Engine/Transmission (1998.5 - 2002) Cracking Exhaust Manifold...

[JoeCanuck]

I've been trying to decide where to put my pyro sensor. I've heard from some that drilling the manifold can cause cracking.



I've heard the safer route is to place it behind the turbo, though I've gotten conflicting accounts about how much this can change the readings.



Who has had manifold cracking caused by pyro placement?



Thanks.

 

[kenny61]

My 96 is fine

 

[MAllen1]

I went ahead and replaced mine on my 99 because I noticed a hairline on mine during a oil change. I went went a 3-piece that already was predrilled for a pyro sensor right at the collector.

 

[darkhorse]

The cracking is caused by heat expansion & doesn't generally occur where the probe goes. Go ahead & drill baby drill.

 

[aircop]

Go ahead and drill it won't cause it to crack. Mine is drilled in two places and about to be three, for drive presure for a BOV to stop barking the turbo.

 

[JoeCanuck]

I asked because my brother had a '99 and he drilled and tapped the manifold for the pyro. It ended up cracking right across the hole.

Every big rig I've ever driven, (many with Cummins engines), has the pyro sensor behind the turbo. I wonder why it's so critical to have it in the manifold on this engine.

 

[darkhorse]

It gives you a more accurate reading of actual cylinder temperature. The gases lose some 300 degrees as they expand through the turbine housing. If I understand correctly, that 300 figure is an estimate & can vary significantly.

 

[aircop]

Because most of our trucks are set up for alot more power then stock. The EGT's are very important pre-turbo as they can be anywhere from 300-500*F differant then post turbo.

 

[Bob4x4]

I can see up to 600 degrees differance between pre and post turbo when acelerating hard or climbing a grade. It takes a bit for the temps to equalize.

All 24v exhaust manifold will crack... ... ... . it is only a matter of when. A very small percent will crack at the t/cpouple,the rest are all in the same place.

Bob

 

[VolsFan]

yeah, i got the ATS 3 piece and now I dont have to worry about it; the stock one was fine, but didnt want it cracking later on down the road with injectors, box, etc. My philosophy is to get rid of all the weak links before you start adding power. Also, when I had the stock manifold, I had the pyrometer drilled post turbo, now it is pre turbo since ATS pre drills it for you. There is definitely a 300-400 degree difference, Im glad I switched to pre turbo now that I have been modding up the truck.

 

[2broke2smoke]

i put a pyro in my '91 when nobody with a dodge knew what they were for ...



only place to buy one was a truck shop ...



sold truck with 275k and all original manifold ...



we use the pyro pre turbo because we mod our trucks ...



big trucks use them post turbo because they operate within the original manufacturers specs ...



i have installed dozens since the early 90's and have never had a single problem ...

 

[JoeCanuck]

Okey dokey... I was leaning towards drilling the manifold and accuracy is always a good thing. Good info, thanks.

 

[Moose Truck]

Just do not drill it in the center of the exhaust flange . There is a divider in between the front 3 cylinders and the back 3. Drill it in the center of the back "hump". That's because the back three run hotter any way.



Use the right size tap for your Probe, Most are 1/8". You may want to grease your tap to catch any chips from going thur the turbo. Best of Luck, Moose

 

[JoeCanuck]

I drill tomorrow... I'll let you know if there's any trauma...