High Oil Pressure

[8upZR1]

Hello all, I hope you are enoying life. I have recently put my ZR1 back on the road after having replaced the head gaskets and lifters and just about everything else. I have noticed that my oil pressure gauge is reading high. It is off the scale in fact when the motor is cold and at idle. When the motor is revved up the needle goes way off scale. When the engine is hot and at idle the oil pressure will go down to the very top of the mark, I think its 80 or 90 PSI. I am not sure if the gauge is reading correctly but I do know that before my head gasket problem it read normally. I replaced the oil filter thinking that it may be clogged but it looked good inside and the new one made no difference. Anybody have any ideas? Earlier this year the motor would not start because the lifters were pumping up and keeping the valves open. Perhaps the high oil pressure caused the old lifters to fail? I dunno, but any help would be appreciated.

[guinnessdood]

Look at the oil pressure sending unit and see if the oil has leaked into the connector side of the sending unit. Oil sending units can be purchased at nearly any auto parts store...ours isn't special. If the oil leaks into the connector you get all kinds of weird readings on the gauge.

[tccrab]

Hello all, I hope you are enoying life. I have recently put my ZR1 back on the road after having replaced the head gaskets and lifters and just about everything else. I have noticed that my oil pressure gauge is reading high. It is off the scale in fact when the motor is cold and at idle. When the motor is revved up the needle goes way off scale. When the engine is hot and at idle the oil pressure will go down to the very top of the mark, I think its 80 or 90 PSI. I am not sure if the gauge is reading correctly but I do know that before my head gasket problem it read normally. I replaced the oil filter thinking that it may be clogged but it looked good inside and the new one made no difference. Anybody have any ideas? Earlier this year the motor would not start because the lifters were pumping up and keeping the valves open. Perhaps the high oil pressure caused the old lifters to fail? I dunno, but any help would be appreciated.

The oil pressure sending unit is a common failure in the early ZR1's.
http://www.zr1netregistry.com/ZR1_issues.htm#4

Pop in a new sending unit before you start ripping the heads off again!:mrgreen::mrgreen:

TomC
'90ZR1 #792

[8upZR1]

Thanks for the advice, I will try the sender tonight. I sure hope it is something that easy. Lately not much has. I could have definetely gotten oil on the connector as a tried starting the motor sans filter a few times and did the same with the valvecover. Quite messy.

On another note, this probably doesn't belong here, but my tach is dead and I'm lazy so my solution has been this great new shift light from Auto Meter. It has like 8 super bright LED's, a digital readout of engine RPM, progressive shift light, 10 variable light colors, launch rpm light, an excellent mounting system, 80 seconds of memory, max rpm. It has solved so many of my problems, I almost feel happy.

Bye all.

[Hib Halverson]

Not only do the engines have occasional trouble with oil pressure senders but the analog gauge are horribly inaccurate.

First thing I'd do if you suspect excessive or (gawd forbid) not enough oil pressure. Is install a known-good gauge and read the pressure from that.