A few weeks ago, I got the 8BA flathead on my 49 F1 freed up. I've been working on one problem at a time. Can the oil pressure sender and/or that tube it attaches to become clogged with gunk over time and make the gauge read low? Have you guys seen that?

 

Not common, I suppose it could happen, but the sender itself can gradually "sag". In fact I am ordering a new one for mine because it reads low compared to a mech gauge, especially at idle.

 

As Ross said, it can happen - especially to one that has been sitting idle for a long time. There is no tube however on an F1 239 flathead.

The 47 and earlier truck sending units were mechanical with a tube to the gauge, but the one you have should be electrical.

 

I assumed his has the sender on the filter Tee, and he means the tube to that?

 

Ross:

I would be interested in what you find as I have the same issue. When doing the rebuild on the flathead, my mechanical gauge would read about 50 psi at a decent rpm. I purchased a replacement oil sender (original one was crushed) and the gauge on the dash now nevers makes it quite to the 30 mark. I attributed the difference to the oil sender and the accuracy of the dash gauge.

If you find a new oil sender that improves the accuracy against the mechanical gauge, let me know!

thanks
Fred

 

Just food for thought: If your engine has been sitting for a while and is frozen up the there is a chance there is or has been some moisture in your oil.

The sender is an electrical device and so it is electrostatically active. That means if you have any moisture in the oil at all that sender is going to attract it and may rust inside. There's probably a higher possibility of that than being plugged with gunk!

 

Thanks guys for all the suggestions. And YES the truck had been sitting since at least 1991 and not even turned over. And I'm not so sure if it was really driven much before that. And yes the sender is on that filter T. Julie, I'd say you are right about the sender being corroded. I'll be swapping it out shortly.