buick oilpressure low

[Guest capricewagon]

I do have problems with no oilpressure after starting the engine.

It takes a few seconds until there is sufficient pressure to switch off the pressure light.

I did install new oilpump gears, a new camshaft and new lifters in a 350 Buick powered 68 Skylark.

This problem did not occur before I installed the new pump gears.

Before starting the engine for the first time after installation of the new parts I turned the oilpumpshaft with a drill until oil reached the rocker arms. The engine is running without any funny noices and performs well.

It seems that all the oil drains from the passages when the engine is not running for a while.

Does anybody have an idee what might cause this problem?

Edited August 24, 2010 by capricewagon (see edit history)

[Larry Schramm]

I would put a gauge on the engine and see what the pressure is. It was not unusual for those engines to have less than 3 pounds pressure at idle. There was actually a low pressure switch that was used for engines that had low pressure to keep the light out at idle. There was (is) a high pressure oil pump available to fix this problem.

[Guest capricewagon]

The problem is not low oil pressure during idling. When I start the engine after it was sitting for about half an hour or more there is no oilpressure at all until it is running a few seconds, this problem only occurs when the engine was shut off for more than half an hour. It is running pretty rough for a moment until the oil reaches all the bearings.

[Guest 75RivGS]

which type of engine oil do you use?

[Smartin]

Don't worry about it. Try to find an oil filter that has an anti-drainback valve. Most do, but that might help the issue.

[JohnD1956]

I thnk this is fairly common and Smartin gave good advice. I just wanted to add that I doubt the roughness you feel, till the light goes out, is related.

As you may know, the oil pump is hanging off the timing chain cover and it draws oil from almost the back of the oil pan. So those few moments with the light on are virtually impossible to prevent. But the light on does not mean there is 0 pressure, or no oil flow. If that was the case I'm certain you'd have a rod knock by now.

[Guest capricewagon]

I will try another oilfilter with a drainback valve, I already got a Fram filter.

I already thought that I forgot some drainback valve when I did install the new pump gears, I didn't imagine that this valve might be inside the filter. The shop where I bought the gears also sold the filter to me.

[NTX5467]

You might have put new gears in the pump housing, but did you check the existing pump area on the front cover housing to see if there was too much clearance there--wear??? What about the end plate the gears ride against--replace it?

The main difference in the "high pressure" pumps is that the relief valve spring has a higher tension. You can probably get the same effect by adding a washer or so to your existing pump body's spring.

"High Volume" is a different situation, though, with (as I recall) longer gears. They can be "high volume-normal pressure" or "high volume-high pressure", just by shimming the spring.

The oil pressure SWITCH, which turns the "OIL" light on and off will have a minimum pressure threshold that is required to turn off the light once pressure is built. Best to, as suggested, remove the switch and screw in a manual gauge to see where things really are! This way, you can watch how fast the pressure builds, hot cold whenever, and how it acts in general.

When you do the check can be important. It takes about 10 miles of continuous highway driving for the oil temperature to equal engine coolant temperature.

Similarly, the viscosity of the oil can have a bearing on the check. A multi-weight would probably "get moving" quicker than a straight 30 oil might, for example.

ALSO, as you probably might discover, not all oil filters have the same flow rates. There's a chart of this somewhat hidden inside the www.bobistheoilguy.com website. It's several years old, though, but still interesting. Generally, though, the more (smaller micron) "stuff" the filter will catch, the poorer the potential flow rate might be. Therefore, it might be advisable to get a GM-ACDelco filter for that application. The earlier PF24 filter might have changed part numbers a few times, but the latest one should work. I believe that in the back of the ACDelco filter catalog, there will be a spec area which will detail regarding the anti-drainback valve.

When you put in the new pump "guts", did you first pack them with a suitable grease? BEFORE you primed the system with the drill motor? How long did it take the drill motor to get a "load" on it?

Remember . . . the front cover housing (that holds the pump gears) is aluminum.

In reality, ANY oil pressure at idle should be acceptable . . . at least by some standards . . . but there usually are few specs for "idle", rather using "2000rpm" for the checking speed for oil pressure.

Just some thoughts . . . Keep us posted on what you find, please.

NTX5467

[d2_willys]

It sounds as if the new gears are narrower in width (across their shafts). This will reduce oil pressure. Another possibility is that if there is a gasket between the housing and gear retainer plate, that the gasket is too thick. I would try going back to the original gears if the filter with backflow valve doesn't help.

[Guest brh]

All good advice. I'd just like to add that just because the light is on, does not mean you have no pressure. If she fires up and you hear every lifter on that engine until the light goes out, then I'd say ya had no pressure. Just my .02

[Guest capricewagon]

First of all Thanks a lot for all your help.

I was able to solve the problem, it was the oilfilter. I did install a new Fram filter and now it works as it should. Just started the engine after it was sitting for more than 6 hours after I did install the new filter and the pressure light turns off immediately.

I'm working as an engine mechanic for more than 20 years now but I never had a problem like this. There is a 10W40 Pennzoil oil in the engine, I did smooth the surface of the oilpump cover to get out all the scratches, I meassured the oilpump gears prior to installation, put some of the break in stuff you use on cams onto the gears and turned them by hand before I used the drill, that's why it was so strange to me that it didn't work in the beginning.

So maybe we should avoid Weber flters in the future. I never heard of this brand before, does anybody know them.

[Guest dcdpgh]

Pardon my interjection, but I think there are better oil filter choices out there than Fram. I am far from an expert, but I have read enough to know I will not put a Fram oil filter on my engine. Suggestions I have heard - AC Delco for the purists, while Wix / NAPA Gold seem to be popular choices with performance minded Buick owners.

[Guest capricewagon]

It's pretty hard to get these filters over here in Germany. Do you think a Purolator filter is better than the Fram filter I used? Next time I get parts from the US I will try to include some AC Delco filters.

[NTX5467]

There are a few "issues" with Fram filters. One is (or used to be) cardboard end plates for the filter media, rather than metal. Another is the flat leaf spring relief valve, rather than a coil spring.

Wix is an "old line" brand, but has seemed to improve markedly when Dana/Perfect Circle bought the brand. Now, they are probably better than most everything else and definitely OEM-spec or above.

Fram, also, is an "old line" brand, just as Purolator is. Their main reputations as good brands and quality products were made in the much earlier times, when they were still owned by the originators of the brand. Now, they are part of holding companies rather than being free-standing brands (as they used to be). I would prefer Purolator over Fram, though.

Thanks for the update!

NTX5467

[JohnD1956]

Unless you're racing the car, Fram should be good enough, although I personally use only A/C Delcos.

You obviously have oil pressure so this is for future reference. The manuals all recommend packing the oil pump with pertroleum jelly ( vaseline) in order to effect a prime of the pump. Hasn't failed me yet.