Re: Dealer say oil pumps don't need rebuilt on H

Posted by jim jordan on October 27, 2004 at 20:18:40 from (63.164.212.169):

In Reply to: Dealer say oil pumps don't need rebuilt on H posted by Charles Myers Sr. on October 27, 2004 at 17:48:20:

Most of my experience is with oil pumps in automobile engines, some were high performance engines. The auto maker provided wear limits for the pump gears and for housing to gear clearance. Unles dirt went through the pump or the pump was run dry, they were usually within tolerance when the engine was tore down. With automobiles, especially highperformance ones, it was common practice to replace the pump when the engine was rebuilt even if it was still good. there were usually three choices for a replacement pump. A stock pump, a high pressure pump and a high volume pump. I am not familiar with the pump for the H, but the pumps that I have seen had a pressure relief valve on them that would dump excess pressure back to the crankcase. If you have a relief valve you should check the valve for leakage and the spring for tension. If the valve is leaking or if the spring is weak your pressure will be low. A relief valve problem usually is more noticeable cold than what you have. Many people used to make the mistake of installing a high pressure pump oh shimong the relief spring to rais the pressure without checking to see where they were loosing the pressure. This would put excess pressure on bearings that were already worn to the point that they should have been replaced and often washed away the rest of the bearing surfaces in a short time. The stock pump was usually the best choice unless the engine had been rebuilt loose, this was often done with racing engines, in which case the high volume pump would provide increased oil flow at stock pressure to make up for the extra oil flow thraugh the losser than stock bearings. Oil pressure will drop drastically on a engine with worn bearings when the engine is warm. Worn pump gears will produce a similar drop but is less common. I would check the pump out real good. then put it back together if it checked out. If it was worn or had any other defects that I found I would replace it. If I reused the pump I would fill it with a light grease to prime the pump before I put it back together. If I replaced the pump with a new one I would open it up and prime it with grease before I installed it. I would check the main and rod bearings and if I found a lot of wear I would check the crank journals. I would check the Camshaft and cam bearingsfor wear and replace any parts that were worn. While I had the engine open I would take a good look at the cylinder walls and the rings if the sleeves showed wear. If it needs done it is better to do it all at once than to pull it down again with only a few hours on it. My best guess is that your crank bearings are causing the drop in oil pressure.
Jim

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• Re: Dealer say oil pumps don't need rebuilt on H Allan in NE 04:54:23 10/28/04 (0)

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