Low pyro readings.
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Senior User
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From: Bothell, WA
Low pyro readings.
Sometimes my ISSO pyro reads about 200 or more degrees low. I've learned to spot when the EGT reading is not correct and if I tap on the sensor which is threaded into the uptake the reading will return to normal. Is there a way to service the sending unit or do I need a new part?
Last edited by tdford; Oct 23, 2005 at 12:14 PM. Reason: correct & clarify
Post Fiend
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From: Nutter Fort, WV
First I would do a close inspection for shorts against the engine or body.
Then I would inspect the wire connections themselves.
If your wire connections are tight and corrosion free and there are no shorts I would go for the new thermocouple.
They are very cheap compared to a new engine.
Then I would inspect the wire connections themselves.
If your wire connections are tight and corrosion free and there are no shorts I would go for the new thermocouple.
They are very cheap compared to a new engine.
Last edited by Dave Sponaugle; Oct 23, 2005 at 12:53 PM.
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From: Bothell, WA
Dave,
I had the thermocouple and guage out a couple of weeks ago and checked them against an oven thermometer in my bar-b-que where I tested them to 450 degrees. They seemed accurate so sure nuff I put them back in and they worked fine but just for a few hundred miles and then the problem returned. I know the connections are clean and tight. I was trying to get a little more clearance between the turbo pipes and the fire wall when I bumped the thermocouple couple where it comes out of the uptake with the bar I was using. Got back in & the Pyro readings were good so I've been tinkering with it the last couple of weeks. The problem seems to be either the thermocouple or the wire connection to it.
Thanks for pointing out that I'm not really gambling with the cost of a new thermocouple but with the cost of a new engine. I know from experience I don't want to go there so I'll order the new thermocouple. My set up is about 15 years old so maybe it's time to replace the guage while I'm at it so I can trust the numbers and quit worrying about false EGT readings.
Don
I had the thermocouple and guage out a couple of weeks ago and checked them against an oven thermometer in my bar-b-que where I tested them to 450 degrees. They seemed accurate so sure nuff I put them back in and they worked fine but just for a few hundred miles and then the problem returned. I know the connections are clean and tight. I was trying to get a little more clearance between the turbo pipes and the fire wall when I bumped the thermocouple couple where it comes out of the uptake with the bar I was using. Got back in & the Pyro readings were good so I've been tinkering with it the last couple of weeks. The problem seems to be either the thermocouple or the wire connection to it.
Thanks for pointing out that I'm not really gambling with the cost of a new thermocouple but with the cost of a new engine. I know from experience I don't want to go there so I'll order the new thermocouple. My set up is about 15 years old so maybe it's time to replace the guage while I'm at it so I can trust the numbers and quit worrying about false EGT readings.
Don
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From: Nutter Fort, WV
Well something elso to consider, I right now am dealing with a reman engine failure for the third time in 18 months. The remanufacturer sent me a fouth long block engine since my fuel system was out of warranty. I tore it down before installing it and was glad I did, it will not be going in my truck, and no more of their engines will either.
Bad news is the way it stands right now is I am going to lose 2800 dollars for having to have my truck broke down over three months since I installed their first engine.
The other alternative is legal action, which is not ruled out, but the time factor is against me. Snow season is rapidly approaching, I need my truck, now.
Thermocouples and or entire pyrometers are cheap insurance.
I did have a pyrometer, the engine failures were not related to operating conditions but rather improper reman processes.
What a pain and learning experience this has been, as well as expensive lesson.
Bad news is the way it stands right now is I am going to lose 2800 dollars for having to have my truck broke down over three months since I installed their first engine.
The other alternative is legal action, which is not ruled out, but the time factor is against me. Snow season is rapidly approaching, I need my truck, now.
Thermocouples and or entire pyrometers are cheap insurance.
I did have a pyrometer, the engine failures were not related to operating conditions but rather improper reman processes.
What a pain and learning experience this has been, as well as expensive lesson.
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Joined: Oct 2005
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From: Hillsboro, OR
Is ISSO a common brand? I have a tach installed in my truck that has small pickups attached to the damper for the pickup and a gage in the OEM locaiton that is an ISSO (I'd never heard of them before). I plan to put boost an pyro in my truck as well. Is the up-pipe to the turbo the best spot or directly into one of the manifolds for the pyrometer?
Post Fiend
Joined: Nov 2003
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From: Nutter Fort, WV
Never heard of ISSO.
ISSPRO has been making pyrometers for many years for the big rigs. That is what I have.
ISSPRO has been making pyrometers for many years for the big rigs. That is what I have.
