Thread size and pitch question - W123, W126 oil pressure sender sizes

[jusme]

OK, bit of a long question. Here's the scenario. I have a 1985 W123 300D that had the engine go out. I purchased a low mileage OM617 from a W126 (unsure of year). Everything works with the exception of some accessory fitment issues. My immediate concern is around the Oil Pressure Sender. The W126 uses a electronic sender, but the W123 still used a mechanical gauge. The thread pitch and size between to 2 variants are different, and the end of the mechanical line from the firewall is an inverted flare design which is also different. So, what I am trying to source is an adapter that will thread into the electronic sender port on the engine side, and make a 90 degree bend (or use multiple pieces to get the angles and length correct), and have the correct inverted flare size on the other end to thread the hose from the gauge side into it.

So, in a simplified way, I need the thread size and pitch for both the W126 oil pressure sender, and the thread size and pitch for the W123 mechanical gauge hose end with the inverted flare.

Also, I'm open to other ideas to achieve the end goal of getting the OE oil pressure gauge to work.

I tried swapping manifolds on the filter housing, and they are different, which led me to believe the oil filter housings may also be different had I tried to undertake swapping the whole filter housing with the engine installed the car (not sure how involved that is).

Thanks again!

[whunter]

The turbo oil filter housings are interchangeable.


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[jusme]

Actually, I did verify that the housings are indeed different. The W126 engine oil supply line to the turbo routes to the filter housing. In the W123 it is different. No extra port for that on the housing, and as I previously mentioned, the manifolds are different, so I cant swap those. Looking like the adapter is the route I have to go.

[whunter]

If I understand correctly ?

You want the W126.120 300SD (donor) engine to use the W123.133 300D (recipient body) oil pressure gauge.

The last swap where I did this (as I recall) required:
* The W123 turbo oil feed tube.
* The W123 oil filter housing.
all installed on the W126 engine, before it would work.


To assist you, the following part numbers are from Mercedes EPC.
I am assuming neither of these engines are Grey market or California models.

300D and 300SD
1981 - 1985

intake manifold MB# 6170980307
exhaust manifold MB# 6171400409
***********

300D
W123.133
1981 - 1985

oil feed tube
MB# 6171800927 all up to end of model year 1984, then 49 state 1985
MB# 6171801327 California 1985
***********

300SD
W126.120
1981 - 1985

oil feed tube
MB# 6171800827 all up to end of model year 1984, then 49 state 1985
MB# 6171801227 California 1985
***********

.

[macdoe]

We had to do this exact retrofit you have going on....I thought we listed the different adapters I used to get this to work on here somewhere....does'nt matter. It is expensive for those adapters. And you have the parts already to make this work without stupid adapters.

If you have the engines out...do what Roy says and just swap the whole w123 housing and turbo line onto the w126 motor. Don't confuse yourself trying to swap the plates on the back of the oil filter tower cause you are right ....they won't swap over....but like Roy has told you, swap the whole filter tower over. You will want to put a new gasket in between there anyways cause they leak and are not fun to change with the engine in the car. It is however possible though, to do it if the engine is in the car. Get the Mercedes dealer brand gasket for your filter tower. Accept nothing else for this application.....you will see why when you get the gasket.

[jusme]

I don't have the W123 engine. By the time I bought the car, the mechanic that was doing the job for him basically stopped working on it. Parts were "cleaned up" (thrown out), and the owner reached a point where he had a low mileage replacement engine he purchased, and a car with no engine with parts strewn all over the garage and driveway. So, that's why I wanted to go the adapter route. Also, agreed, it looks like a PITA to swap housings in the car apart from the fact I don't have the W123 turbo line setup. I'll see if I can get enough parts together off the car to head to a hardware store to put something together.

P.S. Macdoe, if you recall the sizes, just let me know. I looked through your previous posts, and didn't see anything.

Thanks again all.

[barry12345]

Oil filter cap drilled and tapped for the sender should get you by cheap if unable to source another tower etc from a wreck.

[Dan Stokes]

I'm going to a plain old aftermarket gage on my OM617 in the S-10. I took the factory OP sender to our local Parker-Hannifin shop (you may have a local Parker or maybe Swagelok dealer) and had them figure out the thread into the filter body. I went from that to 1/4NPT but you can have them take you to the right thread for your sender. They have a block with different sized metric threads and can determine what you'll need. Our store here has a decent but not complete stock but still they were able to get me where I needed to go. I think I have a pic of what I came up with.......

