I just bought this car with about 125k miles and soon after the oil pressure idiot light started coming on after about 10-12 miles. It never really stays lit but constantly goes on and off. Last night I took out the oil pressure sending unit and put an oil pressure gauge on it and got this:

60 psi cold idle
35 psi warm idle
26 psi hot idle after 10-12 mile drive
63 psi hot reved to around 3000 rpms

This seems to be in spec according the Haynes manual I have, does this sound good to you guys? Do you think the problem will be solved with a new sending unit?

Thanks

 

You could have had a bad sending unit and now you fixed it.

 

So I replaced the oil pressure sensor last night but the problem did not go away. I have a fairly cheap oil pressure gauge but I don't see how it could be off the 20+ psi it would take for the idiot light to be coming on. Any ideas?

 

Did you replace the oil sending unit? Other things to look at would be the oil pump or pressure relief valve. If you have good pressure though, then I wouldn't think it coould be your pump.

 

Yes, I guess it's called the sending unit and I replaced it. That's also the port where I tested the oil pressure with the guage so this doesn't make any sense. Where is the pressure relief valve? Could that be opening at the wrong time and killing the oil pressure?

 

It's in the oil pump and it could be getting stuck open.

 

Great, I looked at the manual and the oil pump looks like it's a real pain to get to. But I might just have to check that out.

 

I'd change the oil first. Make sure you have the right amount and type of oil in it first. You probably already did this but i didn't see mention of it. Wrong oil could effect your pressure. Always assuem everything is incorrect when you buy a used car. Don't know about pressure relief valves. Why would it be necessary to relieve the pressure? When I oil pressure a bad thing?

 

I already changed the oil and filter. I put in 10w30 because I live in austin and drive in 100+ weather and it never really gets cold. The oil looked pretty clean and probably had less than 1000 miles on it. The filter wasn't obviously clogged or anything.

 

Im having the same problem. It just started about a week maybe 2 weeks ago. I'm using 10w-30 fully synthetic extended protection oil. I havn't changed it since it started. I was told I might have to change my oil sending unit as well, but im thinking other wise now. Keep me posted on what you find with your oil pump if you do pull it. My brother and I are going to dig into the problem when he gets some time away from his shop.