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1971 Mercedes W108 280SE 3.5 V8 conversion to OM606 diesel.

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Comments

  • Registered Users Posts: 185 ✭✭pryantcc


    mannurse wrote: »
    You beat me to that car. Seen it advertised on DD in Tallaght? Although it's great to see these cars coming up frequently at affordable money. The om606 is a fantastic engine. Well done on making it work with a bypass on the ecu. Any issues with the other systems that are integrated to the ecu? Have you thought about the sensor on the bellhousing picking up a signal from the flexplate needed for the ecu? If you go manual you will need to weld some tabs on the flywheel to give this tach signal.
    Did you consider using a mechanically controlled IP from an om603? That's the route I took with my w126 with 2.24 diff ratio, the car is still quick. This pump can be turned up by any diy mechanic. My w116 has an om603 in it but am swapping in an om606 using the om603 IP. Not going to turn it up though as the rear diff is 3.69 and is quick enough.

    good luck with project.

    Yeah, the 300 was on Adverts for a very long time too. Same one you saw on DD. No problems so far running with the doctored ECU, but I haven't had it out on the road, so I don't know if I have full boost, etc.
    Yes, plan is to weld tabs onto the flywheel for the sensor.
    Thought briefly about a mechanical pump, but I wanted to keep costs down as well as power and economy up. Its not so easy to find a mechanical pump for a turbocharged engine either.


  • Registered Users Posts: 185 ✭✭pryantcc


    Another big step along the way. The donor engine liberated from its former home. The auto 'box is going to a new home elsewhere and I've ordered what I hope will be all that is needed to add a flywheel and cluch. Time will tell!

    P1010220_zpsc4082d89.jpg


  • Registered Users Posts: 44 mannurse


    Good work! Very interested to see how this turns out.
    Do you know if something similar could be done to the common rail engines? I have a c220 cdi with manual trans and it returns 60mpg and would love to use it for my old w123.
    You are right about the mech IPs with an alda are hard to find, this is a good solution.
    Are you going with a dualmass flywheel? I think the manual transmissions from the early 90s all used DM so the gearboxs have short input shafts as the spigot bearing is in the flywheel.


  • Registered Users Posts: 185 ✭✭pryantcc


    mannurse wrote: »
    Good work! Very interested to see how this turns out.
    Do you know if something similar could be done to the common rail engines? I have a c220 cdi with manual trans and it returns 60mpg and would love to use it for my old w123.
    You are right about the mech IPs with an alda are hard to find, this is a good solution.
    Are you going with a dualmass flywheel? I think the manual transmissions from the early 90s all used DM so the gearboxs have short input shafts as the spigot bearing is in the flywheel.

    I've no idea about the commonrail stuff, I'm afraid. The guy did say that my ECU was pretty basic compared to some of the modern stuff coming out.
    I'm going to use a single mass flywheel. I've ordered what is a conversion kit for a dual-mass sprinter van. So, hopefully, it takes into account the shorter gearbox shaft!! I just got a text saying its sitting in Parcel Motel in Finglas because it's "Oversize". Might try to spin up there tonight to pick it up! If it all works, I'll post up photos and the part numbers, etc so others can copy.
    Thanks for your interest in my project, it's great to get a bit of encouragement, especially when I get to wondering if I'm nuts to be bothering with it at all!


  • Registered Users Posts: 44 mannurse


    I love these sort of projects but particularly yours as you are doing something few have tried.
    The w108 is a great car and coupled with an om606 will be a great combination, refined but with reliability and economy.
    I have done many diesel conversions to Jags, Range Rovers, and Mercs. Some people get so worked up when you mention diesel conversion but it's something that makes sense to me.
    If this works out, you could get more of the ecu's made and sell them. If your friend could make one that allows the 5 speed auto to work with the engine that would be really good.
    Keep up the good work.


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  • Registered Users Posts: 185 ✭✭pryantcc


    I bought a bunch of brownie points with an iPad last week. I've been cashing them in hand over fist over the long weekend, and made some more good progress!

