Troubleshooting oil pressure gauge

[BruteForce]

When I fired up my engine, the oil pressure idiot light went out, indicating pressure. But the (stock) oil pressure gauge didn't budge. With the power off, I measured the resistance of the water temp sender as a few ohms, but the oil pressure sender measured as infinite resistance (open circuit).

What should be the resistance of the sender when the engine is off? (It's a new one I got from Rockauto, as my old one disappeared.) Anyone know what the resistance of the sender should be at, say, 50 psi?

I've looked at a lot of ads for senders, and not one of them mention any of their electrical characteristics.

[BruteForce]

I should add that yes, I'm getting a pulsing 5V signal on the sender connector, and the gauge pegs when the sender wire is grounded.

[BruteForce]

I did some more googling, and suspect that 0 PSI should be 240 ohms, and max pressure (whatever that is) should be 33 ohms. As my sender measures an open circuit, it's probably bad.

[Chryco Psycho]

I agree , if you have 5 v at the sender & the gauge moves when the wire is grounded the sender is the problem , do not tighten with the body either , there is a nut under the body for tightening it in ,use it

[BruteForce]

Hmm, I did hand tighten it using the bell, not the nut. Could that have busted it? I didn't apply much force. Anyhow, I ordered a cheapo mechanical gauge I intend to screw in to test to see that I really do have oil pressure and it's the sender.

[Chryco Psycho]

Yes it can damage it threading it in by hand , I bet you have oil pressure , the lifters would be talking to you if you didn`t have pressure

[BruteForce]

Well, with just headers and no exhaust, there wasn't much hearing of other things going on! I expect to get the new mufflers delivered today (the ones TTI originally shipped to me didn't fit, they are sending replacements at no charge. Their customer service is very good.  ).

I'm also pretty sure there is oil pressure because the engine was run in on a dyno before sticking it in the car. I figured it would be a lot easier to correct any deficiencies that way rather than having the aggravation of having to pull it out again.

While I wait for the mufflers and a few other parts needed to get the car rolling, I worked on cleaning the mags. It has old school mags which I really like. The modern Foos style spoked ones don't work for me.

[Chryco Psycho]

 

[BruteForce]

A standalone mechanical oil gauge arrived in the mail today. I screwed it in and fired up the engine. Got lots of pressure, so it clearly is a bad sender. That's a relief!

[dodj]

I did some more googling, and suspect that 0 PSI should be 240 ohms, and max pressure (whatever that is) should be 33 ohms. As my sender measures an open circuit, it's probably bad.

Good to hear it's all sorted out. Just out of curiosity I checked the resistance of my stock sending unit with the engine off. 83.5 ohms.

[dodj]

Well, with just headers and no exhaust, there wasn't much hearing of other things going on! I expect to get the new mufflers delivered today (the ones TTI originally shipped to me didn't fit, they are sending replacements at no charge. Their customer service is very good.  ).

I'm also pretty sure there is oil pressure because the engine was run in on a dyno before sticking it in the car. I figured it would be a lot easier to correct any deficiencies that way rather than having the aggravation of having to pull it out again.

While I wait for the mufflers and a few other parts needed to get the car rolling, I worked on cleaning the mags. It has old school mags which I really like. The modern Foos style spoked ones don't work for me.

I like your taste in rims. Let me know what you think of the TTI's. I'm looking around for an exhaust system to install this winter.

[BruteForce]

So far, the TTIs have been a struggle. I haven't figured out yet if I'm doing something wrong or not. I'll try again tomorrow. Part of the problem is the 3" exhaust X pipe is big and heavy, and I'm working on my back under the car with very little room to maneuver. A bit of graphite paste helps with the slip fits.

I may wind up having to take it to a muffler shop.

The TTI headers are nice, though you'll need a 90 degree oil filter adapter and a mini starter. On the passenger side, I had to grind a half moon out of the Lakewood bellhousing to clear the headers. On the driver side, it interfered with the torsion bar and I had to put in some Schumacher spacers to move the engine to the right.

Just out of curiosity I checked the resistance of my stock sending unit with the engine off. 83.5 ohms.

That's great information, thanks! I suppose what I can do is hook up a potentiometer and measure the ohms that correspond with various gauge positions, then I can match it to a sender. I don't like the stock sender, it's too large.

[BruteForce]

I like your taste in rims.

Me too  I got lucky in that these came with the car. I don't know what brand they are, and have never seen them elsewhere. I also like the satin finish, rather than chrome. My bumpers need rechroming, and I've been toying with the idea of doing a nickel plate rather than chrome. Nickel has a more understated, elegant look than chrome.

[BruteForce]

Update: Schuck's had senders in stock, so I bought a new one, installed it, and it appears to work fine.

[Chryco Psycho]

when installing the TTi exhaust start at the rear , hang the tail pipes first then slide the mufflers in ,, use the rear hangers & the large hangers to support the system then slide in the X pipe & the front adapters to the headers , line up the system so it sits straight & start tightening everything up