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Engine conversion from Gen 1380 to Gen 2 500

Posted: Mon 14 Jan, 2019 6:34 pm
by schand
Hi all,
This is my first post to this forum, so please be gentle in case this topic has been already discussed...
I have a 1982 380sec. Recently, I picked up a complete engine from a 1988 500se (gen 2) that did only 104k.
I have been told that cars with 500 motors were private import and have no pollution control, and so I will not be able to register the car after the conversion (or face challenges in doing so)?
Please advise if this is the case... I spent more than $1k to buy this motor, and wouldn't wanna spend more if I can't run it legally. Also, is there any way around this?
P.S. I have attached a photo of my 380sec.

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Mon 14 Jan, 2019 6:48 pm
by CraigB
I'm not sure what the rules are in Victoria but certainly plenty of 500's on the road I would have thought and people seem to do all sorts of engine swaps on things. Did you realise the later 500 was ke jet and has crank angle sensor etc etc. Did you get all the associated electrics and wiring? I think you can fit the earlier injection stuff and make a bit of a hybrid but I'm not an expert. Also check your diff ratio, some 380's have quite a short diff ratio and might want to consider something taller. I think the 500 would have been something like a 2.47.

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Tue 15 Jan, 2019 9:28 am
by schand
Thanks Craig. I have also seen many 500SEs and SELs on road in Victoria, so I believe the conversion should be fine but I'll check the regulations.
My 380SEC currently runs on dedicated lpg... I have been thinking of putting it back on petrol, and while doing so, I thought it would be better to put a Gen 2 500 motor and transmission for better performane. I read somewhere that they are 1:1 fit (not sure though this is actually the case) but they differ in electronics... unfortunately, I haven't got the wirings from the donor vehicle but I think there are similar recking cars around that I can get cheaply.
Also, I not sure but I think the diff ratio of 380SECs of that era is 2.47. I am no mechanic but does that mean I have change some mechanical parts for compatibility or would I be fine but at a cost of different torque and fuel efficiency?
Wondering if anyone in this forum has done the conversion of 380 with Gen 2 500?
Best wishes,

Re: Engine conversion from Gen 1 380 to Gen 2 500

Posted: Tue 15 Jan, 2019 7:35 pm
by Dean 560 SEC
Its a very straight forward conversion as long as you have the correct wiring, EZL and ignition control module etc. The motor and box will drop straight in.

Clyde did the 380 to 500 conversion in his Gen 1 380SEC and I understand that OZBenzhead is on the process of doing it to his 380 SEC.

Do you know the engine number of the 500? This will tell you a lot about the type of M117 you bought. You need to understand what configuration motor it is (e.g Us delivered or Euro Hi-Comp) before you start buying parts like ICM's etc

Also I highly recommend getting you hands on a set of tri-y's while you going through this process

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Wed 16 Jan, 2019 8:10 am
by CraigB
I was thinking if it is gen 2 500 it may well have the tri-ys. Diff is easy to check. Look at it from rear of vehicle and at the bottom you can see two faces of the housing that are not covered by the rear 'cap'/housing. Clean it off and you can see stamped into it the ratio. Also I think something is stamped if LSD but can't remember but if LSD should have a tag that bolts go through saying "....speziale..." or something like that. My 380SEC has something like a 3.72 and it gives it quite a spritely feel, but with a 500 in front of it I think it would have it 'buzzing' along revving while cruising and particularly if it wasn't LSD it would probably break free in the rear end fairly easily if you put your foot down. All should bolt up but if changing the rear end a Gen2 rear end is not just straight bolt in. But the gen 1 common 2.24 is a straight bolt in. Threads on here about the differences.

