Mercedes OM617

[TeriAnn]

I've been asked to step into this thread with my experiences with my '66 II-A, so I offer these experiences:

<BIG SNIP>

Together with a good tune-up, my fuel mileage is as high as 18-19 mpg [highway driving at 60 mph], and as low as 14 mpg [pulling a loaded trailer at slow speeds all day].

My experience tells me there's nothing inherently fragile about a Land Rover 2.25 petrol engine or transmission, especially with today's oils. My experiences with my self-maintained engine and transmission have demonstrated their strengths to me.

Jeff I don't think anyone is arguing that the Rover 2.25l petrol engine isn't built to last. I think every pro mechanic who first opens one up remarks about how seriously overbuilt the engine is. And I agree that with proper maintenance the engine will keep running long past the point where others won't even start.

My personal beef was that the engine is not powerful enough to be safe pushing a 109 Dormobile in traffic when everything around you had 2X to 3.5X the power. I personally went to a higher power engine for safety in some of the places I drive and I hate failed climbs because the engine just grinds to a stop.

The Series gearbox was considered quite robust and advanced when it was first used by Rover in 1932. The design has undergone a number of upgrades since then and the box seemed a good match for a topless 80 inch SI with its 1.6L petrol engine.

But with the SII the body got a lot heavier, especially the 109 stationwagons. The 2.25L engine was a decent power increase over the original 1.6L engine. Rover uprated the gearbox a few times. Early gearboxes tend to break lay shafts and main shafts at the circlip groove positions. Late 2A lay shafts without the circlip groove are stronger than the early ones. By the D suffix the SII box got about as robust as it was going to get. But even then it is reliable for only up to about 120 HP and 160 lbft of torque.

As you say it is plenty good for a Series 2.25l engine and even a 2.5L upgrade and at 200/300 tdi stretches it close to its reliable limit.

I agree completely that a stock 2.25L engine with stock LR gearbox all with genuine LR parts is a reasonably reliable combination that if treated properly and well maintained can last for many many miles. Uprated rear axles would really help though. If this is the performance envelope you feel comfortable with and have access to genuine parts then it is a good solution.

However, Rover has been happily discontinuing genuine parts for Series rigs and the aftermarket parts available for SII gearboxes are proving to be substandard. Too many people are rebuilding gearboxes these days and having aftermarket component failure within a year of heavy use. I think that's why so many people are looking for alternatives to a Series gearbox these last few years.

As for your 18-19 mpg [highway driving at 60 mph] figure, I'm guessing it is a little high unless you are running an 88 with spare on bonnet, no roof rack, a Weber one barrel out of the box and possibly a soft top. Oh and you are driving 100% petrol and are below 3000 feet. Add good street tyres and that is about as good as it gets. A lot of the time a Weber right out of the box is a little under jetted. Have you had a sniffer put up the pipe & got an air:fuel ratio test?

Alcohol gas blends alway decrease mileage from 100% pure petrol.

I agree the thread's starter has got some issues going on with 12 MPG IF HE IS TALKING HIGHWAY MILES ONLY. I think 12 MPG COMBINED highway and city is fairly common for most people. I think most Series rigs get between 14 and 17 MPG highway depending upon their configuration, weight, tyres and state of tune. Those claiming 20-22 MPG highway are likely figuring imperial gallons or running real lean and cruising for a bruising in the form of burnt valves or a hole in a piston.

If you are happy with the performance of a 2.25L engine, don't over stress your drive train and have a source of 100% genuine parts, I agree the stock drive train is good and reliable. Except for the 10 spline rear axles. You will never get me to say good things about them other than they make good pry bars. But 12 MPG combined mileage is pretty much ball park for a stock Series rig.

Some of us look for more and I think that is what this thread is all about.

[martindktm]

Sorry ti hi-jack the post a little bit but I sometimes think about a conversion in mine and no-one semms to have done it like I think. If I was to do it I would try to find a Toyota 22r engine and 5 speed gearbox and drop it there and forget about it. Should be pretty easy to fit..

[yorker]

Sorry ti hi-jack the post a little bit but I sometimes think about a conversion in mine and no-one semms to have done it like I think. If I was to do it I would try to find a Toyota 22r engine and 5 speed gearbox and drop it there and forget about it. Should be pretty easy to fit..

