a mate has just had his cu engine rebuilt its back in the van and starts ok.but when it gets hot it will not restart and when you turn the key the engine is very tight what is wrong with it.it was put back together and put in my a vw garage has anyone got any ideas thanks.
Maybe it's a weak battery or a bad connection on the starter or a bad earth.clean all connections and make sure there tight.maybe even stick some jump leads on the battery and jump start it from the car and see does it speed up the starter.
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Smile. I think you need to be alot less cryptic and lot clearer and take more time to post a question with some 'real' information in it..
Trouble shooting can't be a one way street - you have most of the information and opportunity to investigate further, are you asking for a thousand guesses or do you want to help peeps home in on something reasonably likely to achieve a useful answer without another 15 pager only to find a crucial piece of information was missing from the start.
Try putting together a more rational explanation of where we are with the history of exactly what was done and why in the first place to this engine, who did it (and their experience/provenance/reputation), what analysis troubleshooting your mate has made since finding it is tight when restarting hot. What he has done as a logical set of exercises to discover something that might lead someone to give useful advice remotely (that is online)
Many thanks...
Oh. If it's a complete rebuild with rebore/pistons then it could well be tight to turn over for a few hundred miles but if everything is as it should be then it should fire when the first piston goes over compression and not be an issue.
How has it been driven in this hot weather from new rebuild... etc. etc etc. How many miles on it from this new rebuild... etc etc etc
And crucially.. What has the mechanic who rebuilt it to say about the situation.. could you at least tell us that?
right i can only go by what im told as its not my engine.i ask my mate and he said that it drives ok untill it gets hot.then when you turn it off it will not start.it will turn over but very slow like if the timing is way out but its not.its got a new battery and all the connections have been cleaned and the voltage is good new starter motor ect.the oil has changed and looks ok no metal in it.he did that he has bench started it and run it on the bench he has put about £50 worth of fuel through it and it seems to be getting a bit better if you need any more info just let me know thanks.
If it was put back together and put back in by a "VW garage".. why isn't he on there doorstep telling them to fix it...
Something is clearly wrong and we can take a load of random guesses..
not turning over when hot could be the starter motor bush is nipping up..
Or.. the engine is actually overheating and is partly seizing..
Is all of the cooling tinware and seals there?? if it isn't.. then its a hot engine, sucking in hot air.. which wont cool it... I have seen this loads of times...
But.. He ought to be asking the garage that did the work to sort it out......
a mate has just had his cu engine rebuilt its back in the van and starts ok.but when it gets hot it will not restart and when you turn the key the engine is very tight what is wrong with it.it was put back together and put in my a vw garage has anyone got any ideas thanks. 
hi thanks but the person who done the rebuild went out of business and we can not find him.