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

[white exec]

That sounds ok to me.
The all-steel 'flat' oil coolers PSA use are pretty long-lived items, provided that decent coolant (corrosion protection) is used and maintained.
Fingers crossed!

[kenbw2]

I'll give it a go this evening and report results. Thanks guys for the help so far.

[van ordinaire]

". . . nipped to the local scrapyard . . . "I remember those days - but it must've been 20, 25 years ago!

Sounds like a plan, but I'd still flush before fitting the "new" cooler - & flush that separately!

Good luck, keep us posted.

[kenbw2]

Got home, fitted the cooler, put the filter back on.



The new one's thinner, Which means the threaded bolt that goes through the middle is too long and doesn't hold it on securely. Dammit.

Back to the scrappy tomorrow to see if I can get its shorter bolt.

[white exec]

Yes, they come in a variety of thicknesses, each with a matching length through-bolt.

[ekjdm14]

On the plus side, that cooler does look a lot nicer internally from what can be seen of it so hopefully this one hasn't suffered any corrosion internally.

Interesting comparison really, showing the long term results of not paying attention to coolant strength & replacing before the corrosion inhibitors fail Vs. how it looks if one takes care of their cooling system from the get go... (obviously not saying you're at fault here Ken, rather the previous owners to you over many years!)

I know our American counterparts can appear a bit anal over stuff like coolant replacement, (from videos ive seen anyhow!) but then I guess they'll experience corroded cooling system parts much less frequently as a result.

[kenbw2]

Interesting comparison really, showing the long term results of not paying attention to coolant strength & replacing before the corrosion inhibitors fail Vs. how it looks if one takes care of their cooling system from the get go... (obviously not saying you're at fault here Ken, rather the previous owners to you over many years!)

I notice the newer one is a *lot* lighter than the old one, so I assume it's aluminium rather than the older steel one, so it might be a bit apples and oranges to compare the corrosion in the two in this case. But you're right regardless - the corrosion on the *inside* of the older one serves as a warning (to me as much as anyone) about how important it is to flush coolant regularly.

[white exec]

New one does look ali on the outside. Check with a magnet.
If it is ali, and almost certainly Valeo brand, then I'd advise being thorough with good coolant, and replacing it on schedule.

My experience with Valeo ali oil coolers isn't good, but limited to the very deep one on the XM. These have a reputation for perforating.

If replacing coolant, do a complete drain down and flush out. Final flush with deionised/demineralised/distilled water, if possible. Fill with a known good brand, and never mix types or brands. Colour of mix means nothing: there are no standards for coolant colour. In this age of engine, avoid using OAT (organic acid) (long-life) types, as the installation wasn't designed for them. Stick to standard glycol mix, and do all topping up with the exact same. Keep tapwater out of the system.
Sorry to lay this on with a trowel, but mixing types can lead to all sorts of problems if you are unlucky.

[CitroJim]

Sorry to lay this on with a trowel, but mixing types can lead to all sorts of problems if you are unlucky.

No, it's very sound advice indeed Chris In fact the longevity of any XUD and related engines - of which the DW8 is - is critically dependant on the health of the cooling system in my experience.

[kenbw2]

Woohoo! Replacement cooler fitted:



Turns out the thinner aluminium ones are *not* interchangeable, even with a smaller bolt because the gasket on the back where it mates with the engine block is about 4mm wider, so when fitted it pours oil out underneath.

Went to another scrapper and got the steel one and it fits perfectly.

Now to do a bit of a test drive and coolant flush.

[ekjdm14]

Ah, yes I do believe I can see the evidence of this all over your undertray At least if it is on there it might get into the threads of the fixings that hold it on & make it easier to remove in future lol

Fingers crossed for you & the Dispatch.

[CitroJim]

Fingers crossed here too Ken...

[white exec]

Yes indeed . . . nicely lube'd underneath.
Fingers crossed for you.

[van ordinaire]

The only time I've ever flushed a system, other than when dealing with an overheating issue, was preparing my 3.6 XJ40 for its 1st S. African trip.
My thinking was that within the life expectancy of the antifreeze, if the car lasts that long, you're going to lose it all at least once, split hose, damaged rad, new stat., head gasket/top end overhaul, whatever.

I did drain the C15, refill the system adding some propreitary flushing agent, drain it & flush the block & rad separately prior the the cambelt job, because when I checked the level, the tank appeared to contain apricot nectar - unfortunately it still does, I discovered recently, despite being re-filled with readymixed antifreeze.

[white exec]

Apricot nectar! That's different!

There are plenty of reports of the accidental mixing of different types of coolant/antifreeze mix producing various nasties, including sedimentation, syrupy deposits, and goo. Bluecol (who know a thing or two about coolant) publish some very firm guidelines on their site about not mixing types or brands.



Photo above shows what I removed from our XM header tank a few years ago. The blue is clean coolant, but floating on top of it was a thick, dark-grey layer of sticky goo, with the consistency of marmite/evostik.

The grey goo could be laboriously fished out of the header tank with paper towel and a scoop, but I was staggered to find that the layer re-formed where the coolant found itself in contact with air. Nightmare! The sobering conclusion was that this could be happening anywhere in the cooling system where there was an air pocket. Fortunately, the system had been properly bled as part of the previous refilling, so the goo formation was only found in the header tank.

It had occurred only because two types of coolant had become mixed, when I attempted to switch the system to a long-life brew, without completely removing all the previous mix.

I spent a long time cleaning and flushing the system, with bio detergents etc, involving removing the header tank several times. Cleaning was finished it off with the Liqui Moly cleaner, which left everything pretty much spotless.

Much googling revealed that this problem is not unknown, and hence the advice above. I now run with PSA's own ready-mixed "Pro" coolant, a traditional glycol mix with good anti-corrosion properties. It even smells of Fernox.