Where should I put my EGT Probe?

[bigbillyboy]

I have a 1985 300D turbo. I want to install a pyrometer and I know pre-turbo is better than post turbo, but where exactly? It looks like no matter what I'll have to drill a hole and tap it, but my thermocouple is about 2" long and it looks pretty tight under there, pre turbo. Where have you guys added them? Photos?

thanks

[jbaj007]

I've read that the EGT probe should be placed the same distance from the head as is the diameter of the exhaust valve. Supposed to be a "rule of thumb" ?

That said, mine's about 3/4" from the head/ manifold junction.

[bigbillyboy]

Do you have a picture. It is pretty cramped in there. Did you drill a hole up from bottom? Do you have the stock air filter? How far in does your probe go? I don't want to start drilling and then find out I don't have enough room.

[derherr65]

I'd also love to see a few pictures of someone pyrometer install... the engine half please.

[bgkast]

I'll be putting one in soon too. I'll take some pictures along the way.

[Kynetx]

Please do. Since Ill be towing with mine next summer an EGT is a must-have.

[Jeremy5848]

...in the exhaust manifold. See the pictures I posted in the following thread:

Where's the boost???

If yours does not have such a thing (unique to California version w/trap ox?), you will have to do the drill/tap thing. Some posters here have suggested that coating the drill and tap with heavy grease will trap the chips and keep them out of the manifold but I would be leery of trusting in such a scheme. The only other alternative would be to pull the manifold.

Mine is installed under the manifold where all the exhaust collects before entering the turbo.

The highest I've seen is 1400*f and it usually idles in the 300*f range.

[biobenz617]

Has anyone ever thought of that pesky EGR port on the manifold for a place to put the thermocouple? I'm not sure if there are thermocouples out there that are long enough to reach to the exhaust stream though. Just a thought.

[networkboy]

Somehow seem to have posted this in the wrong thread ?!?!
So here's a copy and paste:

Originally Posted by biobenz617

Has anyone ever thought of that pesky EGR port on the manifold for a place to put the thermocouple? I'm not sure if there are thermocouples out there that are long enough to reach to the exhaust stream though. Just a thought.

I'm sure there are
In fact I have a K type thermo couple on a 1 foot solid stem that I use for process monitoring, check out http://www.omega.com/ppt/pptsc.asp?ref=TJ36CAXL_NNXL&Nav=tema06
They've got tons of stuff.
-nB

Update:
This looks perfect: (K type is only $34)
http://www.omega.com/ppt/pptsc.asp?ref=TC-NPT&Nav=tema09
and an intro to thermocouples:
http://www.omega.com/thermocouples.html

[derherr65]

The EGR idea did occur to me. The question is, is there a flange you could bolt a plate to(plate drilled and tapped for the thermocouple naturally), or is it pressed in?

EDIT: It's pressed in on mine. I supposed you could thread the area for an adapter down to 1/2" or whatever is needed.

The EGR won't work to measure EGT's. It's not directly part of the manifold galley. It's actually a separate (but cast in) tube.

[derherr65]

Ah, not good. Thanks Forced... I say that way too much. Anyway...
Looking at the manifold it should not be hard to put the thermocouple in directly above Forced's location by only removing the turbo. I guess the question is, once you've pulled the turbo is the exhaus manifold only a couple bolts/nuts or do you have to remove the intake and other things?

Originally Posted by derherr65

Looking at the manifold it should not be hard to put the thermocouple in directly above Forced's location by only removing the turbo. I guess the question is, once you've pulled the turbo is the exhaus manifold only a couple bolts/nuts or do you have to remove the intake and other things?

Pretty much. You are there, might as well go all the way. Besides, drilling and tapping at that angle from the underside would be pretty tough.

[derherr65]

I was thinking drilling from the top. With the turbo off the exhaust manifold port is visible and accessible, plus it angles down so any chips should fall out, especially when aided by a shop vac. Kinda depends on how long your thermocouple is outside the manifold. Can't see it's length in the pic. Do you think that route or pulling the manifold to use a drill press is better?