Spun big end bearing
Discussion
Ed
I spun No 5 shell at the Diamond Rock event. The cause was possibly the air lock I had in the coolant system that day which in turn led to engine overheating to the point where the oil lost its viscosity.
There was also a suggestion that the oil flow was interrupted for a moment
This obviously this is all theoretical.
The reason the SP6 is sometimes hard to start when hot is due to the gap between the pistons being small which can create expansion after being switched off.
Hope this helps
Mark
I spun No 5 shell at the Diamond Rock event. The cause was possibly the air lock I had in the coolant system that day which in turn led to engine overheating to the point where the oil lost its viscosity.
There was also a suggestion that the oil flow was interrupted for a moment
This obviously this is all theoretical.
The reason the SP6 is sometimes hard to start when hot is due to the gap between the pistons being small which can create expansion after being switched off.
Hope this helps
Mark
"
The reason the SP6 is sometimes hard to start when hot is due to the gap between the pistons being small which can create expansion after being switched off".
Do you mean piston to bore clearance? I'd have thought the pistons would cool/shrink quicker then the bores or is there something unusual about this engine that I'm missing.
The reason the SP6 is sometimes hard to start when hot is due to the gap between the pistons being small which can create expansion after being switched off".
Do you mean piston to bore clearance? I'd have thought the pistons would cool/shrink quicker then the bores or is there something unusual about this engine that I'm missing.
ehasler said:
Has anyone else had one of these go? One of mine has just failed... If you have experienced this, I'd be interested in knowing what caused it as I'd like to prevent it happening again!
Sorry to hear that's what it was. Assuming you are having this fixed under warranty(hopefully) then is it being repaired by the same company that rebuilt the engine? If so, have they offered a reason as to why their rebuild has failed so soon? (I don't mean that in an inflamatory way!, just wondering why you need to ask why on here, unless you are just seeing what others think before telling us what they told you)cheers
Whitey
PS. I'm particulary gutted for you, as my rebuild is approaching the same mileage!
It's currently back at the place that did the original rebuild 6 months ago, and the only thing they've said at the moment (bearing in mind that it hasn't yet been inspected fully by the warranty company engineer) is that spun bearings can be caused by over revving.
I'm still in discussion with them and the warranty company about it, so can't really say much more at the moment but I'm curious to know if anyone's had a similar failure as I know for sure that the engine hasn't been over revved since I got it back.
I'm still in discussion with them and the warranty company about it, so can't really say much more at the moment but I'm curious to know if anyone's had a similar failure as I know for sure that the engine hasn't been over revved since I got it back.
NCE 61 said:
Some information on spun big end bearings in this Topic
That was quite an interesting topic. My take on the bearing locating tags is that they provide lateral positioning of the shells. Get that wrong and the shell can foul against the crank cheek which prevents the oil flowing across the shell. Crush is what stops them from rotating.
Boosted LS1 said:
NCE 61 said:
Some information on spun big end bearings in this Topic
That was quite an interesting topic. My take on the bearing locating tags is that they provide lateral positioning of the shells. Get that wrong and the shell can foul against the crank cheek which prevents the oil flowing across the shell. Crush is what stops them from rotating.
ehasler said:
It's currently back at the place that did the original rebuild 6 months ago, and the only thing they've said at the moment (bearing in mind that it hasn't yet been inspected fully by the warranty company engineer) is that spun bearings can be caused by over revving.
I'm still in discussion with them and the warranty company about it, so can't really say much more at the moment but I'm curious to know if anyone's had a similar failure as I know for sure that the engine hasn't been over revved since I got it back.
Interesting that the first diagnosis although only suggested is that it could be caused by over revving. Considering a spun shell can be caused by a multitude of reasons they pick on the one that's least likely due to a rev limiter but the diagnosis that points most likely towards human error which will obviously exonerate them. I hope you have a good relationship with them. I'm still in discussion with them and the warranty company about it, so can't really say much more at the moment but I'm curious to know if anyone's had a similar failure as I know for sure that the engine hasn't been over revved since I got it back.
