TR2/3/3A Anyone running an Oil Temp sensor on their TR3/4?

[karls59tr]

just wondering what would be involved for the install?

 

[Darrell_Walker]

I have one on my car, though I recently removed it to add a different gauge. It was easy to install, because my alloy pan already had a hole for it. For a stock pan, you would have to have a bung welded in.

 

[Twosheds]

I put an oil temp gauge in the TR3 racecar. I put the sensor in the oil cooler line adaptor. It sensed the oil coming out of the engine going to the cooler, I think. I got it from Pegasus or Racer Parts Wholesale, one.

It never worked. Probably because the car was wired for positive earth. I tried all sorts of wiring connections, but it never worked.

I sold the car. Don't know if the new owner converted to negative earth or got the gauge to work.

 

[Darrell_Walker]

Here is a picture of the sensor installed in the alloy pan.

It really wasn't too interesting, about all I learned was that the oil takes a lot longer to get up to temperature than the coolant.

 

[karls59tr]

Thanks for the info. instead of an oil temp gauge I'm now considering a temperature sensor for an air cooled engine. You can get them for VW. They mount at the thermostat housing. Only problem is to obtain a Pos Ground unit? The reason for the extra gauge is to be forewarned when there's a coolant loss as the temp gauge often won't let you know.

 

[Darrell_Walker]

Thanks for the info. instead of an oil temp gauge I'm now considering a temperature sensor for an air cooled engine. You can get them for VW. They mount at the thermostat housing. Only problem is to obtain a Pos Ground unit? The reason for the extra gauge is to be forewarned when there's a coolant loss as the temp gauge often won't let you know.

OK, in that case, I don't think an oil temp gauge will do what you want. Based on mine, it is very slow to indicate any changes.

Another option might be to find a place in the water jacket to install another temp sensor. Like the maybe the block drain tap hole? That should hold water longer, and perhaps show a temp rise.

 

[karls59tr]

Block drain tap hole. Good idea. I guess I could put a threaded plug into the tap drain hole and modify the plug to take a sensor. I'd have to fabricate a setup but it sounds like that would do the trick.

 

[TR3driver]

I would think you'd want it in the cylinder head, rather than the bottom of the block. Not much heat down there, so it might not show hot until after the head is badly overheated (if there is no coolant in the head).

Some cars even came from the factory with a head temperature sensor. Ironically, the early Stags had such a sensor, but they removed it because it gave too many "false alarms". (In truth, many Stags overheated even when new, but the temp gauge was much more vague than the head temp sensor.)

 

[Hap Waldrop]

We've not had alot of luck with electric temp gauges and sensors on the race cars, mostly we use mechanical oil temp gauges.

 

[karls59tr]

Hap. I'm assuming the mechanical oil temp gauge is a similar setup to the oil pressure gauge on a TR3? Where would the oil line run from that goes to the gauge? Does your shop supply the sender and the gauge?
Randall Whereabouts on the Stag head did the temp sensor mount? Would it be practical to mount that sensor on a Tr3 head and if so are there any of those sensors still kicking around anywhere? I believe I read an article once about clumps of sand from the casting process being found in some Stag engine blocks! That might account for the Stag overheating issues from the factory?
I guess I've become obsessed with engine overheating and blown head gaskets because in the last couple of years I've had that problem with a 76 BMW 530i and an 86 Saab 900S so I don't want my TR3 to be next.

 

[TR3driver]

Mechanical oil temp gauges are readily available, any racer supply or almost any gauge supplier. They are virtually identical to the water temperature gauge (not oil pressure), except perhaps for having a somewhat higher range. So just like the temp gauge, they have a bulb that has to be exposed to the oil; and a armored "capillary" tube that runs from the bulb to the gauge.

ISTR the Stag head temp sensor mounted on the back of the head, but I don't recall which head offhand. Dad's 455 Buick had two of them, one for each head and they were on the back. (That model engine had a bad habit of developing air bubbles in the heads that would allow them to overheat even when the radiator was full.) Unfortunately the TR head doesn't have a lot of extra tapped holes and no good place that I can think of offhand to add one. Maybe if you could find a sensor that would screw into the plug for the cam oil feed?

When they rebuilt "Uncle Jack" (a Stag that was restored for charity), they literally found not only sand, but a casting core, still buried in one of the block passages! Somewhere there is a photo of Joe pulling out the core, but I don't have the link handy.

But I will say that the TR3 motor is very tough (at least part of the reason we sometimes call it a TRactor motor) and at least in my experience rarely suffers any damage from overheating. I now believe that pretty much all of the head gasket problems I've ever had with a TR motor can be traced to inadequate liner protrusion.

 

[Andrew Mace]

If you want to keep it "in the family," the Smiths Classic Gauges line includes both electrical and (preferred?) mechanical oil temperature gauges.