vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by Forden341 »

I think the only way it could be linked to the clutch cover plate would be in the unlikely event that the cover bolts were possibly too long and are protruding through the flywheel and hitting something on the block maybe?
They would have to be over 25mm long I’d imagine to cause a problem.

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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by spanishfly »

Hmmm I don't have a block or flywheel to look at but from pics on tinternet there are 3 holes in the flywheel which would mean that the distance between 2 of them would be about 120 degrees which is probably the amount of movement I have.....? Perhaps a coincidence?
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by Oldiebut goodie »

I note that you still have not said how you ascertained that you had the compression stroke. That is a basic thing on rebuilding any engine. All you say is that you have checked an upward movement of a piston.
As far as I can tell you are grasping at anything else that could be a possibility without doing the first check for the basic timing.
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by spanishfly »

You are right I do seem to be trying to avoid removing the rails , mostly as I'm worrying recentring the push rods from underneath would be harder than on the engine stand.

All isn't/ wasn't clear and it was a while ago, hence the lack of clarity but as far as I recall guided by Bentley and others I set the v to the TDC position aligned or near to the case split, cross checked the rotor arm lined up with the groove on the dizzy at 4 o'clockish then used my chop stick to confirm each piston was at the top before centring the push rod checking with a torch and adding 1 and a half turns continuing through the sequence 180 degrees at a time as per Bentley 1 - 3 - 2 - 4?

I'd not done it before so quite possibly I made a mistake, or mistakes (confusing cylinders 1 and 2 conceivably?) certainly failed to check using a Rizla, thumb, plastic bag to see compression. That said in order to complete all the tappets I had to continue rotating clockwise back to the beginning and didn't encounter any hard stops then. Like the feeling when the van is in gear.

I transported the engine to the van , fitted clutch and gearbox then manhandled the whole cursy lump into position on my back in a puddle with the aid of lots of bits of wood and a jack!

Also having slackened off the rail nuts last weekend until all the push rods swivelled I thought I might have discounted the idea that a valve being open at the wrong time was what is creating the resistance as none were under tension?? I guess it would be better to remove the rail and see if that removes the obstacle.

Just to be clear I tried twice to use the starter with the king lead and fuel pump disconnected so the engine only turned a max of 120 degrees and only the first time probably less before meeting the hard stop. I'm hoping as the engine didn't fire the force of the starter would not have been sufficient to bend anything or 2 things given the engine hard stops in 2 places backwards and forwards 120 degrees apart.



I realise this is difficult to answer and appreciate the time...

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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by Stesaw »

1 - 3 - 2 - 4? hope not

1.4.3.2 the same as the dissy rotation (clockwise) in that picture I posted.

Cylinder 1 is front right on engine
Cylinder 4 is rear left on engine
Cylinder 3 is front left on engine
Cylinder 2 is rear right on engine

Dissy should be by checking the cap and leads

Bottom Right point Cylinder 1
Bottom Left point Cylinder 4
Top Left Point Cylinder 3
Top Right Cylinder 2

It's not tricky to get the pushrods set right when the engine is in the van. If you spin the pushrod when you seat the arm onto them they should center, if you really wanna be sure buy a cheap USB endoscope. I've got one and its come in handy. Make sure the lifters are all primed so if you were to push on the rocker to try and move the pushrod there should be no spongeyness, shouldn't be able to move them at all once you adjust.
Last edited by Stesaw on 17 Sep 2021, 23:58, edited 8 times in total.
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by Oldiebut goodie »

Hitting a valve by turning over with the starter is certainly enough to bend a valve stem - have seen the result many moons ago.
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by tobydog »

Try turning the engine by hand and feel the valves when it jams to rule them out?
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by ajsimmo »

It won't be valves, as Simon has removed the rocker assemblies and it still locks up.

There was vague talk of something being machined before assembly. It may possibly have been the back of the oil pump to give clearance for the cam gear bolts (unidentified flat 3-bolt aftermarket cam), as I discussed with Simon yesterday. He's fitted a new oil pump, so may have unwittingly reintroduced a problem that's previously been "solved" by the builder.

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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by tobydog »

spanishfly wrote: 17 Sep 2021, 23:05 You are right I do seem to be trying to avoid removing the rails , mostly as I'm worrying recentring the push rods from underneath would be har
Simon
?
 
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by spanishfly »

ImageImageImageThink that's what you call a smoking gun! 120 degrees!!! Thanks to Andy Simmons for his clear thinking and hand holding help. 
 
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by Oldiebut goodie »

Aaaaaahhhhhh....... good call.
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

Post by ajsimmo »

Boom!!
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Re: vw t25 wbx engine won't turn over after top end rebuild with gearbox fitted

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===================
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