    The old 280SE was very reluctant to give up its 3.5L V8. It looks like the designers intended for the engine & 'box to come out through the bottom of the car. Well, I don't have the head room nor the equipent to get the car that high up, so I had to pull the gearbox out from under the car and then lift the engine straight up. It was a real pain getting it all out as every electrical connector was corroded solid, the bolts holding the 'box to the engine were all but inaccessible, the exhaust joints had all rusted solid and I couldn't upen the connections to the oil cooler and didn't want to cut them.

    Anyway, it's out now!
    re_P1010225_zpsbb6c063b.jpg

    I haven't made a detailed study yet, but some stuff I've found out over the weekend:
    The 280SE engine bay is about 3cm narrower than the E300 donor car. This shouldn't be a big problem.
    The manual gearbox I intend to use is about 11cm shorter than the auto I'm removing. no problem in terms of mounting, but I'll need to extend the prop shaft to meet it.
    The rad from the donor is way too big. I'll wait to see what space is like with the new engine fitted before doing naything drastic, but I might have to go buy an aftermarket one.
    It looks like the steering box in the 280SE is enormous and might get in the way of the exhaust, but again, I'll see what its like with the engine fitted. I might even explore the possibility of insalling the rack out of the E300 if it works out anyway handy as the old steering box is incontinent and making a mess of my garage floor.


  • Registered Users Posts: 4,938 ✭✭✭Bigus


    Ooops , the first few different types of turbo diesel Mercs weren't available in RHD for years 300 Sd etc, I hope the RHD steering box isn't going to be a show stopper.


  • Registered Users Posts: 35,339 ✭✭✭✭BorneTobyWilde


    I've seen a mercedes 300sd turbo diesel . It was 1983 original Irish car.


  • Registered Users Posts: 4,938 ✭✭✭Bigus


    I've seen a mercedes 300sd turbo diesel . It was 1983 original Irish car.

    In RHD ? First officially irish supplied diesel s-class was 1999 model W220.


  • Registered Users Posts: 185 ✭✭pryantcc


    This is going to be a long post, I hope I've explained what's going on well enough for others to replicate it if they want to!

    I'm not sure what you call this plate, but this is the original plate which had the ring gear attached to it and sat behind the torque convertor. You might or might not be able to see there are 6 tabs protruding from it which whizz past a sensor which I guess is for an engine speed feed to the ECU rather than a crank position.
    re_P1010229_zps3f169a12.jpg

    The ring with the tabs on it looks pretty crude, but it was obviously machined after being welded on to make it perfectly circular, at least on the outside!
    re_P1010230_zpse5c8f855.jpg

    Anyhow, that bit is getting dumped as I'm changing to a manual gearbox. So, I bought one of this on a wing and a prayer. It was listed as a dual mass flywheel conversion kit for a Merc Sprinter van, 2.2CDI and others from 2002 to 2006:
    re_P1010227_zps4315c5b7.jpg
    re_P1010228_zpsbb9e8148.jpg

    It contained all of these bits:
    re_P1010237_zpsafb8c6dd.jpg

    The first problem I encountered was that there is a protruding flange on the end of the crank shaft, and a corresponding recess in the flywheel. The flange was 11.2mm and the recess only 10mm. This meant that the flywheel could not be tightened right up against the end of the crank, so the crank shaft flange was duly ground back to be shorter than the recess in the back of the flywheel.
    re_P1010235_zps1236de65.jpg

    Problem number 2 is that the new flywheel is completely surrounded with ribs which, I can only suppose are used to generate a signal for the Merc Sprinter it was intended to be used in.
    re_P1010238_zps65dff908.jpg
    These ribs also slightly contact the sensor. Plan "A" was to machine away the ribs I don't need in order to leave 6 remaining, simulating what was in place before, I could then put a spacer behind the sensor so that it didnt stick out so far and wasn't hit by the remaining ribs. The main issues with plan "A" were that the ribs weren't in the same place on the flywheel as the tabs on the original item (I'm not absolutely sure that there isn't some kind of timing function along with RPM!), and that I would then need to have the flywheel balanced.