That has been done before but every time I'm aware of it was done with the transfer case too. Matt Stoffregen's: http://www.4wdandsportutility.com/fe...r/viewall.html

[yorker]

The Series gearbox was considered quite robust and advanced when it was first used by Rover in 1932. The design has undergone a number of upgrades since then and the box seemed a good match for a topless 80 inch SI with its 1.6L petrol engine. But even then it is reliable for only up to about 120 HP and 160 lbft of torque.
As you say it is plenty good for a Series 2.25l engine and even a 2.5L upgrade and at 200/300 tdi stretches it close to its reliable limit.

I'm curious where these figures come from? I've seen them passed around as fact for years but have never seen any indication that Land Rover's engineers considered them to be the case. If they did then why bother to develop the LT95 for the RRC and 101? The original incarnation of the LR 3.5l v8 is pretty anemic at 91bhp (net) at 3,500 rpm 166 lb ft at 2,000 rpm. The most powerful engine the transmissions were ever meant to cope with was the 2.6l at a paltry 83bhp (net) at 4,500 rpm 128 lb ft at 1,500 rpm. Considering the troubles Land Rover was having in the 1970's they wouldn't have designed and used a new transmission unless they really felt it was necessary.


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As for 2.25 mpg claims you can get a better idea of how they do on a whole by searching through Fuelly and the other MPG tracking sites. Neil (Moses) is one person who has well documented his mpg pretty well and incorporated some reasonable upgrades in his 88's 2.25.

http://www.fuelly.com/driver/drfisher/series-iii

Scott Osta has done a decent job of tracking his MPG with his 2.25 propelled 109 ambulance

http://www.fuelly.com/driver/osta/series-ii

Contrast them to Solemn Warning's:

http://www.fuelly.com/driver/solemnwarning/series-ii

I know for a fact that Solemn's consist of short 10-25 mile trips so I'd be inclined to consider his MPG at the worst end of the spectrum.


I'd love to see more people post and track their MPG there, it would be interesting to see the results compiled over time, the sample right now is too small to be anything more than interesting but not statistically significant.

[Alk-3]

My primary concern at this point is the gearbox. If I'm going to go through the trouble of the swap, I want to know that my gearbox is up to the task. I'm currently considering the smaller Mercedes diesel (615?) or maybe just putting in a turner block when i need it, and leave the swap till I have the time to swap in a stronger gearbox, and swap out the axles as well.
Right now I have a tuner gas flowed head in the truck, that I just replaced, and have maybe 1000 miles on, so I would really only need their 3/4 option. This would be the cheapest and easiest option, but I will have to address my fuel consumption. I could also explore possibly fitting a 2.5 cam.
I am in fact getting 12 miles per gallon. I have checked it a dozen or more times. What I normally do is fill up the tank, drive about 4 hours with my iPhone running a gps app that tells me exactly how far I've gone, then I fill up again and see how much I can fit in the tank. It's about as accurate as I can get it, and it's always 12 mpg or slightly less. This is driving at 100km/h for about 2.5 hours, and 80-90km/h for 1.5 hours. So it's not full out for the whole way, but nearly.
I think I need to get a reading on my emissions to figure out what needs doing, as I don't want to risk burning a valve or worse by running too lean.
If I could get my mileage up to the high teens, or better on the highway, I'd be happy, at least with the mileage. Power is a different story..

[Alk-3]

I'm curious where these figures come from? I've seen them passed around as fact for years but have never seen any indication that Land Rover's engineers considered them to be the case. If they did then why bother to develop the LT95 for the RRC and 101? The original incarnation of the LR 3.5l v8 is pretty anemic at 91bhp (net) at 3,500 rpm 166 lb ft at 2,000 rpm. The most powerful engine the transmissions were ever meant to cope with was the 2.6l at a paltry 83bhp (net) at 4,500 rpm 128 lb ft at 1,500 rpm. Considering the troubles Land Rover was having in the 1970's they wouldn't have designed and used a new transmission unless they really felt it was necessary.

I can't answer for Teriann, but I've always assumed those numbers where a result of trial and error putting different engines into land rovers over the years.

[CMorris]

I can speak from real world experience having already done what you're thinking about with a lot of help/advice from Jim Young. I transplanted a 240D engine into a SII 88, used a reman. SIII tranny from Rovers North and installed a Fairey OD. The truck returns low to mid twenties MPG around town. I've clocked just over 6000 miles to date.............two oil changes, diesel fuel, and one burned out glow plug.............it's a wonderful combo IMHO. The truck will not out perform a good running 2.25, but I'm pretty sure it will out last the 2.25 long term. The conversion is not without it's challenges. problem solving, aggravations, etc., however, if asked whether I would do it again the answer would be absolutely. Tons of info. at SeriesTrek and Jims thread on Expedition Portal.

