Either my oil pressure sender failed or I've lost all oil pressure!

I had to do a ThermoQuad rebuild on my 440, so I took the opportunity to also remove the valve covers and intake manifold in order to clean them up and paint them. I did nothing to the crankcase or oil pump, and of course there aren't any oil galleries that become exposed in removing and replacing these items, so I think it would have been impossible for me to have screwed up the oiling system in any fashion because I did nothing to it.

After I removed the intake manifold, I noticed that the insulation on the yellow wire going from the engine wiring harness to the oil pressure sender had deteriorated due to heat and was falling off the wire, so I carefully cut off the old deteriorated wire and soldered a new wire onto the harness, putting a spade lug on the other end to push onto the oil pressure sender terminal. I had some trouble getting the spade lug to go on. And the fact that the oil pressure sender is so inaccessible on the back of the engine didn't help any.

When I fired up the engine, the dashboard oil pressure gauge said I had no oil pressure! When I removed that yellow wire from the sender and grounded it, the gauge went all the way to the right, so the gauge circuit is working (including the wire that I replaced).

With the yellow wire disconnected, an ohmmeter between the sender and ground shows an open circuit with the engine running, so I either have a bad sender or I really have no oil pressure!

I wonder if trying too hard to shove that spade connector onto the old sender sent it belly up? This must be an example of "if anything can go wrong, it will!"

I can't think of anything I could have done to lose my oil pressure, can you?? And how do you remove the old oil pressure sender? There doesn't seem to be enough room to get a wrench under it. Do you need one of those special "claw" wrenches? If so, what size?

Thanks in advance for taking pity on a fellow FABO member by trying to help me.

The oil sender uses a special sized socket to remove it. They used to be sold at any auto parts store, should be able to get one now.

pull a valve cover and crank her over for a couple of seconds -Don't start it up just crank it a little -see if she squirts any on the valve train ,if it make a mess you have pressure .

You need a mechanical to temporarily hook in. That will tell you yes or no.

It was a bad oil pressure sender! The engine had plenty of oil pressure (60 lbs. at idle). Scared the hell out of me, though!

I wonder why the sender chose this moment to crap out??

Bill Crowell said:

It was a bad oil pressure sender! The engine had plenty of oil pressure (60 lbs. at idle). Scared the hell out of me, though!

I wonder why the sender chose this moment to crap out??

Click to expand...

Old chinese proverb "crap happens".

This is kind of unrelated to your question, but what Thermoquad rebuild kit did you use, and where did you get it from? I'm trying to find one for my '73 TQ.

Glad it was just that.....

wish4hemi wrote: "what Thermoquad rebuild kit did you use, and where did you get it from? I'm trying to find one for my '73 TQ."

I had no problem at all finding one, wish. The first place I went to (dare I admit it?? - AutoZone!) had it. The brand is "GP Sorenson".

I'm no TQ expert like Demonsizzler, but from my limited experience the most troublesome parts of the carb are the O-rings at the bottom of the main fuel wells and the metering rods and jets. The rods and jets had greenish crud all over them from gas evaporating in in the fuel bowl, and I'm sure that the crud was interfering with fuel flow. The most difficult part of the job for me was getting the metering rods to go into the holes in the step-up piston rack while at the same time getting them to go into the metering jets.

It's really a cool carburetor, though. The only way Carter could flop open those big air doors to the secondaries to achieve the TQ's 850 CFM rating without flooding the motor is to very carefully control the mixture when the secondaries open, which the step-up piston assembly does very well. And the fuel never comes into contact with any metal that conducts heat from the engine, so it stays about 20 degrees cooler than in all-metal carbs.

I have 3 Mopars with TQs. Once the fuel bowl cracked on one of them. I sent it to a plastic "stitcher" (repair company) and when they returned it, you couldn't even tell where they'd repaired it, except that they reinforced the area that broke. So it's really no problem keeping the TQs going.

I wish I had your luck with TQ's, I have two and can get neither one to work very well. Give me an AVS and I'm happy