C36 Amg engine into R107 SL project

[bigben]

I am looking to do a swap for my r107 (1973 450SL). The engine has been sitting for 14+ yrs and at least the cams have developed rust pits from moisture. Probably there are problems in the rest of the motor. I was able to start and run it for couple of minutes.

I have located an M104 for my car and wanted to know what was the outcome of your swap (i.e. sump pan, engine mounts, other clearance issues, etc)? I have not purchased the motor yet.

To my shame I don't have the engine fitted into the car yet, somehow spending time in the garage is less compelling when it is cold.

With retrospect I 'think' the M104 will fit without sump modification but won't know for sure until I do the job. I am planning to put the new engine in using a different method that involves removing the front sub frame which the engine mounts to and lifting the car over the engine, this should be much more comfortable than coming out through the top.

Since I will be removing the sub frame I am going to renew / rustproof all the bits around it whilst I am at it which will delay things even more........

Somewhat agree with the poster above that if you are just looking for a later engine for your 450 then don't write off the M103 as this should be an easier swap.

Ben

 

[CASELowner]

I am getting the entire 1995 car for dirt cheap with only 20K mi on it. I will have access to all the parts needed for the swap. It is a the 3.2ltr M104 and I have read about the wiring harness problems. If the wiring is intact on the donor car then maybe I can sanitize and coat them with some clear finish to keep the degrading bugs out.

The miles and price on this car is what really attracted me to the M104. M103 is definitely my other option but will have to wait for the right donor. I also intend to turbo charge these engines sometime down the line.

Bigben, I understand why you would not want to go in the garage during the cold. I too have been delaying my project for the same reason. Do you think you will have to modify the front arm of the subframe to get the sump to fit?

 

[bh13coupe]

I understand the m103 is easier to turbocharge/set up than the m104, a few guys on here have done the turbo thing and will be able to assist nearer the time

 

[CASELowner]

I had also been considering the M117 560 motor because it was also native to R107. However, with M104 I could get nearly the same power (USA spec) without mods but with weight savings. I am sure M103 weighs a bit more than M104 but don't know where it falls among M117 and M104.

 

[bigben]

Do you think you will have to modify the front arm of the subframe to get the sump to fit?

At first I was certain it was not going to fit and went as far as trying to marry up the M103 sump to the M104 engine and realised the M104 sump shape was different so extended further forward meaning my measurements were off. My current thinking is it might well fit but not 100% sure yet.

Out of interest if it does not fit I plan to modify the sump rather than the front of the frame as I think it has less potential to go wrong / is easier to replace if it does!

 

[CASELowner]

Sump gasket should give you an idea on whether it will work. As far as the bolt holes go you might be able to weld the old ones closed and drill the new ones. It's really the shape of the mating surface that might cause you come up with a different plan.

I am torn between M104 and M103. Guys here recommend against M104 but this one is so cheap and low in mileage. Any idea on M103's weight?

 

[bigben]

Sump gasket should give you an idea on whether it will work. As far as the bolt holes go you might be able to weld the old ones closed and drill the new ones. It's really the shape of the mating surface that might cause you come up with a different plan.

I am torn between M104 and M103. Guys here recommend against M104 but this one is so cheap and low in mileage. Any idea on M103's weight?

The M103 and M104 block are the same so at a guess they are of similar weight.

The sump gaskets don't help as the sump is 2cm longer on the M104, I suspect the extra length is at the back of the sump so won't effect sub frame clearance. I will know soon enough.

 

[Druk]

Does a 95 car have a four or five speed gearbox? Four is OK but if it's five you will have the same trouble I'm up against in that the 107 chassis hasn't got the speed signal input required for the five speed box.

 

[jonnyboy]

Derek, how difficult would it be to jury-rig the speed signal?

 

[bigben]

Does a 95 car have a four or five speed gearbox? Four is OK but if it's five you will have the same trouble I'm up against in that the 107 chassis hasn't got the speed signal input required for the five speed box.

