Non-starting Sharan After Top-end Rebuild

[chrisbeeching]

Hi guys.

 

Hope you can help.

 

Quite used to rebuilding engines, but this Sharan 1.9Tdi (standard issue on a 97 plate) had dropped a valve head off no. 1 valve. Result; damaged piston top (replaced), hole in bottom of head (replaced), but nothing else apparent.

 

Solution: I got a head off a running Sharan, same (AHU) engine code, similar mileage from a breakers, complete with injectors, cam, all valve gear etc. Head complete!. Rebuilt engine, new gaskets as appropriate, took care to keep job clean as always. Turns over, some compression (*see below), but won't start. No fault codes (have reader and resetter) - well, the driver's door lock showed a fault, reset, but nothing else - but won't start. Good (new) battery. Timing marks all carefully aligned (including the cam on its tapered dowel!)

 

I have heard since that it's prudent to evacuate the hydraulic tappets before reassembling and refitting a head on these engines. Could it be that some are 'overfilled' and holding valves slightly open enough to sound like there's compression, but not enough to fire the engine up?

 

Not desperately keen to take the cam off again (don't like disturbing things once they're set, but will do if you think it's worth it).

 

Any advice or experience gratefully received.

[f0ster]

Hi guys.

 

Hope you can help.

 

Quite used to rebuilding engines, but this Sharan 1.9Tdi (standard issue on a 97 plate) had dropped a valve head off no. 1 valve. Result; damaged piston top (replaced), hole in bottom of head (replaced), but nothing else apparent.

 

Solution: I got a head off a running Sharan, same (AHU) engine code, similar mileage from a breakers, complete with injectors, cam, all valve gear etc. Head complete!. Rebuilt engine, new gaskets as appropriate, took care to keep job clean as always. Turns over, some compression (*see below), but won't start. No fault codes (have reader and resetter) - well, the driver's door lock showed a fault, reset, but nothing else - but won't start. Good (new) battery. Timing marks all carefully aligned (including the cam on its tapered dowel!)

 

I have heard since that it's prudent to evacuate the hydraulic tappets before reassembling and refitting a head on these engines. Could it be that some are 'overfilled' and holding valves slightly open enough to sound like there's compression, but not enough to fire the engine up?

 

Not desperately keen to take the cam off again (don't like disturbing things once they're set, but will do if you think it's worth it).

 

Any advice or experience gratefully received.

 

Hello

does it sound normal when cranking over, when they have no compression or if the valve timing is out they sound different when cranking over, if ok then check if it is injecting any fuel, crack the injector pipes loose and spin it over, is there any fuel squirting out from under the pipe nuts, you might have to double check the valve and pump timing settings, autodata has an A4 print out of the belt layout if you have access to the program, if not I can email you a print, take off the inlet pipe to the manifold, and listem when cranking over, can you hear air escaping when it goes over compression, do the same at the exhaust,

[chrispb123456]

Hi and welcome to the site

Its been known for the Mk1 to struggle to pull diesel from the tank after being dissmantled

Disconnect inlet pipe to fuel filter then temporarily fit an old mechanical lift pump in the line, then you can pump by hand clean fuel through the filter and injection pump, then just crack open injector pipes breifly while turning on starter.

[chrisbeeching]

Hello

does it sound normal when cranking over, when they have no compression or if the valve timing is out they sound different when cranking over, if ok then check if it is injecting any fuel, crack the injector pipes loose and spin it over, is there any fuel squirting out from under the pipe nuts, you might have to double check the valve and pump timing settings, autodata has an A4 print out of the belt layout if you have access to the program, if not I can email you a print, take off the inlet pipe to the manifold, and listem when cranking over, can you hear air escaping when it goes over compression, do the same at the exhaust,

 

 

Hi. Thanks for your reply.

 

It does sound 'normal' when cranking but it was a mechanic friend who suggested the tappets may be a smidgeon too tight as he'd had a similar problem with a Golf with a similar engine.

 

I did put fresh fuel in and bled they system through, including taking off the 'return to tank' to make sure it was getting right through the system. I also slackened the injector unions to check fuel supply to them - all appears fine. I also had injectors pressure-tested, and all are well within rated spec, and show good spray pattern.

 

I could also try using an electric pump to pressurise the fuel inlet side and see whether that makes any difference, but poking around last nigh, although there is certainly 'resistance' at the appropriate parts of the rotation cycle it now doesn't feel 'enough'. Maybe I'll whip the cam off, evacuate the lifters and see whether that works.

 

I'll update when I've tried it.

 

Thanks Guys.

 

Chris

[chrispb123456]

Hi there

Can't see that with the oil,if you have taken the head off a running engine and have not disturbed the camshaft there should be no problem, sounds more like timing problem if there's little compression