69 Pontiac Oil Pressure Sending Unit
 

I've been having bad luck as it pertains to oil pressure sending units. Previously I had been running the ones that you get from the local parts store and they continued to fail. I switched to buying an AC Delco one for my car and that lasted about a year. The unit failed, basically it would get erratic and peg the needed intermittently where you could hear chatter from the gauge. So I ordered another AC delco unit from Summit. Installed it and it worked perfectly for about a week and now have the same problem. Any suggestions on getting a good sending unit that's dependable?

Everything sucks today. I have a new ac oil sender on my 5.3. It jumps around also. The old ac was smooth. I used to trust Standard Motor Products. I bought a voltage regulator and a multi switch lately. Both suck. Made in china. The cruise function has already failed. So, where are the good parts?:confused:

My solution isn't for everybody but I bought Autometer gauges for oil pressure, water temp, and voltmeter. All are "mechanical" gauges, no electric senders as the senders all seem to be s*** these days. Not a stock look I know but I, too, am at a loss with these current senders.

When an older GM gauge "chatters" that is a sure sign that the buffering fluid inside of the gauge is gone.

FYI: GM put inside of all of it's gauges 2 or 3 drops of glycerin. The fluid actually serves 2 purposes: A) it acts as a lubrication for the moving parts inside of the gauge and B) it dampens the movement of the pointer so that the gauge reads smooth and steady. Over a time span of more than 50 years (summers & winters) the fluid eventually leaks out of the gauge. Once the fluid is absent the gauge bounces around with a herky-jerky motion, especially an oil pressure gauge. The final failure is that the pointer will detach from it's shaft and fall down into the cluster.

The fluid can not be expected to stay inside there forever.

I agree with all posts above that, in general service parts (in this case the sender) sold today for a 50 year old car are no longer made to the same quality standards as the original GM parts.

The cure in this case is to replace the dash gauge.

Fluid in an electrical gauge? I've had my cluster completely apart including repairing a needle on my temp gauge. There is no fluid in my 69 GTO gauges and the jerky crap is caused by intermittent direct ground being supplied to the gauge causing the erratic movement.. The electrical gauge position is controlled by the amount of "ground" being supplied to the gauge through the sending unit which positions the gauge in the respective position based on electrical current. Agree, the erratic "pounding" of the gauge caused by intermittent direct ground could eventually cause damage and knock the needle off I would assume. Furthermore, this issue is solved when you replace the oil pressure sending unit, in my case I've seen it work for a year and the recent replacement failed after about a week. My assumption is the ACDelco part being produced is crap.

Anyone try the "Standard Motor" alternative sold by Summit?

And you're SURE that the wire leading to the sending unit isn't intermittently grounding on something? Wouldn't be the first time the sending unit/switch got blamed for a wire-harness problem.

Not sure how that can happen in any vehicle unless you have cut up / bare wiring down to that connection point as there's plenty of room between where that sending unit mounts and the firewall. My engine bay is clean and all wiring is tied up and enclosed/routed in wire loom. As described in my initial post it appears these AC Delco units do work at first but then fail at some point. Probably a cheap ass spring internally being used that doesn't have the rigidity in it like they used to make and fails.

I found a couple of NOS AC-Delco oil pressure senders on the Bay. The units and original blue and white boxes are date coded from the early 80s. They seem to be doing much better than the Echlin units I was getting from the local NAPA. The ones I picked up from O’Reily didn’t last a dozen drives.

My fix for this was relocating the sending unit to the fitting near the distributor.
As others have said, the current replacements are inferior to the originals and I believe exhaust manifold heat is what takes them out so quickly. I've got at least a couple thousand miles on without a failure in the new location.

Another problem with the last few I've used is they don't read accurately. I've read that an inline resistor solves this problem.

Can you tell me what to look for to find the date code?

FYI, I tried the standard last year from Summit and a year later it has now failed.

I've had great results from using Lectric Limited temp and oil senders. Accurately calibrated to the vehicle and not generic like the off shore auto parts store stuff. I finally got my rally temp gauge in my '65 to read accurately after 30+ years using one of their sending units.

Thanks for the info, checked their site and doesn't look like they do oil, just temp.

I would like to know what value the resistor needed to correct currently available sending units. Any idea?