My new engine has the 5-speed box and believe me rigging the speedo to work is the least of my worries, loads of places sell electrical to mechanical speedo converters and if they don' t I will make one!

What worries me more is the whole immobiliser / transponder / multiple ECUs that the earlier cars simply did not have, if I can get them working (I am an electronics engineer by trade so have some advantages) then the rest can only be easy

Ben

 

[CASELowner]

I overlooked one important parameter on M104. The compression ratio of 10:1. This is not suitable for my later plans of turbocharging. Your suggestion of M103 was better so I'll go that route.
Ben, I wish you luck and better weather for your project. Five speed gear box (5G-Tronic 722.5/722.6) requires that the rear gear ratio be exactly the same as the donor car. I think the controller computes this through a signal from ABS unit which gets the signal from the wheel sensors. R107 wheel sensors are not the same and may not work. I gathered this information from Roncallo's (guy who transplanted M120 into R107) engine swap. You may want to visit his thread. To simplify electronic issues, his final recommendation was to use after market engine management systems.

 

[Druk]

Ben. It's not the speedo that's the problem but that the 5speed needs a road speed input signal from the abs unit to work. And, as Case says, the rear axle ratio needs to be the same or the box simply wont change gear. The remedy would be to use the old 4speed non-electric box except that the engine ecu needs a gearbox ecu to talk to. Which is why the guy in the US (129 transplant) changed the later electronic injection pump for the earlier one from a w124. (which is quite happy keeping it's own company )

 

[bigben]

Ben. It's not the speedo that's the problem but that the 5speed needs a road speed input signal from the abs unit to work. And, as Case says, the rear axle ratio needs to be the same or the box simply wont change gear. The remedy would be to use the old 4speed non-electric box except that the engine ecu needs a gearbox ecu to talk to. Which is why the guy in the US (129 transplant) changed the later electronic injection pump for the earlier one from a w124. (which is quite happy keeping it's own company )

Ah ok understood. I will probably use the diff from a C36 so that should all match up (more or less).

I retained all of the ABS sensors etc from the donor car but will have to buy a new diff as I ran out of time to remove it before the scrap men came.

Quite a few people have carried out C36 to 190E transplants, I wonder what they did ?

Ben

 

[bigben]

Quite a bit more progress this weekend after my winter break and aided by my new toy which is a scissor lift capable of lifting the car to a decent working height (wish I had bought it years ago)

i) discovered that there is no chance of the C36 brake callipers fitting onto the R107, the mounting points are the same but the brake pipe connection would collide with part of the suspension. I suppose it might be possible with some clever pipe work, but currently I doubt it and there is not much room. Something to re-visit.

ii) dropped the front sub frame from the car, which was a surprisingly simple task. Having said that any advice on how to remove the final bolt on top of one of the shocks would be welcome......

iii) Had a chance to have a good look around the front underside of the car, generally rust free apart from the ARB mount on the driver's side which also contains the towing loop. Also stripped back some of the under-seal on the wheel arches and again no rust.

The next step is to marry up the C36 engine to the subframe and check the sump for clearance.

Currently I am leaning towards detailing / restoring the engine bay such that I only have to install the engine once but am not sure (the original plan was to install it, get it running then remove it for bodywork restoration purposes)

Ben

 

[jaymanek]

Good Work,

quite intrigued by which scissor lift you went for? ive been casually looking at them for my garage.

 

[bigben]

Good Work,

quite intrigued by which scissor lift you went for? ive been casually looking at them for my garage.

Wish I had got one ages ago, much more civilised working on the car from a comfortable seat with room to manoeuvre!

I went for one from a company called B&H supplies like this

CAR LIFT, MOBILE SCISSOR LIFT. on eBay (end time 26-Jan-11 01:18:40 GMT)

So far I am really happy with both the product and the service they have provided (I had a few questions post delivery and they were quick to help). It is rated with enough capacity to lift the S500 and has done but TBH I was not 100% confident and I think you should be with 2 tonnes above your head!

