Aftermarket Mechanical Temp Gauge Hookup Location

[Stephenorf]

I'm adding a set of aftermarket gauges to my 1959 Monterey. The stock gauge is still hooked up, but it pegs to the hot side after the car idles for 5 or 10 minutes (incidentally, the fuel gauge also pegs to the full side....I'm thinking the CVR in the dash is maybe bad?). Anyway, the only other place I could find to mount the sensor was at the water pump.



Running for 20 or 30 minutes at idle the new mechanical gauge barely moved off the cold side (like ~170 degrees), whereas the factory gauge was pegged all the way to the right.

I assume the waterpump is an OK place to gauge water temperature? I'm mainly concerned with monitoring the coolant temperature so as to avoid the engine from overheating.

[dmsfrr]

Yes the CVR for the gauges may be failing or has already failed.


The only(?) drawback to that spot on the water pump is it's the inlet to the engine from the radiator... so it will always indicate 20 or as much as 30 degrees cooler than the coolant temperature in the engine. Even lower / worse if the thermostat happens to stick shut or the radiator is obstructed.

It's not necessarily a 'bad' place to locate the sensor, just something to be aware of.
.

[Stephenorf]

Originally Posted by dmsfrr

Yes the CVR for the gauges may be failing or has already failed.


The only(?) drawback to that spot on the water pump is it's the inlet to the engine from the radiator... so it will always indicate 20 or as much as 30 degrees cooler than the coolant temperature in the engine. Even lower / worse if the thermostat happens to stick shut or the radiator is obstructed.

It's not necessarily a 'bad' place to locate the sensor, just something to be aware of.
.

Hmm...the reason I put it there was that it was the only other place I could find with a threaded port. I saw that some people drill and tap the intake near the thermostat housing, but the metal is thin there, and I don't want to mess up my intake.

[Stephenorf]

Originally Posted by dmsfrr

so it will always indicate 20 or as much as 30 degrees cooler than the coolant temperature in the engine.
.

So maybe that explains why the gauge barely moves off the cold-side, even after the engine has been idling for 20-30 minutes.

[miker98038]

Unfortunately I haven’t seen any good second location for a water temp sender except drilling and taping the intake manifold by the thermostat on the drivers side. And then you need to be sure the bulb will clear once you install it.

[Stephenorf]

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Originally Posted by miker98038

Unfortunately I haven’t seen any good second location for a water temp sender except drilling and taping the intake manifold by the thermostat on the drivers side. And then you need to be sure the bulb will clear once you install it.

OK, Thanks. I just wanted to make sure I wasn't overlooking something.

[dmsfrr]

Perhaps a Tee fitting in the heater hose connection just behind the thermostat??? But it won't get much flow unless the heater hoses are circulating coolant.

Or on the rear of the right/passenger side head there's a welch plug in a coolant passage just below the distributor. It's a mirror image location of the one for the oem coolant sensor in the left/drivers side head.
IF... there's enough clearance to the distributor for the height of the sensor, the original welch plug can be replaced with an oem style threaded bushing.
Those replacement bushings are available with 1/4 or 3/8 inch NPT threads.
.

[miker98038]

I’ve used the heater hose with a T. Dmsfrr is correct, they only work with the heater valve at least partially open.

[KULTULZ]

The only way to read correct coolant temp on a FYB is to place the sensor directly behind the thermostat.

Why engineering put the OEM sensor on the rear of left cylinder head only read coolant temp coming off the LS cylinder barrels cooling jacket and not sensing the cyl head temp is beyond me. If the engine had a cooling problem, you wouldn't know until damage(s) has occurred.

Now they put a hose nipple on the 1957 E-CODE 8V intake coolant crossover.

The sensor has to be mounted on the intake coolant crossover behind the thermostat.

The early 1958 FE had the coolant temp sensor mounted in the by-pass hose.

Something like this should work (IMO) if you have a period intake you don't want to butcher ... er ... modify.

[Gene F]

Remember the critical thing you are trying to protect from temps a little over 210F is the head. Head gaskets fail if overheated. Mine is in the port that originally had the indicator light probe. DMSFRR shows that little bushing I used. on my 1957 Y-block the throttle linkage assembly needs to come off.

If you unhook one, does the problem with the other gage go away?

[KULTULZ]

The ILL below shows the placement of the sensor in the cooling crossover -

It has to be here to get a true reading of the entire cooling system and especially if one adds an EFI THROTTLE BODY INJECTION to one.

[Stephenorf]

Originally Posted by Gene F

If you unhook one, does the problem with the other gage go away?

I'm not sure about that. Next time I'm running the engine I'll unhook the temp sender and see if it affects the fuel gauge.

If disconnecting one gauge affects the other gauge, what does that indicate?

Thanks,
Stephen

[Stephenorf]

Originally Posted by Gene F

If you unhook one, does the problem with the other gage go away?

I unhooked the temp gauge, and the fuel gauge still went to FULL. I messed around trying different fuel sending units and found one that registers 1/2 full when the float is all the way down (empty). If nothing else, I can use that FSU and just know that 1/2 take = empty! Better than always showing full and not knowing when I might run out of gas.

When I swap the FSU, the original is being used now, I'll mess with the original FSU to see if I can get it to register anything other than full. It seems there might be a short in the FSU, since grounding the FSU feed will cause the gauge to read full.

[cos]

This question was put up over on Y-Blocks forever forum awhile back. Putting sender on right head at rear, unless using a 1/8" sender and recessing it down with interfere with dist. on y-block. Above pic is best if everything works, boring and tapping.

[KULTULZ]

The placement of the adapter bushing on the above photo is 1954-56 intakes. If using a later ECZ-B intake, the carb pad was enlarged and you have to be careful of possible thermostat and/or coolant sensor conversion interference -

Now here is a TED EATON DEDICATED QUESTION -

That adapter looks gnarly to me. I wonder if the 10911 coolant sensor adapter can be modified to fit within the coolant crossover (either welded or preferably machined to thread into the drilled hole)?