Bought Z28 3 years ago. Spun a main bearing. (long story, dealership put 1700 kms on it and I found out later. Somebody missed a shift. I'm sure of it).

Had the motor rebuilt from a colleague my Uncle (owns a shop) has been using for 20+ years.

The motor has done about 140,000 kms of mileage since then.

EVERY WOT run when the oil is up to normal operating temperature, my oil pressure gauge on the cluster drops down, then bounces back up. Normal driving, the gauge operates fine, but flutters a bit around sometimes.

I have checked the wiring to the sending unit. All fine.

Pump pickup was welded upon rebuild.

The last 60,000 kms I've used Mobil 1, 5 w30. I run the truck sized filter and put in 5.5L of oil.

Is oil cavitation in the LT1 REALLY this noticeable? Is the sending unit faulty? There have never been any traces of bearing, or the like in the old oil. I did one oil analysis last year, and there were no indications of metal in the oil.

I've tried to put it out of my mind, many times, but cannot stand watching the flicker of the gauge down the track (car is not driven hard, but sees "some" track time).

It is my intention to use a mechanical gauge to confirm.

Wondering about some preliminary thoughts here.

Thanks in advance.

 

Your sending unit is probably going.

You didn't install a high volume oil pump did you?

 

No. Stock volume, stock pressure.

Any experience on the cost of this unit?

Thx for the quick reply.

 

Hey ZED, mine does about the same thing as yours in pressure area and like you no metal in oil, but I however have a high volume blueprinted oil pump does this make a difference Gripenfelter? TTT for us

 

This probably is better suited for LT1 Tech, and will yeild more response there.

Moving, thanks.

 

Does it drop after it shifts?or does it just kinda bounce around?

 

It seems to drop as I'm accelerating, not shifting.

Almost like the pump is starving the motor, but I am confident that is NOT the case. It did it since day one of my rebuild, and I am confident in this motor builder.

All weights of oil yield the same result.

 

Try a new sending unit. Mine was doing the same thing.I brought it to gm to check it out, they said it was fine,i got one anyway. Guess what the problem was gone.





NICK

 

Cost of said unit?

 

About fifty bucks.




NICK

 

i bought my car and it was doing the same thing within week i had a spun crank bearing...... i am not shure why it was doing it's little dance but it can not be a good thing. keep an eye on it. i was told that a cam bearing that is spun or is spining can cause that, i do not know it that is true but i wish you the best and i hope that you do not have to do what had to. new motor..........


brad

 

I know this is silly but is the oil level correct? The sending unit is likely the culprit, confirm with a mechanical gauge. I bought one from O Reillys and it was bad new, went and bought a new GM one and it works fine, the GM one is more expensive but at least I know it works, it was 54 and change the O Reillys one was 38.

 

Thanks for the responses.

I believe either the unit was NOT a GM unit when replaced at the rebuild OR it wasn't changed with the rebuild, and was damaged with the oil when I spun my bearings.

I truly wish I took a picture of the oil at the time, but I needed to run away quickly and ball my eyes out like a baby... (not really)...

The oil was silver. Pure silver.

 

Same problem I had, best of luck with the rebuild.

 

you sure the pickup on the oil pump is the right distance from the bottom of the pan? it's not sucking air or pulling more oil than it can get between the pan and pickup cause they are too close? What about the bypass spring in the pump, could that be the culprit, or faulty pressure spring?

good luck.