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New User
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From: Hillsboro, OR
Heh, sorry -- I went by what was in someone else's post, and didn't bother to go look at my truck. I'll have to check and see what we install in our trucks at Freightliner/Western Star.
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Post Fiend
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From: Nutter Fort, WV
Sorry I missed the part about pyrometer location.
I put mine in the exhaust manifold, drivers side rear just above the cross over pipe connection. Nice big area there that the thermocouple in with room to spare.
I had my engine out when I put it in though.
My logic for the location is the pistons are the first thing to suffer heat damage.
So put the thermocouple as close to the pistons as you can get it.
The farther it is from the pistons, the more error in the reading you have.
To get it any closer to the # 8 piston, I would have to have it in the head.
Piston damage starts at 1250, so I just keep mine under 1200 at all times, and start backing out of the throttle at 1150.
Freightliner was my truck of choice when I was driving over the road. They make a nice rig.
I put mine in the exhaust manifold, drivers side rear just above the cross over pipe connection. Nice big area there that the thermocouple in with room to spare.
I had my engine out when I put it in though.
My logic for the location is the pistons are the first thing to suffer heat damage.
So put the thermocouple as close to the pistons as you can get it.
The farther it is from the pistons, the more error in the reading you have.
To get it any closer to the # 8 piston, I would have to have it in the head.
Piston damage starts at 1250, so I just keep mine under 1200 at all times, and start backing out of the throttle at 1150.
Freightliner was my truck of choice when I was driving over the road. They make a nice rig.
Last edited by Dave Sponaugle; Oct 26, 2005 at 04:54 PM.
New User
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From: Hillsboro, OR
Originally Posted by Dave Sponaugle
Freightliner was my truck of choice when I was driving over the road. They make a nice rig.
New User
Joined: Oct 2005
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From: Hillsboro, OR
If the EGT's are 1200, the pistons aren't that hot. When you say that 1250 is when damage occurs, is that based on past experience? I only ask because on my toyota, I've run up to 1550*F egt's and no damage, and it cruises on the highway at 1200-1300deg, but it IS a gas motor. I have installed a few Edge programmers on later powerstrokes though, and they recommend keeping it below 1350*F (on the Juice w/ attitude, that's when it starts de-fueling).
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From: Bothell, WA
What a pain and learning experience this has been, as well as expensive lesson
To bad someone doesn't host a web site to post buyers reports and followups on engine replacements. It would be a great starting point for those of us stuck with the neccesity of replacing an engine and trying to find the best bang for the buck in terms of getting a quality rebuilt engine. The format would be be limited to reporting facts like date of purchase, rebuild shop, installer, purchase price, miles driven since purchase, and most importantly a report of any problems with the install or the product and the miles associated with the problem along with the resolution.
Post Fiend
Joined: Nov 2003
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From: Nutter Fort, WV
Well it goes something like this.
The pistons in this engine are made out of hypereutectic aluminum.
The melting temp is 1250.
BUT
There are cooling jets that spray engine oil on the bottom of the pistons to cool them.
The combustion temp is only applied to the piston for 2 out of 4 strokes, power and exhaust.
The intake air is cool and cools the piston for two strokes.
The damage to the piston is cumulative, not instantaneous catastrophic failure.
And you want this engine to last for many years and several hundred thousand miles.
Yes you can run the temp up to 1500 degrees and it still works OK, but you may have just used 50,000 miles worth of piston in the last 2 miles.
Was it worth it?
The pistons in this engine are made out of hypereutectic aluminum.
The melting temp is 1250.
BUT
There are cooling jets that spray engine oil on the bottom of the pistons to cool them.
The combustion temp is only applied to the piston for 2 out of 4 strokes, power and exhaust.
The intake air is cool and cools the piston for two strokes.
The damage to the piston is cumulative, not instantaneous catastrophic failure.
And you want this engine to last for many years and several hundred thousand miles.
Yes you can run the temp up to 1500 degrees and it still works OK, but you may have just used 50,000 miles worth of piston in the last 2 miles.
Was it worth it?
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Senior User
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From: Bothell, WA
run up to 1550*F egt's and no damage, and it cruises on the highway at 1200-1300deg, but it IS a gas motor.
If the EGT's are 1200, the pistons aren't that hot.
I have installed a few Edge programmers on later powerstrokes though, and they recommend keeping it below 1350*F
It's my understanding that the recommended EGTs for our engines were determined based on the experience and tests of the various turbo manufacturers. I'm remembering the maximum EGT recommended by ATS when non-waste gated turbo was installed 15 years ago was 1100 degrees. The sensor was factory installed on the uptake to the turbo.
Last edited by tdford; Oct 26, 2005 at 11:50 PM. Reason: Correct information