Engine operating temp - too cold?

[Tom '74 911]

Hello -

I've got a '90 3.6L engine in my '74 911. For oil cooling, I have the stock thermostat, ER finned oil lines, ER fender cooler in the right front fender and a large ER front mounted oil cooler behind a front IROC bumper w/the center cut out etc.... and I am wondering if my engine is running too cool. When it's cold/cool out (25F to 50F) my temp needle barely budges to the lowest reading on the gauge - 120F. Last fall I blocked off the front bumper opening which made only a slight difference in the temp. readings.

Is this too cool for the engine to be running? I am wondering if maybe my thermostat is stuck open as I think in stock form it's supposed to open at 180F? The only time I've ever seen temps higher than 180F is at the track during the summer. How would one check to see if the thermostat is stuck open? I also run 20-50 oil and I'm wondering if the thermostat's built in pressure relief valve is opening when the engine is cold and the oil is thick - allowing cold oil to circulate through the system and never letting the engine heat up. . .

One of the reasons for posting all this is that I am having a hard time getting any warm air out of my heat system. I have Fabspeed headers w/heater boxes plumbed only on the driver's side. When it's cold outside, it blows luke-warm air at best, even after driving for a while. . . I'm assuming I might get better heat if my engine actually ran a little warmer?

I've also thought of bypassing the front cooler altogether and just plumbing the fender cooler to see if that makes a difference. I have the appropriate oil line to plumb it that way, I'd just need some plugs for the lines to the front cooler.

Any thoughts/comments are appreciated.

Thanks for reading,
Tom

[Flat6pac]

The temp guage on the dash may be your problem. The 74 uses a 901 part number on the temp sender. On the 3.6 and install the copper shouldered 901 temp sender and you should get good information to the dash.

[RallyTom]

The part number you need is 90164163200. This is compatible with the original oil temperature gauge for a 69-76 911.

[Tom '74 911]

Bruce,

Thanks for the response. I had thought of that, but obviously dismissed it! I also emailed Elephant Racing to see if they had any oil line caps so I could disconnect and plug the lines to my front cooler and he responded with the same suggestion - I may need a different temp sender to get accurate readings on my gauge. I'll look into it!

Thanks,
Tom

[Tom '74 911]

Originally Posted by RallyTom

The part number you need is 90164163200. This is compatible with the original oil temperature gauge for a 69-76 911.

Thanks for the PN. Do you know if this sender is a direct replacement on a 964 engine - same dia. & thread etc... as the 964 sender?

Thanks,
Tom

[Flat6pac]

I think I would have to go with the word "probably"
Bruce

[RallyTom]

Yes, same thread, etc.
Tom