W108 Mercedes 280SE diesel conversion project

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pryantcc
Posts: 289
Joined: Wed Jan 05, 2011 6:35 pm

Re: W108 Mercedes 280SE diesel conversion project

#81 Post by pryantcc » Sun Sep 07, 2014 8:07 pm

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:
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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.
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Here you can see the angle which has been introduced.
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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!
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pryantcc
Posts: 289
Joined: Wed Jan 05, 2011 6:35 pm

Re: W108 Mercedes 280SE diesel conversion project

#82 Post by pryantcc » Fri Nov 28, 2014 11:52 pm

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.
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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.
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I also took the bitumen coating off the passenger floors and found a few bits that need patching. Nothing structural nor particularly serious.
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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.
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cdodgyd
Posts: 10
Joined: Tue Mar 25, 2014 4:09 pm

Re: W108 Mercedes 280SE diesel conversion project

#83 Post by cdodgyd » Mon Dec 01, 2014 11:50 pm

Epic stuff. Makes my restoration/conversion look like a walk in the park!

It'll be worth it in the end though - fuel prices have dropped here but diesel is still £1.24-ish. You can buy fresh oil in 20L containers from cash & carry joints for 14 quid or 70p/L now, so the savings remain massive.

I continue to drive mine daily and will throughout the winter as always. Lately I've done some cosmetic work inside and out, I can post some fresh pics if you wish?

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JPB
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Re: W108 Mercedes 280SE diesel conversion project

#84 Post by JPB » Tue Dec 02, 2014 11:45 am

At £1.24 per litre, it would be worth your while travelling to get the cheaper Diesel. AsDa locally (12 miles away) are £1.19.7ppl this morning, yet if I go to the Torx forecourt that's only six miles away, it's a whopping £1.22.9ppl. In the modern daily, whose MPG readings actually agree with my own book for the first time in any car, this represents a massive saving over petrol even though the unleaded is down around £1.17.7ppl.
I have a costco account and their corn oil works out at £82ppl at the grade of my user account but the turps is the elephant in the room; it's actually gone up in price and with the temperature when I left this morning being a mere 30F, it brings the total to nearer the cost of forecourt fuel. This makes forecourt fuel more cost effective than cooking oil for the first time since I've been counting!
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So imagine how frustrating it is that my only Diesel-engined classic has a manual gearbox. :evil:
John, Operating knackered old sheds as daily transport since 1981. :|

cdodgyd
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Re: W108 Mercedes 280SE diesel conversion project

#85 Post by cdodgyd » Tue Dec 02, 2014 6:17 pm

Well, even at 1.20 for diesel that remains a full 50p/L more than (soya) oil from Bookers. I don't use turps, that's pricey stuff. Best to use petrol as antifreeze IMO (as indeed Mercedes recommended in the old days) but I only add it when its well below freezing and even then no more than 5%.
Around 5'C here now so still running 100% oil. The old 617 starts right up with around 10 secs glow. Pity the oldies don't get modern MPG but give me a classic any day, that's why we're here isn't it!
Agreed on savings over a petrol car though - I have a Frogeye Sprite, half the size of the Merc, which I use in the summer months. It costs far more the Merc does to run!

rich.
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Re: W108 Mercedes 280SE diesel conversion project

#86 Post by rich. » Tue Dec 02, 2014 8:34 pm

dont put too much petrol in your diesel, my old boss tried that in the 70s for his fleet of lorries.. there was a nice collection of melted pistons put on the side to remind him every time he went into the workshop... :D

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JPB
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Re: W108 Mercedes 280SE diesel conversion project

#87 Post by JPB » Tue Dec 02, 2014 10:02 pm

Bookers only give the buyer £2 back per every twenty litres of exchange oil with a fresh purchase of the same amount, Costco pay £2.80 so that puts Costco ahead, though it's reasonable to assume that this depends on how much they pay to have it cleaned out on a site by site basis. That's the rape seed oil, I'm not seeing how much they give you back for their soya stuff.
As Rich says (and in spite of the Peugeot 305's user instruction book saying that </= 20% can be used in the GLD [N/A engine] in winter conditions), I'd go with turps as it doesn't do any damage and (from UCL in Leith) is cheaper (much cheaper) than petrol within ten miles of the place.

(C77LTN is now 29 years of age, "modern"? To me it is in every significant way apart from the noise and the superior comfort of the old Poo on its skinny Michelins. There's precious little difference between how that would drive and how something split new and of similar spec does..) And if a small car with an A series uses more fuel than a large, heavy private hire vehicle then there's a petrol leak on the Sprite! Try as I might, I could never get my A40's consumption to the wrong side of 40mpg and that thing was regularly pounded from just south of the capital all the way down to Gatwick to pick up her indoors, then back within the day at a constant 70+ mph on the A1 and the various roads that linked it to the A23 before the M25 appeared. Maybe the thirsty Sprite needs a similar 800+ mile workout?
:)
John, Operating knackered old sheds as daily transport since 1981. :|

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TerryG
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Location: East Midlands

Re: W108 Mercedes 280SE diesel conversion project

#88 Post by TerryG » Tue Dec 02, 2014 11:21 pm

wow, I put diesel in my modern at £1.34 (if I hunt about I can find it for £1.27 but the diesel to get there means I am worse off). at 50mpg I can live with it.
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.

tractorman
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Location: Wigton, Cumbria

Re: W108 Mercedes 280SE diesel conversion project

#89 Post by tractorman » Wed Dec 03, 2014 9:57 am

I went to the expensive filling station yesterday (in the nearby town rather than the "big" city) and it was 134.9 for BP Ultimate diesel. I only bought £20's worth because I know it will be a lot cheaper in Carlisle - even though I buy Shell and not supermarket stuff!

The Golf says it averages 56.8 at the moment, but the spreadsheet says it's nearer 53MPG. The first Golf (1.6D) averaged 55MPG, so I don't think that the "Bluemotion Technology" is anywhere near as good as VW pretend and perhaps proves the lie about modern diesels being much more fuel-efficient! To be fair though; I suspect that an amount of diesel is used to clean the DPF on my relatively short journeys. If I did loads of M-way miles, it would do a lot better!

Our 1.3 Marina did about 33MPG (less than the Maxis!), the first Metro did 54MPG (4* fuel) and my Wolseley Hornet rarely got over 35MPG - driven on country roads by a young idiot!

rich.
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Re: W108 Mercedes 280SE diesel conversion project

#90 Post by rich. » Wed Dec 03, 2014 10:15 am

i used super carlos fandango diesel in several motors.. less mpg than the supermarket stuff..as for young idiots, when i had my celica gt4 i could only get 17mpg where wifey would get 35mpg :D we got rid of that before we lost our licences :lol:

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