Oil pressure drops

shawn

So, I thought I had a bad gauge, for like the past 1 1/2 years. I put in a mechanical (CJ7 with 304). It's just my trail rig, not a DD. Anyway, I guess my guage was right, I don't have crap for pressure. In fact, when cold, it's like 30 psi. After it warms up, at best like 14 psi. And hot or cold, when the rpms go up the pressure drops, the pressure goes down! I replaced the gears (with the square root cut ones) and the plunger and spring with parts from BT. So I thought it was the plunger sticking. Nope, I've messed with it and put in the old one and even different combo's of the old and new plungers and springs, all the same effects. Are my bearings trash? Or am I still having oil pump issues? This motor is solid and strong! And quiet! No noises, or issues, except this oil pressure. Any help is greatly appreciated, I really need to get out wheeling soon!

jeepsr4ever

Shawn you either have a worn out pump or some worn out bearings. Most likey a combination of both. You have replaced the oil pump gears and thats the logical first place to start. From here 14PSI isnt the end but it isnt a good oil pressure for an idle no matter who will quote old AMC technical bulletins online. If your not going to the races it can run a long time like that but if it was mine I would try and replace the oil filter adaptor and from there look at either a new oil pump/timing cover or live with it. You could also do a tear down but that is the last step and AFTER it is knocking.

shawn

Yeah, I'm thinking about geting a new adapter and seeing if that helps. When I drive this thing, I drive it to the trails, it's no trailer queen. So driving it until it knocks is not what I want to do. I may just drop the pan and replace all the bearings too, that wouldn't cost much. How hard is it to replace the cam bearings with the motor still in the Jeep?

I also want to say, I love this place! I mod some other off road we forums (gl4x4.com, glfwda.org {part of United}, member of Soldiers of Fortune Offroad {part of glfwda}), and am always refering people here and to the BT products, MC is top notch!

Anyway, here is the Jeep.

82Waggy

shawn wrote
Yeah, I'm thinking about geting a new adapter and seeing if that helps. When I drive this thing, I drive it to the trails, it's no trailer queen. So driving it until it knocks is not what I want to do. I may just drop the pan and replace all the bearings too, that wouldn't cost much. How hard is it to replace the cam bearings with the motor still in the Jeep?

Pretty much impossible to change cam bearings while the engine is in the vehicle. If you are going to tear it down that far you might as well pull the motor anyway - and here comes the never ending cascade of, "well, might as well do that too while I'm at its".

Like MC said, loss of pressure is either going to be a worn pump or worn bearings - probably both. Start by pulling the filter adapter and pump gears to inspect the pump housing for scoring. Also check for excessive gear end clearance. If that all checks out then new bearings are probably in order.

The drop in pressure with increased RPM suggests to me that bearings (and maybe lifters) are worn. A heavier weight oil may get you by for a while longer before overhaul - what oil are you running now?

How many miles are on this thing?

shawn

Less the 50 K on this motor. And it's been untouched, except for the newer gears and spring/plunger, and an Edel Intake and Holley Carb. I run 10W30.

shawn

Well, I never thought a stupid filter would have caused this kind of massive oil pressure drop! But, FRAM is JUNK, once again, FRAM IS JUNK! I don't normally run FRAM, but I now remember in January, I had a club run, and on the 200+ mile trip I noticed something was NOT right, with oil pressure, gas milage, and when I stopped to get gas and check the oil it was really low! I put all that together and quickly came to the conclusion that I lost the fuel pump. I got to the closest Auot Parts Place (which was Autozone I think, Garmin helps in this type of situation if you have the right model loaded with the area's info). Got my Fuel pump, but all they had was Fram Filters. Oil pump was deffinately bad, had fuel sitting on the arm as I pulled it out, must have been thinning the oil causing pressure issues and major losses. So, I went back to my local auto parts place (Mid 5 in Livonia, Mi) and got my self a Wick, and some 15W40. I HAVE PRESSURE!! LOTS OF IT! Almost 75 when first started. Then after warm idle was a solid 40. And about 60 at cruising RPM's. Only question now is, with this mechanical in here now, the pressure is really bouncy. It starts to smooth out around 2000 rpm's. Is this normal? My OEM one seemed pretty smooth, but also really slow reacting, so maybe that is why?