445 Low oil pressure

DanZemcik · May 27, 2015

Hi everyone I am looking for some advice on my MM 445 Utility. With the engine cold I have about 40 psi of oil pressure. After about 30 minutes of use the pressure falls off badly. About 5 psi at 1500 rpm. Less at idle speed. Changed the oil, used 30wt oil. Still the same. Adjusted the external screw on the oil pump, but it only changes the cold pressure and had no effect on the hot oil pressure. Double checked the pressure gauge with another one, and it is accurate. I am considering replacing the oil pump and see if it improves, but fear the problem really is worn out crankshaft or bearings. Is it worth the try to replace the bearings without removing the crank? Any ideas for me to try? Thanks!

rpllr · May 27, 2015

Pull the side cover off and make sure the pickup screen has not fallen
off or stuck in the up position it floats with the oil level. I had one a
stroker motor get knocked off and would have good pressure till things
got stirred up in there. Easy to check if not that pull the center main cap
while there and look at bearing. What weight of oil are you usuing?

DanZemcik · May 27, 2015

(quoted from post at 09:08:46 05/27/15) Pull the side cover off and make sure the pickup screen has not fallen
off or stuck in the up position it floats with the oil level. I had one a
stroker motor get knocked off and would have good pressure till things
got stirred up in there. Easy to check if not that pull the center main cap
while there and look at bearing. What weight of oil are you usuing?

Using 30 wt oil

Curt Cooke · May 27, 2015

I would. It only takes a matter of minutes to remove the center main bearing and a rod bearing. You can then determine if they are worn to the brass and what size they are. If those two are worn, they likely all are and maybe you can get .002 over to replace.

JOCCO · May 27, 2015

If a canister filter check that I have seen it caused by filters before also look to see if it has any check balls and springs in the pressure relief or adjustment screw. That can cause it too. Others covered lower end but if it has pipes in side the engine to the bearings that will cause it/ (My MM R) had that issue.

fastfarmall · May 27, 2015

If u do take it apart, make sure, if the crank has been cut 0.10, make sure it doesnt have standard brgs in it. Yes that happened, the parts guy grabbed standards gave them to the mechanic,he never looked what the machine shop stamped into the first throw on the crank, the good news is i didnt ruin the crank or block ! But i had to pay for it!!

Alan K · May 28, 2015

When I worked at a shop in town, I was overhauling a 3020 JD. Ive always inspected parts before installation and good thing I did. The rod and main bearings we were given were for some other model. While the bearings fit, the oil holes didn't line up. Glad I caught that one.

Roger H MI · May 30, 2015

It sounds like a crankshaft. Or that was what was wrong with mine. Will cost about $500 to
replace. It runs about 50lb now. Make sure your governor is working good.

DanZemcik · Jun 28, 2015

Thank you all for the input on this. Put a new used oil pump on it, and picked up about 20 psi of oil pressure. Happy with the results! Then I put it up for sale and sold her to someone else who may want to tinker with it some more, as I do not.

445 Low oil pressure

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