Big end shells

[Richair]

Det will have little short-term effect on the big-end other than giving it a bit of a pounding (no way near enough force to heat it up enough to quench it though!!!).

This must be down to an oil starvation problem. I can't think of anything else that would cause a failure so early on in an engines life. However, check that the journal for that rod is straight as if its on the p1ss due to heat it could cause failure.

Remove the crank from the block and test all of the oilways by blocking them off in-syc (rig up a bottle of oil to the oil-way input and pressurise the bottle with an airline). Also test all of the oil-ways on the crank by the above method.

Also ensure that the builder hasn't just done something stupid like not lining up the key-way holes on the bearings.

Never, ever trust an engine builder until you are convinced they no what they're doing. Many places are usued to building run-of-the-mill low comp, ecconomy engines where any f5ck-ups are hidden my massive tolerances. Belive me, there are a lot of cowboys out there.

HTH!

Rich

[Daveuk9xx]

marT350T said:

The engine builder did say that there evidence of detonation one one psiton. Dont know which one though.

Please could you explain why/what effect this would have on the bottom end.

Cheers

Detonation creates pressures of thousands of psi in the cylinder. Several times those of normal combustion. Usually the piston melts first but it can easily be enough to destroy the big end bearing if that's already heavily loaded or marginal on lubrication. If the engine builder just keeps replacing the same parts without curing the basic fault it sounds like you need a better engine builder.

[stevieturbo]

There's a difference between a detonation damaged bearing, and a fried bearing from lack of lubrication.

As he has already said, when rebuilt, they used a new crank, and rod. ( I assume this is correct ? )


You need to do a full test on the oil system, and visually check for flow.



Again though. What flywheel are you using ? Crank damper ? Ive seen cases where an ultralight flywheel has been fitted, which was supposedly balanced, and within a very short space of time, big ends failed. Twice this happened. Rebuilt again with a standard flywheel, and it was all good.

[dickkark]

Are you using the same piston,it could be cracked expanding oddly once heated
its worth a look and might explain the cylinder temp problem as well.has it been bored? or bored correctly? is the heat damage confined to the big or small end or entire rod?
Heat up the piston and rod assembly and have a feel for clean movement,though you would expect to see marks on the skirt and bore really.

Regardless of what peoples views of running in are,I dont bother but any new bearing of any design or style will still need a certain amount of initial bedding in which makes it hotter and less tolerable of extra stresses,s as you seem to have changed everything else twice and are sure the oil feed is good then it can only be something that is connected directly to the rod/journal,which dont leave a lot really. it`s also far cheaper to replace a piston and get the block measured properly than take chance on a new crank and rod only for it to go tits up again.

[marT350T]

stevieturbo said:

There's a difference between a detonation damaged bearing, and a fried bearing from lack of lubrication.

As he has already said, when rebuilt, they used a new crank, and rod. ( I assume this is correct ? )


You need to do a full test on the oil system, and visually check for flow.



Again though. What flywheel are you using ? Crank damper ? Ive seen cases where an ultralight flywheel has been fitted, which was supposedly balanced, and within a very short space of time, big ends failed. Twice this happened. Rebuilt again with a standard flywheel, and it was all good.

I had the fly wheel replace for a lighter one when I had my clutch replaced last year. I shall mention this point to the engine builder, Thanks.

Dont know about crank damper

[stevieturbo]

marT350T said:

stevieturbo said:

There's a difference between a detonation damaged bearing, and a fried bearing from lack of lubrication.

As he has already said, when rebuilt, they used a new crank, and rod. ( I assume this is correct ? )


You need to do a full test on the oil system, and visually check for flow.



Again though. What flywheel are you using ? Crank damper ? Ive seen cases where an ultralight flywheel has been fitted, which was supposedly balanced, and within a very short space of time, big ends failed. Twice this happened. Rebuilt again with a standard flywheel, and it was all good.

I had the fly wheel replace for a lighter one when I had my clutch replaced last year. I shall mention this point to the engine builder, Thanks.

Dont know about crank damper

It is a longshot, but possible. But fully check and test the oil system first.

I had a problem with a Cossie once with no low pressure...turned out an oil gallery plug in part of the block had come out, although it was hidden behind the dizzy/oil pump drive housing. I only found it when I spun the pump up, with the engine on a stand, and holding the sump so I could see what was going on !!!!

[Deltaf01]

stevieturbo said:

marT350T said:

stevieturbo said:

There's a difference between a detonation damaged bearing, and a fried bearing from lack of lubrication.

As he has already said, when rebuilt, they used a new crank, and rod. ( I assume this is correct ? )


You need to do a full test on the oil system, and visually check for flow.



Again though. What flywheel are you using ? Crank damper ? Ive seen cases where an ultralight flywheel has been fitted, which was supposedly balanced, and within a very short space of time, big ends failed. Twice this happened. Rebuilt again with a standard flywheel, and it was all good.

I had the fly wheel replace for a lighter one when I had my clutch replaced last year. I shall mention this point to the engine builder, Thanks.

Dont know about crank damper

It is a longshot, but possible. But fully check and test the oil system first.

I had a problem with a Cossie once with no low pressure...turned out an oil gallery plug in part of the block had come out, although it was hidden behind the dizzy/oil pump drive housing. I only found it when I spun the pump up, with the engine on a stand, and holding the sump so I could see what was going on !!!!

Sounds a little like the old fiat ducato's (diseasel i know) that used to chuck their plugs out of the crank drillings as they were miniatures of the coolant core plugs and wernt staked.... knock knock knock...

[marT350T]

So just found out the No1 big end shell has gone again exactly the same as last time.

My question is now, last time it happened he said it was not under warrenty as another garage had fitted the turbo and mapped it. If the same thing happened again am I now in a position to ask for a refund for the first time this happened as now one else has touched it ?

[stevieturbo]

marT350T said:

So just found out the No1 big end shell has gone again exactly the same as last time.

My question is now, last time it happened he said it was not under warrenty as another garage had fitted the turbo and mapped it. If the same thing happened again am I now in a position to ask for a refund for the first time this happened as now one else has touched it ?

Performance items like this, carry no warranty.

Without knowing a cause, and doing a full test on the oil system....its hard to lay blame for an attempt at warranty.

You need to ensure No1 was, without doubt getting adequate oil flow. If it wasnt, then perhaps some blame can lie with the builder.

If it was, then some external variable was causing the problem......which is why I mentioned flywheel. As impossible as it seems...we had a Sub engine years ago, die twice in a very short period of time. Big ends. the only common part between the 2 engines, was the flywheel.
Needless to say, we never used it again, and never has such problems again.
It was a second hand, ultralight billet flywheel. No obvious signs of unbalance when driving...seemed totally smooth. Obviously something was up though.