Oil Temperature Gauge(s)...so what do I have here? Options

[GregAmy]

I've got a '74 2L, 4742918315. Thing was a rebuildable basket case when I got it, been hacking away...today's task was the center oil temperature gauge: it doesn't work.

In reviewing the wiring diagram it appears that I should have a green/black wire running from the sensor at the bottom of the engine to a green/black wire in the center console. However, while I have the red/white and brown wires going to the gauge, the third wire is...white. I used a VOM to ring out the white wire, and it does not go to the sensor wire in the engine compartment.

But here's another odd thing: the car also has a fuel combination gauge ("silver button") with a temp sensor in it. In reviewing various pages on the web, I'm thinking that's not what's supposed to be in this car; best I can tell, this car with a center console oil temp gauge should have a blank area at the top of the fuel combo gauge.

- What do I have here? Is this a center console that someone added on? It has an operational clock and voltmeter (which sucks, by the way).

- If this is the case, what is the plug with the white wire supposed to be for? I don't see anything obvious in the wiring diagram, there's no voltage to this wire, nor does it ring to ground at all.

Stumped, but intrigued...

Greg

[Dave_Darling]

Your car seems to be a late 74, so the silver-button 73-style gauge is wrong. Someone swapped it in. They may have connected the oil temp gauge there, or they may not.

There is a connector under the rear of the center console with several wires on each side. One of them should be the green/black signal wire. If there is something plugged into it, that's likely going up to the gauge in your combo gauge.

The white wire is certainly an addition. The only way you'll figure out where it goes is to trace it yourself.

--DD

[GregAmy]

Thanks Dave. You sure about that white wire? Except for the white color, it looks decisively factory, using the stock plugs, stock electrical pin inserts, and it goes into and through a factory wiring loom with all the other wires in that vicinity. Based on the other hacking I've seen on this car, it's not the quality of work I'd expect from someone swapping something in...in fact, the quality of its insertion lends me to believe it was done at the factory.

[Dave_Darling]

Let's say I'm pretty sure... It could be that someone on the factory floor grabbed an oil temp combo gauge and then had to hunt up a piece of wire to make it work, but I'm skeptical of that. Especially with a silver-center combo gauge in a late 74 car, which should have no center marker in the combo gauge.

--DD

[GregAmy]

So I pulled the shifter boot cover and traced the wires back...and you're right, that white wire goes to nothing, it's clipped off under there and hanging out. The green/black wire goes into the factory connector then forward through the factory bundle.

I'm guessing you're accurate in that someone tried to install the console. Reading on Pelican's web site it seems to be an easy install. I'm not clear why that wire is white - it does look like a factory harness - or why a prior owner decided not to connect that to the sensor. Further, I cannot explain why I have an earlier "silver button fuel/combo gauge; either it's a late-inventory factory install or someone replaced it later in its life.

So, I have a decision to make. This is not a concourse restoration so I'm not concerned about having "incorrect" parts. Further, I find the center console gauges to be wucking forthless: the clock is disconnected so it doesn't drain the battery (who needs a clock, anyway?), the voltmeter displays inaccurate info (and gave me a heart attack a couple times when I stepped on the brake and/or use the turn signals), and the oil temperature gauge is giving me info I already have on the dash (I've seen that gauge move, but not a lot). I'm sure the "appearance group" gauges are more attractive to a future buyer, but maybe I'm better off finding one of those cubby hole center consoles and selling of this one? Otherwise, I'll have to move the sensor wire to the center console gauge and find a replacement fuel/combo gauge...

Dunno, thoughts appreciated.

GA

[GregAmy]

Another thought: how hard is it to fit a VDO oil pressure sender where the oil pressure switch is now (I don't know where it is)? I could add an oil pressure gauge to the center console with only a single wire addition (one that I think is already done for me, as a prior owner had an aux fan switch back to the heater blower...)

GA

[Dave_Darling]

The oil light sender is next to the distributor. The gauge sender doesn't really fit in the area, so you locate it remotely with a grease gun hose and a couple of adapters, or with the kit which is basically a grease gun hose and some adapters. Ground the case of the sender if you do that!

In stock form, there should be a wire from the heater lever back to the heater blower relay on the relay board.

I replaced the gauge panel of my center console with one I cut out of MDF and glued vinyl onto, and used a hole saw to cut the appropriate sized holes for the aftermarket VDO gauges. (Note that the commonly-available ones are slightly smaller than the stock gauges!)

--DD

[ChrisFoley]

The oil light sender is next to the distributor. The gauge sender doesn't really fit in the area, so you locate it remotely with a grease gun hose and a couple of adapters, or with the kit which is basically a grease gun hose and some adapters. Ground the case of the sender if you do that!
...

We recently stopped using grease gun hoses.
They (the newer ones at least) collapse internally after a short time with hot oil inside.
Now we're making our own remote mounted pressure sender hoses from Aeroquip materials.

[GregAmy]

Chris, you have a gauge and sender laying around for sale?

[malcolm2]

Paint gun hoses. The threads match, and they come in many lengths and they don't cost too much.

sender on the left with a ho-made mount to the fan housing. also needed a male-to-male coupler from Home Depot. Follow the metal braided hose back to the distributor and thread into the block. I used the sender with 2 connections, 1 for the OEM oil light in the combo guage and the other for the VDO gauge.

[ChrisFoley]

Chris, you have a gauge and sender laying around for sale?

I have a new gauge and might have a used sender.

[bdstone914]

The oil light sender is next to the distributor. The gauge sender doesn't really fit in the area, so you locate it remotely with a grease gun hose and a couple of adapters, or with the kit which is basically a grease gun hose and some adapters. Ground the case of the sender if you do that!
...

We recently stopped using grease gun hoses.
They (the newer ones at least) collapse internally after a short time with hot oil inside.
Now we're making our own remote mounted pressure sender hoses from Aeroquip materials.

You can also use a rear flex line from a 928. It is the right length to mount the sender to the tin at the coil mount nuts. I bought one from O'reilly for $22 and it was an ATE hose. 1/2 the Pelican price. I would not use the paint ball gun hose as they too are probably not intended to see hot temps.

http://www.oreillyauto.com/site/c/detail/B...9&ppt=C0066

[GregAmy]

Follow up to this mystery...I bought one of those dipstick thermostats and drove it for the first time today. Car got up to about 200* and stayed there (45-50 degree day). However, the dash combo temp gauge barely came off the peg; it came up maybe about 4 needle widths from its stop with the key off, and maybe two widths off the lower hash mark. It obviously came nowhere NEAR the 2/3 mark where the red starts. It has been that way since I bought the car.

Does this seem like a bad gauge or sender? Or are there two different senders for the early and late gauges? Any suggestions on how to troubleshoot/resolve this?

GA

[luskesq]

Sender likely does're March gauge.

Keith

[GregAmy]

Um...ok?

[Harpo]

Hint hint someone needs to put together a group buy for these with -04 aero quip lines and appropriate fittings.

Any volunteers?

David

[GregAmy]

Hint hint someone needs to put together a group buy for these with -04 aero quip lines and appropriate fittings.

You're talking about the stainless braided line to remote mount the VDO oil pressure sensor? Chris Foley is making up one for me..I can inquire for a final price and ask how many he's willing to make...

As a related aside, on the race cars we avoid mounting these on the engine to avoid vibration failure (I mount mine on the firewall)...has that been an issue on these engines on the street? - GA