Mercedes-Benz Forum banner

OM617a into Unimog 404.114

10K views 21 replies 10 participants last post by  sdibaja 
#1 ·
Hi everyone,

Please stick with me. I've searched the forum a lot for info on this and, in my perspective, it all comes together like fragmented pieces of a puzzle, probably becasue my automative knowledge isn't very advanced, but I'm going to give it my best try!

I have a stock 1963 404.114 (2.2l m180). I also have a stock 1985 300cd (OM617a with an automatic transmission (I can get a part number if it's necessary)).

As I understand there are a few different ways to do this. I'd rather not use the expensive special 13 deg tilt bellhousing. I also do not want to sacrifice durability, longevity, reliability, etc.

Could anybody give a full description and tips/tricks for getting the m180 out of the Unimog and getting the OM617a in?

Thanks!
 
#2 ·
The 13 degree housing is required, otherwise the fuel injection pump would be in the driver's gas pedal. If you were map out the bolt patterns on the bell housing and OM617, you could have a local CNC shop cut one out of aluminum for you. I have not seen anyone actually selling an OM617 housing in a number of years.
 
#4 ·
The engine can be bolted up, but you would have to have your right leg amputated to sit in the cab. I would think an adapter could be made to rotate the engine and then an extension of the crank shaft to get the flywheel in the right spot. Should be easy, but who knows.
 
#5 ·
There was a factory diesel. But at 45hp (OM615.911) I don't think it would be an improvement.

The bellhousing however, might be the same as the OM617? Doubt it but weirder things have happened:

A4042510101
 

Attachments

#6 ·
The bell housing for the M180 and OM615 versions of the 404 appear to be the same part, but they list different intermediate plates for the engines (actually attaches the bell housing to the engine block). Comparing the diagrams of the plates (assuming they are correct, not always true), and looking at the plate from my 404, both would seem to have the same block bolt holes centered on the crankshaft and alignment pin. But there is a bit of difference in the bell housing alignment pins (one seems to be missing infact) and the upper block bolts seem to be at a different distance... Hard to tell if it is real difference or just a artifact of the drawing. I don't think anyone will have much luck sourcing an Angolan plate to verify though.

M180.928 engine: A 180-011-14-05


OM615.911 engine: A 621-011-01-05
 
#7 ·
I was just curious because the OM615 looks like a mini OM617 and maybe it was clocked from the factory as well.

AFAIK the OM617 is basically interchangeable with the OM615 in a bolt up sense, so if a person had that plate, perhaps that would be an easy-in for the conversion. But it's likely made of unobtainium since it's NLA from Mercedes (A6210110105). And there might be bellhousing, clutch differences, etc.

I'd say if you want a diesel Unimog, buy a diesel Unimog :)
 
#10 ·
How about the plate used in the 421? as it uses the OM615 motor. Maybe the same plate is used to give the correct angle, and should be a few kicking around.
 
#11 ·
Just to clarify, these various different types of plates you all are talking about, the intent is to allow the stock Unimog 404.114 bell housing to bolt into one side and the om617a (is there a specific name for that area of the engine? Crankshaft housing?) to bolt on to the other side WHILE providing the 15 degrees of engine tilt required to clear the stock cab dimensions?
 
#13 ·
Yes-ish and no-ish.

The 404s used either a M180, M130, or OM615 engine (the later only in one specific model that went to Angola). The OM615 is just at the 4-cylinder version of the OM61x engine series, the OM616 being the 5-cylinder and the OM617 being the 6-cylinder versions. (Ignore the OM611/OM612/OM613 as that is a much later/different engine series).

All 404s have a plate between the bell housing and the engine block. This plate is a roughly 1/4" thick (6mm I believe) steel with several punched/drilled holes for bolts and aligning pins. The plate is bolted to the block, the flywheel put on the crankshaft, and then the bell housing bolts to the plate (a few of the bolts go thru the bell housing/plate/block, others only attach to the bell housing to the plate).

The adapters between the block of a M180/M130 or OM61x engine and bell housing/transmission in a 200/300-series car are typically a cast aluminum plate about a 1"~1-1/2" thick. These plates have the same engine side holes, but the transmission side is usually significantly different as it was designed to be mounted to a completely different transmission series. Though presumably one could acquire a carefully selected one and mill/drill to accommodate a 404 bellhousing.

The 404 OM617 conversion is done by replacing the standard steel plate with a new plate drilled to align the OM61x engine to the passenger side. This allows the fuel injection pump to clear the drivers foot well. A new front engine mount is also required, plus possibly other axillary work to the engine.

