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Low or No oil Pressure

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pjm3609

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I have a 98 Fatboy (EVO Engine) with 25K miles on it. The oil pressure is very erratic and not consistent. I've already changed the oil and filter and checked the oil level. I also replaced the relief valve spring. I even took the valve out to verify it wasn't sticking. The oil system is stock and it has a Harley filter and Harley 20-50w oil. I also checked and cleaned the tappet screen. Oil pressure can be 40 at start up, 30, 10 or zero. Sometimes it will increase when I rev the engine other times nothing. I have both an idiot light and a gauge. I expect to see a decrease when the bike gets up to temperature and at idle but this makes no sense as the oil pressure is all over the place. I changed the oil pressure sending unit and added the gauge just above the tappet screen. I also removed the the sending unit when it started I had pressure and oil was pumping out of the hole. Also did this when the gauge was reading zero and the oil light was on and no oil was pumping out of the sending unit hole. Basically this is a real problem and intermittent.

Has anyone ever had this problem?
Thanks and ride safe.
 
pjm3609 said:
I have a 98 Fatboy (EVO Engine) with 25K miles on it. The oil pressure is very erratic and not consistent. I've already changed the oil and filter and checked the oil level. I also replaced the relief valve spring. I even took the valve out to verify it wasn't sticking. The oil system is stock and it has a Harley filter and Harley 20-50w oil. I also checked and cleaned the tappet screen. Oil pressure can be 40 at start up, 30, 10 or zero. Sometimes it will increase when I rev the engine other times nothing. I have both an idiot light and a gauge. I expect to see a decrease when the bike gets up to temperature and at idle but this makes no sense as the oil pressure is all over the place. I changed the oil pressure sending unit and added the gauge just above the tappet screen. I also removed the the sending unit when it started I had pressure and oil was pumping out of the hole. Also did this when the gauge was reading zero and the oil light was on and no oil was pumping out of the sending unit hole. Basically this is a real problem and intermittent.

Has anyone ever had this problem?
Thanks and ride safe.
Click to expand...

From what you said and the checking you have done and no flow of oil at the open plug. I would say replace the oil pump. It isn't a big job on the EVO and I would go with a high volume one.

signed....BUBBIE
 
I would change the pump pay attention to the bushing the shafts run in check them for scoring, I have seen Evos chip a gear in the pump and cause this type of problem, like Bubbie says it is a pretty easy job do you have a manual?
 
I forgot to mention that I bought some different rate springs for the pressure relief valve. When I put the higher rate springs in I had 50 or 60 lbs of pressure at idle but never ran the bike with them in. When I put the lower rate spring in I had pressure for 20miles. I haven't gone back and put the higher rate spring in to see what it will do yet. If there was a problem with the pump it seems like I wouldn't be getting 50 lbs of pressure. I was thinking of taking the lines off and cleaning everything I could get to see if there is a blocakage some place before removing the oil pump. Maybe something broke such as the gear you suggested and is creating a blocakge. I have the manual and it looks like hardest part of replacing the pump is centering the new one.
 
I have a 96 evo and I have the same problem I put an adjustable oil preasure relief valve and it helped abit but my oil preasure is all over the place too but I havnt had any problems it could be that when at idle the gauge is not very accurate and it just seems like no oil preasure is there just a thought (If you had no oil preasure at all the lifters would make noise fairly quickly )
 
There were metal chips in the oil (not aluminum). I had the lifters and bearings replaced. The oil pump and rockers were ok.
 
So your fixed and good to go? Oil pressure is now "steady". By chance do you know what part the metal chips came from?
 
I shouldn't have typed in chips. More like dust or very small particles. The particles were trapped in the lifter screen. No we could not determine where it came from. I'm the 3rd owner of the bike and it looked like someone had been in the engine before. I have the idiot light and a oil gauge so I can monitor the pressure.
 
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