Firing On 3 Help Needed

[Paul Smith 0]

Hi

 

I have a couple of questions, i have jut done the head on the gti and she wont idle to well and the reason for this is due to the engine now only firing on 3 the answer may be simple, 1 of the HT leads fell apart when i was stripping her down so i am using a different ht lead that is sparking but it appears its quite weak. I have ordered new HT leads and new plugs and am hoping this will sort it but any other ideas of something I may have missed or easily missed?

 

The other question on the bottom of the inlet manifold at the front you have 2 water pipes and advice on which way round these go i think they are correct but worth a check.

 

The 205 is a 1.6 gti 1989 (earlier parts)

 

Thanks

 

Paul

[Paul Smith 0]

Hi

 

ok checked the compression working drivers side to passenger

 

CYL 1 is 200PSI

CYL 2 is 40 PSI

CYL 3 is 140PSI

CYL 4 is 200 PSI

 

so cyl 2 and 3 are the problem any advice?

[Tom Fenton 1,542]

Obviously there is a problem, some more background may help us, why did you take the head off in the first place?

[Paul Smith 0]

The head was taken off due to a failed head gasket the head was then put in to a company to be repaired but then the company seemed to disappear so I had to pick up another head I then had everything done to the head as in valves, seats, skimming, springs all that and now put back together I am wondering if I may have got some of the shims muddled up. As the original disappeared the new head and parts had none of my markings on so it is possible a mistake would have been made and thinking back it would have been a good idea to re shim the head. That doesnt help now though lol.

 

Is there a standard shim size or how i measure for new shims?

 

What is the standard compression as 200 psi looks really good. (trying to look on the positive side)

 

Thanks

 

Paul

[Paul Smith 0]

Planning to see if I can recover this lost compression this morning, gonna put a small amount of oil in each cylinder to see if the compression changes if it doesn't or not by very much then it will be a valve issue, now not sure how I know if its sticking open but the valves were lapped in and the valve seats skimmed so I am kind of hoping it is just 2 shims letting me down. I have a couple of shims from gti's laying around so I may try measuring the 2 to see the difference and swap them over.

 

What do you think?

[Super Josh 4]

I would get your feeler gauges out and measure all of the valve clearances. Then shim up any discrepancies and then recheck the compression.

 

Haynes gives a good overview of the procedure and your local dealer should carry some shims. Although if you have any lying around from your old head you may get lucky and be able to set them all within tolerance

 

 

Josh

[Anthony 1,003]

If the valves had been reground or you weren't fitting the original cam, the original shims probably would have been wrong even if you had got them in the correct order. Using the shims from head 1 on head 2 would likely be even worse. As Josh said, a set of feeler gauges to check the clearances and reshim as required.

 

If it's holding the valve(s) open slightly because there's no clearance, that would cause low compression.

[Paul Smith 0]

Hi

 

Ihave fitted the different shims in the correct order the only slight change is cyl 2 is now 70 PSI, the next problem is the smallest feeler gauge I have is 0.05 and it will not go under most of the cam? So how now is best to measure them so I am within distance of the car running, she will idle but if you rev her slightly she drops off the rev count and dies.

[Anthony 1,003]

If even a 0.05mm feeler gauge won't go under, then that's almost certainly your problem (and will be considerably worse hot)

 

Swap the shim(s) on the valve(s) that have zero clearance with smaller ones, until you can fit the feeler gauges in and get an accurate measurement. Some vernier callipers to measure the existing shims, deduct one from other, and that's the thickness of shims that you need.

 

Obviously you need to do all eight valves even if the compression test results are OK, not just the zero clearance / low compression ones though.

[Paul Smith 0]

Thats cool,

 

I have done it i ground the shims to fit and they work beautifully all are within tolerance and compression has now been restored, yippee. I took her for a test drive where she was a little rough for about 5 miles then she seemed to clear and ran excellently I am well pleased she has been sitting for quite a few months and to finally have her back is wonderful. Now a new probelm has occured.

 

On the way back from the test run where she wasn't pushed at all as I didnt want to damage her if i had made a problem she developed an oil leak again the cam belt side of the engine which all i can do is presume it is the cam seal. The oil leak is the sole purpose the head came off in the first place as I couldnt track it.

 

Has anyone got a picture of a head where the cam seal would go so i can compare this to mine. Mine has a small hole there which I'm not sure if its meant to be there if it isnt then that could well be the leak if it is then i am unsure how to stop the oil leak.

 

Thanks again for all the help so far, it was brilliant to drive her again