503 - EGT - Thermocouple Thread Size

[Trez]

Does anyone know the standard Rotax 503 exhaust manifold thermocouple/sender threaded boss size?
Does M8x1 sound correct? If not, any takers?
Also, how 'long' should the probe be below the upper wall of the manifold?
Just halfway? Are the probes usually 'slip' jointed, allowing the tip depth to be 'adjusted' in/out?
Don't have ready access to the machine and want to order an EGT.
Some help would be appreciated.......
Thanks,
Trez
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[Joe Pires]

Does anyone know the standard Rotax 503 exhaust manifold thermocouple/sender threaded boss size?
Does M8x1 sound correct? If not, any takers?
Also, how 'long' should the probe be below the upper wall of the manifold?
Just halfway? Are the probes usually 'slip' jointed, allowing the tip depth to be 'adjusted' in/out?
Don't have ready access to the machine and want to order an EGT.
Some help would be appreciated.......
Thanks,
Trez
************

Give ed a call. He has his machine at work so he might be able to get to it.

[edypaul]

Trez
I used a micro 1000 dual EGT Gage from aircraft spruce P/N 10-01467 and 2 ea EGT probes P/N 10-01475 also from Ac Spruce. The Probes are Factory Rotax. The Micro 1000 Is a better choice then westech. Its temperature compensated.

Ed

[edypaul]

I think I ordered the EGT extension wires too. P/N 10-01480 If memory serve me I think I used about a foot or two of the EGT extension wire.
The red wire goes to the NEG- term on the gage! Go Figure?

[Trez]

Trez
I used a micro 1000 dual EGT Gage from aircraft spruce P/N 10-01467 and 2 ea EGT probes P/N 10-01475 also from Ac Spruce. The Probes are Factory Rotax. The Micro 1000 Is a better choice then westech. Its temperature compensated.

Ed

Thanks, Ed.....
I've decided to try a gauge I found after much, much looking on the web.
It's made by Hewitt Ind. I like the quality, the scale (seems like it's made for the Rotax) and the warranty, too - gauge three years, thermocouples lifetime! You can get them with red needles, or other configurations. And the price is less than most of the crap that's out there.

http://www.murcal.com/Catalog/Pyrometers/Dual-Pyrometer-300F-1300F

http://www.murcal.com/Catalog/Thermocouples

They have the leadwire extensions as well.
It'll be awhile but, if these are as good as I expect they will be, I'm going to let everyone know. I'm tired of reading about the garbage that Westach, etc. is putting out.

I really need to know, though, the SIZE fitting to order with the senders that will be a screw-in fit. Looks like I'll have to wait 'til I get back to Wauchula and check it myself.......
Thanks anyway.
Hey, Ed, how's the engine change coming along?
Trez
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[scottessex]

Trez, I am pretty sure it is 8mm, the dia of the probe should be 3/16"
But M8 sounds right. Metric pipe thread is as screwed up as NPT!

[Trez]

Thanks, Scott...........

After combing through all manner of Rotax info on the net the consensus seems to be 8mm as you said.
I have never heard of 'metric pipe thread' 'til you mentioned it. Shows you what I know:noidea:.

I'm just glad those threaded bosses are already in place on the manifold.
Makes for a lot cleaner install..........

Trez

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[edypaul]

Trez
The threads in the manifold are 8 MM with a 1 mm pitch. They are not pipe threads They are straight. My probes come with an adapter to fit to the 8mm threads in the manifold to 1/8 pipe threads on the probe.

[Trez]

Trez
The threads in the manifold are 8 MM with a 1 mm pitch. They are not pipe threads They are straight. My probes come with an adapter to fit to the 8mm threads in the manifold to 1/8 pipe threads on the probe.

Bingo!
Just the info I was looking for. I guess the adapter was what was throwing me. Figured the probes would be SAE and, no doubt, Rotax would be metric. That explains it.
Thanks Ed.
Trez
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[scottessex]

Yeah that's it!

[Trez]

Thanks to all!
Got it now.
Goin' to the sto'.

Trez

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