Another one... Low Oil Pressure..AGAIN.

[pedrazamarcos]

I just purchsed a 98 Catera with 140 k miles(i pay $450.00)Car was over heating and sending coolant to #6 cylinder,and coolant was in the oil but NO oil in the coolant.(no oil cooler problem,just head gasket and low oil pressure).
i did replaced the head gaskets,and cleaned all engine from contaminated oil.

when engine warms to normal temperature oil pressure drops to 5 psi and engine start knocking in the bottom.When engine is cold,i have around 60 psi,no noises.verygood pressure.
I removed the upper oil pan and visually inspected main and rod bearings.I don't see excesive wear on bearings.they look very good also crankshaft journals look good.No play on rods also mains look good.
I have seen LOTS of Catera owners complaining about this,but i have NOT seen anyone come with a good diagnostic or fix.
I like to know if anyone have been able to come with a fix for this(besides of changing oil grade or replacing oil sending unit) i mean a real fix.
Anyone can tell me what can be the cause of this?

[CateraMV6]

So is it the oil pump thats worn out?

When the oil is cold its more thick... and once it warms up it flows easier... so have you tried oil like 20W50? Or Lucas additive?

[pedrazamarcos]

I have Penzoil 10 w 40 and Lucas oil Stabilizer.i also think may be the pump,but this one is too expensive and i don't want to make $500 mistakes.i wanted to know if anyone have this problem and actually corrected(i don't mean putting thicker oil and adding lucas)i mean getting oil pressure back to 25 psi hot at idle.
Someting very interesting is that engine has a lifter noise ALWAYS,very loud and noise is cold or hot.Posible loosing pressure somewhere in the engine?Like a hidraulic lifter???
my point is: the pump not building pressure or the pump is building pressure and pressure is escaping somewhere in the engine oil galleries?

[JRomano]

low oil pressure is usually because of a worn out oil pump or worn out bearings, if the bearings are fine then its probably the oil pump and you can either replace the oil pump or band-aid it by using a thicker oil grade. By the way I hope nobody ever falls for that Lucas Oil Stabilizer bull****.
See here for why http://www.bobistheoilguy.com/images/lucas/lucas.htm

[pedrazamarcos]

where can I buy an oil pump besides the Cadillac Dealer?Cheapest one i have seen is $320.00 any ideas?

[JoshinWV]

Originally Posted by pedrazamarcos

where can I buy an oil pump besides the Cadillac Dealer?Cheapest one i have seen is $320.00 any ideas?

Uh... How about a genuine GM oil pump for $268.05. Actually you can get it yourself. I have bought many parts from GMPartsDirect and they are the cheapest place that I have found for genuine GM parts. Shipping is a little high, but you usually still get the parts for cheaper than most dealers will sell them to you at. If I am not mistaken as well, they carry the 12K / 1 Yr warranty on them as well because they are genuine GM replacements.

[TitanCTS]

Are you sure you really have 5 psi of oil pressure or are you relying on the unreliable oil pressure switch? Take off the switch and install and actual mechanical oil pressure gauge to verify your actuall oil pressure. On several occasions I've had my cars oil gauge go from 60psi on the highway to zero and start flashing and beeping... Pulled over, shut off the car and restarted and it was fine.. The oil pressure switch I believe is the culprit... But I have not changed it yet.. So stick on an actual gauge, it's real easy to get at on the front of the engine on the bottom near the oil pan.

[pedrazamarcos]

Originally Posted by TitanCTS

Are you sure you really have 5 psi of oil pressure or are you relying on the unreliable oil pressure switch? Take off the switch and install and actual mechanical oil pressure gauge to verify your actuall oil pressure. On several occasions I've had my cars oil gauge go from 60psi on the highway to zero and start flashing and beeping... Pulled over, shut off the car and restarted and it was fine.. The oil pressure switch I believe is the culprit... But I have not changed it yet.. So stick on an actual gauge, it's real easy to get at on the front of the engine on the bottom near the oil pan.

Yes, i did hook a mechanical gauge and the pressure was 5 PSI hot @ idle.

[pedrazamarcos]

Originally Posted by JoshinWV

Uh... How about a genuine GM oil pump for $268.05. Actually you can get it yourself. I have bought many parts from GMPartsDirect and they are the cheapest place that I have found for genuine GM parts. Shipping is a little high, but you usually still get the parts for cheaper than most dealers will sell them to you at. If I am not mistaken as well, they carry the 12K / 1 Yr warranty on them as well because they are genuine GM replacements.

Thank you very much for the info,i did check the web site and is very good place for GM parts.Thank You.

[pedrazamarcos]

my main bearings and oil pump are worn out(bearings top layer is gone and oil pump gear has lot of play on the pump housing)I know where is an engine i will go inspect bearings and if look good i will take them and put on my engine.I doubt there are worst bearings and pump than mine.I can't afford new bearings and pump.I will post results.

[pedrazamarcos]

I went on a mission and found my good main and rod bearings and an oil pump(used motor)I took all bearings and oil pump,installed on my engine and drove the car untill the engine pressure drop.I hooked up a manual gauge and i have 18 psi hot @ idle in park and 15 psi on drive.The gauge is abiut 1/4 when hot @ idle.The day after i drove 100 miles on highway just to test the car and everything is good so far.(NO didn't spun a bearing)soif you have Low Oil pressure be redy to speng in an oil pump but don't overlook the bearings.Case Closed!