    I have a great engineering friend who came up with a far superior plan "B": We would drill the 6 'valleys' which correspond to the tabs we had removed, tap them and screw in bolts which would protrude above the existing ribs. We'd have to move the sensor even further out, but that's no big deal, and we wouldn't be disturbing the balance of the flywheel. So, to the implementation of plan "B".

    We marked the valleys which were to be drilled and tapped, then mounted the flywheel on the engine. We turned down a big bolt so that it matched the shaft size of the sensor and would fit snugly in the sensors mounting hole. We then drilled a hole down the centre of the bolt and poked the bolt into the sensor hole. Now, we had a guide which we could use to make sure the holes we drilled were directly beneath where the sensor would be.

    Here's the sensor fitment:
    re_P1010236_zpsdf1caf2a.jpg

    and the bolt we guntered into a tool:
    re_P1010239_zps4f1f3198.jpg

    and some drilling underway:
    re_P1010234_zpse83ba8da.jpg

    Here's a bolt inserted in the hole. I plan to get longer bolts, loctite them home and then remove the heads so that the part left sticking out proud of the ribs is closer to the 5.5mm of the tabs which were originally present.
    re_P1010240_zpsd5256111.jpg

    Aside from these alterations, Everything else seems to work out in terms of the position of the bearing which accepts the end of the spigot shaft, the position of the clutch friction plate in relation to the splined part of the spigot shaft, and the position of the pressure plate in relation to the release bearing/concentric slave culinder which is mounted in the gearbox. Happy days!


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  • Registered Users Posts: 185 ✭✭pryantcc


    Well, plan B turned out to be a bit of a disaster! I attached the modified flywheel to the engine, and after setting the height of the RPM sensor so that my newly attached studs didn't hit it, we hooked up fuel and sealed up the oil & water pipes after a emptying a can of water in and seeing it flow across the floor! My self and a friend hoisted the engine up on the engine crane, hooked up a battery and hit ths starter. There was the usual click of the starter followed very closely by a thump, and the engine was locked solid!

    It turns out that it isn't just the gear on the end of the starter which pos out to engage with the ring gear, most of the end of the starter comes with it!

    re_P1010241_zpsb139c309.jpg

    So, while the starter was engaged, the studs would whack straight into it and the flywheel do no more than 1/6 of a rotation.

    Plan A was re-hashed to become plan C and required some more extreme flywheel modification. The studs which we had inserted were removed with great difficulty. The Loctite we used had "Extra Strong" or something along those lines written on the bottle. It was amazing, the studs were locked solid after only an hour ror two! So much so that 2 of them broke off when trying to get them out!
    My friend set the flywheel up in his lathe and cut down all of the ribs from around the outer edge, then fitted new studs in the old holes and turned them down to the appropriate size.

    Here's how it was before:
    re_P1010238_zps65dff908.jpg

    And after:
    re_P1010243_zps41273024.jpg

    And a closeup:
    re_P1010244_zps7601b839.jpg


    Now the flywheel is re-attached, the RPM sensor located appropriately and the engine runs suspended from the engine crane! It's a bit cold, and smoky as a reslt, but works fine.
    I don't know how to embed a video, but you can see the startup on youtube here.

    To say that I'm a happy camper would be an understatement! So, now on with the rest of the work: making engine mounting brackets, making clutch pedal assembly, adapting drive shaft, etc...


  • Closed Accounts Posts: 9,607 ✭✭✭toastedpickles


    The engine sounds fierce

    I approve!


  • Registered Users Posts: 185 ✭✭pryantcc


    The engine fits (kinda). Wohoo!
    Last night we dropped the engine in and attached the gearbox to it. The good news is that there's room for everything (just about). The tightest part is fitting the gearbox into the transmission tunnel. The manual 'box is higher towards the prop shaft compared to the auto 'box which came out of the car. That means that the shift mechanism which attaches at the top, rear is going to be tight. It needs modification anyway though, for length, so if required, we can make things more streamlined.

