, work gets in the way until then!

[sparksie]

I struggled to find the correct oil cooler for my XUD equipped Xantia.
I tried one for a HDI, which was dimensionally correct, but the hose stubs were too small.
In the end I used one intended for a non-turbo Peugeot Partner.
It's physically smaller, but has the right hose connectors.
This means, should I ever decide to cross the Sahara, I may need to source a new one, but in temperate northern Europe I'm happy it will be quite safe as it is