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Oil Pump

2522 Views 5 Replies 4 Participants Last post by  flitecontrol
Alright, I said I would post some pics of the tear down of the engine. So here is what I found. :(Oil pump seized due to FOD from oil drain plug filter. The oil plug bolt was stripped and I couldn't get it opened. I did take it to a dealer and I thought they had replaced it but I was wrong:confused:. So, the washer came out, was broken up into several smaller pieces, and a couple of those peices made it into the oil pump and seized it. During that process the external gear shift mechanism was bent and the oil pump chain guide was bent as well. My only question is the crankcase has some damage where the oil pump sits, any suggestions on buffing it out?

Also, since I've got the engine torn apart, any suggestions for replacements parts, upgrades, etc. that I may as well change. The bike has over 100K on it. Its a 1989 VN750.

Also, any good threads on putting this back together or just follow manuals?
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I guess there a several things you may want to look before you get full on the renovation. First I would check the crankcase damage you mention above, can't really tell by the photos but if the damage it's rather small you may be able to get away with it by removing all the sharp edges. Check free play around the bearings in the crankcase to look for extra play. All bent pieces must be replaced so you may want to start making a list of the replacement parts. I would also replace the balancer rubber dampers on the left side damper (stator side) and gaskets may be needed.
The manual should tell you the free lenght of the drive chain for the oil pump you want to check that.
So far that's what comes to mind... uhmmm maybe the piston rings as you have significant mileage on them. You may want to give them a look
Hope this helps
First of all, does this engine have over 100,000 miles on it without having been apart before? I was just wondering because I put over 80,000 on a '93 without it having ever been apart, and currently have 45,000 on an '02.

I have never had a VN750 engine apart, so I can't tell you what to look for. I suspect however, that with 100,000 miles on it, there will be significant wear to a lot of parts, including the cylinders, rings, valves, cams, cam chains, gears, and of course all bearings, including the crankshaft bearings, which are not easy to replace. If I were going to tear an engine down to the extent you have, I wouldn't want to have to do it again for another 100,000 miles.

Lance328 is probably the one to answer your questions, I believe he has rebuilt several of these engines. Jerry.
Yes it does. I already have a pretty long list. I didn't think about the balancer rubber dampers. I am going to hone the cylinder block this weekend and buy new pistons with new rings. Also a new water pump impeller as was suggested in a different thread. Not sure if I need new clutch plates. I was going to change the clutch springs though. Also repacing all the chains (cam, oil pump). They are getting stretched close to the limit and I don't want to do this again in a few years. Taking the crankcase to a mechanic to check the damage, I may be able to weld a patch and smooth it out to fix it. Will also replace the crankshaft bearings since I'm in there.

Any other parts that come to mind would be great to know about especially after market improvements? Someone mentioned a better designed gear shift mechanism but I can't find the thread again.
Yes these are original miles without being split before. It was taken care of well. The person I bought it from used the bike as his only means of transportation. I do plan on replacing as many parts that I can afford. I don't know exact miles because the speedometer cable broke and wasn't replaced for a couple years of driving.
There is an internal shifter rod that wasn't designed properly on the first few model years. According to lance, it will eventually fail (although you'd think it would have already done so on a bike like yours with so many miles). The rod was modified in the later models and is much stronger. I'm not sure when they began installing the heavier rod, but believe it was after 1989.
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