    The steering box which I thought might be a big problem and get in the way of the turbo exit and exhaust isnt too bad at all.

    Next thing to do is to position the engine as precisely as possible and figure out how to mount it so that it doesn't fall out!
    I'll try to get some photos up over the weekend.


  • Registered Users Posts: 185 ✭✭pryantcc


    Well, here it is, the "new" engine in its new home. It's only sat there, but it fits in well. The engine bay looks a bit empty but will soon fill up with a battery, air box, computer box and screen washer bottle. the blue shopping bag contains the wiring harness for now!!

    re_P1010248_zps93dd75c7.jpg
    re_P1010251_zpsd99213ea.jpg
    re_P1010249_zps5bbb1afb.jpg

    This intercooler pipe had to be sacrificed as it was sitting on the anti-roll bar, I'll just re-route it, or might even get away with squashing it a bit:
    re_P1010247_zps903beab3.jpg
    re_P1010250_zps86e46e23.jpg

    Lots of clearance between subframe and sump:
    re_P1010260_zps1f0aa30f.jpg

    And the exhaust clears the steering box:
    re_P1010252_zpsd03285f4.jpg
    re_P1010253_zps6e2d6e10.jpg

    It's difficult to get a decent photo of it, but here's the attachment for the shifting mechanism on top of the gearbox. It's pretty tight to the top of the transmission tunnel. That long self-tapper is someone else's legacy!
    re_P1010256_zps1775fcfc.jpg

    This photo shows the original V8 engine mount and the new, improved wooden version.
    re_P1010261_zps797cbc1d.jpg


  • Registered Users Posts: 4,938 ✭✭✭Bigus


    Very nice so far, I wonder is there another alloy engine bracket from another model that would allow you to use the original engine mounts ?
    German auto parts in walkinstown behind Brennan's bakery have a load of merc engines with brackets on the shelf,pre export .

    Some sort of aluminium heat shield / heat dissipator might be in order to take heat away from the steering box.

    That'll be one quick economical car when it's finished. They handle like a sports cars too , compared to later models and some more modern yokes.

    Well done


  • Registered Users Posts: 185 ✭✭pryantcc


    Bigus wrote: »
    Very nice so far, I wonder is there another alloy engine bracket from another model that would allow you to use the original engine mounts ?
    German auto parts in walkinstown behind Brennan's bakery have a load of merc engines with brackets on the shelf,pre export .

    Some sort of aluminium heat shield / heat dissipator might be in order to take heat away from the steering box.

    That'll be one quick economical car when it's finished. They handle like a sports cars too , compared to later models and some more modern yokes.

    Well done
    Thanks for your interest Bigus!
    Thought about swapping brackets, but the existing ones line up so well with the subframe that I'll either move the existing mounts in to meet them or find some off something else and stick them in.

    I kept a big lump of heat shielding off the donor car which I'll use to protect the steering box and engine mount.

    Hopefully it'll go well, I'm particularly looking forward to the 6 speed manual box.


  • Registered Users Posts: 2,280 ✭✭✭commited


    Great project and great progress! While I'm not a massive diesel fan, the OM602/603/605/606 engines are an example of some amazing engineering and if anything goes wrong, cheap enough to throw in a replacement! I know a chap that does a fair bit of work on these engines and he's not a fan of the OM605/606 as the heads can give trouble.


  • Registered Users Posts: 185 ✭✭pryantcc


    commited wrote: »
    Great project and great progress! I know a chap that does a fair bit of work on these engines and he's not a fan of the OM605/606 as the heads can give trouble.

    Thanks commited, that's the first time I heard that. Have you seen there are guys running 2 and 3 turbos with getting 400 & 500HP from these without changing the internals!?
    Do you know what kind of head problems there are and anything I can do in terms of prevention?


