QuestionI have a 1927 Chrysler I-52 4 cyl, at idle the oil pressure is 22 lbs and 40 at high speeds. Manual calls for 4 to 8 lbs. at low speed and 10-22 lbs. at high speed. I pulled the bearings, tubes no obstructions, relief valve backed out. Have destroyed two oil pumps from excessive pressure so far. Can hear the thumping increase as the pressure builds up. Has not been hooked up to the vacuum tank since I had the vehicle (electric fuel pump)and this just started recently. Help!!!!! Thanks Joe
AnswerI can think of six questions to ask:
1. What oil are you using? For this engine, I'd use SAE30W oil in summer, and SAE20W when the temperature is going to be below 32F before the next oil change. Do not use any additive. Do not use multi-viscosity oil such as 15W40.
2. Are you sure that the oil pressure gauge is correct? To be sure, obtain another gauge of the type that is hydraulically operated (not electrical) and thread it into a fitting that is plumbed into the oil pump output lines.
3. When you say the oil pressure relief valve is backed out, are you certain that the piston is free to move in the valve? Backing out the spring usually will lower the maximum oil pressure, but if the piston sticks, you will have excessive oil pressure regardless of the spring tension.
4. Is there any possibility that the main and rod bearings are fitted too tightly?
5. When the oil pump fails, what exactly fails on it? The pressure of 40 PSI does not seem high enough to cause any problem for the pump.
6. Is it possible that the wrong oil pump is fitted to the engine?
I have no direct experience with your engine type - so I am not going to be your best bet to figure this out - if you can find someone with more knowledge about the early Chrysler 4, you may be able to get better suggestions from that source. You could contact Egge Machine Company in Santa Fe Springs CA and ask to speak to someone with knowledge about this engine.
I hope these ideas are some help -
Dick
