Cadillac Allante Forum Discussion, Oil Pressure issue with 1991 Allante in Past Cadillac Vehicle Discussion; Hey
Here is the situation. Ii'm hoping someone may have a solution. I have a 1991 Allante. It has the ...
Here is the situation. Ii'm hoping someone may have a solution. I have a 1991 Allante. It has the 4.5 V8 Cadillac engine. It has an oil pressure problem ONLY immediately following an oil change. I do the oil change at a local garage.
Oil and filter are changed every 3000 miles
Have always used 30 w Rotella since I got it in June, 2009 with 67,000 on the clock
The Allante currently has 130, 000 miles on it This issue has been occurring consistantly since the 90,000 mile mark.
At oil change interval,.....
car goes up on rack.
oil is drained
car is lowered
oil poured into the new AC Delco oil filter
oil filter is screwed onto engine
6 qts of Rotella 30 w oil is filled into engine
engine oil light illuminates immediately
No engine oil pressure noted on gauge
After a few seconds you can hear valves lifters begin to rattle. (collapse)
Repeated attempts result in the same scenario.
Push car out of garage bay, and allow the car to sit for at least 4 hours.
Attempt start : result is oil pressure and everything OK.
I have tried every thing I can think of ...., 20/50 oil, 10 /40 oil, doing the change as quickly as possible. No variation makes a difference.
The engine does not leak any oil. Between oil changes, there is NEVER an oil pressure issue. Oil pressure on gauge is always at the center or better. At idle, never get an oil pressure light. If the car sits unused in my gagrage for a week, at start up after sitting, there is immediate oil pressure.
The car runs great; I have no issues with it other than this annoying one.
This has occurred at EVERY oil change since 90,000 miles
Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
Re: Oil Pressure issue with 1991 Allante
The oil filter adapter has a bypass valve within it. Could be sticking shut? What I find odd is the oil pressure sender seeing no oil pressure should turn off the fuel pump. I dont think the adapter is specific to the Allante, any 4.5 part should work. Personally, I would use a multigrade oil all the time. Thinner oil flows quicker cold. I used Rotella in mine but 15/40 and I changed mine at 6 months or 5000 miles. 3000 is too early if you drive 10 to 12k a year. IMO
Hi Carnut. Thanks for the reply. Yes, I drive the '91 about 20 K a year. I just prefer the straight 30 weight in Rotella. The owner's manual does list it a a viable weight oil considering the region of the USA I reside... South east (Florida) .
Don't know about the fuel pump and oil pressure sending unit dependency. I do know that they are tied together in that circuit, but it is bypassed by another cirtcuit during starting.
I think somewhere along the way the concept about a lack of oil pressure in the sending unit wouild not allow the fuel pump circuit to continue to be energized, (thus effectively killing the engine before damage is done) was floated out there, but in reality is not the actual principle in place.
So much of my issue with oil pressure is inconsistant. I am wondering if there is not an internal seal or something that may have become dislodged or a seal which may have become degraded or otherwise compromised. I would also think that I can not be the only person with this issue with these symptoms.
This sounds like a priming problem to me...a leaking check valve in the pump or a leaking seal at the pickup tube...
As far as the oil pressure vs fuel pump thing... I know the engine will run without the sending unit even connected, and I've never witnessed low oil pressure shut the fuel pump off on any engine of this series (4.1, 4.5, or 4.9). I've only read it on these forums. I'm thinking it's misinformation.
On my 92 Allante I had some oil pressure issues because of a lost oil gallery plug. I'am not suggesting you have that problem but my engine kept running with almost no oil pressure. I believe the connection between oil pressure and the fuel pump shut off was not on the 92's perhaps not on the 91's as well.
I wish to state that there is a connection. You will find the description in the Service Manual on page; 6E-C2-3 under the heading; Oil Pressure Switch. I feel that Rotella oil is too harsh for these engines. It is a diesel engine oil and as such has a high detergent action which is not the best for gas engines. I would suggest staying with the engine manufacturers recommendation of 10w - 30. I had similar problems with my '90 and after changing out the oil filter head with no change, I dropped the oil pan thinking that the oil pump relief valve had stuck, i found that the O-Ring between the pump and the block had broken allowing the oil pressure to dissipate at idle. I don't think this is the problem here, but I don't have any other suggestions.
I have used nothing but Rotella, straight 30w in all of the vehicles I have owned and have not had an issue. The vehicles include :
1975 Ford F-100 with 302 V8 (Drove it to 175 K and sold it . It ran great.
1976 Ford F-100 with 300 6 (drove it to 170K and sold it. No problems.
1979 Ford F-150 with 302 V8 (Drove it to 175 K and sold it . No problems.
1983 Eldorado with 4.1 (it went 245K with me ) and I sold it. It ran great.
1985 Eldorado conv. with the 4.1 ( I drove it 268K) and sold it. It also ran great.
(the key to the Caddy 4.1 was regular oil changes and strict close monitoring of coolant levels.)
I was advised right after I first started driving to use 30w oil. It has always been listed in the owner's manuals as a viable oil to use for the vehicles I have owned. I have used Rotella and continue to use it now primarily for the reason that it continues to have the zinc additive. Other oils do not. This zinc is critical for upper engine lubrication in particuilar. Since I have only had used vehicles, the type of oil used prior to my ownership has not been a concern of mine. Initiating at my ownership, I verify that 30w is applicable and use 30 w Rotella. I have never heard of any oil, even Rotella being labled as "harsh". Kind of sounds defeating of its' purpose to me.
Anyway, anyone have any other ideas regarding my Caddy, lack of oil pressure AFTER an oil change issue?
No need to remove a valve cover to inspect. The oil is getting to the oil pan (no obstruction). Have verified this by both a visual during the fill stage and immediately following the fill, as observed on the dipstick. I am using the CORRECT viscosity oil as recommended by the owner's
manual. I live in South Florida and going by the chart in the owner's manual 30w is an appropriate viscosity oil to use (SAE 30 w for use where
temps are ranging from +4 degrees to over 100 degrees) As stated, I also have tried various (multi grade) weights of oil. Oil pressure is always at the middle of the gauge. At idle, after warm up, it drops to one line below the center of the gauge. This issue is a real puzzle for sure.
Thanks MC ....That is exactly what it sounds like to me. I too am unfamilioar with the working/ arrangement of the inside of the 4.x series. I agree, it seems as if the pump is losing its' prime, but I wonder why it does not lose prime between periods of time of non use. Do you think it might be getting air locked during the change and the oil does not go up into the oil pump or whatever, as I guess it would typically do, but does so over an extended wait ? I am still at a loss for a reason for this odd issue and why no one else had experienced it. Thanks for the replies !
Well, here I am some ten months later with the Allante pushing 140 K now. Just did an oil change. Waited 4.5 hours to be able to see oil
pressure at start. NO GO !! . Valve train rattling for sure is all. This has been the issue with this darn car since 90 K. I will never be able to
unload this car. In all other respects it is such a nice car! Ended up leaving it at the garage. Got a call . Some 8.5 hours later about a start
attempt: success it is running fine. Oil pressure gauge is sitting right at middle of the gauge. The garage owner is retired so it is not an issue. It
was the perfect day for top down driving too. This whole routine is getting real old I find it incredibly difficult to believe that I am the only one
with this issue.