BXProject

It's regarding the van (VW LT35 straight 6 turbo diesel). Neither problem is more than a slight annoyance at this stage, especially given the small annual mileage I do in it, but I thought I'd see if any knowledgeable people could shed a bit of light on my ponderings.
First problem is coolant loss. It's losing about a litre or more every thousand miles (or as the ebay seller put it, an eggcup full) but with no signs of external loss (drips or residue). If I leave the (new) expansion cap slightly loose the problem is less, otherwise it gets through a litre in a couple of hundred miles. No excessive pressurisation of the system, no overheating and no mixing of oil and water. These engines apparently have a slight tendency to crack the heads, so I'm wondering whether there is a crack between a waterway and the exhaust, but no steam from the exhaust, and I would have thought there'd be *some* pressurisation of the cooling system. Does that sound like a plausible cause to you guys? I should add it's been like this for at least 25k miles without getting any worse, including a trip down to the s***h of France. I realise that a sniff test would be the way to go, but I've still to find a garage round here that I trust to do the job.
Second problem is noisy (hydraulic) tappet(s). Fine from cold, and usually OK with hot idling but will occasionally give a clatter and then go back to normal. They're actually worse on the overrun when slowing down, especially towards the end of a service interval when the oil is probably getting a bit thin. I don't think it's a case of them sticking, as to my mind that would be worse when cold, but I think that either the tappets are worn and letting the oil escape rather than pump them up, or I have an oil pressure problem. I suppose it could be them sticking and the higher oil pressure when cold overcomes the stickiness? Do you reckon it's worth a go with a can of engine flush? I'm very sceptical of any 'magic in a can' type treatment...
It's all pointing to a head job, which I'm not really looking forwards to as I can't find a workshop manual for the engine. I'm sure it's all straightforward enough, so long as I can find the torque settings. Need to find a friendly garage with a copy of Autodata...

My two penneth:

All VAG diesel cylinder heads of that period crack for fun, regardless of if they've been cooked (I once foolishly ended up with a VW transporter, and was fairly pissed off discovering that the 'good' engine that I'd bought in a Golf had several cracks. The works manual actually stated that this was inevitable, and went on to describe what was an 'acceptable' crack, and what wasn't. I promptly threw it together and immediately sold it, before the 'acceptable' cracking developed into big trouble...)

If I were you I'd do the following.

1) Remove the rubber sealing ring from the radiator cap so as to run the coolant at atmospheric pressure.

2) Change to semi-synthetic diesel oil and add a bottle of magic additive of the type intended to free sticky hydraulic tappets. Remarkably this usually works.

3) Continue to run on semi-synthetic oil. Hydraulic tappets are not necessarily FTW on diesels, as they tend to get clogged by the soot residue which inevitably ends up in the sump. This is why the goos old XUD had solid tappets, at the time oil technology was not regarded as being suitably developed to avoid problems. Semi-synthetic helps to alleviate any issues, and I would always advocate the use of semi-synth in any diesel with hydraulic tappets.

With the above treatment, the engine will probably continue to run well for many years.

The four cylinder VAG diesels tend to crack between the valve seats, and from the valve seats to the pre-chambers. I think that (as with the CX diesel) it is the between the seats cracking that can penetrate a waterway. I dare say the bigger engines are designed in the same manner, and share the same weaknesses.

If you are tempted to rebuild it, I would recommend trying to find a NOS cylinder head, as my experiences and that of an engine rebuilder I spoke to suggest that a secondhand engine is also likely to be at least slightly cracked.

My cam in head Opel Manta cylinder head failed at 90000 miles. I stuck in a can of
"Wonder weld" and it cured it till 126000, when it failed quite spectacularly and was replaced by a new 400 engine.

The oil issue has been a VW problem for years, They quote ever more complex API numbers until your not sure they want.
Always a cure for me was Duckhams Diesel, if it's still available. Quietened the little chaps down a treat.

/\ all that lot really, wouldn't be at all surprised if the head was cracked TBH, they seem to do it for fun...

I have autodata...

Exactley what torque settings do you require?

Oh, I'll need the year of the wagon, and the engine code aswell for full and proper torque settings..
I'm assuming it's the 2.4 TD?

I'm about to tackle the 2-0 HDI (90) head gasket in a couple of weeks.
If anyone has had the pleasure I would be grateful for any passing comments

It looks a bastard of a job, as you would appear to have to dismantle 1/2 the car !!!!!!

Even mr Haynes starts off with warnings and a fist full of black spanners

Easy tips...

Don't do it Phil!

Actually it's not too bad a job...

You have torque settings I guess if you have the Haynes?

Thanks for the advice guys! I am a member of a VW forum as well, but given the general standard of the advice on there I haven't even bothered asking...

