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Pyrometers probe placement

Tovar

Active Member
Messages
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Location
Arizona
I've got a '99 Chevy 3500 6.5 turbodiesel. Is there a problem with installing the pyrometer probe on the driver's side exhaust manifold (using the drill and tap variety)? That part of the engine compartment is less "cramped" than the passenger side. If this is an acceptable area, where on the exhaust manifold would be the best place to drill and tap?
 
The probe needs to be close to the turbine intake before turbocharger or in down pipe close to the turbine after turbocharger. The before reading generally reads 200 deg f more than after.
 
Yeah, thats where you have to put it in hummers and vans with the center mount turbo.

What I do is start the engine and let it idle while drilling the hole. That way the exhaust blows out the shavings instead of dumping them in the turbo. Then when (if) you tap threads in, use a lot of cutting oil and the fine shavings will stick to the tap. Remember to do 1/2 turn in and 1/4 turn back to not break tap. Every 2 full rotations I like to remove, clean, reoil tap.



As for the "exact temp" things should be, it will change based on many variables. Just learn where "normal" is when not loading the engin heavy. You will start seeing a correlation between an egt range and coolant temps when pulling hills or towing. Then you know where to back out of it.
 
IMO on a truck put it in PS manifold. If in DS and you develop a problem on PS you won't know it. EX: bad injector?
At least you got a shot at seeing a problem.
 
There is a small raised flat spot on the PS manifold a couple inches below the turbo flange
 
You can also go 90° around from that flat spot to the front of the pedestal and drill and tap for the pyrometer probe there for easier access than through the wheel well for the square pad on the side of the pedestal.
 
Of course, the easiest way to do it is with the passenger side exhaust manifold off the vehicle and sitting on your bench!
 
Anybody know where I can buy a 5/16" letter R drill bit. I've checked ace, Napa, fastenal, and nobody seems to have ever heard of a letter R drill bit.
 
Harbor Freight in their master drill bit set has both letter and number series bits as well as 1/64" increment from 1/64 through 5/8" all in cobalt.

If you have a real hardware store near you they should have the correct letter bits for both 1/8" and 1/4" pipe taps (usually as a drill bit and tap set for that size). Try Ace or Truevalue (they carry them at my neighborhood Truevalue) or your local mom and pop hardware store.
 
Got them. It all seems to boil down to who you get waiting on you. I got the bits from a store that told me they didn't have them. Came back another day spoke to another individual, and bang, handed them right to me. So, now I can do the job.
 
This post is probably too late for the OP, but might help out others in the future.

There is a flat spot on the PS exhaust manifold that can be accessed from the top side without having to pull the inner fender. When I drilled my manifold I did almost what Will said. The big difference was that I started drilling before starting the motor. When I thought that I was at least halfway through I started the motor. And yes, the exhaust blew the chips out of the manifold. One thing I did in addition was to add a bit of grease to the drill bit tip just before finishing the drilling, to help keep any metal fragments from being lost inside the manifold. I tapped the hole using grease added to the tap also, and did like Will also.

Don
 
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