I need a little advice on the best procedure to remove or rebuild an oil pump on a 350. My 72 service manual seems to say I have to remove the oil pan. I am not too excited about doing that right now....my back is killing me! Local Buick club Skylark guy says all I have to do is remove the distributor and then I can rebuild the pump externally. Does anybody have a good method of doing this? Thanks for the input!! Chris
I agree with the local guy. I have removed the timing cover on a 350 before without removing the pan, and the pump is attached to the cover so.... It shouldnt be that hard, just listen to the advice from the Skylark guy. Take out the distrbuter, then take off the pump down below, I'm thinking there are just two bolts that hold it on, but I'm not sure. Just take a look and you should be able to figure it out. :TU:
thanks Steve. The irony is I had all the accessories off the car up until this weekend so I could clean up the front of the engine and put in a new radiator and fuel pump easily. Well....here I go again! Chris
There are actually 6 bolts that hold the oil pump cover on. Once you have removed the dis. you can remove the oil filter and then the pump outer housing. Don't forget the bolt that is inside where the oil filter covers. Be careful as the gears could fall out and hit the ground or your head. Don't damage the gears unless you plan to replace them any ways and then it won't matter if you hit the ground. If you can get a new thrust plate from your local parts dealer you will better off than just puttin the cover back on especially if the cover is badly groved. Use Vasoline to pack the oil pump when you go to put the gears back in. This will help keep every thing in place and help prime the pump when it back together. Thats about it just replace in reverse order using a new gasket. Also once everthing is back in place you want to check and make sure the pump turns easily and doesn't bind by putting a long screw driver down the Dis. hole and turning the pump by hand. A drill and pump priming tool can be used but always check by hand first.
Chris, Why do you need to rebuild the pump? Are you getting low oil pressure? I would not rebuild the pump unless it needs it. Do you have a good mechanical oil pressure gauge hooked up? Oil pumps will normally last the life of the engine. The main reason they go bad is because of increased clearances inside the pump. There are alot of people who don't change their oil on a timely basis. This increases wear in the pump, and other parts of the engine. The oil pump on a buick is contained in the timing chain cover. The oil filter nipple and pump cover plate can be removed once you remove the oil filter. You do not need to remove the distributor. The rebuild kits contain new gears, gaskets, relief valve and spring. Whenever you disturb the pump cover or remove the timing chain cover, you lose the prime in the pump. You must fill the gear pocket full of vaseline, and then push the new gears into it(displacing the vaseline). You may need to turn the gear with the shaft to get it to line up with the bottom of the distributor shaft. Then remove the excess vaseline, so that all of the air space around the gears is filled with vaseline. Then bolt it back together with the new gaskets. Like I said before, the clearances from increased wear are what kill pressure. The timing chain cover is aluminum, and the gears are steel. The aluminum expands more, so that clearances increase as the oil and motor heat up. It is normal for oil pressure to drop off in a Buick motor when hot. If you feel you need to rebuild the pump, be careful with the bolts that attach the cover/nipple to the timing cover. Sometimes they seize and break. If you intend to go for it, post again, and we will give you ways to check for excess wear, and how to set up the correct clearances(very important)
I just installed a new booster plate on my pump, and it was a major PITA with the motor in the car, but not out of reach for anyone. Larry and JW helped me out a bunch over the phone, when I had some questions about proper end clearances with the pump cover and gears. I actually had to pull my distributor and turn the oil pump gears by hand a few times to determine if the gears were turning freely or not.
What Larry told you was correct. To be on the safe side, before I Ever pull my distributer from the engine I make sure to have the engine at TDC on #1 cylinder.Makes for an easier start-up when re-installed and eliminates any timing problems:TU:
I am going to get a good oil pressure gauge and find out what the actual pressure is before I do anything. I really appreciate the help. How do you set #1 to TDC? Chris
I put in an oil gauge.........crusing hot 25-35 low rpms at light about 6-8 I noticed a bolt was broken on the oil pump nipple cover...somebody attempted to remove it in the past I guess. 6-9 psi is pretty low.......too low? if so I am not sure the problem is the oil pump but maybe wear in the timing chain cover? Chris
Chris, Yeah, that's low. Are you hearing any knocking or tapping in the engine? What oil are you running? Try moving up one grade in oil thickness. Those bolt heads have a habit of snapping off. They usually come out with some soaking(PB Blaster), heat, and a small pair of vice grips. A booster plate will help your idle pressure some. If you pull apart the pump, check for wear between the gear teeth and gear pocket(.004 max), and end clearance. The end clearance is very important. The gears will protrude past the timing cover gasket surface. With the gears installed, put a straight edge across the gear faces, and measure between the straight edge and the gasket surface(feeler gauges). You want between .002-.006. The preferred end clearance is .002. The gasket actually determines your end clearance. If the gears protrude .004, and you use a .006 gasket, you'll get .002 end clearance. TA Performance sells an oil pump gasket shim kit. It has gaskets in various thicknesses to dial in the end clearance. They can also sell you the booster plate.
Thanks a lot for all the great info! I picked up some 20-w50 oil tonight. If that doesn't help than I will be rebuilding the pump. Chris
Wont shimming the oil pump relief spring raise the pressure a bit? 6-8 psi sounds a little low. But what should normal be at operating temperature with your foot on the brake? I dont think any of my cars are over 15-20 at idle. I dont know about the 350s, but Buick used 40 lb relief springs in the 68-69 430s. If thats the case, 35 psi may be normal?o No: Jason
Jason, Shimming the pump spring will raise the maximum oil pressure the pump will produce at higher RPM. But at idle, the pump isn't producing enough volume to even open a stock relief valve/spring. Increasing the spring tension won't do a thing for hot idle pressure.
Tried some 20/50 oil. It raised it to 8-10 at idle. I will be pulling the the oil pump cover off Friday night. Chris
Oil pressure Chris If you are talking 8 to 10 lbs at idle that is enough...my 350 runs just about that at idle..700 rpm...and it is a rebuild...and right after the rebuild it has been the same...at 60 mph I have close to 60 lbs of pressure...I was always told for every 10 mph you should have 10 lbs of oil pressure... Chris if you could get a oil pressure gauge and hook it directly to the side of the block where your sending unit is..start the car and check what the gauge says...it will give you a good idea of your oil pressure...:grin:
Bill, It was no higher than 35-40 lbs at 50. 8-10 at idle but seemed to be dropping below 8 as the motor got hot. I have the gauge hooked up. I will take it for a final road test today on the freeway ...get it good and hot and see what I get. Thanks ! Chris
the oil pump is run directly off the distributor which is turned by the cam so it makes sense to have high pressure at higher rpm's. i tried to replace the oil pump gasket last time i had the timing cover off but i forgot about the bolt that the oil filter covers. i gave up after about 10 minutes of fiddling with it. ou:
Thanks for all the help. Following Larry's advice I was able to get #1 at TDC, -Got the cover off...had to drill out one broken bolt from the last guy who probably tried this. -The cover has swirl marks from the gears grinding against it. I am attaching a picture. -The lower gear and shaft fell out onto a soft surface...yes almost hit my head -The upper gear fell right off the shaft but the shaft didn't come out. Should i attempt to pull the shaft out with a vice grip or some such tool? -I checked the clearance but not sure if I am supposed to check after I rebuild or put new gears in.....old gasket and gear clearance appeared to be in range but I will recheck tomorrow. Thanks again! Chris
Here is a picture of the stuck shaft.......I could not see any evidence of obvious ware but take a look at this pic and let me know if anyone sees any? What kind of evidence should I be looking for?
