1.9TDI Head Gasket Replacement Questions

[nial]

I think I have read so much conflicting information about this particular problem that I really don't know what to think any more! I thought I would try on this forum before I finally bite the bullet, as the advice I have received has always been good in the past.

I have done lots of head gaskets on vehicles other than VAGs and indeed a lot of petrol VAG and a few VE TDI engines in a past life. I gave up the spanners some years ago (as a job) but I still look after my own vehicles. I suddenly find however that I am faced with a dilemma which seems to contradict the time-honoured approach to HG replacement (remove head - skim/reface & pressure test - refit with new gasket set & head bolts).


I have a 2009 VW Touran 1.9TDI with a BKC engine I believe. The head gasket is gone (pressurising the header tank and spitting out the coolant after ~20 miles). It is our family car so I want to sort it out properly. However I have read so much about HG replacement on these engines (PD) that I don't know what to think anymore. There are three approaches from what I have read and gathered:


1) The VAG workshop manual states Note: "Reworking diesel cylinder heads is not permissable" This implies that after checking for distortion if it is >0.1mm then the head should be discarded? But even if it isn't distorted what are you then supposed to do in order to re-use it?


2) Following on from 1), a former colleague (from my days on the spanners) says that he has done two 1.9 TDI-PDs in the past and his approach is: a) inspect the head surface and block meticulously, b) check for distortion of the head, c) clean down the block and cylinder head spotlessly and refit everything with new gasket set, and head and rocker shaft bolts. Everything in my training tells me that you should skim a head when when doing a HG however - am I wrong?


3) 'Stuff-the-workshop-manual' approach (my least favourite at the moment). Skim/reface the head. Check the piston protrusion and make up the difference in the head gasket, assuming that: a) you haven't removed too-much material from the head to allow you to do that and b) that your engine has a '1-hole' or '2-hole' gasket *prior* to refacing. If you don't then you'll need another head or: just f$%k it - fit it anyway (as long as you haven't taken too-much off the face of the head) - some claim to have success in this regard...but I am not sure...


Sorry for the encyclopedia-sized post but I would be interested in and grateful for your opinions particularly from those of you that have done a number of PD head gaskets. Many thanks.

[niall campbell]

I would say in my very humble opinion ....................... take the head off and get it pressure tested. You have to anyway.

I had the same dilemma in my sons Polo 1.2 ........................................ engine rebuild due to piston oil seals stuck in & valve stem guides & seals etc. Supposed to fit a new VW head , but with a 2002 car ; was it really worth it & couldn't afford more than a £1,000 car ................................ I bit the bullet and went for £120 head rebuild

So take the head off & see if you actually have to skim the head

I would also turn over the crank & see if piston liners are ok

[Crasher]

You should not have VAG PD TDI heads skimmed as this removes the HIP (Hot Isostatic Pressing) heat treatment which seals pours in the aluminium face, if this is removed there is an increased risk of premature gasket failure. The other problem is that to skim these heads they need to be stripped right down which is when you find the injector location bores are damaged, that you need new exhaust valves and guides plus a valve job and then suddenly fitting a quality replacement head by AMC of KS seems like a good idea.

[nial]

Many thanks indeed for the (as always) helpful and knowledgeable response Crasher.

Very quickly: can you tell me if method 2) in my original post above is a reasonable approach?

Many thanks again.

[Crasher]

Personally in 40 odd years I have never done that as I can’t stand doing jobs twice but I know many people have and got away with it. The modern problem is that MLS (metal layer shim) head gaskets are very fussy about the surface finish, known as the Ra or roughness average so cleaning is going to reduce the RA and unless you own an RA gauge you have no idea what you have restored the surface to, VAG usually state a paper grit minimum. Basically it is a gamble involving the potential for a lot of wasted parts and many hours work as it is a LOT of work.

[nial]

Many thanks once again for taking the time to respond.

I tend to agree with you.