As to whether the OM615 fitted in the 404.117 (Angolan) is tilted or not... I have not seen any pictures to know. It could be that the factory drilled the plate to tilt the engine, the same as later custom mods have done for the OM617, or I believe the factory did on some later diesel Unimog versions. Or it could be that the the fuel injection pump could be smaller/realigned on the specific OM615 engine used. Or there could have been different body work that allowed the fit.

There is very little information out there about the 404.117 with the OM615.911 engine. Additionally, not very many people have put up highly detailed/technical descriptions of the engine swaps they have done with OM61x/etc. engines.
 
#12 ·
Hi, welcome to the forum.

I admire your desire to put a proper turbo-diesel engine into a 404, but I'm concerned that this conversion might be a bit beyond your abilities, since you mention that your "automative knowledge isn't very advanced", and you're looking for "a full description and tips/tricks for getting the m180 out of the Unimog and getting the OM617a in."

The only way to fit a 617A into a 404.1 cab without cutting up the cab is to use the 13-degree bellhousing, AND lift the cab 3 or 4 inches at the same time. I wish that I'd not cut up my cab before I lifted it. I now have a "Frankenstein" look to the passenger side footwell, because I had to modify the engine covers and the cab floor on that side.

Do you have the facilities to remove and replace the cab, because that's the only way you're going to get the 617A installed? You'll probably need to take the cab on and off a few times before you get the cab-to-engine clearance right.

The heavy-duty Dietrich conversion bell-housing is the easiest way to do the conversion.

Before you begin your conversion, you'll need to locate the proper flywheel for the 617A engine. It was installed on 617-powered Gelandewagens. This flywheel is VERY hard to find. If you can't find this flywheel, I would not bother to proceed with the conversion.

Seriously, the flywheel is going to be your biggest problem.
 
#16 ·
Funny, that's exactly what I learned first hand, and was gona recommend, your like one town away, do I now you?

I just did a conversion for someone localy a few years back, just as you discribed. Thats the only correct way of doing it.

Maybe you seen the black 404 with a 617 td I worked on, Ya PM me sometime, feel like a spoke with you already?
 
#17 ·
Lengthy and a little repetitive but hopefully it makes sense

Thank you everyone for all of the insight so far. I really appreciate it!

Diesel_Canuck:
Thanks for the welcome! It's great to get the input. Hopefully, I'll be able to share some useful information after this as well. This conversion is probably beyond my current abilities, but I'm still going to give it a try, especially because I do have access to an auto shop. As well, I learn pretty quick, I've been reading for years, and I'm focused on getting my abilities up to par through the conversion. I'm looking for as much description as possible to avoid as much headache and extra money with "guess and check, use it till it breaks" automotive fabrication. I know doing it "cheap and right" is an elusive balance point, but, dang it, I'll exhaust myself trying to find it before I give up and spend a bunch of money.

In regards to fitting the OM617.952, my cab is very rusty, missing parts, and I don't mind the "frankenstein" look. I just want it to work well. Since I'll be cutting up my cab to replace rusted out sections and reworking the structure for better soundproofing, I figured accommodating the OM617.952 by cutting the cab would make more sense because I'll be doing it anyway. The only way it wouldn't make sense is if it doesn't work as good. DokaTD mentioned I would have to "amputate my right leg" to make a point (probably) that there wouldn't be enough foot space on the driver's side. It sounds like your build had issues on the passengers side. Is there still enough leg/foot space for a passenger to sit comfortably? With enough internal cab dimension modification (keeping the stock overall width and length and preferably not increasing the height), could it be made for the driver and passenger to both have a comfortable amount of foot/leg space? or is it simply not possible?

In regards to the flywheel, maybe it's just wishful thinking, but can really no other option be done "proper"? The OM617 g-wagen flywheel is the only "proper" option? Why? Others have mentioned modifications of the M180 flywheel or modifications of the OM617.952 flywheel. What are the shortcomings of these routes? Do they only "sort of work" short term and not "work well" long term?

choprboy:
Thanks much for laying out those plate details! If cab modification alone can accommodate the OM617.952 it'd be great if the stock 6mm steel plate would work just as well. Any input?

Snow mogg:
Any long term report on how well your build is holding up? Mileage/hrs on it so far? Things you would've done differently and why? Areas you think you could've saved time and/or money without sacrificing quality? I'm really interested in all information of your build because it seems very similar, if not exact, to what I am about to embark on!

To all:
Cltuch options? Keep the Unimog 404.114 stock clutch? Modified? not modified? Completely different clutch?

Once again, Thanks so much everyone. Any and all input is greatly appreciated!
 
#22 ·
Etzicle I would advise having a look at that one.
It may be a classic example of cobbed up mess, or fine craftsmanship.
Go look, get dirty and take a hundred photos with the hood open, and the doghouse open, and from underneath.

It is definitely a stretch job, not an original doka. Looks nice.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top