Sounds like how I'd feared, if I can get a NOS head, or a known good second hand one I'll probably go for it. Jonathan, are you saying that my symptoms sound like sticky (rather than worn) tappets therefore the sticky tappet additive may work? Or just that it's worth a try given the cost of it... Got to be worth a try I suppose, I find it very embarrassing when it starts clattering like an old Kent lump!
Chris, if you do have a moment to check torque settings that would be great. Not a job I'll probably be doing for a while, but good to have on file...the engine code is ACL 2.4TD and it's a '93 model. At least if I have to do the job before the workshop goes up I can do the whole thing from the comfort and dryness of the cab!

I always found vewubbleyou stuff responds well to a good flushing agent adding to the oil 20-30 miles before draining off. If the engine is getting on a bit a slightly thicker rather than thinner viscosity oil, hence the suggested Duckhams D. It wasn't all that dear so I used to change between 6 and 8 thou, no more clatter, although it aint that quiet of an engine anyway.

Yeah Doc I was reading Haynes, he just recommends things like dropping the front suspension coz there aint much room at the bulkhead, or even taking the whole unit out!! What's that all about?
I don't see the need. Not yet at least
One of my old mates swears by Amsoil, says it lasts for about 25000 miles. Never used it myself
Discuss ?

Aye, I think they are more likely to be sticking; I'd expect it to be happening constantly (and/or) bad when cold if it were wear. What sort of oil are you using?

Philhod wrote:One of my old mates swears by Amsoil, says it lasts for about 25000 miles. Never used it myself
Discuss ?

I think that if you ask on any forum what oil to use, you'll get about a thousand different answers...
I use Morris Servol 15w50 in the van, as it's the only oil I've found of that viscosity that meets the VW spec. Changed every 5k, annoyingly recently given the talk of flushing agents and the like. Also annoying after Jonathan's points about semi-synthetic seeing as I have about 18 litres of the stuff left!
I'd always been of the opinion to use mineral in a low revving, low tuned engine and change it more frequently rather than pay more for a semi-synth and leave it longer between changes, but I hadn't thought about semi-synth being better for the tappets until now. The engine has done about 225k, so getting on a bit but an almost full history for what it's worth...

Ugh, that is annoying. I am usually an advocate of mineral diesel-specific oils for older diesels, but not where the hydraulic tappets are involved...

Given that you've recently changed the oil, and have gallons of the stuff left, perhaps it would be best just to stick a bottle of magic in it and hope for the best

I think that's the best plan really. With the best scenario (noisewise) when it's cold, ie oil thicker. and semi synths being generally thinner but constant.

Almost certainly sticking tappets, I'll bet my pension they'll be full of crud.
If you can get some throw some Fotre Engine Flush in it before dumping the oil, run it for about 50-100 miles or so, it's fucking magic stuff that, then throw an addative in as per Jonathon's advice.

Phil, Citroën themselves say about dropping the engine out the bottom, for access purposes, but it aint required.
We've done a few down the garage now, and whilst access is a little bit of a pig we've never yet pulled the whole engine out just to get the head off.
It's easier once you've done one, since then you know where all the nuts and bolts are that you cant really see.. but it's entirely possible to do in situ, and shouldn't pose any problem at all for a man of your ability.

Ok then, torque settings for a 93 ACL 2.4 go a bit thus:
Cylinder head:

Always use new bolts.

M12:
1) 40NM
2) 60NM
3) 180 deg

M11:
1) 50NM
2) 70NM
3) 90NM
4) run engine to 50 Deg C
5) 90NM

If you need any firther settings, just ask.
Or, if you like, assuming the PC stays usable long enough, I'll burn you a copy of AutoData..

Cheers Chris, nice one. All I need now is a shiny new head...maybe I'll trawl German ebay for one.

Mind, on the four cylinder VAG diesels, there were two types of head, those for solid bucket tappets, and those for hydraulic tappets. Be careful in case this is the case for the bigger lumps, as if you ended up with the other version you'd have to source additional bits to make it work....

That may well be the case, as the 2.4 lump is basically 1 and a half of the old 1.6 engines. That would suck big time, need to brush up on my automotive German...
Krankenwagen (ambulance) and Schwimmenwagen (amphibious vehicle) always raise a smile!

mat_the_cat wrote:...my automotive German...
Krankenwagen (ambulance)

That's one for the Doc to have on a vinyl sign on his ambulance!

Nasty little trick to find out just where the bloody hell the water is going:

Fill the cooling system to the top, and then fit a modified header cap, which has an airline fitting welded/soldered/beaten into it. Fill air receiver on compressor to 15psi, and connect to the cap, and hence pressurising a cold system, with a nice big reserve. Leave overnight. See where is wet. (may have to remove the glowplugs to be sure)

If one of the cylinders fills up with water, you have your answer. You may find that there's an external leak somewhere that you'll never find, as it only leaks onto a hot engine, and hence evaporates.

he's clever thisun!