# YES it is possible to fit a Turbo into an old Hymer, but do I recommend it? NO



## Ian Wood

I own and live in a Mercedes Hymer S660 in the South West of England. I really love the van & the deep quality engineering that is behind it. I bought it with the intension of not travelling more than a county (ish)  in each direction from my base, the forecourt of a warehouse. Recently though I have had the idea of touring to France, but the thought of doing this with the normally aspirated engine was not that appealing. If I really logically think about the van it is not that slow on the flat, it’s just the reality of hitting a hill & you tumble down the gears. If I was a little bit patient this would be fine, but I’m used to having a turbo’d transit & I wouldn’t want to go back to my old transit without turbo. You so get used to that power! So why not buy a newer MH? I looked at newer Hymers, (I’m sold on them a bit like Apple Mac’s v Windows I like quality & the benefits that design & build quality bring, I’m not interested in other makes of older van) and considered spending an additional £14k (£27k rather than £13k) on a turbo’d modern Fiat base vehicle, tempting but some how I’ve invested so much time in this van making it suit me and I actually love it in a strange way! So I decided to really research the possibility (or not) of fitting a more powerful engine and higher gearing to match the extra power.
So I’m going to share my experience and journey with you, so are you sitting comfortably? I set my self a budget, excluding my time, of £3k surely that should do it! Also I had a free month coming up between projects/events in my life, September 2014, lets do it, why not, it’s going to be tough & there will be lots & lots of hurdles to cross, I was going into this with my eyes open. Here are some facts:
The engine I have is the 5 cylinder 2.9L (OM602). Base vehicle is a Mercedes 410D, 1989.
So a lot of time was spend on research, here are my results:
The next generation of this engine (phase 1 Sprinters) had a turbo option (129bhp) but it had a complex electrical control system and injection pump that makes it almost impossible to retro fit into a Hymer.
The South Korean four wheel drive manufacturer Ssangyong had a deal with Mercedes where they assembled engines from Mercedes parts. Their version of the OM602 is known as the OM662. The interesting thing is they made their own turbo version of this (120bhp) engine with a mechanical injection pump. Also the turbo on this engine is self controlling/regulating which also saves a lot of work with sensors etc.
So great it looks like there is an option and also there are a lot of these engines available. I bought one on ebay for £700 with 83k miles. I wanted to find out if one would fit and the only way to do that was to have it on the floor to measure off. Well what a disappointment there is no room for the turbo because of the bulkhead & engine cover. Maybe these could be cut to make room. I was not rushing to this conclusion, I did not want to risk more noise in the cab, it’s loud enough as it is. So I looked for somewhere to remount it and decided on the space that was available lower down & just in front of the bell housing, it was just possible to squeeze it all in there.
The engines have the same mountings points and same main features like exhaust & inlet mountings on the engine, but lots of detailing is different.

The things used from old Hymer engine:
Inlet Manifold (with 5 small holes welded up) and attached fuel lines and accelerator linkage).
Oil Filter Housing.
Fuel Filter Housing.
Sump.
Steering pump (so as not to have to disconnect & then bleed it).
The Old Oil Dip Stick Assembly (with a new hole drilled into the crankcase for it).
The Internal Oil Pump that sits in the sump.
Some of the old air intake pipe work was very handy.
The Oil Filler.


The things used from the Ssangyong engine:
The Injector Pump.
The Vacuum Pump.
Exhaust Manifold.
The Intercooler and pipe work.


Things bought new:
Clutch kit.
New Pinion & Crown wheel (different ratio wanted +25%) from Mercedes.
Ssangyong exhaust this was cut to fit the Hymer. Bought because I wanted to keep the same backpressure, ie it is a larger diameter than the Hymers to allow more exhaust gas to flow.
Ssangyong workshop manual.
Mercedes 410D workshop manual (Peter Russex).
Lots of hoses & aluminium bends from Viper Hoses.


Things made / fabricated:
An extension to fit between the exhaust manifold & the new position of the Turbo.
A new mounting for the steering pump.
Reworking of the 4 wheel drive exhaust to fit the motorhome.
A mounting bracket for the Turbo.
The EGR cut off & sealed off.
A heat shield to protect wiring from the new Turbo. 

