I've looked at a couple aftermarket mechanical temperature gauges, and the end that should thread into the hole in the top of the head, where the sending unit goes, has been too large. Have any of you been able to find one with a probe, small enough to fit in a slant six head? If not, where else on the block can I install one that will give an accurate temperature reading? The installation instructions on one I read says the probe needs to be in the path of flowing coolant.

Jerry

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There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

You can drill and tap the thermostat housing/water neck as long as you do so in a manner that won't interfere with the stat itself (usually not too hard). This method has the added bonus of letting you "see" the thermostat open (needle jumps up).

I ran into the same problem. So I bought an Automete electric gauge, the sensor is much small and treaded right in on top of the head. It's more expensive but easier to install. I did the same with my oil gauge. I didn't want an oil filled tube running to my dash.

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There is no problem that cannot be solved by the proper application of thermo nuclear weapons

I bought a set of 3 gauges (oil pressure, water temp, and volt) at pepboys for like $30. The probe came with a couple adapters, that thread into the whole, then the probe fit right in. No modifications necessary. The gauges are sunpro.

Nick

I've wanted to look into an all-in-one gauge device for my truck. I'm not really talking black box type stuff. But more along the lines of RPM, Speed, Oil Pressure, Water Temp, Voltage/Amps, Gas level, and various other data. But everything I find is either a single guage or cluster of guages that add on. Any ideas?

You can put a T in the heater hoses or go to speedway motors .com they have a adapter for the 1/2 pipe.
Frank

My Australian slant six truck has a factory mechanical temperature gauge.
The sender is mounted in a drilled and taped hole in the head casting, drilled into the flat in front of the rocker cover, where the thermostat sits into the head. There is an insert that is threaded into the casting, then the actual sender is fed into the bore of the insert, so the sender can be removed without loss of coolant, and I suppose, protecting the sender from corrosion.
If you need a photo, I can post it.

Regards, Andrew.

Typhoon, I know this is an old post but would you mind posting a picture of your mechanical sending unit in the head?
Thank you,
Herr Otto

Hello,
well,these pics are of electric senders,but are fitted in the place that Typhoon mentioned.
the first pic is the standard fitting point on a slant head,the second is the recommended place for an after-market sender which will tell you if your thermostat is opening correctly.





Hope this helps you.

regards,Rod

I never did like the idea of the temp sender in the t-stat housing. It will read correctly once the t-stat opens, but not if the t-stat fails closed. The engine will over heat and you will not see it on the gauge.
I have some heads that have the 1/8 inch hole for the sender and some heads the have a larger hole(3/8 I think). Why not just drill and tap the smaller hole to the larger size, and install the mechanical gauge there?
PS: needs to be a NPT thread

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

hello,
Charlie,as I live in a relatively warm part of the world, I cheat the thermostat a little by drilling a 1/8 " hole in the thermostat plate. This allows enough coolant flow through to mirror the factory guage almost.
There is a bonus with the hole in the plate also - if the thermo is installed with the hole to the top - no air lock when you are filling the system.
Works for me.

regards,Rod

I agree about the hole in the stat. I do that to every stat I install on any engine, if there is not one from the manufacturer. Many stats come that way, now. But if you have to drill and tap a hole in the stat housing, why not do it in the head?

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Walpolla, thank you for the pictures and reply. Would the hole in the thermostat be a bad idea living in a colder climate like Chicago?
Herr Otto

hello,
well,never having lived in a really cold place,I would think it may have issues with engine warm up times. Apart from that, most likely not.

regards,Rod

Yes, it will be a problem. The engine may never come up to operating temperature, and your heater will blow cool air, at best. Even a thermostat that doesn't seat fully closed will cause a problem.

If you want to monitor coolant temperature, locate the sensor on the engine side of the thermostat.

Ken