I search and could not find something similar to my problems-I know most of the time it is the sensor but I have a manual guage installed already and it reads the same as the one on my guages.

What is happening is in the morning I have 30-40psi, then goes to 20psi at idle once warmed up. but once warmed up when I slow down or come to a stop I drop down to 0-psi . sometimes for 3-4 seconds. if I rev the engine (at dead stop) it will come up but only to ~15-20psi.

Here is what I find weird though, when the car is under load, say if I am driving 40mph in fourth and I press the gas- pressure goes down from ~30 cruising to 10-20 if I stay on the gas it will climb up slowly, but if I get off the gas it shoots up to like 50-60psi then goes back down.

any opinion/ideasof what could be wrong?, or other question(s) that I need to answer to find out what is wrong?

 

Dropping to "0" under braking may indicate the pickup tube has fallen off the pump. Not sure if that would explain the loss under part throttle, followed by gradual increase though....

 

Actually it is usually on the low side once it is warm, when I have a load on the car it is at part as well as full throttle that is loses pressure(no load=pressure rises as normal), an it does not gradually increase it shoots way up, then drops down again, it is just sort of a "pressure spike" only after giving it throttle under load.

One thing is the oil seems somewhat thin and it barely has ~170 miles on it, it was penzoil 10-30w, before I used it I flushed the engine with a CRC flush then let it totally rinse out then installed new oil & filter
the car has 12X,XXX miles on it and it is usually very hot here so I think I am going to change my oil again and go with a straight 30w

 

What do you mean when you say you let the "I flushed the engine with a CRC flush then let it totally rinse out"? What did you "rinse" it out with? Or do you mean you let it drain?

Hard to follow what the oil pressure gauge is actually doing, when its increasing, when its dropping, when its a "spike"..... your second post seems to contradict your first post.

 

Yes, I let it drain, that is what I meant it was a can I put in of liquid then let the car idle for 10min. then I drained it and the oil, then let it drain out for like 10 more minutes- sorry I just used the wrong word.

And what it does is it drops under load but as soon as I let off the throttle is when it spikes for a second, then continues to drop.

 

There's a chance that residual flush solution diluted the oil. First move should be to fully drain the oil and replace the filter. I wouldn't go to a straight 30-weight oil. All that will do is increase the engine wear on cold start. With a good quality 10W-30 oil, it should retain the same viscosity at 100*C as the straight 30-weight oil. The "10W" only describes the "thickness" under cold conditions.

Removing sludge removes the buildup that may be blocking the oil passages. Oil pressure may drop, because of less resistance. If it is still very low after replacing the contaminated oil, it may be time for engine work, or at least some 10W-40 oil to provide a temporary cure.

 

tomorrow (fri.) afternoon if I get out early I was planning to try the oil change, I f not I will do it Saturday.

Also I think you are right about the diluted oil, last night I checked it and it was in the range it should be level wise, but it looked pretty thin,but not milky looking, nor did it smell like fuel or anything so as you suggested I think that it might be the left over solution diluting it.

Also would it be alright to run an OEM replacement Gen1 SBC oil pump(melling but not HV) with the white spring if I could just raise engine to get oil pan out and swap from underneath- reason I ask is I have a new oil pump I was going to use on an engine rebuild I was doing but sold the engine(TPI but swapping to LT1 in IROC) - it was also a 1 piece rear main seal?

hopefully I just need this motor to last me til around Aug. til I can build my other LT1 I have on the engine stand because this is my daily driver(15-20 miles a week) and even though it is not very miles I need a vehicle to drive.

 

I did do the 10-40w I used castrol GTX for high mileage.
seemed to have helped out , only thing I am still having a problem with is that when I stop now it just goes down to "near zero", I will see when I can get some one to ride along with me to record what the guages are doing so you can see for yourself.

 

Sounds like your engine is just getting worn out. But not totaly sure on that.

 

well, I do have quite a few miles on it already and already have another complete lt1 that I want to do an LE2or3 on it and rebuild it but I don't know when and I would prefer to take my time and do everything right than rush a rebuild and be doing this again anytime soon

 

sounds like it is so.

but just so you know li have seen that engine flush, "flush" peices of gunk and buildup into the oilpan and right into the pickup to get stuck and clog the flow of oil

 

in about 2-3 weeks I plan to go ahead and drop the pan and clean it out and also install a new oil pump, I have an extra melling (non-HV-I think it is an M55) that I was going to use on a TPI rebuild and I want to go ahead and try and use that with the GM white spring if that would work well.
Any opinions on doing so?