Deadheaded oil pump?
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Deadheaded oil pump?
KiwiAlfa156
Forum Mentor
It looks like those shell bearings have worn through the top 'white metal' layer to the copper layer underneath. This means the crankpins haven't been supplied with enough oil at sufficient pressure to create a cushion of oil between the pin and the shell and metal to metal contact has occurred. Given all the end big bearings appear damaged, its likely that low oil pressure/no oil flow has caused the all that damage. What caused the low oil pressure isn't obvious and whether it was caused by a bad bearing, a bad pump, or a blockage is a bit chicken and egg.
What condition were the crankshaft/main bearings in? Generally the main oil gallery feeds the crankshaft bearings that then feed the big ends. Where the damage begins and ends might help troubleshoot where the problem lies.
Have you inspected the oil pump? There is a specified rotor lobe to star clearance and side clearance. Any wear or scoring will lower oil pressure especially at idle/low rpm. The pic below is from the 750 manual, so specs might be different. Did it knock? Big-end failure is generally noisy.
What condition were the crankshaft/main bearings in? Generally the main oil gallery feeds the crankshaft bearings that then feed the big ends. Where the damage begins and ends might help troubleshoot where the problem lies.
Have you inspected the oil pump? There is a specified rotor lobe to star clearance and side clearance. Any wear or scoring will lower oil pressure especially at idle/low rpm. The pic below is from the 750 manual, so specs might be different. Did it knock? Big-end failure is generally noisy.
Sadly, those shells are pretty typical of a GSX400/4 of thsi age. Earlier on this thread there is mention of the 2nd gen 750/4 and it's plain bearing troubles. The 400/4 I think hit the Jap home market fractionally earlier than the 750. Same design team, same problems.
If the crank is marked, it's very possibly cracked too. If you take it to a reconditioner, before anything else, get it crack tested.
Grimly's mention of inserting a bigger engine is one possibility - if Aussie regs allow it.
If the crank is marked, it's very possibly cracked too. If you take it to a reconditioner, before anything else, get it crack tested.
Grimly's mention of inserting a bigger engine is one possibility - if Aussie regs allow it.
G
Guest
Guest
Hi everyone
sorry for the late update on my engine. There must of been some glass media from the hydra blasting that I had done on the engine case's. I had used a gerni to flush out all remaining media from all the oil passage ways , but unfortunately this was not the case . If any else is going to have this done to there engine please please be very careful and be 100% sure that all passage ways are clean.
sorry for the late update on my engine. There must of been some glass media from the hydra blasting that I had done on the engine case's. I had used a gerni to flush out all remaining media from all the oil passage ways , but unfortunately this was not the case . If any else is going to have this done to there engine please please be very careful and be 100% sure that all passage ways are clean.
I had a set of Honda CBR600 cases aquablasted. They sat on the shelf for a month waiting for parts. Slowly but surely a small pile of white dust accumulated in and under them.
And yes, they had been pressure washed several times. That stuff is very very hard to get completely out.
And yes, they had been pressure washed several times. That stuff is very very hard to get completely out.
Hi everyone
sorry for the late update on my engine. There must of been some glass media from the hydra blasting that I had done on the engine case's. I had used a gerni to flush out all remaining media from all the oil passage ways , but unfortunately this was not the case . If any else is going to have this done to there engine please please be very careful and be 100% sure that all passage ways are clean.
Wow, rough luck.
You're certainly not the only one to have been caught out by that. First I came across it was a UK bike mag ran a series about a rebuild of a classic (750-4, iirc) and all was shining bright and glorious until it shat the blanket one sunny day. Turned out the chap doing the rebuild hadn't totally cleared the cases of blasting media, with exactly the same result.
I must admit I've been leary of any blasting media near my cases ever since. I prefer to just get in with plenty of degreaser and elbow grease.
KiwiAlfa156
Forum Mentor
The only media I've ever blasted cases with is blasting soda for this very reason. Soda is water soluble...
G
Guest
Guest
I will not be going down the same road with my next project. 1978 gs550e . Once again thanks to everyone on this forum.
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