Whitey said:
Boosted LS1 said:
NCE 61 said:
Some information on spun big end bearings in this Topic
That was quite an interesting topic. My take on the bearing locating tags is that they provide lateral positioning of the shells. Get that wrong and the shell can foul against the crank cheek which prevents the oil flowing across the shell. Crush is what stops them from rotating.
Sorry just meant, how long would the fault of a spun big end bearing take to show up on a rebuilt engine? You have almost answered the question in that it could be an assembly fault that could take some time to appear or a more sudden fault if things move about.
The luck of the draw I guess!
The luck of the draw I guess!
I can't see how over-revving can cause a spun bearing, but maybe someone can explain that? For the bearing to rotate there must be greater friction bewteen the bearing and journal than the bearing and cap/conrod. This implies a lack of lubrication or debris as Boosted already said. With a dry sump the lack of lubrication thing is a long shot so the first thing would be to inspect the shells very carefully for any debris, and work out where it came from. After so long would you expect a dirty engine build to cause that? maybe not. Would you expect debris from another component of the engine breaking down to cause it? possibly .. that's the job of the engine builder to work out, until the engine's in bits we're only guessing.
I think over revving could cause possibly cavitation but you'd be talking about massively over revving and probably something a stock or normal tuned engine just couldn't accomplish. Think more F1 rpm's. Usually it's a clearance issue, dirt or poor lubrication. Could also be oil type, there are quite a lot of possibilities to consider once you think about it.
Boosted LS1 said:
I think over revving could cause possibly cavitation but you'd be talking about massively over revving and probably something a stock or normal tuned engine just couldn't accomplish. Think more F1 rpm's. Usually it's a clearance issue, dirt or poor lubrication. Could also be oil type, there are quite a lot of possibilities to consider once you think about it.
Following that reasoning, if you could rev the engine to such an extent that that alone caused the spun bearing, would you not expect other damage? What I'm wondering is if the absence of other damage rules out over-revving as the cause. ^ I can't really answer that as all the other factors come into play. On an ordinary road car normal occasional over revving is the sort of thing factored into it's design to cater for botched downshifts etc. If you blitzed it to silly rpm's then I'd expect all manor of things to fail but what would fail first would depend on a number of things. Multiple failures might not happen.
OK, the warranty company are refusing to pay out as they've looked into the history of my car, and have found out that it has done track days in previous years - even though there is nothing in the terms and conditions to say that this is not allowed.
The place who did the original rebuild have also just said that the repairs will be down to me, as it is likely to be down to me over-revving the engine - even though a full inspection hasn't yet been done as far as I know. The rebuild was done about 7/8 months ago, and the car has done 2500 miles since then.
So - any advice on where I go from here? It looks like I will need to get solicitors involved, but I've not done anything like this before, and want to make sure I have everything covered.
The place who did the original rebuild have also just said that the repairs will be down to me, as it is likely to be down to me over-revving the engine - even though a full inspection hasn't yet been done as far as I know. The rebuild was done about 7/8 months ago, and the car has done 2500 miles since then.
So - any advice on where I go from here? It looks like I will need to get solicitors involved, but I've not done anything like this before, and want to make sure I have everything covered.
I think you're going to be stuck as far as the builder is concerned. You'll have to prove they were at fault and that'll probably be impossible given that there are lots of ways to damage a bearing. They may not have been at fault and things like this do happen, unfortunately.
As for the insurance company, were trackdays done before the engine rebuild? If so they may be a better target as the trackday issue would become largely irrelevant if the engine had been rebuilt afterwards, fresh fluids etc. Legal action would be expensive so I'd aim for some sort of damage limitation but you need proper advice first.
As for the insurance company, were trackdays done before the engine rebuild? If so they may be a better target as the trackday issue would become largely irrelevant if the engine had been rebuilt afterwards, fresh fluids etc. Legal action would be expensive so I'd aim for some sort of damage limitation but you need proper advice first.
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