Mechanical temp gauge and heater - how to?

[parisian62]

Hi everyone,

I have an EJ grey motor with two holes in cylinder head - one for temperature idiot-light switch at the front of the block and one for heater return hose at rear of the block.

I've got a period Smiths mechanical temp gauge I want to add too.

How do I do it?

Stewart

[Craig Allardyce]

Stewart,
if you have the head off I would drill and tap another hole at the rear of the head. I plan to do the same for mine. Its the best spot to monitor engine temp as its the hottest point usually so it will give you a good safety margin. Don't fit a tee with the two senders as the sender needs to be immersed in the flowing coolant with no possibility of air locks around it. Senders don't work too well in pockets of steam and you'll get little to no temp reading.
If you head is still on you could drill and tap further back from the original rear port.

[parisian62]

Thanks for that Craig. The head is back on. I should have done it when the engine was being rebuilt...

[Harv]

Stu,

One way to do it is to drill and tap the upper thermostat cover. Not as good as the cylinder head, but easier to get the cover on/off for drilling. I've got a set of NPT taps here if you need a lend.

Cheers,
Harv

[Devilrod]

I'd do away with the idiot light, no good really by the time it comes on its probably alreadt too late!

[Blacky]

I would run both - you dont always notice a guage but a light gets your attention

[parisian62]

I'd do away with the idiot light, no good really by the time it comes on its probably alreadt too late

That was my inital thinking too and where I was heading with this. I just wanted to hear other experiences and see what my options are.

I thought there may have been a way to keep the idiot light plus the new temp gauge without drilling and tapping holes at this stage.

What about using the current sender and hooking it up to an electronic gauge??? or wont that work...

Stewart

[Smooth customs]

I do it like this.

[Blacky]

You're a clever bugger Mr Kelly !!!

[Harv]

Paul,

If I'm reading the picture right, the stainless branch coming out of the head has a tee, which the temperature sender screws into?

Would work good, though I guess you would need hot water flowing to the heater all year round to get a good signal.

I wonder...
a) if you put a small (say 3/8") line from the heater hose (just after the new sender), and
b) ran that as a bypass to the other heater hose (on the engine side of the cable-driven valve, and
c) closed the cable-driven valve in summer (no hot water to the heater), and
d) opened the small bypass,
... whether you could get a nice flow to feed the sender?

Cheers,
Harv

[Smooth customs]

The sender works fine in this location as there is ample hot water in this fitting for the heater at all times. And its location so close to the head and water jacket.
There will always be hot water in the hoses and fitting, as the valve only stops flow through the heater. But doesn't stop the heat transfer in the water through these hoses.
The best heat transfer through a heater is when there is constant water flow, as a heater works like a radiator cooling the supplied hot water as the process of heat transfers to the interior of the car .
What I posted was how I have solved the problem of where to put the sender and the heater supply fitting. And it works for me.
I am not saying this is the way it should be done, and would be interested to see other alternatives.

[Craig Allardyce]

Thanks for that Craig. The head is back on. I should have done it when the engine was being rebuilt...

Stewart I had a look at this again this arvo and drilled and taped an old head I had lying around. It took all of 15 mins to do and you could do it with the head fitted. I've showed the spot were the sender can be fitted at the rear of the head but you have to be careful with spacing between the sender, the firewall seam, and the throttle bar. The other option is next to the rear head bolt on the left hand side. There is plenty of meat in the head to tap a hole and heaps of gap inside the coolant jacket around the port and combustion chamber. I drilled and taped to 1/4 NPT and used a adapter to fit a VDO sender (1/8 NPT). Looking at a EK you might have to remove the wiper motor to make room to drill the hole. Alternatively you could drill a smaller hole next to the original sender spot as there is good room there for a 1/8 NPT fitting. I would also use a suitable amount of grease or similar on the drill to catch the swarf and do a flush of the cooling systems afterwards. Hope this helps.

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[parisian62]

Great stuff. Many thanks for all the replies - all good useful info.

Paul - did you make that fiting yourself?

Craig - many thanks for taking the time to do a 'test run' and posting the pics up.

Stewart