1999 1.9D DW8 Dispatch: Thick black sludge in the coolant, no mayo in the engine. Head gasket?

[white exec]

Just on checking out the oil cooler, a few thoughts...

- in your first picture, are those coolant take-off pipes uppermost (not sure about orientation of the photo)?
If they are, then just possible that a small amount of oil, slowly leaking, might take some time to emerge.
Agree that it might be necessary to run the engine (normal driving) for quite some time to show up the leak, especially if it's a slow one - which it looks like, because the oil accumulation in the header tank looks limited.

- I don't have a schematic diagram of your cooling system, but in other similar systems the oil cooler is usually 'shunted' across other cooling pipework, and does not get the full pumped flow which runs through block, pump and rads. As such, the flow through the oil cooler could seem slow. Needs confirming with a diagram.

The two oil cooler spouts do not look coated with oil. As you've said, oil floats on water, and it will acculmulate at the upper levels. When I had a perforated cooler (twice!) on the XM, a litre or two of dirty engine oil injected itself rapidly onto the system. When I started "fishing it out", it was obvious that underneath it sat nice clean blue coolant; there was, for example, no oil trapped in the top of the radiator - it was all in the header tank.

Roughly what volume of oil have you fished out from the header tank?
Was it sitting on top of clean coolant?

[kenbw2]

Hmm, so the pic of the pipes under the comment about no pressure... was that with the engine running? If so then it does seem likely the water pump isn't pumping, and again that could lead to localised overheating/HG failure...

Yea, with the engine running. No pressure at all. Agreed that's probably what caused this

Be interesting to look at when the cambelt/pump were last done if possible & what the cost was, I have heard of cheap water pumps having plastic impellers that fall off the shaft.

I have very limited documentation from the last owner (he had it for about 3 months. Shenanigans? Who knows.

On the plus side, I'm sure there's at least 10p towards repairs sat in your water bucket in the last pic!

It's only 5p. And I put it there =/

Anyway, I'm mentally prepared for a big bill. But such is life.

[kenbw2]

- in your first picture, are those coolant take-off pipes uppermost (not sure about orientation of the photo)?

Yes

If they are, then just possible that a small amount of oil, slowly leaking, might take some time to emerge.
Agree that it might be necessary to run the engine (normal driving) for quite some time to show up the leak, especially if it's a slow one - which it looks like, because the oil accumulation in the header tank looks limited.

You're suggesting I could rejoin the coolant pipes, take it for a drive, and then check for oil on one of those pipes? I'll give that a go.

- I don't have a schematic diagram of your cooling system, but in other similar systems the oil cooler is usually 'shunted' across other cooling pipework, and does not get the full pumped flow which runs through block, pump and rads. As such, the flow through the oil cooler could seem slow. Needs confirming with a diagram.

It's not just slow, it's completely nonexistent. I'm gonna check the header tank inlet though to confirm.

Roughly what volume of oil have you fished out from the header tank?
Was it sitting on top of clean coolant?

I haven't fished anything out of the header tank. The liquid you see in the bowl is what came out of the oil cooler pipes when I disconnected them. Worth mentioning it'd been sat without running all day, so any oil would have reached the top. The liquid that was in the bowl was very gritty, but not oily.

[CitroJim]

Be interesting to look at when the cambelt/pump were last done if possible & what the cost was, I have heard of cheap water pumps having plastic impellers that fall off the shaft.

Yes, seen one in a 2.0 16V HDi in a Pug 407... Surprised me a lot but after we eliminated every other cause of overheating that was all that was left...

And it was the cause...

Jim, that's the 2nd time you've mentioned washing powder recently - you got shares in Lever Bros. perhaps?

No, but I am a very clean person by nature and do a lot of washing so I guess it's always on my mind!!!

[kenbw2]

So I just tried the oil cooler bypass test, and then took it for a blast under heavy load (thanks Yorkshire hills!).



If that's not oil coming out of the left pipe then I don't what is.

For reference, this is what it looked like earlier:



I also checked the pipe going into the header tank and coolant was definitely flowing. I also had plenty of pressure in the oil cooler coolant pipes after I took it for the blast.

I lost about 2 litres putting it back together. I've put it back in the top, but should I worry about airlocks now?

[elma]

No, just check the level after the first decent run. These engines tend to take an extra litre after a fill up but only after the first time the thermostat opens.

[white exec]

Leave the oil cooler out of circuit (ie bypassed) while doing your test running, to see whether more oil emerges.
The black stuff in the LH oil cooler pipe doesn't look like oil - more like dirtied rust.

Pressure/flow through oil cooler (water circuit) with it re-connected:
There might well be pressure in the pipes (because system is hot, and pressure cap on), but no flow.

If there is pumped circulation at the header tank, then water pump must be working.
If no circulation at the oil cooler, then maybe there's a blocked pipe somewhere, or possibly a thermostat not opening.

Could someone post a coolant circuit diagram for this car?

As no significant volume of oil has been found in the header tank, where is it ending up?

[jgra1]

the good news is that had your water pump have gone, I suspect you wouldn't have got very far, either on the test or in previous trips.. allied to the fact that there are no signs of overheating either..


but.. I do wonder where the coolant you put in goes, to have to top up every couple of weeks.. what is the dipstick colour like? and level

[kenbw2]

Leave the oil cooler out of circuit (ie bypassed) while doing your test running, to see whether more oil emerges.

So another blast or two up the hill, maybe with kitchen roll jammed into the hole?

The black stuff in the LH oil cooler pipe doesn't look like oil - more like dirtied rust.

Why would it only be on the one side though?

There might well be pressure in the pipes (because system is hot, and pressure cap on), but no flow.

