Diesel conversion discussions:
Engine-Swaps
unimog 404 overview
Dieselization of the Unimog S – 404

Recent hardtop discussion on Benzworld:
http://www.benzworld.org/forums/unimog/2241098-what-questions-should-asking-about-63-a.html

 

Yeah about that... The factory made some angolan diesels with OM613/14 engines and they are described as mobile sand dunes. The hot ticket is the OM617 but it requires making or buying some premade stuff and adds a good quarter to half of your purchase price just in hardware.

Big diesels don't fit and most of the small ones don't work too well with manifold placement etc. A TDi swap is very doable but requires a lot of "black magic" if using a modern ALH/BEW.

What is your plan for the project? Where do you see this project going, what do you see it doing? Knowing where you want to be helps in buying the right truck to start with and not bleeding money going down a road that has already been trod and may not go where you want.

 

Fill out your profile so we know where your from. If you want a diesel mog, start with a diesel mog.

 

Just a short while ago, there was a link to a Tdi 404 Mog. Perhaps someone smarter than I can put up the link. There are a couple of videos of it on utube too. It seems to do quite well with the tiny, but mighty 1.9 ALH. I have been waiting to see someone do a Tdi/404 for a while now. I want one! I think there are merits to dieselizing a 404 rather than starting with a 406/416 or bigger diesel Mog. Sure, it will be a lot of work, but what on a Mog isn't?

EDIT: ADDING LINK TO 404 TDI -trev

 

I'd look towards the guys that do TDI swaps in the vanagons. They have a fairly easy self contained system for the ecu and whatnot. The hardest part would be the bell housing adapter and front engine mount.

 

One of the big bummers is the lack of true road going speed. Even the 404 struggles to get up to 60 or 65 (I do not know from direct experience, but from what I read) and is probably revving quite high for that little gas motor. The Tdi will rev up much higher than the OM352 and freeway cruise at 2800 RPM all day long, but it's probably not good to cruise the freeway at 4k RPM. Can one integrate a reduction gearbox between the engine and the main transmission?? The Tdi engine is so tiny, yet it is comparable (exceeds, really) in power to the original engine that you might be able to do some really cool things like that.

It came up on Tdi club too. Here is a link. I may watch the utube videos a few more times today. Dreaming.

http://forums.tdiclub.com/showthread.php?t=426252

 

If you start to get an OD involved on a 404, whatever you're doing is going to end up like a frankenmog.

Random idea:

Acme adapter for bellhousing to a short 3 speed auto trans on the TDI, "simplify" the auto transmission and wire it up so you can actuate the clutch bands from a clutch switch.

Use the unimog transmission as a 6 speed transfer case, pressing the clutch release to shift gears on the mog gearbox.

You'd want to build some sort of strongback to keep the auto trans output aligned into the mog gearbox.

Don't forget the big frame rail member that the factory bell housing humps over.

By the time you're done, just go get an SBU and wedge a 404 cab on it.

One of the big bummers is the lack of true road going speed. Even the 404 struggles to get up to 60 or 65 (I do not know from direct experience, but from what I read) and is probably revving quite high for that little gas motor. The Tdi will rev up much higher than the OM352 and freeway cruise at 2800 RPM all day long, but it's probably not good to cruise the freeway at 4k RPM. Can one integrate a reduction gearbox between the engine and the main transmission?? The Tdi engine is so tiny, yet it is comparable (exceeds, really) in power to the original engine that you might be able to do some really cool things like that.

It came up on Tdi club too. Here is a link. I may watch the utube videos a few more times today. Dreaming.

Mercedes Unimog TDI ALH powered conversion, harness done by OttoStadt - TDIClub Forums

 

I own 2 Unimog 404's, both with OM617 turbo engine and very happy with these conversions!
One has the 404.0 / 406 cab which is really comfortable...

Frank

 

Dieselization of the Unimog 404

Hi Fellas,

I'm new here, and haven't yet finished
my OM 617 engine swap. But I want
to let anyone know that we went through
the expense of translating into English
Gerald's book on Dieselization of the
Unimog 404. Gerald has also given us
permission to sell the translated version.