  • Registered Users Posts: 2,280 ✭✭✭commited


    I had to go and find it, but this came from a chap who has a standard OM603 turbo on the continent:
    605/606 - I just don't like them. They need revs to work, they have a nasty plastic fuel system and we had countless heads that had to be removed and sent away for a glow plug change at the machine shop. They make big power with a few mods, no doubt. But if power kicks in at 5000RPM it just doesn't do it for me. I want a cruiser, not a race car. All reasons why I opted for the 2 valve engine(s).

    Just a note for anyone trying to source an engine to do the same/similar job - the C250TD is another option with manual available as standard, or an OM662 from a Musso - it's basically a OM602 with a larger capacity and turbo and a few other small mods - the only OM602/603 that came here in turbo form. They're both 5 cylinder engines, so a bit shorter which helps when trying to squeeze in engine bays.


  • Registered Users Posts: 185 ✭✭pryantcc


    Ah, I have heard about guys snapping glow plugs off in the head alright, I thought that you were talking about head gasket/valve gear troubles.

    I'm not looking for big power, I'll be using the engine in standard form.


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  • Registered Users Posts: 185 ✭✭pryantcc


    Drive shaft sorted!
    The original shaft is used up to the carrier bearing, and it turned out that the splines on the shaft which came with the manual gearbox match it, so my very good friend just shortened the front section of the shaft which belongs to the gearbox. You can see how it was before and how it is now in the photos below.

    re_P1010262_zps72732a43.jpg

    re_P1010263_zpscc299f5b.jpg


  • Closed Accounts Posts: 634 ✭✭✭cabb8ge


    Wonderful :)
    Lucky Mercedes to have survived to today without having Nissan diesel thrown in:pac:


  • Registered Users Posts: 1 ho55


    Hi Pryan, very nice work and an interesting thread. I would be very interested in your wiring information even if preliminary as i am doing something similar with a 606.962.
    On comment on your engine mounts - Diesel ones are normally thicker and more absorbing to take the extra vibration of the motor. You may find if you use the old v8 ones too much gets through. But using the diesel ones means raising the motor or dropping the mount point...


  • Registered Users Posts: 185 ✭✭pryantcc


    A long time since the last update so a long one to catch up! I spent a long time getting the auld Hilux through its test, doing some house alterations, parenting and that kind of thing! A few bits and pieces have still been done on the car. I've made up some brackets to change the old lever/rod operated throttle to a cable one for the throttle position sensor.
    This is the new bracket to mount the sensor in the engine bay.

    re_P1010314_zps50956a6e.jpg



    This bracket is fot the other end to hold the outer casing of the cable. Some rustiness in the bacground which will need to be dealt with!

    re_P1010310_zps764a2ec2.jpg

    The clutch pedal and master cylinder are in. They are from the gearbox donor clk. The fluid line to the slave cylinder is routed on the inside, but I still have to sort it out on the outside. It connects with a length of flexi hose coming from the gearbox housing.

    re_P1010316_zps2335b9f6.jpg



    In other news, I've done some work to get the engine into its final position. My resourceful and very talented engineering friend made a mounting bracket for the gearbox. The OM606 engine is rotated to one side so that is isn't so tall in an engine bay. Although the bell housing on my gearbox fits the engine crank case, the engine the gearbox was attached to mustn't have had the rotation because my gearbox now sits at an angle as you can see in this photo. The steering componenets are horizontal, the bottom of the gearbox is not!

    re_P1010322_zps8c6a6821.jpg



    The gearbox bellhousing could be cut and rotated to straighten out the gearbox, but I'm going to just leave it as it is. It doesn't look like it will present any mechanical issues with the build. I'll be crossing my fingers a bit regarding internal lubrication....

