Alternate coolant temp gauge, best places on E30?

#21

Put your coolant pressure switch into the port at the block. The charm of that solution is that coolant pressure is pretty high there it’s easy to make work. Everywhere else in the coolant system the pressure is so low that it can be hard to find a pressure switch that will reliably do it’s job. There’s an old thread around here where I tested coolant pressure at various places.

Use the OEM oil pressure switch and the harness connector. It will thread right in.

If you do choose to block off the coolant port on the block, you don’t need a block off plate, just use a 12mm bolt. Note that there are two of these ports, one on each side of the block. But the one to put the switch at is the port on the intake side. That keeps your switch wires away from the exhaust.

If you stick with your mechanical probe, make sure it’s put right into the coolant flow, not touching any metal and won’t move when the car bangs over gators.

#22

Ranger, thanks for the tips regarding the best placement for the coolant pressure switch i will definitlely keep that in mind. I’llhave some more questions regarding that at a later time :wink:

Regarding the temperature sender:
My question is in reference the heater port on the back of the head. I am considering threading the temperature sender into a similar plate:

Do you think taking temp from here will be a good idea?

#23

broken link in the post above. this is the plate i will make, but with a fitting for the temp sender.

#24

Sorry, you were saying back of the head and I was thinking back of the block.

Well, I’ve not seen anyone use that port for anything, but your idea ought to work. The downside is that space behind the head is very precious. There’s a number of tasks that are made easier with some free space back there. Also during engine swaps or work on the engine harness that area gets banged around on, so you’d have to be careful.

There is an image missing from the pic above. That kit comes with an AL plate that fastens into place over the port on the head. Might as well make your own little plate tho. Just make it out of something beefy so it’s nice and rigid.

The plug in the pic above goes in the tstat housing.

I still say tho that you’re making this awfully hard on yourself. The easy way is at the tstat with a 14mm sensor or a 1/8NPT sensor and and adapter.

#25

[quote=“Ranger” post=70508]
I still say tho that you’re making this awfully hard on yourself. The easy way is at the tstat with a 14mm sensor or a 1/8NPT sensor and and adapter.[/quote]

I agree about this solution, but the problem with this is that my gauge has a mechanical sender with 3/8NPT threads.

#26

Not on the back of the head!!! That will be the hottest part of the motor and no one has any data on what temps you should be seeing. Stick with the tried and true methods mentioned earlier.

#27

[quote=“silence” post=70509][quote=“Ranger” post=70508]
I still say tho that you’re making this awfully hard on yourself. The easy way is at the tstat with a 14mm sensor or a 1/8NPT sensor and and adapter.[/quote]

I agree about this solution, but the problem with this is that my gauge has a mechanical sender with 3/8NPT threads.[/quote]
Ok, well at least the 5/8NPT idea went away.

The real problem is that you are fixated on sender requiring 3/8NPT threads and you don’t like the best solution for that size port…the hose adapter. You’ve got 2 ways to do this right…walk away from that sender or use a hose adapter. Every other solution will be troublesome. Troublesome solutions have a way of requiring a “re-do” down the road.

How about this…mose OEM radiators have a port for a temp sensor controlling the aux fan. I don’t know what the thread is, maybe 18mm. But it’s a port that might be big enough that you can buy or make a 3/8npt adapter.

Related, if you’ve never tapped something with npt threads, be careful not to run the tap too deep. NPT threads are tapered, not cylindrical like a normal bolt. So if you tap deeply the hole’s dia becomes too large. This also means you can’t tap NPT from the rear because the taper will go the wrong way.

#28

That is what i was wondering… do you think it will be that much hotter? I guess there’s no way of knowing without running 2 temp gauges.

[quote=“Ranger” post=70514]
Ok, well at least the 5/8NPT idea went away.

The real problem is that you are fixated on sender requiring 3/8NPT threads and you don’t like the best solution for that size port…the hose adapter. You’ve got 2 ways to do this right…walk away from that sender or use a hose adapter. Every other solution will be troublesome. Troublesome solutions have a way of requiring a “re-do” down the road.

How about this…mose OEM radiators have a port for a temp sensor controlling the aux fan. I don’t know what the thread is, maybe 18mm. But it’s a port that might be big enough that you can buy or make a 3/8npt adapter.

Related, if you’ve never tapped something with npt threads, be careful not to run the tap too deep. NPT threads are tapered, not cylindrical like a normal bolt. So if you tap deeply the hole’s dia becomes too large. This also means you can’t tap NPT from the rear because the taper will go the wrong way.[/quote]

I like the idea about putting it in the radiator, but that could read a lot cooler than it should depending on the direction of coolant flow.

#29

Easy button:

https://www.pegasusautoracing.com/productdetails.asp?RecID=5994

#30

[quote=“silence” post=70515]
I like the idea about putting it in the radiator, but that could read a lot cooler than it should depending on the direction of coolant flow.[/quote]
I wouldn’t worry about it. I think both early and late models have the coolant going top to bottom. Aux fan sensor is at top.

As long as coolant is flowing you don’t have a crisis. Warning you about a crisis is the job of your coolant pressure switch, not temp sensor.

With a temp sensor you will soon ID what is normal for your car. Take notice when temp gradually creeps outside of the normal range.