Mercruiser 4.3 Oil Pump

[Dan F.]

Great site yall have here and what I've read in the last 9 months tells me there is a wealth of knowledge to be had so I finally decided to join in on the fun. Okay heres the situation. I had a 2000 model engine that was cracked and got a '94 model that wasn't and swapped everything over after numerous trials and tribulations. Alum. oil pan don't go on engine that had steel pan,oil pump pick-up screen from Alum. pan engine now hits steel pan,etc,etc,etc. Well after getting all this stuff figured out and finally assembling the engine and goin for a break in cruise for 1 1/2 hrs at lower rpm it was time to let her eat. Bam,lower end knock! Pull engine last weekend and pop pan off to find #2 cylinder rod bearing hammered all to heck. Pull a couple other rod caps and #2 main journal cap to find other bearings not looking so good(not as bad as #2 rod bearing). Only thing I can figure is a lubrication issue.
Now the question. I used the oil pump for the 2000 model block and the guys at a local auto parts place helped in finding a screen from a buick engine that was the right pipe size(3/4"),shape and deep enough for the steel pan. After looking at several Mercury engine application,the earlier model motors used p/n 17617 for the pump and p/n 35354 for the screen(NLA). Could it be that the 3/4" pump could have sucked the pan dry which caused the damage or am I just chasing my tail and should look elsewhere for a lubrication problem? Sorry to be long winded but this is very frustrating trying to figure out what went wrong. Thanks for any help in advance

 

[Don S]

Re: Mercruiser 4.3 Oil Pump

Could it be that the 3/4" pump could have sucked the pan dry which caused the damage or am I just chasing my tail and should look elsewhere for a lubrication problem?

Nope, that pump will not suck the pan dry. Lots of things can take out the bearings, and it may not be oil pressure. Can you post some pictures of the bearings so we can see what they looked like? What was the oil pressure on the gauge doing all this time?

 

[Dan F.]

Re: Mercruiser 4.3 Oil Pump

Don't have the bearings on hand at the time but can tell ya #2 looked like it was put on an anvil and beaten severely. The others just looked like damage from bearing material in the oil since it was very silvery. Oil pressure at the time of knock was about 70psi running at 4600rpms. Doesn't make sense. Fresh engine bored .030 over,all new componants,crank was in spec.and only polished. Well now it will have to be ground down due to minor scoring but I did back the throttle off when the noise first happened.

 

[Don S]

Re: Mercruiser 4.3 Oil Pump

http://www.engineparts.com/publications/CL77-3-402.pdf

Have a look at the link above and see if any of the pics look like yours.

 

[Dan F.]

Re: Mercruiser 4.3 Oil Pump

Well the closest one I can figure by memory(and that ain't so good no more)would be insufficient crush but can't be sure till I get one from the garage. I'll reply with the findings tomorrow. Appreciate your time this evening sir and you have a good night.

 

[Don S]

Re: Mercruiser 4.3 Oil Pump

I would be looking at how the main bearing was installed. Did the oil hole line up OK? How about the cam bearings, were they replaced? The oil flow is through the cam bearings to the crankshaft and rod bearings. If the hole isn't lined up properly for the cam bearing, it could shut down or restrict the oil flow to the crankshaft and rod bearings.
70 Psi of oil pressure is too much, which would indicate to me that there is a restriction somewhere.

PS: My name is Don, not sir.

 

[cr2k]

Re: Mercruiser 4.3 Oil Pump

70 psi oil could float the bearings out too.

 

[Don S]

Re: Mercruiser 4.3 Oil Pump

70 psi oil could float the bearings out too.

Sorry, but I have personally never heard the expression "Float the bearings out", what does that refer to?

 

[Bondo]

Re: Mercruiser 4.3 Oil Pump

Ayuh,... Who assembled this motor,..??
Were ALL of the bearings,+ their Clearances measured during assembly,..??
Was everything Pre-lubed,..??

Why wasn't the 94 rebuilt,+ installed, Vs. mixin', 'n matchin',..??

 

[ENSIGN]

Re: Mercruiser 4.3 Oil Pump

Unless you plasti-gauged the bearings first you have no way of knowing if that engine was any good from the getgo!!!

 

[mkast]

Re: Mercruiser 4.3 Oil Pump

70 psi oil could float the bearings out too.

Maybe, more likely improper air pressure in the trailer tires.