Differences in oil temp gauges

[tirwin]

I've been thinking for a while that there is no way my oil temp gauge is correct. It works but seems to read too cool. I have verified that the internal and external thermostats are working so the problem is either with the sender or the gauge. The engine harnesses were replaced last year so the wiring is good.

When I bought the car it had a numeric gauge that a PO had installed instead of the typical 'line' style gauges. The PO recently came across the original gauge and sent it to me. It is just the left side temp internals/face of the whole gauge so someone had to open the gauge to replace it at some point.

I'm wondering if it is possible that the 'new' numerical gauge is incompatible with the temp sender? Was the numerical gauge possibly from a different model year or was it maybe something once sold as an aftermarket option at some point?

I thought it might be a good idea to verify compatibility before digging in much further.

Any thoughts?

[Arne2]

Quite possible, yes. You may want to try to figure out he part number of the numbered gauge now in the car so you can try a matching sender for it.

[Reiver]

Tirwin....I've an '83 and bought a numerical decal that was placed over the original hash mark front.....yours may be the same.
Remove the gauge and the temp side comes off from the back with no issues and you can check for an overlay. There are different overlays for the different years so some PO may have gotten the wrong one.
The gauge serial numbers can also be checked for correctness.

BTW, am switching to an MSD and appreciate the input on that thread.

[javadog]

Yes, there were different sending units. It's very likely that the sending unit should have been changed with the gauge. Look at the maximum value on the sending unit. It will be 150C, 170C, something like that. Compare that to the upper limit of your new gauge. Is the upper limit on the new gauge different from the upper limit on the old gauge?

JR

[tirwin]

Thanks, guys, that is exactly what I needed to know. I will check it out and report back. Might be a good job to do while I have a little breather from work.

Reiver, I have been pleased since switching to the MSD when my PermaTune unit failed. I tried looking for your thread and didn't see it. Can you post a link? To answer your question there are actually two different gauge mechanisms, not just an overlay. Although I suppose someone could've bought a different mechanism and put a decal over it.

[Joe Bob]

Most gauges have temp number under the temp gauge bezel to the left. Stick head past the right side of the steering wheel, look left, may need a flashlight. Temps are in Centigrade.

The validate temps, a hand held pyrometer can be used to shoot via IR beam temps of oil lines, tank, cooler etc.

BTW, temp gauges have different senders and you can match them up by checking the date on the rear of the gauge and the sender serial number. BTDT.

[Reiver]

Originally Posted by tirwin

Thanks, guys, that is exactly what I needed to know. I will check it out and report back. Might be a good job to do while I have a little breather from work.

Reiver, I have been pleased since switching to the MSD when my PermaTune unit failed. I tried looking for your thread and didn't see it. Can you post a link? To answer your question there are actually two different gauge mechanisms, not just an overlay. Although I suppose someone could've bought a different mechanism and put a decal over it.

Yes there are different gauges and sender so that could be it. There are also two different number scale appliques for the two and if someone put the wrong applique in place that could be the issue.
One applique starts with 120 degree's and on my '83 SC the applique I found starts at 140 degrees and lines up with the off scale 140 degree tic mark 60 degree Celsius.

I didn't start a thread on my CDI...you guys already did it so it would just be replication. I sent Timmy2 an email and he's sending me the proper Bosch male plug so it'll be sanitary. It's all wired and ready just awaiting the plug.
BTW, I wired the power from the second fuse in the 3 fuse panel on my unit. That was a continually hot (tested) 25 amp source for my engine mounted heater fan (that no longer exists as I've backdated)...I put a 16 amp fuse in place.
Oh, and NAPA still has the non resistor rotors eb 407 Echlin....they still show a resistor rotor on the website (generic pic) but the one that shows up is the tan resistorless.