[Mercedesrover]

^^^^Don't listen to this guy^^^^
He's cRaZy!!!
(but he does nice work!)

[yorker]

I think the 4cyl Mercedes like Jim has in his 88 makes a lot of sense for what you want to do. Depending which one you get they have more or less the same power as a 2.25 Diesel all the way "up to" a 2.25p. Before I embarked upon that though I'd go through the 2.25 and see if I couldn't find a way to improve it. Maybe there is something simple you are overlooking. What carb do you use?

http://www.summitracing.com/parts/SUM-G2986/

http://www.scirocco.org/tech/misc/afgauge/af.html

[Alk-3]

That 4 cylinder diesel makes sense. That would satisfy the mileage issue indeed, however, it leaves a bit to be desired on the power end. I thing I might be asking for trouble swapping in the merc om617 without also upgrading the rest of the driveline. In the end, I do want to have more power. Hmmmm.

I use a webber 34ich, and it might be running a tad on the rich side, but not by much, if any.
I have a very slight intermittent miss, based on listening to my exhaust, but I also have the upgraded stainless exhaust sold by RN which is a bit bigger and louder than stock, so it's hard to really tell if it's missing.
I have the timing dialed in pretty good, with no detonation under load, but good power.

[yorker]

You have an OD too right?

Much more power opens a Pandora's Box of either upgrades or failures. You'll always run into a "that guy" who has hooked a Chevy 350 to a Series transmission with "no trouble" but when it comes right down to it it isn't suited to much more power.

Why not contact Simon Schofield ans ask him about his 2.8l swap? EFI, decent but not excessive power and I believe he was getting good MPG.

Simon Schofield Future@execulink.com
Future Patterns and Prototypes
167 Industrial Boulevard PO Box 831 St. George, ON NOE 1NO

519-448-4605
519-448-4610 Fax

[mongoswede]

Or buy a 03/04 Dodge/mercedes sprinter van and drop the drive line in from that...inline 5 cyl 2.7 turbo diesel. at 70 mph on the highway I just got 23.6 mpg over the course of 500 miles in the van. Should be better but mileage goes down fast at 70....60 - 65 is a better range.

[Alk-3]

yes, I have a overdrive. My original thinking was that the original axles would be like a fuse, and be the first to break if I applied too much power, and in turn that would save my transmission. this is a bit flawed I think, and not really the way it works.
Simon is less than an hour from me. I may get in touch and see what he says.

[CMorris]

^^^^Don't listen to this guy^^^^
He's cRaZy!!!
(but he does nice work!)

Thanks Jim!..................I think!?!?
Hope all is well!

[rdavisinva]

Here is the history and facts regarding the OM617 conversion kit you reference...

Hi everyone. I was hoping to open up a bit of a dialogue about the Mercedes OM617. I am very seriously considering doing a swap with the Robert Davis kit. The kit apparently comes with everything needed to swap the motor into my land rover, but requires a pusher fan, and requires a swap to a thinner series...

Back in the early 1980s had a job that allowed me to travel to places like Malta and Greek governed Cyprus. I saw several Series IIA Land Rovers with Mercedes 4 cylinder diesel engines. At the time knew little about the Mercedes diesels and don’t remember exactly which engine, but they all looked similar to the OM616.

All were based on an adapter similar to what Mercedes Jim developed years later with a custom portion about 2 or 3 inches long sandwiched between the Mercedes rear aluminum casting (that is about 1.5 inches long) and the Land Rover transmission bellhousing. In all cases was told that the stock Mercedes flywheel was used.

Fast forward to 2002 when I bought our 300TD Wagon and was very impressed by the performance and outright reliability. For a few years did several one off diesel conversions with Perkins Prima, Isuzu, Diahatsu, and Rover 200 & 300 TDIs. Also decided to eventually phase out the GM gasoline engine conversions I was building at that time.

