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

[kenbw2]

I've had a bit of a loss of coolant since I bought the van. No biggie I thought. Here's the background:

- Half a litre or so of water in the coolant every 2 - 4 weeks
- Last week I threw a bit of radweld in

Went to check how it'd gone today

- Thick black sludge in the coolant header tank
- Oil is at the normal level, maybe a bit lower than last time I checked
- No mayo in the engine cap
- Drove it home and didn't notice anything different
- Dashboard thermostat at the 70 degree mark
- When I got home I checked to see if the coolant was flowing and saw no movement in the header tank





Obviously classic signs of head gasket failure. But it's also been suggested it could be a leak in the oil cooler.

Anything I should check?

If it *is* head gasket obviously it's gonna be a big job. Options as I see it are

- Get the head gasket replaced with the obvious strip down that that requires
- I gather the DW8 is an XUD9 with a different head (from a TUD5?). Could I maybe replace the head with one from a N/A XUD9 and have a bona fide XUD?
- Ridiculous option for #3: I have a dead 1.5 TUD Peugeot 106, could I take the head off that and put it on the DW8?

[CitroJim]

I'd suspect, if it has one, the oil cooler has let go and allowed oil into the cooling system... Not uncommon sadly, seen it before...

The cooler, if fitted, is sandwiched between the oil filer and the block and is a water/oil type...

One other cause of this I've seen is where someone confused the coolant header tank with the engine oil (or Power Steering) header tank and topping it up with oil by mistake...

[kenbw2]

That seems much less disastrous than head gasket. I gather from my research I can test that by taking the cooler off, replace it with a transparent pipe and idle it, watching for oil coming out of one of the pipes.

I assume before I do that I'd need to fully flush the coolant till it's clear, then do the above test? At which point oil coming out = head gasket, and clean coolant = possibly oil cooler

[CitroJim]

Yes, on both questions Ken...

Clearing the cooling system of all that oil will be quite a task but I think there's some tips on here... Some even recommend running a bit of biological washing powder in the system - not sure about that one personally but logic says it might work...

[white exec]

That is oil getting into the coolant, and doing it slowly - otherwise there would be huge quantities of it there.
As Jim says, likely that the oil cooler has become perforated - not uncommon.
For oil cooler failure, oil will always be injected into the water (rather that water appearing in the oil), because the oil is under much higher pressure than the cooling system.

To check out the oil cooler:
- Remove the coolant pipes from it, and join them together (bit of 15mm copper pipe and hoseclips usually does) so that the coolant circuit remains intact.
- With the oil cooler still in place, and the engine running, look to see if oil drips/seeps out of the oil cooler's coolant pipes. If it does this, the unit is perforated, and needs replacing.

The small, flat steel coolers usually last years (unlike some aluminium ones) but can give way if coolant quality has been neglected.
______________

Other possibility, as you say, is HG. Some PSA HGs have a small O-ring let into one corner of them (= oilway from block to head), and if this gives way/hardens, it can let oil under pressure into an adjacent waterway. Not sure whether this can apply to your engine.
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To clean the oil out of the cooling system, when you've nailed everything, I can recommend this stuff. It works brilliantly and quickly:
Liqui Moly Radiator Cleaner, 300ml, Art.No.2506
Buy a couple of cans, although one should do the trick.
It is specifically designed to purge oil/grease from cooling systems. Good instructions on the can.

[kenbw2]

Thanks guys for the suggestions.

To check out the oil cooler:
- Remove the coolant pipes from it, and join them together (bit of 15mm copper pipe and hoseclips usually does) so that the coolant circuit remains intact.
- With the oil cooler still in place, and the engine running, look to see if oil drips/seeps out of the oil cooler's coolant pipes. If it does this, the unit is perforated, and needs replacing.

That sounds pretty straightforward, I'll give it a go!

I'll give the oil cooler a flush out before I test (since it's gonna be full of the black sludge), hopefully that should do the trick.

[Peter.N.]

To remove the oil from the water you can slowly add water to the header tank with the engine running and hot, the oil will come to the top and overflow from the filler, you will need to do this a number of times but it will work eventually. Needless to say the oil will stain so don't do it on the living room carpet.

Peter

[white exec]

Good reminder, Peter, I'd forgotten about that.
You can also continually dip a bit of kitchen roll into the oil floating on top; kitchen roll will hike the oil out and leave most of the coolant behind. Long job, lots of kitchen roll.
When the worst is gone, finish off with the Liqui Moly cleaner.

[kenbw2]

This I assume is if and when I've successfully diagnosed and replaced the oil cooler?

I assume for testing the oil cooler this isn't necessary - I just need to flush out the water side of the oil cooler itself?

[white exec]

Yes - test the oil cooler first, and identify where the leak was coming from. Then do the clean-out.

[CitroJim]

I wonder if an oil spill kit might help...

Such as one of these

Or something similar...

[van ordinaire]

Bit late here, but I don't think I've seen a post that produced so many responses in such a sort time.

Personally, having established the fault is the cooler, I'd run the whole clean-up procedure BEFORE fitting the new cooler.

Rather surprised there is a specific flushing agent to deal with oil in cooling systems - although I suppose I shouldn't be. Wouldn't have used it without a recommendation though!

Jim, that's the 2nd time you've mentioned washing powder recently - you got shares in Lever Bros. perhaps?
Reminds me of 2 things:-
the TR2500 that produced a cascade of bubbles, rather than froth, on removal of the rad. cap (nope, never did work that out)
long before flushing agents were readilly available, a country garage suggested Harpic - worked as well, rather too well!

Interested in the reference to poor coolant quality, only come accross that on a Cadillac forum, where much importance is attached to the "right" anti-freeze & religiously changing it at the specified intervals. But then, I've learned Americans are obsessive about fluid changes & replacing plumbing!

[kenbw2]

Yep, makes sense. My priority is to establish if the cooler is at fault, which I'll be doing once I get home from work. Got my washing up bowl to catch the spillages.

I'm not thinking about cleanup yet - that's dangeously close to getting my hopes up that it isn't head gasket. I'll reserve the plan for after I've established if the cooler is at fault.

[kenbw2]

OK oil cooler test done. Took the coolant hoses off, piped them together (15mm copper pipe fit perfectly, thanks white exec!).

Ran for 15 minutes at idle, with a few bursts of revs from the throttle cable. Temp got to about 60 degrees on the dashboard thermostat.

Here's the results:

There's *no* oil coming from either coolant in/outlet:



There's *no* pressure in the coolant (dead water pump?)



The coolant I collected from the hoses is dirty, but not thick like what's in the the header tank (oil floats and all that).



Am I therefore pretty much definitely looking at head gasket?

[ekjdm14]

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...

I'd suggest running it for a few miles with the cooling system bled up & cooler bypassed, and then dipping a strip of kitchen towel in the cooler stubs just to make sure. (if the HG is gone and water pump at fault the damage is done anyhow so a few more miles to prove it shouldn't hurt).

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.

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