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Wed 16 Jan, 2019 10:59 am
by schand
Thanks Dean and Craig for your replies.
The engine is from a 1988 500SE. I decoded the donor car's VIN (WDB1260362A454245)... it was a Hongkong import, built in Dec 1988 and has the engine number of 117965 22 023321. I tried to look up for the number on the engine itself but unfortunately with no luck... all I see is numbers like R117 016 43 01 stamped on the block; NOT SURE WHAT THIS MEANS but I'll try again this arvo after giving it a good clean.
I believe this motor is from the later generation of 500s series as it came with DUAL AIR DUCTS like those in 560s... most other 500s I have seen have single duct.
The engine did come with tri-ys but will need quite a bit of work as they have developed rusts after spending several years in garage... I'll look for better ones if I can.
I am not sure what diff ratio is in my 380SEC, but I'll check that this afternoon as well and will post it here. I don't think I have any intention at this stage to change the diff... my luck if 380 has LSD.
It is indeed good to know that the swap could be straight forward... my next task is to get the engine cleaned and do all necessary diagnostics including for potential damages as it was from an accident car. I'll have all posted in this forum with pictures.
By the way, is there any place I can check engine specks for W126s based on the engine number? I wanted to figure out whether that motor is 185 or 195kW as the versions were made in that era: I later one was without cat.

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Wed 16 Jan, 2019 1:08 pm
by CraigB
engine number is on the face of the LH bank of the block at rear, look directly down behind head

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Wed 16 Jan, 2019 9:11 pm
by Ivanerrol
‘88 Hong Kong cars won’t have cats.
On the original car there would have been a EZL switch which changed the value of the timing resistor ( The famous R16). This switch was there to alter the timing in the case of the particular markets fuel.

Those existing grey import W126 500’s are legal because of a moratorium up until 1988.

I don’t think you will have an issue registering the car with the 500 engine.
The diff will be required to be looked at.

Fuel economy wasn’t the first thing on people’s mind when buying these cars new. Plus these cars were cruisers not traffic light rockets.

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Wed 16 Jan, 2019 11:59 pm
by schand
Thanks heaps all for your discussion and feedback.

Finally, I managed to find the engine number on the block, and it matches the one decoded from the VIN. So I am pretty sure now that the motor is 195kw, Dec 1988 built and HK import...

However , the diff ratio of my 380SEC is standard 2.47 (non-LSD) and that the donor car had the ratio of 2.24. The acceleration, no doubt will be better, but would such a "small" difference in the ratio be noticeable at cruising speed?


Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Tue 22 Jan, 2019 9:47 pm
by CraigB
Certainly most gen 2 560 are 2.47 and the later high comp 560 were 2.65, so I would prefer your ratio over the 2.24 - That is what is in my gen 1 500 and a bit tall for my liking.

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Fri 25 Jan, 2019 12:58 am
by schand
Excellent. Thanks Craig.

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Fri 25 Jan, 2019 1:48 pm
by kimrh
The M117-965 with Tri-ys attached and being an 88 build it will the the high comp 195kw engine same as in my white coupe and also in Steve Nagy's coupe based in Melb which he was now spent a ton of cash with the full Dkubus tune kit/cams & higher stall converter.

Don't get hung up on diff ratio's until you get the engine in and running and see how it feels
My white coupe still has the standard 500 diff which is 2.24 - they did that for better cruising manners and better fuel consumption.
My 560SEL high comp runs a 2.65 diff so i can compare the "butt in the seat" difference off the line
The 195kw 500 engine loves to rev and has some serious pull since removing the factory exhaust from Tri-Y join back with 2.25" stainless pipes mandrel bent into a dual-in-dual out 2.25" Magnaflow resinator that resides under the rear floor pan for better ground clearance and a Magnaflow rear muffler with internal crossover 2.5" dual-in-dual-out being a 14" case and sounds superb!!!

Honestly that 500 pulls just as hard as the 560 and being a tall ratio it really winds out and does not run out of breath chasing the next gear -
i actually like that ratio as the coupe is still very quick off the line but more a stump pulling feel of torque as it winds out (really cool feel) versus the 560 which runs out of revs real quick and is always chasing the next gear. 1st gear starts in the 560 is useless other than revving to box off it.

