Oil Light!

[eagleone1983]

I'm getting an oil light when the engine is fully warmed up on idle only. When I'm cruising or under any kind of acceleration it goes off. I never get an oil light on idle when the engine is cold. It's a 69 Runner and other than the light I have no other indicators to let me know what is going on with this situation. I just changed oil and oil level is good. Any ideas on what's going on here? I'm sure someone on here has had this exact problem so I figured I'd check here first. I tried checking the archives but I couldn't find anything.

 

[rumblefish360]

Ethier or and both

Oil pump is worn out

and/or

Clearances are getting large.

When the engine is cold, the clearances are tight and the oil is thickest. Once the oil gets thinner, when warm, at idle, the pressure gets less.

A high volume oil pump may help and since on a B/B, it's external, it's an easy attempt to swap it out for a fix.

 

[prhousejr]

sounds like once your engine warms up and the oil gets hot and thin you are losing oil pressure.....

 

[69 Runner]

Yep. What they said. To be sure get a "real" oil pressure gauge and run yourself a test to see what your pressure actually is. There is always the remote possibility the sender is a bit clogged (or just going bad) and is giving you an erroneous reading

 

[eagleone1983]

Thanks for the quickness of replys. What's a good oil pressure guage or does it even matter. I'll check with Summit or mancini. How do I go about hooking it up?

 

[69 Runner]

Doesn't matter. I guess if you really wanted to spend the money you could get an autometer gauge. They are liquid filled and are supposed to be the best on the market. But any $20 gauge will do

 

[Meep-Meep]

Normal oil pressure for a MoPar of that vintage is 55 PSI at 1000 RPM with a minimum of 15 PSI @ 500 RPM. Yep, sure sounds like a high mileage engine with loose clearances and thinning oil when warm puts you right over the edge to turn the light on.

 

[godfatherofchry]

if the motor is org.and alot of miles take the slit wt. oil out and try 30or 40 wt. like it had from factry.if its not making any noise put a hi vol.pump on it.big blocks are easy to change

 

[eagleone1983]

It's not the original motor it's a '78 400 block but I'm not sure when the last time it was rebuilt or how many miles are on the engine now. I looked down in the carb and the intake manifold looks pretty gunked up but now that I changed the metering rods it starts right up. I bought a mechanical oil pressure guage but have no dang idea how to hook it up. It took me about an hour just to find the sensing unit (first resto and being born in '83 don't help). Once I get this guage hooked I'll let you know what the pressure is. Also is the 400 and 383 blocks sensing units the same?

 

[69 Runner]

Yup. All the big blocks have the sender in the same place

 

[eagleone1983]

Ok I finally got a mechanical gauge put in and here's what I got and based on Meep's recommended PSI reading I'm screwed. I have about 50 PSI or so when it is cold but once it warms up my pressure drops to about 8 or 9 PSI. It will go up incremently as I give it throttle. So I guess I'm changing the pump? or is there something else I should do first. BTW I'm running Castrol GTX 10-30

 

[dantrap]

You could try running stright 40W or 20w-50. Sounds like your mill is getting a little loose from age or mileage. I dont know if a new hi-volume or hi-pressure pump would help, but it may be worth a try. Good luck.

 

[daredevil]

what filter is on it? i heard about some restrictive filters a while back.

 

[eagleone1983]

I'll try heavier oil but the oil filter should be good it's a NAPA Gold which is basically a WIX brand filter.