I have a 70 Maverick with a 302 from a 78 Fairmont. It has been sitting for a few years but after a lot of body and suspension work it now registered and it runs and drives. At startup it has good oil pressure 40 - 50 pounds but after warmup drops to 10 or lower at idle and 15 - 20 when driving. I would like to replace the oil pump and want to know where to start and how hard is it? Any links or advice is appreciated. Thanks, Don
Oil pump is not the problem. The bearings have too much clearance is the reason the pressure drops after it warms up. Using straight 30 wt oil will help a little bit but don't expect a miracle.
replace oil pump how many mile are on the motor? my maverick has a fresh 302 (about 1500 miles) and runs 50-60pounds on startup then right around 40 pounds cruising at 45mph. higher at hwy speeds. oil pump not hard to change if you can get oil pan off motor while it is still in the car. may have to remove all steering arms.just have to make sure the pump and distributor shaft seats together. other than that it would be pretty much self explanatory once you have the pan off and can see what your looking at. I guess my curiosity is if your motor is just getting tired or if your pump is really the problem. what i do know is 10pounds at idle is NOT GOOD at all. should have more pressure than that. should be able to get a Chilton's manual or something of the sort that would show you step by step how to change it.or do a search on line, but I'm guessing your bearings have too much clearance as previously stated.also i run 10/40 full synthetic mobile one. heavier oil might help but not cure the problem. rthomas771 is dead on.
if you dont have the money for a rebuild you can change the bearings out in the car. its not the easyest thing but its cheaper than a motor. remove the pan first. then do one bearing at a time. on the main bearings you can remove the cap, then take a small cotter pin and bend it into a T. you can stick the leg of the T into the oil passage on the crank. bend the tops of the T so they are flat against the crank. look at the ends of the bearing that are in the block. one end will have a notch that keeps it from spining. turn the crank to have the cotterpin push on the side with out the notch. this should walk the bearing around the crank so you can remove it. just reverse the process to put the new bearing in. this should bring back the oil pressure. really the only other place you can loose oil pressure like that is if a cam bearing got pushed out. i havent really seen that happen but hey anything can happen.
Thanks for all the help and suggestions. I have no idea of actual mileage. I bought the car in the spring with 302 already in it. The previous owner bought it to restore but gave up when he couldn't get his new front springs in (he got them out ok). I had tons of fun getting it on the trailer with my wooden blocks for springs. I plan on replacing drivers fender and doing some bodywork this winter and then a fresh paint job. I am adding "removing pan" to replace bearings as Bryant describes in the thread. Hopefully that will get me through next year and I can replace/refresh motor and rest of drive train. Thanks again, Don
Replace all the bearings - It will take an engine tear-down because you should also replace the cam bearings. Then install a new pump. A new pump will not fix worn bearings - it may hide the symptoms until something lets go but it will not fix anything.