Things needed:
Large space with room to work on two engines alongside each other on pallets.
Really good light.
Relaxed time frame, time to work through problems without pressure.
A skilled friendly fabricator.
A skilled friendly mechanic.
A small fork lift. The space in the engine bay is very tight & the arms of the fork lift just fitted in a treat. Not sure how you’re supposed to get the engine out without one!
Comprehensive tool kit.


Things to Note:
The fibre glass bodywork cross member across the front of the Hymer is not removable (well without major work).
The Turbo has to be mounted with the core so adjusted that the oil feed in is at the top and the oil feed out is at the bottom. 
The bottom of the Turbo must be above the level of the oil in the sump so it can gravity feed back into the sump. I did not know this and by sheer luck it was mounted  2cm higher, phew that was a close one.
I changed the whole engines over because apparently the heads are different internally to allow for the increased pressure of the gasses. I don’t know if this is true but I didn’t want to risk it.
Because of the different shapes of the chassis cross members the sumps are totally different. The Hymer is deep at the front & the Ssanyong deep at the back. So you have to change over the sumps and the matching oil pumps, this was relatively simple to do.

So it all went well. The turbo is tucked away by the gearbox and works well, I’ve just done some comparisons of a hill climb with the old engine (66 k/hr) & the new engine (78 k/hr). That was the kind of improvement I was looking for so I’m pleased with that. I haven’t checked the new fuel economy yet. The differential ratio gets changed next weekend. Including this work the total cost has been around £4k. Would I recommend it, ‘NO’ unless you love solving oily problems, which if that is the case then you will be like a ‘pig in shit’! 
Please see attachments for photos.
Good Luck!


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## Tezza33

Ian Wood said:


> *Recently though I have had the idea of touring to France, but the thought of doing this with the normally aspirated engine was not that appealing.* If I really logically think about the van it is not that slow on the flat, it’s just the reality of hitting a hill & you tumble down the gears. If I was a little bit patient this would be fine, but I’m used to having a turbo’d transit & I wouldn’t want to go back to my old transit without turbo.


Love the post but funnily enough the place you want to tour can be done without the extra power (I would still want it though lol) France is one of those Countries that you arrive in and if you only did 25 miles per day because you found somewhere else for the night then you would be happy, the same can be said for Germany because every corner you go around has something new so you don't need to fly around, the work you have done though is fantastic and going to give a few members ideas, if I had the same engine I would be encouraged to do the same so thank you


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## iampatman

I    Am    Speechless

Hymer owners eh?

All it needs now is an oven (just kidding)

Admire your skills & knowledge. 

Pat


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## Deadsfo

Being the owner of a MERC 508 with the OM364 3.7LTR Engine I love the engineering solid, bullet proof, but noisy and can gasp a bit going up hills ,would love to have the ability to tackle a job like that and turbo my 508 .
  Best of luck with your changes.


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## oldish hippy

Brillant well if you are in deepest dark south west wonder what it would go like up porlock that would be asite to see lol well done


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## Martin P

Proper bit of work , great project well thought through and executed. Top marks


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## Boots

I like that, well done 'but' as you say Do it again? NO!


Boots


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## stonedaddy

*Impressed.*

I am well impressed with your skills and patience. Did you do all this work outside which looks the case. I think we was blessed with a good summer this year which must have helped no end. Great stuff well done.
.... Tom ....


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## antiqueman

*good thread*

thank you for the time taken informing us all, I could not be assed and would not have the skill but can spend 6 years building a steam engine, I admire what you have done. Am I allowed to call you fanatical crazy clever person:rolleyes2::king:


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## K9d

An interesting project, lots of effort but the rewards will last and the efforts will fade into memory.

I thought I had done a lot by fitting cruise control to my 1988 Hymer, best thing I ever did to it.
Fortunately mine has had a turbo retrofitted by a previous owner, I can't compare before and after but its slow enough with a turbo must have been terrible before.


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## phillybarbour

Great job van good for another 25 years now.


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## Deleted member 3802

Total respect !! Well done sir.


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## mariesnowgoose

Total respect for a clever grease monkey!


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## Tbear

It never ceases to amaze me how clever some people can be. I would never have dream't of trying to tackle a job like that. Well done that man!

Richard


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## trevskoda

a man after my own hart,if you can think of it then it can be done,good on you for getting the head down and compleating ,top marks.