In 2007 started doing research to build a Mercedes conversion. At first was going to use a modified version of the OM616 4 cylinder complete with turbo, but the costs were not practical (to do it right) because it required a complete remanufacturing: drilling the block for the oil squirters, using the correct version of OM617 turbo diesel rods and pistons, and upgrading the IP to have the same characteristics as the OM617 turbo diesel. There was also the issue of making a custom exhaust manifold to mount the turbo like I did for the Diahatsu engines.

In 2008 started looking more closely at the OM617 and asked lots of people lots of questions including Mercedes Jim and 2 other friends who had also successfully completed OM617 conversions in their 109s using kits they bought in Germany that may have originally been for the Unimog. All these installs had several common requirements that I needed to avoid. They required a 109 6 cylinder bulkhead, a huge undertaking to swap out for someone who had a 4 cylinder bulkhead making the conversion impractical for the average person. The stock oil pans were modified requiring both steel and aluminum welding and fabrication which is totally impractical for a conversion kit. All these earlier incomplete kits typically included only an engine adapter and an oil filter relocation adapter plate leaving the rest of the parts for the conversion missing. All had an engine adapter based on the stock Mercedes manual flywheel that is on the thick side. With any conversion, the clutch has to be spaced the correct distance from the clutch release bearing. The distance needed for the pressure plate is added to the flywheel thickness to determine the total length of the engine adapter. So a thicker flywheel essentially equals an even thicker engine adapter. All of the conversions I saw also required discarding the stock oil filter housing for a filter relocation adapter that routed the oil to an externally mounted remote oil filter via hoses. The stock oil filter housing has the correct temperature controlled oil flow to and from the oil cooler, something I vowed to keep.

So continued to do a little research here and there to overcome what I determined to be the conversion issues of mounting an OM617 in a series IIA, III, 90 or 110. If these issues could not be overcome, then a complete conversion kit for the average DIY person to install over a weekend would be impractical and the research would end with a "no go".

Determined that in order to build a kit that could be easily installed the 4 major obstacles to overcome were to eliminate the need for the 6 cylinder bulkhead swap requiring the dismantling and reassembly of the entire body, build a custom oil pan from scratch that eliminated the front diff clearance issues that the original pan has in both the Series and Defender style vehicles, locate the engine so the stock oil filter housing could remain in place, and have the adapter between the engine and transmission much thinner to allow the engine to fit in a series IIA or III 109 or 88 engine bay without having to cut up the radiator support and/or use a custom radiator. In other words, build a kit that someone can install in a weekend and drop off for a custom exhaust on Monday and drive home that same Monday evening. Indeed a tough "nut to crack".

Was it s "go or no go" ???

After building several prototypes and improving each one, was finally able to overcome all of these obstacles and am making the second install in a 110 this weekend. Then will make the second install in an 88 the first weekend in September. When fitting an OM617 with my kit into an 88 and 109 that originally had a 4 cylinder, the engine falls short of the stock radiator with about 1/2" - 5/8” clearance which leaves enough room to slip a fan belt between the back side of the thinner Series III stock radiator and the nose of the OM617 water pump. This is with the stock 4 cylinder bulkhead in place and the stock Rover gearbox and transfer case in their original position.

It's a go...

Anyone who says the OM617 won’t fit between the stock Series transmission and the stock Series III radiator has clearly not seen my new conversion kit that does fit into this space. However, if you bolt the adapter I saw in Malta onto an OM617 or the adapter Mercedes Jim made (which were both excellent work years ago) then the total length of the OM617 with this much thicker adapter is too long for the 88 and 109 engine bay and won't fit in this same space where my kit does fit.

Let me summarize to be perfectly clear: using my kit, you can remove a stock 2.25 Rover 4 cylinder out of a 109 or 88 and bolt a OM617 in it's place without changing anything (except for the thinner series III radiator if you have the thicker IIA radiator) as a 1 for 1 swap. In the IIA or Series III 88 & 109 (that left the factory with a 4 cylinder engine), there is no need to use a Rover 6 cylinder bulkhead or any additional modifications. The engine bolts in just like the 4 cylinder GM engine conversions I built for over 25 years. This is the key point of this post.

The goal of a complete conversion kit is to make the engine install no more difficult than replacing the stock engine with another stock engine, in other words a bolt in 1 to 1 exchange (less the exhaust system which is different).

