Hi, My 1990 Loyal wagon 2WD no longer has oil pressure. This car has 111k miles on it and I really hope there's a simple explanation...(wire loose?). I looked at the book and it looks like quite a chore to replace an oil pump.

 

When I turn on my car the Oil pressure gage doesn't budge. After the car is warmed up the 'Check Engine' light comes on.

 

Any suggestions? I have been monkeying around with the car (if you read my other post you'll see that I recently had a problem where the car wouldn't start at all. I replaced the Distributer and all was well...until I realized a few days later that the oil pressure gage isn't registering any pressure and the check engine light comes on when the car warms up.).

first thought is to check the oil sender unit wire. It's right by the oil filter, and has a stubby wire that comes out then plugs into another wire. It's very exposed so it can easily get unplugged.

 

Hopefully, all that's happened is this has come undone.

Lets hope its just the gauge, because running it without oil will kill the engine in minutes. If it truly has no pressure the HLAs (lifters) will clatter like mad, so if the engine isn't making lots of noise I'd bet its the gauge, or more likely the sending unit. You can check it with a mechanical gauge (or just install one permanently).

 

Gary

Thanks, i'll check it when i get off work. I do recall that there was a wire that I hadn't tied back and it was frying on the manifold.. lol

 

 

 

first thought is to check the oil sender unit wire. It's right by the oil filter, and has a stubby wire that comes out then plugs into another wire. It's very exposed so it can easily get unplugged.

 

Hopefully, all that's happened is this has come undone.

Check to see if the OPSU wire is connected. If it is, and you still aren't getting any reading when running, try grounding it out (disconnect it from the OPSU and ground it to the frame). When it's grounded, the gauge should go up to the top. If it does, then you're OPSU is fried. If it doesn't, then either your gauge is hooped, or the wire is broken somewhere.

 

BTW, how old is your oil? If it is old and thin, then your pressure will definitely go down - though not usually to 0.

one thing to remember is the subaru stock intrument gauges SUCK. They are some of the most inaccurate gauges I've ever seen.

 

If you had no REAL oil pressure, 5 minutes of running your engine and it would have seized. the HLAS woulda clacked like hell and rods woulda started knocking. the sending unit either went bad, or the sending wire got broke or unplugged.

 

Oh yea the sending wire is yellow and it ties in with a wire going to a intake temp sender

OPSU = Oil Pressure Sending Unit

 

careful if you have to buy one

there is a sending unit and an

OPS (Oil Pressure Switch)

 

The sending units are known to fail and give inaccurate readings.

 

But first

 

Find the unit next to the oil filter as mentioned.

 

If there is no wire on it or in the vicinity look on on the engine directly above it's location.

 

If it comes loose from the sender

it can get caught in the fan belt and it gets

shortened considerably.

You were right on the money!! THANKS!! However, my 'Check Engine' is having issues. I'm going to post it as a new thread. I looked through the other 'check engine' light posts but didn't see one that applied.

 

 

first thought is to check the oil sender unit wire. It's right by the oil filter, and has a stubby wire that comes out then plugs into another wire. It's very exposed so it can easily get unplugged.

 

Hopefully, all that's happened is this has come undone.

one thing to remember is the subaru stock intrument gauges SUCK. They are some of the most inaccurate gauges I've ever seen.

Really? More inaccurate than a Ford oil pressure gauge which does one of 3 things: goes to Low, Normal or High, nowhere in between? Or some GM oil pressure gauges I've seen that stay pegged at 50psi no matter what the engine is doing?

I remember riding in Andrew's wagon to WCSS6. The OP gauge in there starts out about 30 degrees below zero and goes to about 20 when it's started up cold! Negative oil pressure!

my gauge just had -15 PSI of pressure this morning for 15 minutes of warming up.

 

Yeah it is -40 outside... maybe thats why