Am I right in saying that essentially the take-home message is that you should really replace the cylinder head if the head gasket needs to be replaced? That seems a little excessive, but given the fact that 1) "Reworking diesel cylinder heads is not permissable" and 2) skimming removes the HIP heat treatment, then there is really not much choice...

Out of interest, what minimum paper grit do VAG mention - I haven't seen mention of that anywhere.

Again, I thank you for the insightful and knowledgeable information and advice.

[Crasher]

What it boils down to from my personal perspective of doing it professionally and having to charge labour and provide a warranty, is the cost/benefit analysis of rebuilding a head and that is even IF the injector bores are serviceable, which is a matter of judgement and conjecture so in order for me to be confident in my work I specify a new AMC or KS head, not the Chinese rubbish doing the rounds.
I use a good brand BILLET (not cast) cam and lifter kit, Elring gaskets and head bolt set, injector seals, Glyco cam bearings, genuine cam belt kit and water pump plus genuine cam and rocker bolts PLUS a pair of genuine rocker arms as these MUST be replaced (£400 a pair) or else you invalidate the cam warranty so if the cam fails on the injector lobes it is your responsibility. If you analyse the costs involved in doing the job properly where you can confidently offer a two year warranty you can see the costs stack up to a stupid level. This doesn't even take into account that to not have the turbo rebuilt whilst off is bordering on stupid and a big pile of nuts and bolts not listed above so the whole thing gets out of control and can easily get in to the £3k area on parts alone which is pointless on a car that will very soon be taxed off the road

From the old head you could take a reasonable gamble on the valve locks and retainers, possibly even the exhaust valves but this would be my parts list with some typical retail prices but there would be more

AMC head £850
Cam cover gasket £15
Inlet manifold gasket £5
Exhaust manifold gasket £6
Cam bolts £27.10
Exhaust manifold bolts £16.28
Exhaust manifold nuts £6
Injector bolts £15.84
Bosch injector seal set £88
Head bolt washers £25.80
Elring head gasket £54
Elring head bolt set £25
Elring cam oil seal £12
Cam belt kit £149.04
Water pump £60
Tensioner stud £1.38 genuine
Billet steel Camshaft with followers £300
Quality Cam bearing set £40
Rocker arms £430.42
Rocker arm bolts £71.33
Valve spring set £130.27
Inlet valves £48
Exhaust valves £54
Turbo clamp and gasket £15
Plus sump bolt, oil, oil filter and 3 litres of coolant

So that is around £2400 in parts before you add what breaks or I have forgotten and then you need to add 2 days labour PLUS a turbo rebuild, insane!

[bmwdumptruck]

Any update on this? What did you do in the end?
Id have to say I’d go with option 2. Can’t see you’ve much to lose by trying, especially if you value the vehicle low enough to be not worth doing it as per Crashers recommendation. I accept his recommendation is right for him as a trader offering warranty on his work, but for a diyer in a low value motor there’s little to lose by just doing it the old way.

[Crasher]

I have just done the cam on a T5 2.5 TDI using all genuine parts, HUGE bill!

[nial]

Any update on this? What did you do in the end?
Id have to say I’d go with option 2. Can’t see you’ve much to lose by trying, especially if you value the vehicle low enough to be not worth doing it as per Crashers recommendation. I accept his recommendation is right for him as a trader offering warranty on his work, but for a diyer in a low value motor there’s little to lose by just doing it the old way.

Currently doing this job in the evenings. Started yesterday. Just waiting to get the head off and inspect it before I decide what to do....


@Crasher: any idea how you get the manifolds off one of these? It's got a DPF so there's absolutely no room to get at anything- workshop manual suggests removing the DPF entirely by dropping the subframe - wow! I can't see how that might work since the rack and ARB still seem to be in the way

I also get the impression that manifolds come off with the head once the oil lines for the turbo and anything else has been removed - or have I missed something...?

Many thanks for your invaluable input once again.