F head Oil Pressure Low

Put 10 miles or so on the A1 this weekend mild offroading and it runs great. 2nd gear low range is ideal for cruising the pasture. First gear in high range is not sufficient for anything really. First low range seems to be lower than the same in my MB with the 6.00 16 tires which was my hope.

Now the bad... Oil pressure is about 20 psi cold start-up. It drops to about 6 after a few minutes of driving and then finally settles out around 4 or so hot. So it IS pumping oil. I'm not too concerned about running it at low speed, but if you need to throttle it pretty good in the mud or climbing something, could case problems. So- Where to start troubleshooting? I am going to run a quart of Marvel Mystery Oil through it and change the oil and filter. From there do I replace the oil pump? Is there a pressure spring somewhere that may be bad because of age/heat? Any help that doesn't involve bearing shells greatly appreciated!

 

what weight oil are you running? i would recomend at least 15w40 that far south, maybe even 20w50 if the engine is high mileage

 

SAE 30. I think... But 15w 40 is what my plan was to run. I run that in all my non fuel-injected vehicles and diesels. That's partly why oil and filter change will be my first stop. But should still be higher than it is regardless of oil weight.

 

well, i was gonna point you that direction next, plastigauge them and see what your clearances aremehh sae 30w should be fine, think that is what they called for back then

 

not stupid at all, could be a faulty gauge.... ive never been that lucky though

 

I was-- after tearing int the engine (on a CJ-7) and replacing the pump, I still had no oil pressure. Replacing the sending unit (a 15 min job) solved the 'problem'.

 

I had a mechanical Stewart Warner in there when I got it, and replaced with a mechanical Autometer. After seeing low pressure on the new gauge, swapped the SW back in. Same result. Should have mentioned that when I first posted. Off to read from the CJ3B page...

Thanks for the link, a good read. My engine runs exceptionally quietly, especially the valve train so it seems to be oiling the top end OK. It starts easily, idles smoothly with neither smoke on start or at idle.

Looks like I will buy an oil pump if flush and change isn't effective.

 

check your oil that you drain! does it smell like gas?? you may have a fuel pump issue, and if so it will thin the oil, and eventually wipe out the bottom end

 

i recently had my f head engine lock up due to no oil pressure... the problem was the filter inside of the oil pan was clogged (excuse me for not being savvy with technical terms) and didnt allow the oil pump to work at all. i dont know how or why it was clogged but it was. i dont know if this tid bit of info will be of any help, but its worth a check!

 

I checked the oil for gas when I got the jeep. It had an aftermarket electric pump on it and I swapped back to a mechanical (PITA-I had to re-do the line to the filter that was some large fitting hydraulic hose and would not clear the pump) Good idea, though. Thanks for all the suggestions.