weird oil pressure problem

[grimreaper]

i lost 5+/-psi with the rx-7 oil cooler seen at the return line to the block compared to in front of the cooler. Stuck the stock gauge back in the stock port and DAMN, it reads barely above the first line yet prosport gauge reads 30+psi in that range. Prosport is in the return line to engine when comparing those readings. Across the board up 10psi everywhere except idle, still the normal 4-6psi. seems the old aftermarket gauge was not accurate compared to new gauge. new trucool is in and mounted behind intercooler and got that 5psi back.
swapping them around sucks, hope this helps as it is not the cooler.

 

[spoolint78]

Ya, I guess its something in the motor.
I am also slightly below the Full mark. I will top it up.
Funny thing today though, when I started the car and gave it gas, the oil pressure went past 140psi lol.
But it still dips for a second or two in psi, then climbs. Its like there is a delay.

 

[grimreaper]

140? i cant get over 60psi, guess thats the oil squirter's. you have had a hell of a time with that motor and the oil system man... id have shoved a rag in the tank by now!

to much pressure when cold, delays pressure build up when hot, never seen this so hopefully IJ or jdubs have...

 

[jdub]

What's it doing now exactly with the new cooler Grim?

I starting to suspect the squirters....

 

[grimreaper]

sorry jdub i was stating spoolint78's issues in the bottom of my post.

but for me:
new cooler max is 58-60psi (levels off) for me although i havent gone over 5000rpms yet.
idle is 4-6 psi depending on what rpm the idle is at.
3000rpms = above 40psi, seems all to be within range per tsrm.
30w GC.

 

[jdub]

That's well with in spec...actually damn good for an un-shimmed oil pump.

So you did get a 5 psi pressure drop across the RX-7 cooler. Did you get a thermostat for the new TruCool?

 

[grimreaper]

ya give or take depending on rpm range. a guy up the street has the same cooler and he too noticed a similar drop:dunno:. similar setup of motor and cooler circuit (same cooler different adapters and possibly lines)

no thermostat yet, only driven on nicer days for now, my blunders in trying to go out of the box and keep costs down would have paid for one easily but has set me back till after the holidays for supra toys...

 

[spoolint78]

jdub, tell me if this makes sense.
Either the shavings are in the pump, or in the oil squirters, or possibly in the pressure sensor for the gauge.

But what I think is happening is when I give it gas oil pressure dips at first because the squirters are leaking, and then as pressure builds and builds, the squirters will become a restriction cause the oil pressure to keep rising (they can only hold back so much). But when the car warms up and pressure drops, as soon as I give it gas, the pressure is low enough that the squirters can bleed off the majority of the pressure which causes the pressure to dip.
Secondly, I never did change the squirters in the block at all. Is it common for them to leak that much? I never really heard anyone else say they had oil pressure issues relating solely to the squirters.

Lastly, regarding the shavings in the pan, they were magnetic. Engine bearings aren't magnetic are they? I hear no knocking and oil pressure is like 70-80psi at cold start. I'm assuming the shavings were from the oil pump shaft when the colar became really lose.

 

[jdub]

Spool - I thought you didn't have squirters?

The metal could have got in the pump and is interfering with the relief valve or the squirters. Since you shimmed the pump, I would suspect the squirters. Arz did a test on used squirter bolts and they varied all over the place. Opening early is a definite pressure bleed.

When you shimmed the pump, did you use washers?

 

[spoolint78]

Yes,
washers were used. The motor is a 7m-gte and after reading a few posts, it seems very rare to have a 7m-gte block without squirters.
I'll keep you posted.
Thanks for the help

 

[grimreaper]

any update?