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OM617a EGT Probe Placement

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PNZWGN
Posts: 1120

OM617a EGT Probe Placement

Post#1 » Fri Dec 13, 2019 8:44 am

Gentlemen... where precisely should a VDO EGT probe be located on a om617a exhaust manifold?

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Will the probe and wiring clear the block/heat shield once installed if located here? I'm not sure it will...

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Kent... what say ye..?

Also, should the threaded bushing that the sender threads into be welded or brazed on? Some aquaintences are suggesting brazing would be more appropriate for an exhaust manifold.

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Thank you for the time and advice.
"wherever I may roam..."

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Chris
Posts: 3389

Re: OM617a EGT Probe Placement

Post#2 » Fri Dec 13, 2019 9:13 am

Drill and TAP the hole where your finger is pointing. It’s 1/4” thick cast steel.

You can also mig/tug weld or braze that bung on there too.

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PNZWGN
Posts: 1120

Re: OM617a EGT Probe Placement

Post#3 » Fri Dec 13, 2019 9:20 am

Chris wrote:Drill and TAP the hole where your finger is pointing. It’s 1/4” thick cast steel.

You can also mig/tug weld or braze that bung on there too.


Thanks Chris... I was just reading over your/Kent's post when you replied. I knew I had gotten this location from somewhere.

I'm assuming close to where the turbo bolts on the better for clearance? Also, replying to your email now. Thank you.
"wherever I may roam..."

PNZWGN Mk II build thread: https://clubgwagen.com/forum/viewtopic.php?f=18&t=5605

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kafkaonwheels
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Re: OM617a EGT Probe Placement

Post#4 » Fri Dec 13, 2019 9:35 am

Here is location on my engine but I would get it bit more down, towards turbo, if I would do it again. Current probe is long and rubs against block if removed.

I didn’t weld or brazed any extra bushing to manifold, just tapped a hole. The nut/sleeve accompanied with probe had tapered thread – I added a bit of high temp. anti-seize and recon it to be sealed good. The manifold wall is thick enough for thread and welding cast iron without good experience seems like asking for problems to me.

EGT_OM617.jpg
1985 300 GD Turbo (Project)

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PNZWGN
Posts: 1120

Re: OM617a EGT Probe Placement

Post#5 » Fri Dec 13, 2019 9:43 am

kafkaonwheels wrote:Here is location on my engine but I would get it bit more down, towards turbo, if I would do it again. Current probe is long and rubs against block if removed.

I didn’t weld or brazed any extra bushing to manifold, just tapped a hole. The nut/sleeve accompanied with probe had tapered thread – I added a bit of high temp. anti-seize and recon it to be sealed good. The manifold wall is thick enough for thread and welding cast iron without good experience seems like asking for problems to me.

EGT_OM617.jpg


Thanks Ed... this is super helpful also. Are you running the VDO probe/sender also..?

Damn you set-up looks good. And clean. You know I like... Mr. Clean.
"wherever I may roam..."

PNZWGN Mk II build thread: https://clubgwagen.com/forum/viewtopic.php?f=18&t=5605

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kafkaonwheels
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Re: OM617a EGT Probe Placement

Post#6 » Fri Dec 13, 2019 10:09 am

PNZWGN wrote:Thanks Ed... this is super helpful also. Are you running the VDO probe/sender also..?

Damn you set-up looks good. And clean. You know I like... Mr. Clean.

No, it is not VDO, just generic Type K, should be compatible. I actually wanted and ordered one with 90 bend (VDO doesn’t have such) but still in box arrived straight.

Thanks. Siting in garage corner it should be looking clean… waiting for someone, wonder who :roll: , to finish last blockings of primer on shell.
1985 300 GD Turbo (Project)

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PNZWGN
Posts: 1120

Re: OM617a EGT Probe Placement

Post#7 » Tue Jan 21, 2020 3:42 pm

Tapped that manifold tonight... finally. :lol:

Drill path selected...

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Started with a small bit to make a pilot hole. Broke three brand new premium bits in the process. Went back to my old tried and true junk bits. Did it by hand... slowly and carefully. Took. For. Ever. But finally made it through.

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Then I increased the size of the hole stepping up one bit at a time. That didn't take long at all.

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"wherever I may roam..."

PNZWGN Mk II build thread: https://clubgwagen.com/forum/viewtopic.php?f=18&t=5605

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PNZWGN
Posts: 1120

Re: OM617a EGT Probe Placement

Post#8 » Tue Jan 21, 2020 3:48 pm

And then... took the manifold down to my dad's and used his drill press for the last hole. This bit was matched to the tap that was matched to the VDO probe that I sourced locally. Wanted to make sure this last pass was "perfect" but looking back I could have done it by hand and been fine.

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And then... started to tap. Slowly... carefully. Used tap oil and went very slowly. Actually found that a ratchet worked better than my tap wrench for this application.

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Didn't take that long. I just went really slowly and carefully. :lol: Then a test fit...

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"wherever I may roam..."

PNZWGN Mk II build thread: https://clubgwagen.com/forum/viewtopic.php?f=18&t=5605

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PNZWGN
Posts: 1120

Re: OM617a EGT Probe Placement

Post#9 » Tue Jan 21, 2020 3:52 pm

The probe is sitting secure. Nice and tight and definitely not going anywhere.

Question for those who know... is the probe sunk in enough..? Threads are all the way through to the inside...

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I will deburr the inside shortly before shipping it off. Let me know about those threads if they don't look good. 475th thing I've never done before since owning a W460 now complete 8-)
"wherever I may roam..."

PNZWGN Mk II build thread: https://clubgwagen.com/forum/viewtopic.php?f=18&t=5605

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G Nome
Posts: 4856

Re: OM617a EGT Probe Placement

Post#10 » Tue Jan 21, 2020 9:06 pm

Looks great Parker. The probes seem very sensitive.

Let us know how it works.

Kent

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