t-stat housing temp sensor size?

what size is the threads for the temp sensor on the non-renix 4.0?

thanks.

I'm fairly sure they're 3/8" NPT (standard pipe thread.) If they're not that, they're probably 1/2" NPT. Easy way to check - if you have the thing loose, take it to the hardware store plumbing section, and try both.

Most fluid temperature sensors use pipe threads, because they're theoretically self-sealing.

Why do you ask?

5-90

I'm wiring up dual fans on my 89 with a derale adjustable fan switch,so I need a place to install the 3/8 temp probe....would this newer t-stat housing be a good place to install the probe?

Should be. It won't be the very hottest part of the engine, but it should be close (once the thermostat opens, that is.)

Since most OEMs (including Chrysler/Jeep) use the thermostat housing for the location of the temperature switch, it's not a big problem - just be advised, if your thermostat freezes shut, you'll have a larger problem trying to get your fan going. I'd wire in an override switch - you may not use it very often, but it can mean the difference between getting home and not when your thermostat fails... Even if forced circulation isn't happening, there's still some slight convection in the system.

5-90

I understand.....thanx.Wish me luck on this derale switch,this is my third one.

5-90:
one more question.What temp do I want my dual fans to kick on at?I was thinking around 210*?I have a 195* stat so at 210* the stat will be open and allowing full coolant flow to reach the temp probe,right??Oh and,what can you tell me about heat soak after the engine is turned off?Sould I make the fans run for a little while after the engine is turned off to combat this?

Thanks

Normal operating temperature is, as you are probably aware, somewhere around 215-218*F. I'd look into having them come on around then - and you can use that as a baseline to experiment from (I've got my operating temperature pushed down to about 190* with the closed system, with no ill effects, and reduced tailpipe emissions! If they'd only let me do away with the EGR now...)

I realise that many OEM's are now designing the system so that the fans will run after the engine is shut off, but I see limited utility in this. After all, the coolant isn't circulating - so how much heat can you really get rid of? That, and the Derale fans are, as I recall, pretty big "current sinks" - don't they take something like 30A fuzes? Anyhow, I'd want a little extra reserve capacity if I had those fans running after the alternator wasn't.

If possible, you might want to "stagger" the fans - have one come on at 195-198*, and the other at 212-215* or so. This would make for more efficient cooling than having both on at a more elevated temperature. But, that's just my line of thinking...

5-90

I not running derale fans,just the adj.control...My dual fans draw about 30-35amps altogether and I have an optima.You talked me out of it anyhow, because I was thinking that having the fans run after shut down would be kinda pointless...you just confirmed what I was thinking.

Thanks again.