ASV Engine.

A response at TdiForum suggested piston and valve contact.

I took the head off to cure the Drinking of water and exhaust gases in coolant. I found that whoever did the timing last did not line up with the mark on the flywheel. There was a 2 hole gasket ( piston projection 1.01-1.10mm) and I measured actual piston projection at 1.05mm.

Thanks

Mark

what do the valves and followers look like?? defo been contact there and its happened more than once!! gasket appears to be the right one so could have been miss timed or I have seen a few that had stuck pressure relief valves and they would pop the followers open if you revved them :'(

prob be fine tho it would be obvious if there were cracks in the pistons from it.

what do the valves and followers look like?? defo been contact there and its happened more than once!! gasket appears to be the right one so could have been miss timed or I have seen a few that had stuck pressure relief valves and they would pop the followers open if you revved them :'(

prob be fine tho it would be obvious if there were cracks in the pistons from it.

+1

Looks like valve contact from bad timing to me. A good indication of how hard the contact has been will be the condition of the lifter faces. They are mirror-like and will show any radial cracks.

From your picture, the piston bowls look undamaged and whilst the valve recesses have been damaged, I doubt the pistons will need replacing.

Have you put a straight edge on the head to make sure it isn't warped? Did you find damage to the gasket?

also this may be caused by having the head skimmed as that makes the valves project further so while the gasket may have been correct for the piston height it may still be too close for the valves.

+1

Looks like valve contact from bad timing to me. A good indication of how hard the contact has been will be the condition of the lifter faces. They are mirror-like and will show any radial cracks.

From your picture, the piston bowls look undamaged and whilst the valve recesses have been damaged, I doubt the pistons will need replacing.

Have you put a straight edge on the head to make sure it isn't warped? Did you find damage to the gasket?

No I did not find the damage to the gasket so unless the chemical sniff test gave a false reading ( although as suggested I tested the gasses from the exhaust pipe and got a similar colour change to verify) then I am assuming the head is cracked. I haven't checked warping of the head as I intended to get an exchange unit from http://vwenginerecon.co.uk/ for ease and convenience.

Lifter faces look like radial wear marks ( think they are designed to rotate to even out wear?)

Cam lobes

I think the head has been off at some time to repair the damage. It is strange that they couldn't find the flywheel mark considering how easy to set tdc with head off so maybe more than 1 incidents of stupidity.

I have used the car from 140k to 160k miles and it functioned OK except it never seemed to have anywhere near reported economy despite doing EGR delete and intake manifold clean and timing with VAGCOM. It had a pretty decent service record but no mention of new gasket/head valves etc.

Piston 1 and 4 show most impact from the small valve (exhaust?), there is a bit on 3 and none showing on 2.

Is this the original honing marks on the cylinder wall?

I am deciding wether to press on and spend the money on the head considering the car will probably need a new clutch (DMF or conversion kit) before winter and a cat or replacement pipe. Might as well overhaul the injectors as they are out. Where will it end. Still I got the turbo open and the vane mechanism cleaned (after 2 moderately successful previous oven cleaner treatments). Be a lot more fun if I had a garage. Rain stops play today. Hard to keep everything clean in the open.

Thanks so far

Mark

looks like a pretty big blow on the headgasket on cyl 2 and 3 there mate (the bits that are black/discoloured at 12 o clock on the pic). honeing looks origional but that cam lobe looks a bit funny in the pic ?

I really wouldn't worry about getting the injectors done unless you are chasing a fault we have seen cars with 400K on origionals with no probs at all.

Not seen any problems at all with cracked heads even with running a fleet of taxi's that were only serviced every 40K (they would only take them off road for cambelt)but defo looks like a blown gasket in the pics.

were the bolts all the same tightness to undo?

That camshaft looks like it has taken a battering. If I had to guess I would say that head has had a hydraulic problem.

The HG is definely leaking. The HGs on these cars are extremely tough so you rarely see actual breaks.

when you say there is no impact damage on no 2 ! have you checked the piston height compared to the rest, maybe a bent rod lurking there too.

I would look for a decent used head rather than a recon one as there is not really much that goes wrong on them to recon.

I think it wants a new cam to be honest.

Pistons will be fine by the looks of them. And I'm certain they are the original honing marks too. Does it use much oil? Looks as if it may have been run in a bit too gently!

Its worth persevering - I'd bet that the damage was done by human error on a belt change rather than anything more sinister.

Thank you for the encouragement.

I did a few measurements today after cleaning 2 and 3 piston tops. There is sign of valve contact with these also but less so.

My straight edge is supposed to be accurate to 0.01% over its length 450mm so that is 0.045mm.

I have seen it is important to take piston protrusion measurements in line with the wrist (gudgeon) pin. Not much meat on these piston heads in this place but laying the straight edge down this line gives between 1.0 and 1.05mm protrusion. OK for 2 hole even with max error with straight edge.

Using a different part of the piston I can get a measurement of 1.1- 1.15mm at an extreme end of the straight edge at the edge of the block at piston 1 because the straight edge rocks across the 2 pistons ie No. 3 surface is higher at this place on the pistonhead. Hmmm!

I have looked again at the head gasket and I think maybe the blow at 12 oclock on No. 2 and 3 are oil on the gasket from my fingers. I will wipe off and look again and maybe post new pictures.

Not really sure if the block is clean enough yet. Inexperience again.

Thanks for advice on injector nozzle replacement. I will just clean them for now and get new sealing washers along with my list of bolts and new oil turbo pipe.

Mark

Oh yes I forgot. It was using some oil but only needed topping up about every 2 months. Suprised it had an easy early life as I think it was Ex lease.

Edited 6 October, 201114 yr by MarkyD

can you take a pic of the head where the gasket seals on it or have you cleaned that up now?

there really should be no differance in height between the pistons as long as you measure in the same place for both pairs, if there is then it suggests a problem with the conrod (for an easy check I normally turn the crank till the piston is flush with the block and check both are the same) for a visual check anyway.

careful cleaning the injector nozzels as they are easily damaged and the holes are easily clogged up.