My father inlaw has a 1993 w250 with stock pump settings. He installed a autometer pyrometer and it will read 400degrees as soon as the truck starts. Cruising temps are 900 degrees and if he goes into the throttle it climbs fast to 1200. We ran a ground from the engine to the body didn't change. Any suggestions would be much appreciated.

 

That's not bad....but someone may have monkied with the pump before. Or you have a tiny boost leak, or a clogged air filter.

Did you ground the gauge directly to the battery?

That's what you have to do with the autometer Pyro's....

 

He didn't ground to the battery so i will try that thanks.

 

He didn't shorten the wires for the probe did he? i believe they are set to a fixed resistance and if you cut the wires to a different length it will throw off your readings.

 

the pump is stock settings. He didn't shorten the wires installed it according to instructions. When it is cold and first started it reads 400 which is not correct. He tried a ground wire straight to the battery and the gauge dropped below zero. positive and negative are connected properly.

 

mine would always read 400 until temperature dropped, then it kind of stopped working... until i get into it.

 

Mine reads 400 AFTER it's warmed up. After idleing for SEVERAL minutes it will finally drop to 375 or so, and my idle isn't too high. I need to try the ground to the battery as well.

 

The Autometers have an amplifier circuit and will jump when the power is switched on, mine jumps to 100* when it is powered up.

You might have a defective gauge or thermocouple, have you tried to call Autometer Customer Support yet?

http://www.autometer.com/tech_faq_an...x?sid=4&qid=67

http://www.autometer.com/productPDF/0593A.pdf

Remember that the thermocouple is not reading the temperature of the exhaust manifold but it is reading the temperature of the hot exhaust gas passing the tip of the thermocouple so even though the manifold is not hot to the touch the hot exhaust gas is.

Jim

 

Jim's right. Even cold, (winter time,) as the air is compressed in the cylinders it heats up to somewhere around 500° - 600° IIRC. Burn some diesel in there and temp's jump to 3000° or so in the cylinder.
I don't know if your gauge is faulty or not, but it's not out of the question for it to be reading 400° right off the bat.

 

I have the autometer pyro too and my pump is turned up, and I get 200*-250* on cold start-up, 700-800* cruising, and 1000-1100* pulling 5000 lbs, and I don't baby it much. These possibilities come to my mind:

Bad gauge or thermocouple. Make sure it isn't damaged, check connections, look for nicks in wire.

Too much fuel. Are tamper caps in place and undamaged? Any aftermarket parts in the fuel system?

Not enough air flow. Clogged filter, boost leak, restricted exhaust.... Do you have a boost gauge? If so what's your pressure and is it spooling reasonably quick?

Engine loaded. Any tranny issues, brakes dragging, wheel or pinion bearing preload too tight. I doubt this would cause temps to rise like your saying though. Something would have to be really tight to load that engine like that.

IDK, just some suggestions from a non-expert.

 

father inlaw called autometer and they said to ground it to the body not the battery. The guy said his readings were about right.

 

Thats funny. When I spoke to them they said to run directly to the battery. It worked for me and fixed my issue.

 

I was told by an isspro tech that you can put the probes of a multimeter on the thermocouple terminals and run the truck. If the voltage jumps around like crazy the thermocouple is probably bad.