300tdi engine rebuild crank locking SOLID

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martys0uth

martys0uth

Active Member
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Location
The Wirral, Merseyside
Well, me and my dad have been rebuilding a 300tdi we got from breaking a disco.

Tbh in hindsight the engine did not need it but it's going to be 'last engine that goes in the 90' kinda thing.

Shells didn't need re-doing, so it was a nice new rings etc.

Upon putting the pistons back in with correct corresponding big end sequences, we loosely put the con rods in and then continued to Torque the bolts to correct spec, we did piston number 1 to correct spec and went to turn the engine over with a breaker bar and hey presto, the engine is locked up completely solid, off one piston?!

Anyone else experienced this? the engine was a runner before we pulled it and had a very small puff of smoke.
It was that bad that combined with it being cold, it snapped a 20" breaker bar!!

We took the pistons out and proceeded to clean all the bearings, making sure we got any and all dirt off, and then smeared a small (like 2-3 drips of oil) amount of oil on the bearing in case it was the metal on metal contact causing it to stick.

Still can't do anything with it and completely bewildered!
 
The breaker!
 

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Is the head still on?

If so, could it be valves fouling the piston from moving up further?

If not, I trust the piston hasn't protruded so far as a ring has popped over the top of the block and jammed up (unlikey if you say you have fitted the cap and torqued up, but yer never know!
 
An ounce of lubrication is worth a ton of pressure. :) Popular saying in bovine obstetrics!

OP, are you sure the nice new rings were the right size for the pistons, and correctly installed on the piston?
 
martys0uth said:
Well, me and my dad have been rebuilding a 300tdi we got from breaking a disco.

Tbh in hindsight the engine did not need it but it's going to be 'last engine that goes in the 90' kinda thing.

Shells didn't need re-doing, so it was a nice new rings etc.

Upon putting the pistons back in with correct corresponding big end sequences, we loosely put the con rods in and then continued to Torque the bolts to correct spec, we did piston number 1 to correct spec and went to turn the engine over with a breaker bar and hey presto, the engine is locked up completely solid, off one piston?!

Anyone else experienced this? the engine was a runner before we pulled it and had a very small puff of smoke.
It was that bad that combined with it being cold, it snapped a 20" breaker bar!!

We took the pistons out and proceeded to clean all the bearings, making sure we got any and all dirt off, and then smeared a small (like 2-3 drips of oil) amount of oil on the bearing in case it was the metal on metal contact causing it to stick.

Still can't do anything with it and completely bewildered!
Click to expand...
You may have the big end cap on back to front.
Did the crank turn ok in the mains prior to tightening #1 big end cap.
Are the big end shells correctly inserted in the rod, i.e. tangs seated correctly.
 
+1 for big end cap and if you have fitted it back to front and its so tight engine wont turn with a bar I would say new shells needed, also did you keep the caps with their rods?
 
Thanks for all the replies.

Turboman said:
An ounce of lubrication is worth a ton of pressure. :) Popular saying in bovine obstetrics!

OP, are you sure the nice new rings were the right size for the pistons, and correctly installed on the piston?
Click to expand...

yes, when all 4 pistons are in loose they all turn over super smooth without any effort at all.

Gazbo said:
You may have the big end cap on back to front.
Did the crank turn ok in the mains prior to tightening #1 big end cap.
Are the big end shells correctly inserted in the rod, i.e. tangs seated correctly.
Click to expand...

Yeah the crank is perfect prior to the big end cap being tightened. all shells from what I can see are okay, they have a little nib sticking out so it's only possible to go in one way, caps are the correct cap for the con rod etc.

it got to the point where my dad has taken a piston and conrod with the cap to a engineering shop to see if it was out of line or something, but they are perfect no whiff of them bent or anything.
 
lynall said:
+1 for big end cap and if you have fitted it back to front and its so tight engine wont turn with a bar I would say new shells needed, also did you keep the caps with their rods?
Click to expand...
We looked at the shells, thought they'd only need replacing if there's wear to them I.e. Copper colouring. The shells literally looked perfect. Kept them together however would it make the difference if the cap shell was in the piston side and vice versa?
 
Sorry to have to state the obvious, but before you start stripping and rebuilding things it is far better to know what you are doing. If you snapped that breaker bar trying to turn the engine you have done something seriously wrong.:D
 
Saint.V8 said:
Is the head still on?

If so, could it be valves fouling the piston from moving up further?

If not, I trust the piston hasn't protruded so far as a ring has popped over the top of the block and jammed up (unlikey if you say you have fitted the cap and torqued up, but yer never know!
Click to expand...

Come on Ant, i would like to see how he got the pistons out to change the rings and back in with the head on. :D:D
 
Saint.V8 said:
Come on Tony.....

Head off.....pull pistons....replace rings.....replace pistons....head on.....turn engine....jams up....
Click to expand...

Come on Ant. Why would you fit head before fitting con rods to crank and ensuring things are free. There are certain ways of doing things you know that. ;);)
 
wammers said:
Come on Ant. Why would you fit head before fitting con rods to crank and ensuring things are free. There are certain ways of doing things you know that. ;);)
Click to expand...

I'm not saying I'm an expert in engine re builds by far, dad's a lot more knowledgeable than me... But to clarify the head is not on ;)

Going to redouble check the caps when I'm in there tonight but I'm pretty confident they are correct cause they are stamped with numbers :p
 
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