Drilling Manifold for Pyrometer

[Bfulgham]

Preparing to Install Pyrometer thermocouple. I was looking at instructions to drill exaust manifold and tap for 1/8 pipe. My thermocouple has 1/4 inch pipe thread adaptor. Looks like it will require drilling 7/16 hole in manifold instead of 5/16 and tapping for 1/4 inch pipe threads. Anyone done this? Size of hole in manifold a problem? Thanks ---Bob

 

[CRWilliams]

Sounds like the size of the hole in my manifold, I haven't had any problems.

 

[Batman]

Bob..... be sure that you in fact do have a 1/4 npt thermocouple. When I got mine, I followed the instructions, said 1/4 npt, didn't measure the fitting, figured the instructions were correct... ... ... guess what... ... my thermocouple was 1/8 npt, had to install a bushing. Just double check what you have and measure twice before drilling.

Good luck

 

[NOMOFO]

When I did mine I unbolted the turbo from the manifold and unclamped it from the exhaust pipe which allowed me to lay it over and out of the way a few inches. I didn't want to risk shavings going through turbo or back into engine. I was able to shove a rag in the manifold to block shavings that way and pulling it out swept all the shavings out. I covered the turbo inlet too. I then vacuumed it as well. I did use a 7/16" drill for 1/4 NPT. I started with 3/16 then 5/16 then 7/16 and used lots of cutting fluid. Drilled fairly slowly, looking for that desired single ribbon.

Also suggest using adhesive lined shrink tube over connections to the lead wire. Good luck!

 

[redneckdr]

thermocouple

bob, look at the thermocouple probe. it probably has a 1/8" npt on the probe, and a 1/8"- 1/4" bushing to install in the manifold. i'd probably still install the bushing. with anti-sieze, easier to remove the probe in the future, if needed.

 

[Bfulgham]

Thanks, mprtrpr-Batman-Nomofo-Redneckdr

mprtrpr- haven't seen you post for awhile. Sound like the same installation, mine is isspro too. Just need to do it. Thanks again



Batman-Mine is definitly 1/4, must be diffirent probe. Thanks



Nomofo-I am changing to a 16cm turbo housing at the same time so will do my drilling before replacing the housing. Thanks



Redneckdr--Thought that might be the case too but it is 1/4 all the way. Will use anti-sieze. Thanks



Bob

 

[redneckdr]

probes

bob, sorry if i gave you bad info... ... my isspro probes had 1/8" NPT on the probes, but came with a bushing. i scratched my head, and drilled and tapped for the 1/4". worked great. just take your time. herb

 

[Tim1]

Real good posts fellas, I can't add anything!!!! Tim

 

[bflood]

When drilling the manifold, watch out for the center rib (I didn't )! I drilled in the center and hit the rib. Broke off a drill, then I removed the turbo and straightened out my mess. I must admit when it was all over with, and with some good luck for my foolishness, I liked the idea of the probe staddling both sides of the rib to get (I feel) a balanced temp reading. Afterwords I read (I forgot where now) that you should offset the hole by 5/8" left of center to avoid the rib. I would say this is the safer way!

Good Luck! I think the pyro is the most important gauge.

 

[Mel Fuelling]

Bob,

Taking the time and care that NOMOFO describes is often quicker

and less nerve wracking in the long run.



However, I have to admit that I installed my pyro the way that

was recommended for the M&W Turbos some of us use to put

on 4010's and 706's. Bring idle rpm up to 1200-1500(I stuck

a small screwdriver into the linkage), drill hole, Tap threads.

Wear goggles and button up shirt. Works great, they told us

that there is pulsing but constant outward flow. I'm not sure if

their theory was true or just to make us feel better because

nothing that you can do can damage anything at this location

(I've heard that theory too). I guess I wouldn't believe that

this method could be used if I hadn't done it so many times.



I've also taped the crevice nozzle of my shop vac a 1/2" from

where I was drilling and tapping. For those little crumbs that

you knock loose, Sears makes an 1-1/4" down to tiny vac adapter

that has a lot of 3/8" fittings and extensions for cleaning

computers and printers that work real well on motors, etc. if you

tape them together so they can't come apart.



Regardless of what you think of paragraph 2 above, use anti-

seize paste on most fasteners. When the paste is just too messy

NAPA has it in a spray can that really works well.

 

[redneckdr]

thermocouple probe

after i posted above, i realized i had had another of those senior moments... ... my probes for isspro were 1/4" NPT, and there was no other way to install them. the length of the probe is controlled by a compression fitting that fits into the 1/4" brass fitting. have to do it that way. BTW bob, be sure the probes they sent you aren't too long. mine must have been set for a much bigger engine. they were set so that they would have bottomned out on the floor of the manifold before they even got started into the threads. it was a PITA to slide the compression sleeve down to reset the depth. the probe should be set so that the tip protrudes into the manifold about 1/2". some of that depth can be controlled be the depth you tap.

i did mine the lazy way. put heavy bearing grease on the drills and taps. backed 'em out and cleaned 'em frequently. then stuck a small round mechanic's magnet in the hole, and "swept" the few filings out before the probe install.

sorry this got long. i always could make a short story long .

 

[Bob Beauchaine]

I did my '93 pretty much the same way as NOMOFO except for removing the manifold. That was 130,000 miles ago and I've had no problems at all.

Happy Trails

Bob