Spun big end bearing
Discussion
Just been informed my engine has spun a big end bearing (journal 8). Was less than 100 miles old. Obviously gutted.
Built it myself but was the 4th one I've done so not a novice. Advised it looks like oil starvation or picked up some debris.
Anyone with a keener eye let me know if they agree/disagree?
Oil pressure warning light was not seen at any point.
Built it myself but was the 4th one I've done so not a novice. Advised it looks like oil starvation or picked up some debris.
Anyone with a keener eye let me know if they agree/disagree?
Oil pressure warning light was not seen at any point.
Has it actually spun within the rod? Looks like there was heat but to me there's less damage to the crank then I'd have expected. No 7 journal's not great either, how fresh was the crank when you built the engine?
I'd put it down to a clearance issue.
I'd put it down to a clearance issue.
Edited by Boosted LS1 on Thursday 30th August 20:18
Boosted LS1 said:
Has it actually spun within the rod? Looks like there was heat but to me there's less damage to the crank then I'd have expected. No 7 journal's not great either, how fresh was the crank when you built the engine?
I'd put it down to a clearance issue.
Thanks for the reply mike,I'd put it down to a clearance issue.
Too much or too little clearance?
You can feel the grooves in 8 and a definite step between the two journals. Yes, number 7 isn't great either.
Crank was taken 10 thou under just before build and checked on that actual journal with plastigage on assembly. 2.5 thou clearance.
Yes that does mean it was torqued up on a new rod bolts, then undone to check plastigage and retorqued with same bolts. Could that be it?
Hope not...
Boosted LS1 said:
That's a lot of clearance. What grade oil were you using? Do the journals look any different going from front to rear?
10w40 millers running in...BUT in my defence I have a roller cam whose lifters specifically call for oil no thicker than that - was on a big sticker on the front of the box.
I assume they were a known make of shells?
And I assumed they had the normal indentation that fits in the bed of the con rod?
I can’t see it ever being too much clearance, only the opposite.
It is difficult to think of any reason apart from oil starvation which would cause a heat buildup in that area and therefore cause the shells to grip the journal.
I am just about to assemble my engine I will do the usual fit each one, turn the crank over a few times and make sure that everything runs smoothly. There is not a lot else that you can do.
Was it a new crankshaft or a good used one? I suppose there is a very slight possibility that some debris has blocked the oil delivery orifices but they are quite large and that seems doubtful.
Alternatively, there may have been a total oil delivery failure and that will show on the remainder.
Is it a pre-serp engine?
And I assumed they had the normal indentation that fits in the bed of the con rod?
I can’t see it ever being too much clearance, only the opposite.
It is difficult to think of any reason apart from oil starvation which would cause a heat buildup in that area and therefore cause the shells to grip the journal.
I am just about to assemble my engine I will do the usual fit each one, turn the crank over a few times and make sure that everything runs smoothly. There is not a lot else that you can do.
Was it a new crankshaft or a good used one? I suppose there is a very slight possibility that some debris has blocked the oil delivery orifices but they are quite large and that seems doubtful.
Alternatively, there may have been a total oil delivery failure and that will show on the remainder.
Is it a pre-serp engine?
phazed said:
I assume they were a known make of shells?
And I assumed they had the normal indentation that fits in the bed of the con rod?
I can’t see it ever being too much clearance, only the opposite.
It is difficult to think of any reason apart from oil starvation which would cause a heat buildup in that area and therefore cause the shells to grip the journal.
I am just about to assemble my engine I will do the usual fit each one, turn the crank over a few times and make sure that everything runs smoothly. There is not a lot else that you can do.
Was it a new crankshaft or a good used one? I suppose there is a very slight possibility that some debris has blocked the oil delivery orifices but they are quite large and that seems doubtful.
Alternatively, there may have been a total oil delivery failure and that will show on the remainder.
Is it a pre-serp engine?
Can we also assume that the Cap and rod were matched, did you torque up the cap and rod to measure for size and ovality.And I assumed they had the normal indentation that fits in the bed of the con rod?
I can’t see it ever being too much clearance, only the opposite.
It is difficult to think of any reason apart from oil starvation which would cause a heat buildup in that area and therefore cause the shells to grip the journal.
I am just about to assemble my engine I will do the usual fit each one, turn the crank over a few times and make sure that everything runs smoothly. There is not a lot else that you can do.
Was it a new crankshaft or a good used one? I suppose there is a very slight possibility that some debris has blocked the oil delivery orifices but they are quite large and that seems doubtful.
Alternatively, there may have been a total oil delivery failure and that will show on the remainder.
Is it a pre-serp engine?
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