Installing EGT probe?

[TN farmer]

I have the probe on the passanger side exhaust manifold on my 2002. I am going to help a guy install his but he has a 2003. I want to know if it is the same procedure or what I can expect different.

[NWDmax]

TN,before turbo is best as far as accuracy and consistency are concerned.
I think the exhaust manifold location gives you the most reliable information and a faster gauge response time.I believe the same would be true regardless of the year.
Blake smile.gif

[ 02-26-2003: Message edited by: NWDmax ]</p>

[DURA-MAX3]

The t-couple was always on the outlet side of the turbo, that way you know what the exhaust temp is.On my caterpillar engine it is about 6 inchs from the turbo... Don't know why in front of the turbo would tell you anything but the air temp going in the engine...

[NWDmax]

Dura 3,before the gases hit the turbo shows you the higher temps before they start to cool farther down the exhaust stream.You force feed the engine via the turbocharger which creates more power and heat.The reading you take is after the turbo has done its work.Other locations will give a lower reading and won't show what your true temp really is.I want to know the highest reading so my margin of error is as small as possible.
Blake smile.gif

[DURA-MAX3]

You want to know what the temp is after the work. Then the temp right after the turbo is the one you want, immediatly after the turbo. Anything before does not include the turbo. Call Cat, Cummins, Detroit and see where they tell you the t-couple is... I've got an extra 1k if your a bettin man...

[dieselburb]

I worked on a pair of Lugger 6125's today and saw the temp probe right before the turbo. Conversely, when I was in another engine room with a couple of John Deere 6125's, the pyro takeoff is post turbo. Bottom line, as said many times before, expect higher exhaust #'s pre turbo and lower exhaust #'s post turbo, but both should tell you the same thing overall.

[DURA-MAX3]

Well my point is a pyrometer is the turbo protection gauge. Can we agree on that. In order to protect it you should have the reading just past it, if its before you have excluded the key piece of the pyrometer.

[NWDmax]

I think most would agree that the maximum sustained temperature should be somewhere between 1200 and 1300 deg.Assuming we agree on that a pre turbo reading is going to be higher and therefore more reliable if your max allowed egt is lets say 1300 deg.Now if you account for the temp drop placing the probe further away your max allowed egt would drop accordingly.If you have a drop of 3oo deg between pre and post turbo locations your max allowed would become 1000 deg as read on the gauge.Is this making sense yet?
Blake :cool:

[Paintdude]

I am new to this stuff so bear with me here..

If you want to protect the turbo wouldnt you want to know how hot the gasses are going into it..To me this would be how to protect it(hotter in hotter out?)..I thought the pyrometer was to protect the engine also, from gettting to hot( give reading)as not to melt the engine down..Melt head,pistons,etc..I would think the hottest reading would be the one you would want..

I can also understand that both reading eventually mean the same thing, but the furture up the chain the sooner you know having more time to correct..I know, whats a second, but it could make a difference..

Like I said bare with me I am new to this turbo stuff...thanks...
smile.gif

[Wildcat]

In our tractors we have an 855 Cummins and a 3406 Cat, both have pyrometers installed post turbo. Previously we had a 3406 Cat with the probe in the manifold. Both installations seem to work, however, the pre-turbo gives a MUCH more instantaneous reading and the needle will swing with the slightest variation in load which I believe is slightly more accurate. The post turbo gauges are much slower to react to varying loads, but will still alert you to a sustained load producing EG temperatures higher than you want. Just my .02

[Silver Bullet]

I agree with Paintdude..."If you want to protect the turbo wouldn't you want to know how hot the gasses are going into it.."...

and Wildcat "...the pre-turbo gives a MUCH more instantaneous reading and the needle will swing with the slightest variation in load which I believe is slightly more accurate...".

On edit: I have recently seen an EGT Probe (pre-turbo) mounted in the pipe that connects the exhaust manifold to the turbo...just on the exhaust manifold side of the bend. This is on BassinRVer's truck...he had it done at DIS in Dallas.

[ 02-26-2003: Message edited by: Silver Bullet ]</p>

[NWDmax]

I agree that the gauge is there to protect the engine and the turbo.I suspect that the turbo can withstand a higher overall sustained temp than the engine could.I don't know this to be fact its just my opinion.At what temp do the vanes of the turbo start to degrade?Do the bearings or impeller fry first?If you consistantly run to hot what engine parts fail first?I don't have a ton of experience with diesels so someone that does please answer.JK where are you?
Dmax3,I'll take that bet but lets make it a case of your favorite beer or other liquid refreshment!
Blake

[DURA-MAX3]

Well i'm an engineer for Halliburton Energy service and i work on or around I-6, v-12, and other diesel engines that vary in horsepower from 200 to 3500 horsepower. All of our engines have the probe after the turbo, i personally dont think that it drops 300 degree's in just a few inches from the manifold to the turbo. If it did you would not have to let an engine cool down for 3 to 5 minutes after working the **** out of it. A pyrometer gauge is to tell you what the temp of the turbo is, therfor i would think that it would have to pass through it to get a reading.Like i said earlier call Cat, Cummins, Detroit ar any diesel maker and see what they say...

[mdrag]

Pre or post turbo??? Both locations are acceptable and commonly used - but there are differences that should be considered.

The exhaust temps WILL DECREASE significantly across the turbo - the energy of the expanding exhaust gases provides the majority of the energy to spin the turbo compressor. A minor energy contributor to spin the turbo compressor is the velocity of the exhaust gases.

Depending on how far the turbo manifold is from the exhaust manifold, heat loss will occur to varying degrees. In the Dmax, the turbo manifold is located on the top rear of the engine - a good distance from the exhaust manifold, so heat will be lost in the exhaust piping between the two manifolds.

As already mentioned, the pre-turbo/exhaust manifold will give you an almost instantaneous reading of the EGT. Using the SPA DG-111/exhaust manifold probe that I have in my truck - I can see the EGT go up/down 7 to 15 degrees F just by turning on/off the HVAC or headlights. A probe in one exhaust manifold only monitors 1/2 of the cylinders though...

A post turbo probe will give you lower EGT readings, probably on the order of 250 - 300 degrees F for the Dmax. The post turbo will be more like an average EGT temp, more closely approximate the temp of the turbo exhaust manifold, and give you a better idea when the temps have decreased enough to safely shut down the engine after a hard run.

There are pros and cons of both approaches. The consensus seems to be that a pre-turbo temp of 1200-1250 degrees should be safe for the Dmax, and 950 - 1000 post turbo.

On the Dmax, if you see temps high enough to damage a turbo with normal oil/water circulation, my guess is that your engine is toast :eek: or will be soon.... :(

[hoot]

Someone that worked for GM/Isuzu told me that in testing the turbo will fail before the engine with respect to heat.

[ 02-27-2003: Message edited by: hoot ]</p>

[TN farmer]

I have enjoyed reading all this but what the manifold on the 2003. Are they the same as my 2002 and will the probe install in the same spot?