During each install started with the donor vehicle stock engine (88, 109, 90 or 110) in place at 5:00 pm on Friday and using only hand tools. In all cases were able to remove the engine from the Land Rover along with the exhaust system, drained the fuel tank, and completed other tasks Friday evening stopping work at 10:00 PM. On 8:00 AM Saturday started with the built up Mercedes engine with the custom oil pan in place with the custom adapter, custom flywheel with Mercedes ring gear, Land Rover 9.5" clutch, and custom motor mounts. Because the motor mounts bolt directly from the engine and mate to the stock chassis, there is no custom welding or cutting. On the 88 & 109 used the Mercedes alternator with a custom mount that placed it up where the PS pump originally was. The 90 and 110 install uses all the stock Mercedes ancillaries without any clearance issues in both RHD and LHD vehicles.

In both the 88 and 110, by 5:00 PM on Saturday the OM617 engine was in place and could be running if you used the manual shut off or jumped the glow plugs (if the controller was not hooked up). Sunday installed things like an electric cooling fan, any extra gauges (like oil pressure or boost), and vacuum shut off switch. The conversion is not difficult (about the same as the GM), but took longer because of the electric fan, vacuum shut off switch, glow plug controller (which is an easy install kit option), and other odds and ends. This kept me working Sunday from 8:00 AM to about 1:00 or 2:00 PM that in all cases satisfied the weekend install with time to spare.

Having the correct oil cooler with lines that match the stock Mercedes oil cooler housing, radiator hoses, accelerator linkage, and so on makes for an easy install. For the 90 & 110, the custom power steering hoses were bolted in place and connected to the stock Mercedes PS pump.

In this thread, you asked if fuel savings could be realized with an OM617 conversion. I have talked to owners of 80s era Mercedes sedans like the 300D that save over $4,000 a year on fuel that burn Waste Vegetable Oil (WVO) in their OM617. The drawbacks they report are mainly concerns with cleaning the fuel and the time it takes to collect it from a local restaurant. Know a guy who bought a centrifuge and collects once a week and when in his shop, runs the centrifuge and gets pretty clean oil. So far he has not had any issues, but have talked to other people who had to replace injectors and the Injection Pump (IP) from using WVO, but this was after tens of thousands of miles driving free on WVO fuel. At our local pick-n-pull OM617 engines are about $300, and IPs are $50. You can't fill up a 2.25 gas engine from a grease dumpster, but the OM617 seems to run fine on WVO.

Performance is very good and the engine is in the correct torque range to mate in harmony with the stock transmission and differentials. In the early 1990s worked on an aviation maintenance management project with the USCG in Elizabeth City and got to be friendly with the reliability engineering crew. At the time was designing a new cam for the GM 3.0 liter crossflow conversion and did not want to overstress the transmission. The engineering shop analyzed a series IIA and a series III transmission making tests on the gears and shafts. The real limit believe it or not was the main shaft, but regardless, they reported that the max torque for the main box was around 185 foot pounds. In other words to maintain reliability you should not put an engine in front of the stock series transmissions that puts out a lot more torque than 185 foot pounds. I've seen people off roading tear up a series transmission with the stock engine, so driving technique definitely comes into play. The OM617 is near the top end, but still within this acceptable range.

In our 1985 110 pickup, am installing an intercooler. The OM617 has the stock turbo clocked to take the hoses with an inlet manifold from a 1976 Mercedes W115 300D, but that's a totally different discussion. The point I am trying to make is there are some inexpensive options to get just a little more power out of the OM617 Turbo Diesel, but am just getting into this area and am no expert, so for me it is just another learning experiment.

In closing, it has been a long, expensive, time consuming journey, but the OM617 engine fits in the stock location without cutting or welding into an 88 or 109 that originally had a 4 cylinder and also fits nicely in a 90 or 110. A custom oil pan is required, but a custom oil pickup is not with the latest "production" version. We also have a separate kit with a longer adapter to mount the OM617 into a 109 that originally had a Rover 6 cylinder and have one of these conversions up and running as well.

Without the "pioneers" like Mercedes Jim and others who proved this conversion possible, I probably would have never bought our 1982 300TD wagon and would have never looked at using the marvelous OM617 that some claim will go for a million miles and is the most durable and reliable engine in the world. Thanks to all of you, especially Mercedes Jim who provided some advice back when I was doing research. He didn't always tell me what I wanted to hear, but "told it like it was".

With so many activities, have little time for bulletin board forums, but just wanted to make this post to provide some accurate information about the upcoming kits that will be available in the near future. I almost never check posts and only knew about this one when a friend sent me the URL.

RdavisinVA