hi,
4000 miles ago i rebuilt my V7 sti engine, with forged pistons, race bearings and an uprated oil pump (after it melted 2 pistons!!), last week it started knocking after i stripped it i discovered the one con-rod bearing had totally destroyed its self??
any ideas why only one bearing would fail??

 

Mods, fuel used, remapped?

Tony

 

no re-map (yet) and i always use super unleaded, thought it was strange that a bearing should fail so soon after a rebuild! the oil did look like it could of done with being changed, but it was changed only 3000 miles ago, gonna check the oil ways, would a re-map be nessesary with the mods i've done??

 

Unless the new pistons have raised the compression ratio, you haven't done anything that could be deemed as "performance enhancing" mods. Could be your old problem back to haunt you ie. why did it melt two pistons in the first place?

JohnD

 

yeah, thats what i'm afraid off!!
i thought it was oil pump failure the first time, so i fitted a new uprated oil pump, but it still wrecked a bearing this time i'm fitting an oil pressure gauge, apart from maybe a dodgy oil way, what else could it be??

 

Have you checked the fuel pump? If it is dropping pressure at high boost/revs it will lean out and overheat pistons. This can cause the piston to get tight in the bore and the big end can fail. Or you may have knackered injectors, which can do the same.

 

for a drop in fuel pressre to be a big concern you'd have to be pushing the engine (seen the result of running out of fuel and keeping your toe in and i can tell you its not pretty on the pistons) and if its not mapped then it could be just the fact it isnt mapped and being puished.

if you've not been driving it hard then something major indeed is wrong

 

i was pushing it a bit when the bearing went, can see how the fuel pressure might be at fault, is there a way of checking it or is it a case of replacing injectors and pump??

 

tbh my guess is becuase of not being correctly mapped

 

i'm gonna buy an uprated fuel pump and get the injectors checked out, will get a remap after i run the engine in...slowly, haha
thanks for the advice!!!

 

Any half decent garage could do a fuel pressure check for you.

JohnD