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Smitty77 · 08-22-2016, 08:58 AM

Was looking for input on an EFT Sensor I had installed into our exhaust manifold.

It was drilled out and threaded, and double male end threaded bushing/nut was threaded into the exhaust manifold. (The sensor probe is interred into this, and brass compression like fitting is used to hold the sensor in.)

This was about 10 months ago. On this trip, the sensor worked it's way out, and we had escaping exhaust whistling thru the pass thru hole of the compression nut. (The compression nut, looks like it had worked it's way loose enough, to allow the sensor probe to come out.)

In the patching of this until I could get a new probe sensor. It now looks like the double male end threaded bushing/nut has also loosen up enough to move turn it about 1/4 - 1/3 movement left/right. (I went to pull it out all the way, clean it, Red Locktite it and put it back in. But once I got to about 1/3 left to remove, it seemed to really meet some resistance. So I just Red Locktite around the thread as best as I could. Did this three times over 5 minutes, hoping it would seep down into the threads some. Then I tightened the 1/3 the best I could (Limited access, allowed only my fingers a 9" open end adjustable to reach it. Maybe got 35-30 lbs of tightening.).

OK. So my question

!

What should I look for, besides obvious cracks in the manifold, as far as full removal and replacement of this double male ended bushing/nut?

I'm concerned that I may have loss some meat around the threads?

Any tips on what to look for, would be appreciated

!

Best to all,
Smitty

1ciderdog · 08-22-2016, 11:02 AM

Can't answer your question but if you have to do it again you might try using JB Weld (or a similar product) instead of the red.

Smitty77 · 08-22-2016, 02:06 PM

Thanks Bob!

I believe JB Weld has a 500-600F max temp. I doubt the Red Locktite got into the threads enough to even help, and it too is not really made to handle temps that high.

Anti seize compound was used when it was installed by the tech.

I was kind of on the wavelength, and saw very little downside to having it removed completely, clean outage threads, and maybe use something like ThermoSteel when it it is put back into the exhaust manifold(?).

Will be talking with to the tech that did this job for me later today, and we'll kick around options...

I got a bit better look at the exhaust manifold, and it looks solid with no evidence of cracking. So suspect it just was loosened some as I was jury-rigging it to get to the shop.

Appreciated your thoughts, and best,
Smitty

Chuck_Hammer · 08-22-2016, 03:17 PM

Loc-tite has a release HEAT of 275 degrees.. Red or Blue.

so an exhaust manifold is about 800 degrees. so it was burned off.
I know of NO thread Locker that will handle exhaust heat.

I have a feeling you have damaged threads in the manifold... may need to heli-coil it.

but first try to run a Tap down the threads.. may clean up and able to reuse. Worth a try.

DMTTRANSPORT · 08-22-2016, 03:21 PM

Where in the manifold was the hole drilled for the thermo?

Smitty77 · 08-22-2016, 03:43 PM

Middle of number 3 tube.

Tech has not made it to our coach yet to review. But I appreciate the heli-coil and cleaning threads suggestion.

I trust this tech, and am positive we'll get things 'right'.

I was thinking the ThermoSteel, or like liquid metal, might be enough to help assist a damage thread hold. And of course, not even sure the thread is damaged. As I recall, the tapping is is done by a conical shape threader. Going too far with the tapping can oversize the hole/threads. Don't believe this happened. Suspect the resistance I felt trying to ease it out, was a tighter part of the thread catching on the way our. My tool arsenal is not deep in the coach, and the tech will have the proper set of tools to work with. Suspect I'll be tearing apart our bed to get access to the top of the manifold for him, as reaching in from the back is less then ideal

!

Again, thanks for the feed back from all. Exactly what I was looking for, to jog my knowledge tree, and to be ready to ask the tech questions when we do get to review things

!

Will update when we're done doing whatever is done!!
Best,
Smitty

Best,
Smitty

DMTTRANSPORT · 08-22-2016, 04:08 PM

The correct way to get an accurate EGT reading would be to weld a bung on the exhaust pipe after the Turbo or you could buy the pipe with the bung installed (3-4") installed in the exhaust manifold you won't get a correct reading.

slickest1 · 08-22-2016, 09:47 PM

Quote:

Originally Posted by DMTTRANSPORT

The correct way to get an accurate EGT reading would be to weld a bung on the exhaust pipe after the Turbo or you could buy the pipe with the bung installed (3-4") installed in the exhaust manifold you won't get a correct reading.

All the ones I have seen are after the turbo on the exhaust.

DMTTRANSPORT · 08-23-2016, 07:13 AM

Quote:

Originally Posted by slickest1

All the ones I have seen are after the turbo on the exhaust.

Quote:

Originally Posted by DMTTRANSPORT

The correct way to get an accurate EGT reading would be to weld a bung on the exhaust pipe after the Turbo or you could buy the pipe with the bung installed (3-4") installed in the exhaust manifold you won't get a correct reading.

You had stated yours was installed in the manifold @ #3?