There was flow coming into the header tank while the engine was cool:

but.. I do wonder where the coolant you put in goes, to have to top up every couple of weeks.. what is the dipstick colour like? and level

Yea me too. This is the dipstick:

[ekjdm14]

Well, at least there doesn't seem to be a major HG issue from the last few posts. A thought I had on the coolant use/loss is perhaps it's coming out of the overflow/pressure release at the cap due to the oil being injected at a higher pressure. I would have expected to see at least as much oil in the tank though as coolant you've lost. Or maybe the pressure cap itself has been damaged by the oil and isn't sealing to the correct pressure, allowing some overflow.

Having established the water pump is indeed working, I would want to verify the thermostat opening (either by feeling for the top hose staying cool & then suddenly getting hot as it reaches opening temperature, or ideally by removing/testing or replacing with a known good new item) and then give the cooling system a good flush out (with the oil cooler bypassed), fresh coolant, new pressure cap & drive it around for a bit keeping a beady eye on the gauges & checking the cooler stubs & header tank level/contamination after every trip. There does look to be hope though, certainly wouldn't say there had been water in the oil at all.

[ekjdm14]

Oh, another thing. If you're topping up on the command of the warning light, it could be that the oil or years of mineral deposits has affected the level sensor's accuracy. It's a regular problem on VAG stuff where they have to replace the whole header tank because the level sensor is moulded in place.

[kenbw2]

Well, at least there doesn't seem to be a major HG issue from the last few posts. A thought I had on the coolant use/loss is perhaps it's coming out of the overflow/pressure release at the cap due to the oil being injected at a higher pressure. I would have expected to see at least as much oil in the tank though as coolant you've lost. Or maybe the pressure cap itself has been damaged by the oil and isn't sealing to the correct pressure, allowing some overflow.

I assume I'd also see evidence of it coming out in the form of residue around the drain.

Having established the water pump is indeed working

Which I can do by removing the header tank inlet and seeing water flow out of it when the engine is cold?

I would want to verify the thermostat opening (either by feeling for the top hose staying cool & then suddenly getting hot as it reaches opening temperature, or ideally by removing/testing or replacing with a known good new item) and then give the cooling system a good flush out (with the oil cooler bypassed), fresh coolant, new pressure cap & drive it around for a bit keeping a beady eye on the gauges & checking the cooler stubs & header tank level/contamination after every trip

Does sound like a plan. Do you think it'd be reckless to drive it extensively (read: 100 miles+) like this?

certainly wouldn't say there had been water in the oil at all.

I could easily verify this by opening the sump plug and seeing what comes out first (any water would be at the bottom), correct?

I would guess that a new oil cooler is cheap (£30ish?), and easy to replace myself. Could I just replace that, flush the coolant out and check the header tank for oil afterwards?

If you're topping up on the command of the warning light

I'm checking every couple of weeks as a matter of course, not waiting for light to come on

[white exec]

While the source of the problem is a bit unclear, best not to change too many things at once.

Leave the oil cooler out of circuit (bypassed) for a few weeks' use now (it won't do any harm at all), but run a couple of bits of plastic pipe/hose from the two spouts into a catch container/bottle wedged in below, so that any gradual seepage from the oil cooler can be caught. As there's no water in the cooler any more, the only thing it can exude - if it's leaky - will be oil.

If there isn't a great volume of oil in the header tank, just soak up (tissue) any that's there, and top up and properly bleed the cooling system. Run the car normally for a few days, or even longer if no mishaps, and see what happens.

Most Citroen pressure caps have a thin rubber washer which seats on the tank filler rim. In my experience, these washers do not tolerate oil, and go soft, swollen and leaky if exposed to it. Check yours out. Simply replacing with a new cap would probably wreck the new washer too, if there is any oil remaining, so you may have to stick with the old pressure cap for a while - or replace its rubber washer if you have anything knocking around. Not always easy.

The level sensor (= low coolant level warning) in the expansion tank usually consists of a couple of probes, which are looking to be electrically bridged by conductive coolant. If the level drops, the circuit resistance goes high, and the warning light comes on. Trouble is, if the coolant has oil in it, this coats the probes, and stops them being properly conductive, thus showing up Low Coolant Level. If the mistake is made of continually topping up the header tank to a high level, every time the engine gets up to temperature, it will throw out coolant, because the expansion has nowhere to go. In general, Citroen header tanks should be about half full when cold, no more.

Let's see how it all goes. If no overheating, misfiring, exhaust smoke.....it's likely the HG is ok. Do bleed the cooling system properly, though, using all the bleed screws and correct procedure.

Leave using the Liqui Moly cleaner until the woes are sorted - no point in wasting it.

[ekjdm14]

^^ What he said...

I've flipped the rubber washer over on Black's pressure cap as it was failed when we got the car running, it's now doing it's job as it ought to so may be a short term option for Ken? (and yes, I do plan to replace with new when I can)

Agree, running without the oil cooler is unlikely to have any long term effect as long as you're not regularly loaded & towing up to max GTW in hot weather. In any case I think a thermostatically controlled oil/air cooler would be a better solution if that were the case. It can be permanently "deleted" AFAIK simply by removing it's centre bolt and replacing with the one from a non cooler-equipped car, so the filter simply screws onto the face that the cooler would have sealed against originally. (if heavy use is on the cards, proper oil/air sandwich plates with a 'stat built in are available from about £30, and complete kits with pipes etc from around £110)

[kenbw2]

I've gone for another option. I've nipped to the local scrapyard and got a replacement for £15. Not ideal using a used one I know, but the pipes are clean and will help me exclude that.

So my plan it fit replacement cooler, reinstate pipes, flush coolant, drive for a couple of hundred miles (keeping an eye on the dashboard temperature) and check for oil in the header tank.