If you want it, please send me an email at
tommy@paracreative.com

Gerald is also interested in selling the
design for his bellhousing. Not sure we
want to go into that business, but we
sure wish we had one of those units
about now...

 

Cool, man. I bet someone here would want to get on that deal.

Best.

C.

 

Correct starter motor help desparately needed!

Gents Hello, i bow to the superior Mog knowledge...., I'm desperately after some advice on the best starter motor to use on the om617 conversion on the 404
I have an om 617 N/A in a 404 which I bought, truck was almost finished when I bought it, the big problem I have is that the starter motor fitted to is not ideal, its not a Merc one according to the auto electrician, It doesn't line up correctly and stays engaged at times rather than stopping cranking, its basically not very effective and yesterday it burnt its self when it got stuck engaged before i could frantically disconnect the battery. I would be very grateful if you could advise on the type of starter you are currently using and any mods that you had to do to get the starter correctly fitted.

Thanks very much in anticipation!

 

I'm running the stock OM617A 12 volt starter, but I've switched my 404 to a 12 volt system. It works great. I did have to install step-up transformers for the windshield wipers and the heater blower fan.

hope that helps

 

White404
I cannot help you with your starter problem...
But I would like to ask if you have any more pics of your Mog...looks real nice from the one pic you posted..

 

Correct starter motor help desparately needed!

Thanks Diesel_Canuck for the info that's super. Fortunately i'm on 12v as well so potentially that could be an ideal solution for me. Do you know if you have the 404 flywheel fitted and if so does the om617a starter you have mesh ok and function etc as I had read that the standard starter was not a good fit? I cant work out why the person doing the conversion on mine has modified a different starter to fit (not very well) rather than use the standard one.
Thanks again

 

Do you know if you have the 404 flywheel fitted and if so does the om617a starter you have mesh ok and function etc as I had read that the standard starter was not a good fit?

I'm using the flywheel (and clutch, I think) from a Gelandewagen which came with the OM617A. I've got several 617 flywheels from automatic transmissions laying around, but I can't compare them to an original 404 flywheel, because I bought my truck without an engine.

 

Correct starter motor help desparately needed!

Thanks Kimosawboy, its very nearly there, just a few bits to get sorted, couple of pics attached, cheers!

 

Sweet rebody!

 

Correct starter motor help desparately needed!

Thanks for all the advice and comments. I'm baffled! I bought a 617 starter and have just tried to fit it today. The 617 starter doesn't fit up into the recess of the starter hole. I now see why there was a modified reduction starter already on there, this starter has a bigger pinion cog than the 617 one. I can now see there is an adapter plate of sorts that appears to hold the 617 engine to the bellhousing and some basic mods around the starter fixing area. Does anyone know if it would be common practice to use an adapter plate for this fit as I thought they just bolted up?

 

Thanks for all the advice and comments. I'm baffled! I bought a 617 starter and have just tried to fit it today. The 617 starter doesn't fit up into the recess of the starter hole. I now see why there was a modified reduction starter already on there, this starter has a bigger pinion cog than the 617 one. I can now see there is an adapter plate of sorts that appears to hold the 617 engine to the bellhousing and some basic mods around the starter fixing area. Does anyone know if it would be common practice to use an adapter plate for this fit as I thought they just bolted up?

The adapter plate is stock on a 404. That plate bolts directly up to the 617 when you do the swap. I would imagine that you have the stock 404 flywheel which means you will need a 404 starter, which i've heard came in two different sizes, of which you would want the smaller. keep in mind these will be 24V. As you noticed the 617 starter is too big to fit and has the wrong bendix gear.

I used a slightly modified mean green gear reduction starter for a 300D.

 

Thanks Mikeday that's very useful. Would a stock 404 starter physically fit up without any mods to the 617 (appreciate its 24V)? Are you using your mean green reduction starter for a 617 on a 404 or another application?
Cheers

 

I believe that the 404 starter will bolt up to the 617 when mounted to a 404 bellhousing with the 404 mounting plate.

I have the mean green starter on my 404 with a 617 swapped in. I had to call mean green and request a 9 tooth Mercedes bendix gear and center the starter mounting plate, but it fits nicely and has plenty of power to spin over the 617.

