What is a pyrometer gauge?

You had to have a pyro in older motors like a 220 cummins I drove pulling a hill if you got too hot on the pyro you would start stretching head bolts at about 900 degrees you had too back out of the throttle drop a few gears and bring your manifold pressure down to cool it off

 

those cummins heads like to dance around like a chicken --but maybe that is why--the ones i worked on were rode pretty hard--i wish engines were still like that--nice and easy to work on---

 

No doubt about that I don't know how msny times I had to put that old 220 back together on the side of the road. It was in a 52 pete with a 5 and a 4 had to carry around a set of thrust washers for that old brownie changed them numerous times on the side of the road. I don't miss that truck but when I was sixteen and started driving I thought I was high class.

 

that would be a nice truck to have today--just sitting in the back yard

 

My grandpa still has it doing exactly that. Been trying to buy it for years but he won't sell it

 

On the older cumming with turbo and no inter cooler 1200 degs max if the probe was before the turbo go light on the throttle in high elevations, it was part of the job watching the pryo.

 

It's more like a torque meter. When the exhaust is getting too hot you can back off the throttle and/or drop a gear or two. If the exhaust is getting too hot, the cylinder is getting too hot. It's too complex a gauge for the average driver. It's more for an owner operator trying to take care of his engine and cooling system.

 

First of all, you need to see where the sending unit for the pyrometers is mounted. Is it on the "hot" or "cold" side of the turbocharger? Most are on the "cold" side these days but back in the 70s when I started trucking it was about 50/50 either way. I believe there's about a 300 degree drop between the hot side (between the engine and the turbo) and the cold side (between the turbo and the mufflers). Assuming we're talking about one being on the cold side, I was always told to never let the reading exceed 1200 degrees F and don't even let it stay that hot for very long or else your going to start hear the gut-wrenching sound of the fins on your blower going up the stacks.