Photos of the 300SL on the lift

 

[bigben]

A bit more progress this evening, sadly not of the kind I had hoped.

I re-fitted the wheels to the subframe and offered the engine up, looks good right ?

Sadly it does not fit unless I use the same engine mounting points as the C36 used, which are not the same ones as the 300SL requires to have enough clearance at the front of the engine.

You can't see in the pics but the engine is what is technically known as 'on the p*ss'. Looks like I will have to remove the sump again and have the lowest section (the bit where the oil mainly sits) modified so the 'step' is about 2" further forwards. Which I thought I would have to do earlier on in the process but had hoped to have got away with.

Next steps:

-Remove sump, get sump modified.
-meanwhile have subframe sand blasted and possibly powder coated or maybe just POR15ed by me.

Ah well did nothing worth doing is ever easy!

Ben

 

[bolide]

If I were doing this I'd change to MegaSquirt right now and bypass all the wiring nightmares. Most of the kit needed (CPS, temp sensors, etc) is there already and the car has coil packs. Connectors for the coil packs with loom are £7 each from MB and you'd need three

That'd give you a stand-alone engine / injection / ignition setup with its own ECU that would run in any car given fuel and 12 Volts. You could even fit an electric water pump and electric fan but I suspect they'd be less reliable than the originals

I suspect your biggest issue will be the the gearbox. You'll need a vacuum system and a kickdown relay to control a 4-speed and that plus ECU and loom to control the 5-speed

On the 300-24 valve 5-speed the gearbox ECU takes a 12 Volt feed from the OVP, a vehicle speed signal (output rpm, maybe from the binnacle), engine speed from the EZL, load signal (from inlet manifold pressure via the EZL), accelerator pedal signal, E/S mode signal, 4-5-4 gearlever signal, kickdown switch and control valve signal. It parses all this data to give a 4-5-4 change at appropriate revs & load. The system for the later M104 will be related but different as the engine management is completely different

Your engine comes from a C36 so I believe it has a 4-speed. I'd stick with that and change diffs to get the gearing you want

I'd love to do one of these conversions in reality not theory...

Nick Froome

 

[bigben]

If I were doing this I'd change to MegaSquirt right now and bypass all the wiring nightmares. Most of the kit needed (CPS, temp sensors, etc) is there already and the car has coil packs. Connectors for the coil packs with loom are £7 each from MB and you'd need three

That'd give you a stand-alone engine / injection / ignition setup with its own ECU that would run in any car given fuel and 12 Volts. You could even fit an electric water pump and electric fan but I suspect they'd be less reliable than the originals

I suspect your biggest issue will be the the gearbox. You'll need a vacuum system and a kickdown relay to control a 4-speed and that plus ECU and loom to control the 5-speed

On the 300-24 valve 5-speed the gearbox ECU takes a 12 Volt feed from the OVP, a vehicle speed signal (output rpm, maybe from the binnacle), engine speed from the EZL, load signal (from inlet manifold pressure via the EZL), accelerator pedal signal, E/S mode signal, 4-5-4 gearlever signal, kickdown switch and control valve signal. It parses all this data to give a 4-5-4 change at appropriate revs & load. The system for the later M104 will be related but different as the engine management is completely different

Your engine comes from a C36 so I believe it has a 4-speed. I'd stick with that and change diffs to get the gearing you want

I'd love to do one of these conversions in reality not theory...

Nick Froome

It was a later C36 so has the 5 speed electronic gearbox, just to keep it easy!

I had considered a mega squirt but would rather try to get it all working with the standard bits at least at first, I think I have kept all the bits from the donor car (except the diff) to make this possible.

Sounds like the engine should work ok but going somewhere will be a different thing as the gearbox seems to be 'fussy'. I may well change my mind on megasquirt etc after a few months of messing about!

Ben

 

[nick.ged]

for the brake lines, just use banjo bolt connectors, you can have a set made up, or buy nissan pulsar ones , but they will be a bit longer and require mods to the solid brake pipe