 

Thanks Mikeday, would you know if your mean green is more similar to the standard 617 or the original 404? I may try and modify my 617 to fit. Oh to have a nice working starter.....!

 

From what have read not much difference in the Petrol 404 engine power and the 617 N/A. Someone went to a lot of work for little gain. Opens the door to you though for future swap to a 617 Turbo though.

Rebody looks awesome. Good luck with the starter.

 

Having looked into the engine conversion on my 404 it looks like the convertor has fitted the om 617 engine straight to the 404 gearbox using the steel plate which i think comes on the 404 as standard. The engine is mounted straight and not at the 13 deg canter as with the rebody there is no issue of fouling. However this for some reason has made the fitting of a starter motor difficult. I have bought and tried the om 627 standard starter but it fouls against the side of the engine block and just seems too big. I havent tried to see if the 404 starter will fit in size yet, i've a feeling it wont. Even if it did I would then have the issue of 12/24v issue and the power needed to turn the diesel over. Does anyone have knowledge if a 404 starter fits an om 617 engine physically? Thanks

 

mikeday,

I have a similar situation as you have: 404 with OM617A swap. Original 404 starter works but barely turns over the diesel. So, I am in search for a better starter.

Could you perhaps give some more details (part#, order date, sales persons name, etc.) on your order with them? That way, I have something to refer to when I call them.

Thanks a lot.

 

I used this starter 1984-74 MERCEDES 240D, 300D - MG Industries Inc.


When it came in I found that it had a 7 tooth pinion and I needed a 9 tooth. So I called and spoke to an engineer (who's name I forget) and he sent me the 9 tooth to try, which worked.

The other thing to note is the round boss that locates the starter into the bellhousing/plate hole is offset, I hand filed one side to center it. When you speak to someone about ordering it with correct pinion gear you may be able to request that the boss be centered (same size though). Mine is out at the moment, i'll try to take some pictures over the weekend.

Hi Demon 1234, Could I just trouble you on your last re your engine conversion please? How have you bolted your 617 to your bell housing, have you used the standard bell housing or not and have you used the 404 metal plate between the engine and box or the thicker (I think Aluminum) plate from the 617? If I could find a 404 starter to offer up and if it physically fits I think my local company could convert to a reduction gearbox type for stronger cranking, my problem is i haven't found a 404 starter to try as yet would fit.One of the earlier posts suggested there are 2 sizes? I'd be grateful for your feedback.
Thanks

The aluminum plate from the 617 does not fit the 404 bellhousing. The only way it bolts up is with the steel plate from the m180 bolted to the 617.

 

Hi Demon 1234, Could I just trouble you on your last re your engine conversion please? How have you bolted your 617 to your bell housing, have you used the standard bell housing or not and have you used the 404 metal plate between the engine and box or the thicker (I think Aluminum) plate from the 617? If I could find a 404 starter to offer up and if it physically fits I think my local company could convert to a reduction gearbox type for stronger cranking, my problem is i haven't found a 404 starter to try as yet would fit.One of the earlier posts suggested there are 2 sizes? I'd be grateful for your feedback.
Thanks

 

The original trans bell housing bolts up to a custom cut conversion plate (see pic below where it was trial fitted to the ol' M180), which is then bolted to the OM617. As mentioned by mikeday, the Alu OM617 plate does not fit the 404 bell housing. I used the original Unimog 404 24V starter (the OM617 starter OD is too large to fit against the OM617 now that the flex plate is replaced by the smaller diameter flywheel).

As for a spare 404 starter, they are still available through vendors supplying Unimog parts here in the US (Expedition Imports, Eurotruck-imports, Eurotech-services, etc.). Expedition Imports has one for sale for ~$425. I do have one spare but I'd rather keep a hold on this one for my upcoming Moab trip in two weeks. I am unaware of two different size starters. All my Mogs seem to have the same starter. Hope this helps.

mikeday,
Thanks for the link. I'll give them a call today and see if they can help. I'll mention the pinion swap and the center work.

 

I found a (somewhat blurry) picture of the OM617 bolted up against the 404 bell housing (in primer red) through the metal plate (not really visible). You can also see the green 404 starter that fits up nicely to the OM617.