Your 560 engine being an 88 came with Knock sensors and the later 16 pin EZL (8 pins per plug) and if you open the dizzi and look inside you will see no cam advance weights but instead an electronic cam angle (2 wire hall effect) sensor that talks to the EZL in addition to the crank angle sensor at the rear of the engine.
Now you don't have all the ancillary parts and engine harness etc to run this more advanced knock sensor system.

So you will have to swap in a Gen1 Dizzi or earlier Gen2 dizzi without knock sensor set-up and run the engine without knock sensors as per engines up to mid 87 before the 16pin EZL was introduced for knock sensors around Aug 87

Before that the 500's had manual trim version of timing advance via the adjustable trimming knob in the false fire wall for EZL fuel map setting setting depending on what octane fuel was in the tank - it allowed for 91octane right up to +98 octane and you could tell if if was ok by listening for any pinging (detonation) when the engine was under load. If you heard any you simply backed it off one notch on the trim knob until no pinging.

Your 500 engine is running 560 heads 10:1 comp and 560 intake plenim/intake manifold and bigger throttle body plate than a Gen1 500
It was all upgraded for more power and torque and is very sweet and desirable engine and pretty rare over here now as all were imports.
The only difference to the 560 engine is the 560 runs a stroker crank /same rods / pistons pin height set higher to compensate for longer stroke otherwise the piston crown would poke out of the block at TDC
The 500 engine is better balanced motor as in specs hence will rev harder/easier than a 560 as does not have that wider sweep of the crank putting the conrod at a wider angle and more sideways stress on the piston in its travel

The Gen1 trans has different ratio spread and most important it was the smaller diff crown wheel 185mm versus the larger gen2 diff 210mm crown wheel that determined the wide difference between Gen1 diff ratio's versus Gen2 diff ratio's which is obvious because the larger crown wheel gen2 spins faster so it needed taller ratio's to match the Gen1 if that makes sense - so don't get hung up on the diff ratio's when comparing Gen1 diff to Gen2 diff

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Sun 03 Feb, 2019 8:59 pm
by schand
Thanks kimrh. That's a detail reply and answers most of my concerns. You are right... my first priority is to get the motor running.
BUT unfortunately, I could not even turn the motor. I took all spark plugs out but no luck!
The person I bought it from - he seems very nice guy - said the motor was running just b4 he pulled it out from his "accident" car... but it was sitting in his shed for around 9 years.
I dont want to give up hope yet as the motor only did 104k and from now rare 195kw 500 gen 2 1988 model sel. The sump did get damage though after the accident, so all oil seem oozed out.
Anyway, any suggestion how I rescue it - if at all possible? It is currently connected to the gear box, and I am not sure if that is causing any interference?

Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Wed 17 Apr, 2019 9:19 pm
by schand
I am back with this project...
I separated the motor from the transmissions... and somehow "magically the engine turned" revigorating my hope - at the least - that the engine is not seized... may be putting WD40 through plug holes for last several weeks worked. I will upload all photos later.

Next step is to clean the engine, chrome plate parts that can be plated...

But my major challenge now is getting it's ECU and all electrical harness. The motor comes from the post-1988 model 500se with knock sensors etc... getting my hands on these are not as easy as I thought.

Wondering, in an worst case scenario, is there any other alternative e.g using heltech etc?

Kim, I saw some of you posts on benzworld on this... please advise?


Re: Engine conversion from Gen 1380 to Gen 2 500

Posted: Tue 14 May, 2019 7:40 pm
by schand
Finally, I have obtained the ECU and associated harness (+ ignition module) from the same car I got the engine... the engine itself is complete with all parts, and even has all electrical wrings intact! I think this may make the swap easier...
Wondering if there is anyone in this Forum (Melbourne-based) or know someone who can get this engine-swap done for me. I know it may cost me fortune but I want to have this swap done by a professional who has unconditional love for W126s :happy7: . I am in no rush, and so can wait for any convenient time... even several months from now.
Looking forward to your help.