No pressure from oil pump

[Utah Blaine]

Put a oil pressure gauge on the car and had a heart attack. The new gauge shows around 4 lbs of pressure at idle and I can't get it higher than 15 when it warms up. When I first start the engine it's right at 20 and drops as it warms.

From what I can see the oil pump should be easy to work on. Are there any special tools needed and any idea what should be done? I need to fix this asap.

thanks

jd

[bob k. mando]

http://www.buickperformanceclub.com/oilpumpwear.htm

the gear teeth are steel while the housing is alum so after a while the gears can wear excess clearance front to back.

TA has shims.

you might also want to look at the rest of the oiling upgrades if you haven't done so already.

[Utah Blaine]

Thanks for the reply Bob.

Yea, I have looked at TA and saw what they have. That's what made me believe it would be easy to fix. And then I read the See More: No pressure from oil pump. In the posts there, somewhere, they talked about taking the timing cover off and a new cover or gaskets not lining up. Then the author went and clarified his statements and really confused me. I put a new timing chain and water pump on the engine before I installed the pressure gauge you see. I hope putting the cover back on I didn't use a wrong gasket. I supposed the only way to tell is put the shims in and hope for oil pressure. But wait, reading further and I see that it may be a cam bearing lol.

I am going to order the $18 shims (wish I had ordered then with the chain and water pump because of shipping lol.)and hope for the best. I assume they will come with instructions on their use. If that don't work off comes the front again I guess.

jd

[LARRY70GS]

Oil pressure in most Buick engines depends on internal oil pump clearances. Being the timing cover is aluminum, and the gears, steel, clearances increase as the engine heats up and the aluminum expands around the gears. That is why it is really important to set the pump up on the tight side. The gears can wear the pump pocket on high mileage engines increasing clearances and that results in low hot oil pressure. The chassis manual has instructions on how to set up the oil pump. When the gears are installed in a pump pocket that is in good shape, the gear faces will actually be above the gasket surface, by about .002-.006. As the pocket wears, the gears sit lower. At some point, the pocket is worn to the point where the gears sit too low, and oil can bypass above them. The chassis manual has a picture showing how to measure the gears in the pocket. You place a straight edge across the gear faces, and measure to the gasket surface. You then use the proper gasket to set the end clearance. Preferred end clearance is .002. As an example, if measuring from the gear faces to the gasket surface gives you a measurement of .004, then using a .006 gasket will give you the preferred .002 end clearance. That is what the shim kit from TA is for. Some set up the oil pump with the cover off the engine. They set it up as tight as possible without drag. Remember, the cover expands with heat increasing clearances, so tighter is better, but you don't want the pump to bind up.

Also, there is an oil pump relief valve and spring that controls the maximum pressure the pump can make. If the valve sticks in the bore, it can produce low oil pressure as well. TA sells an adjustable oil pressure regulator so you can increase spring pressure on the valve with an external adjustment. The valve and spring are behind the big nut on the oil pump cover/filter nipple assembly.

http://www.taperformance.com/proddet...p?prod=TA_1502

http://www.taperformance.com/proddet...p?prod=TA_1510

http://www.taperformance.com/proddet...?prod=TA_1512B

[Utah Blaine]

Would putting in the shims be the first step to see if the pressure will go up? The car has 78000 miles. That isn't a lot.

[LARRY70GS]

Would putting in the shims be the first step to see if the pressure will go up? The car has 78000 miles. That isn't a lot.

If you take the pump apart, you should check the gear protrusion and measure it as closely as possible. Then select the correct shim to give you as close to .002 end clearance as possible. While you have the pump cover off, check the relief valve and spring.