    Here you can see the new bracket before painting and in its final position in all its glory!

    re_P1010278_zps31f7ff98.jpg
    re_P1010320_zps99db553b.jpg




    Once the rear of the gearbox was fixed in position, the engine was nudged around the place in order to get the drive shaft to line up correctly in the centre of the carrier bearing:

    photo2_zps43ffeae6.jpg



    Now that that's done, it was a case of trying to make sure the engine ends up in the same spot once the new mounts are fitted. So, there are two dots on the sump which line up with two ends of a piece of TIG wire. Once the new mounts are made, the engine should settle back into the same spot. That's the plan anyhow!

    re_P1010311_zps8663a569.jpg



    That's it, the Engine mounts shipped last Thursday, so once they arrive, it'll be a matter of figuring out how much they will compress under the weight of the engine, and making a mounting plates to suit.


  • Registered Users Posts: 185 ✭✭pryantcc


    My 6 speed gearbox is from a 2004 CLK. The gear shifter is attached to it by a long aluminium U-shaped bracket which attaches to the rear/top of the gearbox and to the shifter mechanism. It's relatively straight-forward to re-use this whole setup except that I'm a little tight for space, and, more importantly, my gearbox is rotated in relation to the horizontal plane the gear stick should work on. So, if kept standard, the gear lever would be pointing out the driver window instead of straight up. Hopefully the photos will help explain.

    The plan ended up with chopping the mounting point off the bracket and welding it back on at an angle. The effect being that the whole brakcet and gear shifter unit is rotated back into the horizontal plane. Since the top of the gearbox is leaning towards the driver's side of the car, but the shifter will be mounted in the middle of the transmission tunnel, it will have to operate at a slight angle rather than straight front to back, but I reckon I'll get used to that pretty quickly. So, photos:

    Here's the whole assembly:
    re_P1010323_zps19d03963.jpg


    And this is how it conects to the gearbox. There's a rubber bush which goes in the bracket, and a pin runs through it to secure it all to the gearbox.
    re_P1010329_zpsad3f7d41.jpg


    Here you can see the angle which has been introduced.
    re_P1010324_zpsbd9c45e2.jpg


    A little angle grinder action been going on to make a spot for the gear lever. It'll get bigger before it gets smaller, it's too far forward by a couple of inches!
    re_P1010330_zpsbc9afff9.jpg


  • Registered Users Posts: 78 ✭✭Meso Harney


    Hope life hasn't got in the way of the project


  • Registered Users Posts: 185 ✭✭pryantcc


    Hope life hasn't got in the way of the project
    Only partially Meso! Things have slowed down a little, but life has got in the way of updating Boards! Work is still well underway. i'll get my finger out and upload a bunch of photos since the camera card is now full!


  • Registered Users Posts: 78 ✭✭Meso Harney


    Looking forward to it, it's a project I've been interested in from the start, hope things are going well for you


  • Registered Users Posts: 185 ✭✭pryantcc


    It's been a long time since I did a proper update. Progress has been slow but there has been progress. I've been doing a lot of wiring and its almost complete now. I built a circuit to replicate some of the essential stuff. It's basically 2 relays, 1 for ECU power and 1 for switching the starter solenoid, and a few fuses for power running to various sensors, etc. I have also mounted the ECU under the dash and run the wiring through the firewall to connect to it. It's not beautiful, but works well and isn't visible without some contortionism to get feet up on the seat and head down into the passenger footwell.
    re_P1010351_zps9ea1bf9b.jpg

    I have also started to strip the interior and I'm glad I did. I found a big hole in the inner sill which was fibreglassed over. Repair should be easy enough given the simple shapes. The outer sills are new.
    re_P1010356_zpse8453143.jpg


    I also took the bitumen coating off the passenger floors and found a few bits that need patching. Nothing structural nor particularly serious.
    re_P1010355_zps4f41e90b.jpg
    re_P1010358_zpsb565adac.jpg
    re_P1010362_zpsbc621d37.jpg



    The donor car went to the big car graveyard in the sky today. The first and only time this project will ever give me money :) I got a puncture in the pick-up (screw through the tire) for my troubles.
    re_P1010373_zps809a6d7d.jpg


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  • Registered Users Posts: 78 ✭✭Meso Harney


    The crazy thing about that last photo - you live about 300 yards away from me. Really looking forward to seeing the finished product driving around the place


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