: low (or no) oil pressure



Claude
05-27-05, 02:11 PM
I just replaced the head gasket in the left head of my 98 Deville, 4.6L NS. Did the timeserts and all. Took the car from Utah to Phoenix without any problems. Engine temperature got no higher than 224 (it was 112 in Phoenix).
Never had to add coolant. That was exciting.

About 100 miles from home I stopped the car. On restart the low oil light came on. Reving the engine seemed to keep the light under control and got us home.

Next day the problem seemed worse. There was a small oil slick under the front center of the engine. The leak does not appear to have come from the pressure switch. That leak has also not happened again.

I replaced the pressure switch. Low pressure warning is now constant and there is some noise in the engine.

What would cause the pressure to fail? The pump looks like there is nothing to break or wear out. There is plenty of oil in the system.

Any help will be appreciated.
Claude

blunted
05-27-05, 04:28 PM
Low pressure warning is now constant and there is some noise in the engine. I would definetly not drive the car until you figure out what's going on, the noise is most likely the result of a lack of oil to the engine. If its of any help, a dealership once told me if your oil filter adapter were to begin to fail it would lead to low oil pressure... check it out, although I take everything they say with a grain of salt.

zonie77
05-27-05, 08:01 PM
If you had the balancer off to time the cams it may not be tight enough. The oil pump is behind it on the crank. I didn't have this problem but I remember an old post about it.

mcowden
05-27-05, 08:08 PM
If you had the balancer off to time the cams it may not be tight enough. The oil pump is behind it on the crank. I didn't have this problem but I remember an old post about it.

Yeah, what zonie77 said. The oil pump is driven by the press fit between the pump and the balancer. If the balancer isn't good and tight, you won't get good pressure. That's one thing to check. A restriction at the filter or filter adapter could also do it. The pump is probably fine.

Claude
05-27-05, 08:47 PM
We originally put the balancer on with an impact wrench. Then my brother was worried that it was too tight so we backed it off and then torqued it with the torque wrench. I will definitely keep this in mind as a possible problem.

I have been reading on this site about a mis-aligned screen and a stuck check valve. Does anyone have ideas pertaining to these? I have another post on the site asking about this.

Thanks for your help.
Claude

Spyder
05-27-05, 08:53 PM
I bet that's your problem...if i remember right, its got to be at some ungodly high lb ft...300 stands out in my mind for some reason...

Claude
05-27-05, 11:24 PM
After more thorough reading of the information on this and the Caddy Info site, I boiled it down to 3 possibilities:
1. Stuck check valve
2. Problem with the intake screen
3. Harmonic balancer bolt too loose.

#3 Seemed like it might be more consistent with the fact that the car ran 1500 miles before the problem surfaced. Then it surfaced gradually -- the indicator light would go off if I revved the engine. By the third day there didn't seem to be any pressure at all.

I put the wrench on the balancer bolt and it came loose almost immediately with very little effort. (So what I said about torquing it to the right specs was apparently not correct. We didn't have a number. See below.)

Now my humble, eat-crow question is: What is the torque and angle to properly install this bolt?

Thanks
Claude

Spyder
05-28-05, 12:32 AM
try searching through the archives..I know its been talked about in the past...I can't say for sure what it is though...I do think its somewhere near 300, but am not sure... good luck!

JimD
05-28-05, 10:05 AM
My '98 Service Manual says the crankshaft balancer bolt torque is 37 lb ft plus 120 degrees.

Ranger
05-28-05, 12:48 PM
'97 & '99 manuals say the same, 37 + 120

growe3
05-28-05, 01:36 PM
As JIMD and Ranger both noted, 37 ft lbs + 120 degrees.

Loosen the crankshaft bolt, jamb the flywheel, and tighten as noted above.

If you just try and tighten the bolt by torque, it will not be tightened correctly to lock down the oil pump rotor.

Note: Earlier Northstars had a much higher torque, due to the larger bolt in use. If you tighten to the older spec you will damage parts.

If you no longer get the low oil pressure message all is well.

If the message stays you may have put the oil pump in backwards, and will need to remove it and reinstall as noted above.

-George

Spyder
05-28-05, 08:55 PM
huh...good thing the others chimed in here...I'd have broken your N*! :)

Pjs
05-30-05, 11:57 AM
If the message stays you may have put the oil pump in backwards, and will need to remove it and reinstall as noted above.

-George

I don't think you can put the oil pump in backwards...it only has 3 screws holding it and won't physically fit in backwards. Not to mention that it would never build any oil pressure because the inlets would be facing away from the block

growe3
05-30-05, 06:11 PM
I don't think you can put the oil pump in backwards...it only has 3 screws holding it and won't physically fit in backwards. Not to mention that it would never build any oil pressure because the inlets would be facing away from the block

Actually it can, (the impeller) and the reason that I mention as a possibility was that I was in communication with the person that did it, about a year ago.

-George