Lost oil pressure - what damage

[GreigM]

My engine has a dry sump system which is belt driven. The belt snapped and I noticed the pressure warning light immediately and coasted on lowish revs to a safe place - the engine ran for no more than 10 seconds with the warning light on. Whats the likely damage - will 10 secs be enough to screw the engine, or will it likely just be a little more wear? I intend to drop the sump and drain the oil and look for metal fragments but if I see none will I have got away with it?

I'd rather not rebuild the engine if its not needed, on the other hand if I dont rebuild and there has been some damage - whats the likely outcome, will I blow the engine or just need the rebuild later on?

[Paul.B]

What were the driving conditions when the belt snapped? Full bore track work or gentle town stuff?

If you were off the power as soon as the light came on then that would help.

[GreigM]

It was on track, but a gentle corner - and the light flickered which backed me off the revs so by the time it came on solidly I was way less than 1/2 max revs....and then it was a case of coasting and minimum revs for the few seconds to get me to a safe spot...certainly didnt at any sort of hard throttle during that 10 seconds

Edited by GreigM on Tuesday 14th September 12:30

[Pumaracing]

It's pointless guessing. Remove the sump and check the main and big end shells. If those are ok then the rest of the engine will be too. If they are scored then check and measure the crank journals to see if a regrind is needed but that's unlikely. If the crank's ok then you can just replace the shells but the damage will almost certainly be confined to shells and crank journals only after such a short time without oil pressure. It takes a lot longer to start hurting the pistons, bores or top end.

[Paul.B]

I'm not sure going straight for a re-build is the right action. Well worth some investigation work and maybe taking some advice from an engine guru! (I'm guessing this is in the turbo 'Busa Westie?)

I also doubt you will loose too much by replacing the belt and trying the car, after said advice and starting off gently of course.

[GreigM]

yes its the westie - but not turbo'd - just a stock busa engine, my thoughts are get the sump off and look for scoring - if none and no metal in the oil then I was going to simply reassemble, refill and see if it holds pressure.......is it the kind of thing that will either work or won't? If there is no sign of damage and it holds pressure is it likely to be ok, or could it be a timebomb?

Edited by GreigM on Tuesday 14th September 12:45

[Paul.B]

See what PR has said ^^^^^^ Like I said an engine guru!

[davepoth]

Could indeed be a timebomb - and at the revs you are doing that could make a bit of a mess. Given how easy it'll be to whip the engine out (compared to a big car engine anyway!) I'd be playing it safe.

What pressure does the light come on at? I know in my triumph it's 2psi, so that's more of a "your engine's fked" light.

[garagewidow]

i would think there would be enough residual oil in the oilways to keep the bearing safe,considering how miniscule the gap is between shell and journal the oil film is only microns thick.
suck it and see and monitor the oil pressure.

[ColinM50]

So why did the oil pressure drop? As far as I can see you've either lost the oil or lost the pump. If the former then as others have said drop the sump check the bearings and go from there. If the oil quantity's OK then the pump will need changing. They're cheap as chips so not worth messing about with get a new one but you'll have to whip the engine out, sump off etc etc.

Unless there's another reason for the light to come on?

[Tictac07]

Because the scavenge pump belt broke, leaving the pressure pump high and dry once it had emptied it's tank? Consider fitting a micro switch on the belt, that way you will have oil pressure whilst you react to the problem of a belt failure if it happend again?