So, I bought this 73 Century in northern California. Flew in, test drove it about 70 miles, bought it and drove it 2400 miles back to Michigan. Oil light would go out when started, it runs fine with no lifter noise. We ran for hours at 80mph (about 3600RPM) and even up to 100 at Bonneville. Last fall while tuning it up I see there is no oil sender screwed into the block. It's got a pipe plug in the hole. So this spring I added oil pressure and temp gauges to see what is going on under the hood. The oil pressure would peak at about 22lbs. Would not go any higher. I tried another gauge I had with the same results. I finally got the interior together enough to drive it today for the first time since adding the gauge. It never went over 20 PSI. At hot idle it has about 9PSI which is not uncommon. The engine appears to be a reman and it has the newer style front cover. The oil pump appears stock. I have not pulled the oil filter or even changed the oil yet. Just posting this for informational purposes and will report back as I investigate. I am concerned at the low pressure as I've never seen one with this low running pressure, but as I've said before, if you have sufficient volume that is more important.
My guess is crank bearing clearances are excessive since the valve train is quiet. But how much clearance is there that it flows oil like that?
Make sure the oil filter bypass valve isn't stuck open. I had that happen years ago on my 75 Le Sabre with the 350, they USED to have a flat disc for the bypass valve, and it would get cocked sideways and not seat, they revised the design and went to a conical valve that self centers. Also had it happen a few years ago where the valve and spring popped out while on the highway in the GS, pressure went no higher than 20 psi and hot idle was 10 or so. The pump cover was a new TA piece, the valve was never staked in place.
I’d also pull the relief spring and valve out of the pump cover to make sure the valve moves smoothly in the bore. Install a white spring while you are at it. If that doesn’t do it, I’d pull the pump apart and check for excessive wear and then get the clearances right if the pump cavity was in good shape. I would expect the pump to make 40-50 psi cold even with bad clearances, pump or bearings. http://www.v8buick.com/index.php?threads/oil-pump-clearances-and-oil-pressure.326597/
Think I found the problem. The pressure relief spring had no preload on it. The bolt had no pressure on it when I broke it loose. I pulled another spring from another cover and it was about 1/2" longer. I'm going to order a new spring and see if the pressure comes up. It has the red spring. The other cover I took apart had a black spring. I see some oil pump kits come with several springs.
Sounds like it had the shorter spring from the later V6 and metric style housings. As advised get the white springs in there and you should be ok. Good catch before you revved it up and then started hearing dreaded rod bearing rattle. If you get 55-60 lbs hot you are good to go.
So I get sealed power oil pump kit with 4 springs. I'm not planing to open the pump at this point. I installed the yellow spring the instructions say is for the style adapter that's on it. Says it for about 60PSI. Now I have 30 PSI with that spring and fresh VR1 10w30. The cover I got off the shelf has the black spring the instructions say is for the other type adapter. I have no idea where that cover came from so I don't know what oil pressure that engine had. Has anyone else used the white or black spring in a cover that came with a red or yellow spring? I guess I'll try that tomorrow. I also cut apart the oil filter to look for junk and it was actually pretty clean. No metal that I could see.
Steve, read Mike T's quoted comments at the end of my article, http://www.v8buick.com/index.php?threads/oil-pump-clearances-and-oil-pressure.326597/ " Folks, A few pointers here. First, The pump cover that comes with the TA pump assembles is the new style. DO NOT install a white spring in this cover. The white spring in the newer cover will lock the relief valve shut This cover takes the shorter springs. You may use the stock spring from your original cover but other than that spring you must use the orange, yellow or green. A stock spring from 1978 say through 1987 would be the same as the orange. The original say 1964-1976 stock spring will give more pressure than the orange. Recently we have been providing both the original (steel color) and orange spring with the regulators. With the new style pump covers I have found that the yellow spring works very well and I have since been putting them in our pump assembly's. The green spring which some of you may have is not always in the kits. Now this spring will kick the upper end oil pressure higher. I would say when using this spring, use caution. Thinner oil, larger clearances, then maybe this spring would be the one. Now if you ever install one of these heavy springs and the pressure does not move up, chances are there is an internal problem in the engine. Bearing clearances, bad bearings, oversize lifter bore, gallery plug came out, wrong or bad lifter. Or pump set up way wrong. Just had a customer call having trouble getting oil pressure on a 350. He had purchased the high volume cover from us, which is not one we machine in house. This cover comes with the longer gears as a kit. After some conversation I started to get the feeling that he did not have the longer gears installed. When asked, he said he purchase the gears from Summit and there were no gears with the cover that came. I said they were in the box, do you still have the box. He went to the garage, found the box and what was at the bottom, the gear set. I never seen or heard of this before, but as you see, things happen. Back to the pumps. The tightest I have ever set one up knowingly has been .001. I recently set one up that was between .001-.0015, been awhile since I set one that tight, normally .002-.003. .004 is the loosest I will go. But because this one was between .001-.0015 I did some testing. I froze the timing cover assembly to see if it would tighten up. It still spun freely and when checked frozen it still had .0005 clearance. I have built 100's & 100's of these oil pumps over the past 35+ years, but sometimes I need to walk back over my prints just to make sure."
Whatever spring you use "it should" protrude outside the bore 'round about 1/4" or so. I just went out to the garage and got my box "Buick oil pump" and snapped some pics, hope it helps yah. This spring length is CORRECT for this housing. This spring length is WRONG. Sideways instructions. My assortment of springs I've accumulated over the years. Two different styles of relief valves, a 2 hole and a 4 hole, don't know why, maybe a running change????? Spring package for housing "A"
Great Pictures Mark. I rotated the "sideways" instructions. I'm going to add the pictures to my oil pump thread in the FAQ. Looks like the correct spring protrudes more like 1/2".
Sure thing Larry I tell my wife the same thing "Its protruding more than it looks" Thanks for rotating it too!
OK great info guys. I think where this went sideways was that the actual part on the car matches neither what they are calling housing A or housing B. I can see how someone was confused and put in the red spring. Today I installed the plain or black spring that should be used with housing A and I got 45PSI cold. That's when I started looking closer at the housing on the car and another I had on the shelf and realized they looked more like housing A. I guess the better way to identify these is the style I have basically protrudes farther out from the housing ( right side of the photo) and that is what they are calling housing A. In the attached photos you will see the bore for the relief valve is inline with the 2 bolts that are the most outboard, in fact inline with all the bolts. Both shown in the instructions are angled. I don't know how long this car has been running like this as I just bought it last October. I could not get over 22PSI at any engine speed the way it was and there appears to been no harm done. Makes me wonder if 60PSI is really necessary.
