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Discussion Starter · #1 ·
I'm having an issue with a new Stroker built '06 4.0. After the engine gets good and warm, I lose oil pressure, at idle, and my check gauge light comes on and beeps. I can get the pressure back if I heal and toe with a little throttle. I read the threads of other Jeepers similar problems, "replace the sensor", which I did. "OPDA" (Oil Pump Drive), which I replaced, and still no fix. I also read on a different forum that high volume oil pumps (which I have) should not be used on stroked engine. I also have a ticking sound I can't pinpoint because it only happens under load. I noticed the OPDA that I pulled started to have the teeth on the gear wear down bad and I only had a couple hundred miles on it.
 

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I'm pretty sure there's a port where you can attach a real oil pressure gauge to get true readings of exactly what our pressure is at both idle and running speeds. Once you have that info, you may have a warranty issue if your engine is newly rebuilt.
 

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1. What weight oil?

2. At what RPM do you make 30-40 psi of oil pressure? If you can't make pressure at 2000 rpm, I wouldn't run the engine till I figured out what the cause is.

3. When you built the engine, did you check the rod & main clearances? Possibly have to great of clearance or wrong size/undersized bearing on standard or re-ground crank. I always use a product called 'Plasti-Gauge'.

4. Did you use the old oil pump, did you remove or check the oil pressure relief in your pump. Possibly stuck or miss assembled.

5. I run a High Volume pump, its a great tool for the right purpose. I run one on an engine with 300,000 miles. I replaced rod & main at 150,000, replacing an old pump was just good practice, I went for a high volume because of mileage, highway use, high ambient temperatures, and I wanted to keep the jeep for a long time. Your engine should have all fresh bearing surfaces, and a HV pump shouldn't be necessary.
 

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I know on my 2000 4.0 the service manual says 13psi at idle is what the pump is designed for.
 

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Replace the oil pressure sender with a new Mopar sender. Not a cheapy from a store like Autozone.
 

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Discussion Starter · #7 ·
Thanks for the replies. Well, everything is new on the engine. Crank, cam, bearings, roller rocker arms, everything. The high vol pump is new and now have another one Quadratec sent me in case mine went bad. I'm still in the break-in period on the engine so I'm using the suggested Delo 15-40 (high ash content typical of diesel oil), with zinc additive [Lucas]. Already changed the initial first oil change after 500 miles with filter. I had a good speed shop here do the overhaul and they used the latest machining tools. They were very strict on the quality of the build. I spent $1900 on the labor alone. Unfortunately it turns out these guys, who've been in the rebuild business for over 20 years, decided to call it quits. They're selling all their equipment. So I'm screwed on any warrantees. So, my oil pressure is good if I'm driving. But when the engines good and hot at idle it takes a dump. I bought a cheap-o sensor from O'Reilly's, but I really don't think that's my problem. This all started when I took the Jeep in to have it Dynotuned.
 

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If you verify that your pressure gauge is accurate (new mopar sensor or mechanical gauge) Your problem is most likely your main bearings. It sucks, but that is what I would be checking.
 
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