Franka548 · 08-23-2016, 07:22 AM

The threads in the manifold are probably tapered pipe thread, either 1/8 or 1/4" NPT. If your probe won't stay tight, you will probably need a new probe, if the fitting in the manifold won't stay tight, try using the hi temp copper based RTV on the threads as a thread sealer, if this doesn't work try a new fitting. As far as where the probe is installed, the difference will be the actual temperatures that you read, if they are in the manifold before the turbo, the readings will be above 1000* up to as high as 1400* If they are in the exhaust pipe after the turbo, the readings will be below 1000*. You will need to check with the engine manufacturer to get the safe maximum reading for your particular case. An example is on the GM Duramax the max safe temp is 1350* with the probe in the exhaust manifold.
Frank

TQ60 · 08-23-2016, 07:54 AM

The manifold has substantial heat swings so the threaded thing will come loose if the material is of a different expansion rate.

Anti seize may allow for lubrication to make it worse.

It may have crud on inside or the threads could have failed but only removing would confirm.

Suggest seeking out exhaust repair epoxy as it is rated for the high temperature then carefully remove to mount fitting and chase the threads with the tap.

If tapered then go another turn to freshen them or add a little bite and if straight just clean them.

Wire brush mount fitting or use new and use epoxy on threads.

Do confirm prep to be sure area is properly prepped as it may make a difference.

Epoxy the mount in place then as soon as it is in use a bottle brush or wand to clean center.

Allow to cure twice what the label states then insert probe and be sure to correctly torque send seal lock nut for that.

DMTTRANSPORT · 08-23-2016, 10:12 AM

Quote:

Originally Posted by Franka548

The threads in the manifold are probably tapered pipe thread, either 1/8 or 1/4" NPT. If your probe won't stay tight, you will probably need a new probe, if the fitting in the manifold won't stay tight, try using the hi temp copper based RTV on the threads as a thread sealer, if this doesn't work try a new fitting. As far as where the probe is installed, the difference will be the actual temperatures that you read, if they are in the manifold before the turbo, the readings will be above 1000* up to as high as 1400* If they are in the exhaust pipe after the turbo, the readings will be below 1000*. You will need to check with the engine manufacturer to get the safe maximum reading for your particular case. An example is on the GM Duramax the max safe temp is 1350* with the probe in the exhaust manifold.
Frank

At the rear bend in the passenger side bank on a D Max
All my probes are "exit" Turbo side and read over 1000 depending on the OAT, Elevation or on a grade or not.

Smitty77 · 08-23-2016, 10:22 AM

Thanks Frank & Tony.

Tech and I talked everything over late yesterday afternoon.

Out of the several hundred that he has personally installed, this is the third one where the probe worked loose. It's a balance between tightening the compression nut too tight and damaging the probe, vs not tight enough for the probe to remain in.

He felt that the tapered bushing (My choice of word, he had another word I can't recall.) that is threaded into the exhaust manifold, and the threads of the manifold itself, should be fine. I loosen this by accident, due to poor access and getting the open end adjustable down on that piece vs the compression nut cap that I had been trying to remove to take out my first attempted jury-rig repairs of using a screw with two nuts to temporally plug the hole. I loosened it that 1/4-1/3 turn before I realized the wrench was on the wrong piece.

We agreed that he will remove the threaded bushing that is in the exhaust manifold. He will clean the threads with a wire brush. Inspect. If it looks like it should, he'll insert a new bushing, and properly torque it. (He said that sure, a product like ThermoSteel, or other high temp liquid metal, would not hurt. But he said he really did not feel it was needed. He will put on a new thermo probe, and splice it into the wire lead to the gauge.

IF the inspection of the threads of the exhaust manifold indicate a problem. The tech said he will re-drill, tap, and install the next size bushing to ensure solid metal. (But again, he said he did not feel that would be needed. But would not hesitate to do this if he felt it was warranted.) He even explained that if he did this, he would do what he did last time, and have me start the engine, and in addition go grease on the drill and tap, the air pressure would blow out any risk of metal shavings. When he first drilled the manifold. He got it almost all the way thru, stopped, had me start the engine, and then finished the drilling and tapping. Took maybe two minutes for him to finish the drilling and tapping of the hole. So I'm familiar with this process.

I feel comfortable about our next steps, and hopefully this will be completed on Wednesday, as they have a full shop of other customers, and I'm basically a 'walk in'. I'm OK with this, as if I was in the shop first, I would not expect someone to slot in ahead of me. They are covering all of this, and putting us with water and 50 AMP service as we wait. I asked the shop scheduler, if they could work me into a slot for a full generator service, as it is due, and I wanted to provide some income to the shop for them doing the right thing.

Best to all,
Smitty

Dr4Film · 08-23-2016, 10:37 AM

I am not quite sure where the Banks installation tech had installed their EGT sensor when I had the Banks Power Pack installed back in July of 2013.

I will attempt to take a look to see if I can find it and report back. Wherever it is that's where it should be installed. They ARE the experts.

They added both a new EGT and Boost gauge when they did the install.

Dr4Film ----- Richard