Pyrometer Location Question

[oldspwr]

I am going to put a pyrometer in my Dad's 361... I believe Brockway used Isspro gauges back in the day? Where is the correct location for the thermocoupler? In other words where in the exhaust should I put the bung for the type K thermocoupler?

Thanks,

Tom

[Huskiedrive2]

Being non- turbocharged, the probe can be placed almost any where. The easiest place will be about two or three inches into the first pipe, down from the manifold. Any further and it will be inaccurate due to cooling. You could also drill and tap the 90 degree elbow at the end of the manifold. Isspro was the supplier for Brockway. Don't shorten the yellow cable between the probe and the gauge. It is a calibrated resistance. Just coil up the unused portion and hide it in the dash.

[oldspwr]

Great thank you Stan! Where does it go if it has a turbo? I am getting ready to install a turbo on the 671....

[stubnosebrock]

You will want it Pre-turbo on a turbocharged engine.

[Huskiedrive2]

I agree Stubby, that's where it should go, pre-turbo. We saw a great deal of probe failure from the heat and it would wipe out the turbo. Yeah, I know the probe is rated for the heat and shouldn't fail, but they do. Industry standard now is to place the probe about 3" downstream of the turbo outlet clamp, in the head pipe.

[oldspwr]

I believe you mean 'post turbo' or right after the turbo. On the 671, the turbo bolts directly to the exhaust manifold, so you really couldn't put pre or before the turbo...

I did find some Isspro paper work that said it should be mounted no farther than 6" after the "exhaust manifold to exhaust pipe connection"

[Huskiedrive2]

Surprisingly, it used to be PRE - turbo. Cummins exhaust manifolds were even drilled and tapped just ahead of the turbo mounting flange. You could remove a plug and screw in the probe. On other engine mfg's, we tapped the manifold in a solid area. The probe would eventually deteriorate, break off and take out the fins in the turbo. Remember that most engines of '60's were non-turbo so this wasn't an issue. I'm guessing around 1978 or so, is when they started supplying the weld-in bung in the Isspro kits.

[stubnosebrock]

Most all the diesel pickup guys, myself included, drill and tap the manifold to put the probe. You want the hottest reading so you know when you need to back out of it. Ive done 5 or more Cummins Dodges this way, and is the preferred method. Now granted unless you are changing injectors in the Detroit, you wont be seeing much heat, but putting the probe closest to the cylinder gives you the best idea of how hot it is inside the combustion chamber, which is where the heat is going to cause the problems.

[dbaldwinjr]

I purchased a new isspro pyro unit for my 760. New sensor, thermocouple, and guage. hooked it up and it has never worked. If I recall there is a yellow and a blue wire. Anyone have any ideas? Does the guage need pwr? wires backwards?

[Huskiedrive2]

Dane - give me a call. There is some trouble shooting you can do with a digital volt/ohm meter.

[dockmen027]

Tom,
At WLC, Bob has a dashboard that came out of a Cat powered Brockway, (it had Cat starting instructions inside the glove box lid) don't know if the pyro is factory installed, but I thought I'd put it in the mix.....





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[Huskiedrive2]

Thanks for the pics John. It brings back a lot of memories. I don't ever remember a Brockway coming in with a pyrometer from the factory. We always added them as a dealer upgrade. That might just have been our sales dept. at work though. As a customer was placing an order for a truck (or several) there were always freebies thrown in to sweeten the deal. It would be a salesman's prerogative to mark N/C (no charge) next to a small expense like a pyrometer in order to get the customer to sit still for the deluxe interior or chrome stacks etc.