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Discussion Starter #1
Hopefully someone can help. I blew a head gasket on my 445. Pulled the engine and while apart I wanted to do a complete overhaul. Everything in spec, motor clean, all looked good. Honed cylinders, new rings, lapped valves, new seals, standard stuff. When I went to re assemble the oil pump I noticed the relief spring sat about 1/16” below the housing meaning when the oil pump cover is installed there is no pre load on the relief spring. This relief set up is pretty standard ive rebuilt plenty of compressors and Harley engines and without the ball seating it’s oil pressure relieved back to the sump and no oil pressure. The housing looks perfect where the ball seats, spring length in spec. I ordered a new ball and spring anyway and no difference. I called my local JD shop and no one there was familiar with the Kawasaki engine and said just put it together if there was no oil pressure problems which there wasn’t. I’m having a problem with that, there is just no way it will ever build oil pressure. The service manual and parts breakdown does not show a shim or spacer between the cover plate and spring, which would pre load and seat the relief ball, but I’m wondering if they possibly used one on this engine and somehow I lost it. I don’t want to put the engine in and have to pull it out again. Has anyone run into this? Any help much appreciated - I need this thing back together so I can get the lawn cut! Thanks Bob
 

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Bob, Let me first say I've never worked on a 445 and therefore have no experience, but just follow this through with me. If nothing like a shim or spacer is shown in any manuals, I'd say it's not required. Do you have a low oil pressure indicator? If so, remove the sending unit and install a pressure gauge...at least just temporarily so you are certain you have pressure.

Let me give a possible scenario and these are numbers I'm pulling out of the air: Let's say your lubrication system requires 2 ounces of oil per minute at 30 psi and your pump produces 8 ounces of oil at 60 psi. With the relief ball not seated, you're going to loose flow and pressure. The amount is based on the size of the hole the relief valve is NOT covering. If the engineers did their job, I'd say you'd loose 5 ounces per minute. This would leave 3 ounces per minute from the pump and pressure will rise...as the system will only use 2 ounces..., pushing the relief valve open more until you have 2 ounces per minute at 30 psi. Again, this is only a possibility!

Unless someone else responds differently, put it together, install a gauge and fire it up! Bob
 

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Is it possible there is oil pressure on both sides of the ball? Plus the spring side has a bleed off, so spring only is overcome at a specific psi? :unknown:

Does your service manual list maximum pressure the relief controls the oil to?
IIRC the low oil light is set at 4psi. Taking it out for temporary gauge installation sounds like a good idea.
 

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I wish I could remember the details, but when I replaced mine about 8 years ago, I recall the oil pump was tricky to get it installed just right. I fiddled with it for 20 minutes or more before I had it right. Unfortunately I don't remember what right looked like nor how I reached that point. It was related to getting pressure on the spring as I remember. It has to go together just so. Unbelievable that a JD dealer would know nothing about this engine. They must've sold 10's of thousands, maybe millions of them. You should ask another dealer. I don't remember if the service manual gave details or not. I sold my 425 six years ago and the manual went with it.
 

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Discussion Starter #6
Guys thanks for the response. The thought did cross my mind that maybe this pump puts out much more pressure than required. I think that would always be the case to some degree to meet pressure requirements when the oil gets hot and less viscous and requiring more volume. I mentioned this already but I’ve done many overhauls on other equipment and never seen where there wasn’t that preload on the relief spring/ball, excess pressure then lifting the spring loaded ball. I guess my best option at this point is put it in as is and as mentioned get a pressure gauge on it and fire it up, see what happens. I’ll also try another dealer before I button up the engine. Thanks again sometimes multiple heads are better than one!
 
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