rebuilt engine wont start no compression

got the original engine with my campaign project, from what I can see it had head gasket and looks like new pistons, I was told its been honed and had new rings too.

cant get it to fire after 2 days of trying and lots of turning over. has whole fuel system from a running gti, timing is correct.

just done a compression test and compression on cylinders 1 and 2 is 1 bar, cylinders 3 and 4 were low too but around 8 bar

its not been run since the work was done and don't know how long its been sat, I did put oil in the cylinders when I was working on the body and was turning it over by hand every now and then

any ideas why the compression would be so low on 1 and 2, was really hoping it would at least start since I went to the trouble of fitting it

Many possibilities. But is the head tight I once brought a non runner and all they had forgot to do was torque the head down. Have you seen the engine stripped? If not it could simply be BS from the seller and it needs a strip and rebuild. If you have the space and skill I would whip the head off and get it checked, could be cracked or warped. For sure being low in compression screams take apart and do it properly to me rather than trust what someone say they did. Sorry I can't give a better verdict


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not seen it apart but I can see that its had a new head gasket and the pistons look new, cambelt and tensioner is new, also plugs, leads, cap and looks like oil seals on the crank are done plus rocker and sump gasket. I do believe it was rebuilt just not sure how well

just had another look at the engine and through the spark plug hole I can see the valves have been ground. got me thinking about valve clearance and whether the shims might need changing, will try and find some feeler gauges to check them. tried another compression test with a little oil in the cylinders and the readings were 25 psi on 1 and 2 and 150-160 on 3 and 4

That's Pants mate!

Must pop over some time for a look at progress!

borednow said

That's Pants mate!

Must pop over some time for a look at progress!

its a bit of a let down after all the work that's gone in to it although at least I have a better idea of what has been done to the engine and should be able to get it running well. pop over anytime mate would be good to see yours.

got it to fire up on 2 cylinders, still low compression on 1 and 2. tried checking valve clearance and as suspected there is none on any of the valves.

need to figure a way of re shimming when I cant measure the clearance, I suppose just assume I have 0mm gap and reduce shims by .25 and .45 or maybe more, will have to re do them once I can get a gap to measure. got a spare engine so tempted to see what shims it has

I was gonna say check for valves stuck open, but now you have found no clearance theres your problem.

right I have tried swapping some shims from my spare engine but didn't quite have the right thickness, now have compression in cyl 1 and a bit more in cyl 2,

its a bit low but still have 0 valve clearance, so shows I am on the right track to fixing it.

 also measured and made a note of thickness of the spare engine's head so should be able to rebuild that to right specs, most were only .10mm too thin

 probably going to have to reshim at least 2 more times as still don't have a gap to measure. some of the shims had no readable thickness so just guessed but have swapped them all to ones with sizes on so that should help.

I think its now running on 3 cylinders so definite progress from it not starting at all.

Get a set of these, I bought mine from lidi for a £5.
They will give you an idea of what shins are fitted.
You could get new shins from vw a few years ago when I rebuilt my head.

http://www.ebay.co.uk/itm/6-150mm-Digital-Vernier-Caliper-Electronic-Micrometer-LCD-Measuring-Gauge-Tool-/192248858884?epid=1262782273&hash=item2cc2ecc904:g:MV0AAOSwvc1Zahew

New shins here also.
http://www.vwspares.co.uk/g1other.php

thanks those shims are the cheapest I have seen, however they don't have the thickness I will need classic vw want £4.50 each!   

the problem is I have no gap to measure so don't know how much thinner they need to be even if I have the thickness. so need to change them so I can measure a gap then calculate what I will need from there

Try calling a vw dealer, I did not pay a lot for mine but as I said it was a few years ago.

Very strange having no gap at all,  perhaps someone has fitted the wrong type of valves? There is a couple of types?

few sets on eBay.
https://www.ebay.co.uk/sch/i.html?_odkw=mk1+golf+shims&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xmk1+golf+valve+shims.TRS0&_nkw=mk1+golf+valve+shims&_sacat=0


could you swap some of the other ones to see if you can get a gap?

Not telling you how to "suck eggs" but are you measuring the gap correctly and are the other 2 cylinders correct?

have found them for around 2.50 each so not too bad only problem is I will need to guess what thickness will give me a gap, but a lot easier than taking  the head off and pistons out

 I think there is no gap due to the valves and seats being ground and not re shimmed. following Haynes for measuring the clearance so think it should be accurate, the other 2 cylinders have compression but also 0- 0.10mm clearance so guess the valves are just seated so probably need to reduce shims a little less on these 2  

Take the thinnest shim you have on your spare engine and move to each valve in turn to give you a measure on each. Just a thought if they could not shim it properly what else could they not do. Change the belt while in there in case it is the old one refitted and take it easy once running i case they have messed up other stuff like not torque setting the bottom or bigs ends maybe. I hate the doubt caused by someone else's work when you uncover a fundamental mistake. Keep at it and well done.


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Backinblack said

I hate the doubt caused by someone else's work when you uncover a fundamental mistake. Keep at it and well done.


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Ain't that the truth….

thanks, it doesn't fill me with confidence but was told the engine builder knows what they are doing and all the work that i was told about has been done so don't hold it against the po, the valve cover wasn't bolted on so maybe it was going to be done when the engine got fitted.

 to re grind valves and fit new pistons, rings, cambelt and tensioner, all gaskets, have the head skimmed etc takes a bit of knowledge so not too worried about it but i have a spare engine if it all goes wrong,

my spare engine has the engine no removed and stamped with this so think its a recon engine too, came from an 83 gti. i also have another spare dx engine that was in an 83 cabriolet but it has a hydro head?   


i did get one for my other 83 gti but am leaning towards fitting the abf engine i have

sporttrucker said

thanks, it doesn't fill me with confidence but was told the engine builder knows what they are doing and all the work that i was told about has been done so don't hold it against the po, the valve cover wasn't bolted on so maybe it was going to be done when the engine got fitted.

 to re grind valves and fit new pistons, rings, cambelt and tensioner, all gaskets, have the head skimmed etc takes a bit of knowledge so not too worried about it but i have a spare engine if it all goes wrong,

my spare engine has the engine no removed and stamped with this so think its a recon engine too, came from an 83 gti. i also have another spare dx engine that was in an 83 cabriolet but it has a hydro head?   


i did get one for my other 83 gti but am leaning towards fitting the abf engine i have

 check your pm