I was actually taking a pic of the scattershield but the adaptor, 90* angle, and the riser pipe show up pretty well. I'll need to attach the OP gage wiring after the engine is in the truck so I brought the riser up so I don't have to fiddle behind the OF canister.

Dan

[Diesel911]

Can the Lower Rear Plate on the Filter be swapped for another?
This is a Pic of one from a W123 that uses the Manual Gauge.

The Oil Pressure line on the W123 does not seal on the Threads.

[Dan Stokes]

As far as I can tell none of the fluid fittings on the 617 use tapered pipe and therefore do not seal on the threads. The replacement fittings I got from Parker use what I call a "caged" O-ring - the O-ring at the bottom of the fitting is contained within a soft (maybe aluminum?) washer so it doesn't squish out. The stock fitting just uses a flat soft washer which is probably adequate but I'm comfortable with instrument-grade fittings so I like the O-ring system.

These fittings are not cheap but quality costs. I have about $30-40 in the assembly I showed in the pic. Actually a bit less as I wanted the nipple to be about twice that long and they didn't have it in SS so I went with hardware store steel and saved quite a bit.

Dan

[whunter]

Originally Posted by jusme

I don't have the W123 engine. By the time I bought the car, the mechanic that was doing the job for him basically stopped working on it. Parts were "cleaned up" (thrown out), and the owner reached a point where he had a low mileage replacement engine he purchased, and a car with no engine with parts strewn all over the garage and driveway. So, that's why I wanted to go the adapter route. Also, agreed, it looks like a PITA to swap housings in the car apart from the fact I don't have the W123 turbo line setup. I'll see if I can get enough parts together off the car to head to a hardware store to put something together.

P.S. Macdoe, if you recall the sizes, just let me know. I looked through your previous posts, and didn't see anything.

Thanks again all.

In that case, I suggest posting a request for the W123 turbo oil feed tube and oil filter housing.
Mercedes Used Parts For Sale & Wanted - PeachParts Mercedes ShopForum

Sorry, sold my last spare set in January.

You could also make an offer on these.

Oil Filter Housing Bolts Mercedes Benz 0M617 Turbo Diesel Engine 300SD 300D | eBay

Oil Supply Line to Turbo Mercedes Benz 0M617 Turbo Diesel Engine 617 300SD 300D | eBay


.

[jusme]

Originally Posted by Diesel911

Can the Lower Rear Plate on the Filter be swapped for another?
This is a Pic of one from a W123 that uses the Manual Gauge.

The Oil Pressure line on the W123 does not seal on the Threads.

No. That's what I was saying in the first post. But, I think I've come up with a solution. I have piles of extra parts, and grabbed a M12-1.5mm Banjo Bolt, and the Banjo Fitting with Hose Barb. My plan is to union the plastic lines (like on other universal mechanical OP senders). I was able attach the lines temporarily and drove it, and it worked fine. Just need to iron out the details.

Thanks guys.

[macdoe]

I looked through my posts too....you're right, the info re: thread sizes and adapters is'nt here. I will dig through my recipts to find them for you some time today. I think it was somewhere between 40-50 dollars and had to order them from a hydraulic hose repair shop. The problem is finding the right combination of adapters that will fit in such a tight spot.iirc.

[macdoe]

I found the receipt or at least a couple that might help. We did this awhile ago so make sure you check this info out with wherever you get the adapters. I took the hose for the oil pressure sending unit out of the car and down to the store with me. You want to make sure whatever fitting used allows the hose to bottom out when it is tightened into the oil filter tower.

Here are some numbers:
9635-18-L12-04 Adapt All $18.25
9325-04--12x1.5 Adapt All $33.02

The reason I say to make sure this works is because I vaguely remember having to send something back to them cause it was'nt correct. I can't remember if it had to do with this project or another bunch of stuff I ordered from them. The bill also says in pen at the bottom 12x1.5 coupler and 12x1.5 nipple....again this was awhile ago so I can't recall everything going on at the time. I hope this helps.

[Simpler=Better]

I pulled my W123 turbo backing plate and drilled & tapped the hole for a 3/8 NPT. There is enough material to do this-then you have an easy size to convert to/from.