Sudden low oil pressure

[BigBrother-84]

All of the gauges, save for the ammeter, are the same. You may have gotten by with it, but when I tested to create that writeup on the gauges I smoked a few resistors.

I probably ought to rewrite that page to include those calculations so people will understand the amount of power they'll be playing with.

But right now I'm writing up a 3D page...

Gentlemen, I unplugged the connector from the oil pressure sending unit and grounded it.

With key contact on, the gauge needle slowly went to maximum.

I let the contact on, unplugged the connector, and the needle went slowly down to zero.

So I thoroughly cleaned up the connector and the sending unit terminal.

Started up the engine, and the oil pressure gauge needle climbed right in the middle.

Later today was the manure duty, and a hot idling engine gave a lower oil pressure, would say first third. Higher RPM and the gauge needle goes back to the middle.

So, I think Big Bro's problem was a dirty contact at the sending unit.

Thanks for the advice!

[Gary Lewis]

Gentlemen, I unplugged the connector from the oil pressure sending unit and grounded it.

With key contact on, the gauge needle slowly went to maximum.

I let the contact on, unplugged the connector, and the needle went slowly down to zero.

So I thoroughly cleaned up the connector and the sending unit terminal.

Started up the engine, and the oil pressure gauge needle climbed right in the middle.

Later today was the manure duty, and a hot idling engine gave a lower oil pressure, would say first third. Higher RPM and the gauge needle goes back to the middle.

So, I think Big Bro's problem was a dirty contact at the sending unit.

Thanks for the advice!

Glad you got it sorted, Jeff.

[delco1946]

Glad you got it sorted, Jeff.

Well I need to do some more investigating but it does seem to be the oil sender wire. It is toast and I know I hit it while checking spark plugs. Lots of oil around the sender its self. Not sure where the oil was coming ( dripping from valve cover?) from but yuck what a mess.

Not sure how to replace the sender wire as it merges into a larger wire harness ( I hate splicing 😂). The harness looks toasty too but that’s gonna to expensive to try and replace.

It’s so hard to see and get to. No wonder I’ve never paid attention to it before! Thanks for the lead.

[Gary Lewis]

Well I need to do some more investigating but it does seem to be the oil sender wire. It is toast and I know I hit it while checking spark plugs. Lots of oil around the sender its self. Not sure where the oil was coming ( dripping from valve cover?) from but yuck what a mess.

Not sure how to replace the sender wire as it merges into a larger wire harness ( I hate splicing 😂). The harness looks toasty too but that’s gonna to expensive to try and replace.

It’s so hard to see and get to. No wonder I’ve never paid attention to it before! Thanks for the lead.

I've seen the sending units leak and squirt oil. So I'd clean the area up around the sender and try to determine where it is coming from while you are on this mission.

[mat in tn]

Well I need to do some more investigating but it does seem to be the oil sender wire. It is toast and I know I hit it while checking spark plugs. Lots of oil around the sender its self. Not sure where the oil was coming ( dripping from valve cover?) from but yuck what a mess.

Not sure how to replace the sender wire as it merges into a larger wire harness ( I hate splicing 😂). The harness looks toasty too but that’s gonna to expensive to try and replace.

It’s so hard to see and get to. No wonder I’ve never paid attention to it before! Thanks for the lead.

absolutely. start by cleaning as well as possible.

it is understandable why the sender is wired the way it is for an assembly line, but if you want the best connection then use a ring terminal. the factory 90 degree, slip on connector is not the best but it has proven to work well enough for many years. you cannot remove or install these senders with a pigtail I'm place so it will need to be done in place and it's a pain to get to, so I understand the slip on. but a better connection can be had. then a bullet connector or any more positively locking connector could be used where it meets the harness.