Oil pressure light... After filter change

[jrobie79]

Car was off the road for 5 years, engine on a cart for about 8 months, 1 if those was outside with a tarp over it... pretty much fired right up, only drove it in and out of the garage for about 3months while I put it all back together. Finally drove it for the first time a few weeks ago, zero issues. I changed the oil after about 300 miles, figured any residual rust and whatnot would be in the filter. Mobile 1 15W-50, but I didn't have a new filter at the time, so I used the old one for about a week. Changed the oil filter on Sunday with a brand new MANN. Noticed the cluster oil pressure light is illuminated when I start it. It's not a constant brightness, it dims and lights back up continuously. Dims when I give it throttle, but never goes fully out. If I open the oil cap oil still splashes out, so it would appear oil is still reaching the head... First thought was faulty sensor, but I'm not really sure.

Mechanical gauge shows everything is fine. Guess I'll swap the sensor

[82eye]

sounds like the pump is failing and the sensor is doing its job.

edit: you'll want to get a gauge on it to test if it is the pump or the sensor reading wrong. in practice it's almost never a sensor.
did the pump get packed with build grease or primed after the rebuild? m42 pumps are notorious for not priming.

[TobyB]

The dimming thing makes me suspect an electrical issue,
but yeah, I ALWAYS go straight to the mechanical oil pressure
gauge first, and then, once there's 50 psi, then start troubleshooting the rest of it.

t
oil pressure is life.

[jrobie79]

sounds like the pump is failing and the sensor is doing its job.

edit: you'll want to get a gauge on it to test if it is the pump or the sensor reading wrong. in practice it's almost never a sensor.
did the pump get packed with build grease or primed after the rebuild? m42 pumps are notorious for not priming.

I didn't rebuild the engine. Just the car. And I have been driving it every 4 or 5 days for the past 3 weeks, put about 600 miles on it before this happened. What's the easiest way to get a gauge on there? Just take the sensor out and use an adapter?

[82eye]

I didn't rebuild the engine. Just the car. And I have been driving it every 4 or 5 days for the past 3 weeks, put about 600 miles on it before this happened. What's the easiest way to get a gauge on there? Just take the sensor out and use an adapter?

i've never had to do one on an m42. i know it's been done here before, might have to tee in an oil dist block. would just run the gauge temporary under the hood for diagnosis.

edit: if the light can be trusted it's indicating a low pressure on start up which is really hard on the engine.

[jrobie79]

There's a threaded hole on the front of the filter housing. Gonna put a gauge in there tonight. I'll see what happens

[jrobie79]

Looks ok to me. Time to swap the sensor

[82eye]

Looks ok to me. Time to swap the sensor

best news yet.