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## whitevanwoman

Good post, nice thread. Interesting read. Even to someone who has no idea of how engines work or what part is what. 

The big question, could you recoup the costs in added value to the van? Or was it really just a labour of love?


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## Debs

Brilliant job, especially in the light of you saying you have the inside just how you want it. Would have been a shame to get it just so, then replace it with another committee designed vehicle. Your Hymer also has that other magic ingredient....character. :goodluck:


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## 1978lovebus

That is pretty remarkable, I too have been contenplating on an engine conversion for the very same reason, I was looking at removing my old M115 2.3ltr petrol engine along with the box and diff, and replacing with the 2.9 M602 drive train without the turbo and the electrics from the donor vehicle, but it seems the only thing I will gain is the range per tank, so for me I may as well stay where I am.. not only that, Ive spent months looking for a LHD merc 2.9 to no avail, Ive found a few newer 2.4's in a sorry state, .. So your right "No" would be the right word to use. Well done that man.


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## Ian Wood

*More*

Well some good news. Hopefully I will get even more power from the engine. There was an extra vacuum powered 'control' on the new Ssangyong injector pump that I didn't know what it was for. I have just learnt that it will be a 'boost' for the engine. That is it will pump more fuel in when there is more pressure from the turbo, so my performance comparison should be better. So I've just rigged that up & will let you know the results after the next round of tests. I would like to post up a couple more photos, how do I do that mid thread?


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## sparrks

Ian Wood said:


> Well some good news. Hopefully I will get even more power from the engine. There was an extra vacuum powered 'control' on the new Ssangyong injector pump that I didn't know what it was for. I have just learnt that it will be a 'boost' for the engine. That is it will pump more fuel in when there is more pressure from the turbo, so my performance comparison should be better. So I've just rigged that up & will let you know the results after the next round of tests. I would like to post up a couple more photos, how do I do that mid thread?



Right click on your post and click edit?

Just looked at this post - just click on the edit button on the right of it, next to the 'Reply With Quote Button' and and upload photos in the usual way


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## Deleted member 207

I've got the earlier OM617 3litre and a meagre 88hp. I've just replaced the timing chain and tensioner and fitted new nozzles from Bosio into the injectors. Its amazing what that has done to performance, lack of smoke and economy. I'd suggest that anyone with one of the older Merc engines does a simple tune up first.

The timing chain had stretched (probably the original) and was putting the timing out just marginally.

The injector nozzles are just great, the engine runs very smoothly now. 

I also checked valve clearances which have not been done for quite a while >50,000kms - not one valve was out of spec.

I've thought about using a SsangYong Musso as a donor as well - but for a rear axle as there are diff locks available.


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## bouke

*Nice work.*

Nice work. I have been scheming of doing the same thing. Could you give us a breakdown of the costs? e.g. how much the new engine was? Would it have saved a lot of work to only put the turbo and pump etc across? Looking forward to hearing more about the results.


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## lebesset

as they say in cornwall ...proper job !
sorry Alan


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## vwalan

lebesset said:


> as they say in cornwall ...proper job !
> sorry Alan



cheeky monkey. 
nice to meet you lebesset.
we are down near torrevieja now . at punta prima . still sunny . 
have a good one .


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## GRWXJR

I've got all of 75 stampeding stallions in my non-turbo Ford Transit 2.5Di engine, which has to cope with 2 Tonnes or so of LDV Convoy Hi-Top to haul about.

At one time the lack of go would have had me going :banana:'s ... but not so much now.

Maybe some of it has to do with me being slightly older and less frenetic, more 'chilled' - especially in the camper :drive: ?

I know some of it is the draconian anti-speed war which means more Traps and lower limits, meaning that traffic is coming back to me, rather than me pushing my 75 Dobbins into keeping up with traffic.

Some of it is a trade-off - I like the lack of complication of my engine, associating simplicity with lower cost, easier maintenance and greater reliability - do I want more 'Go' and with it more 'Electronics' and garage bills?

My LDV doesn't have the suspension, brakes and handling to make anything other than a good A Road, Bypass or Motorway something it'd tackle much over 50 - 55mph anyway (it'll do it, but you aren't going to enjoy it and neither will the van).  The limit is 60mph on Dual Carriageways anyway, plus faster than that and the fuel consumption takes a hit anyway so what is gained on the road is spent in the Fuel Stop - so 60-ish is a sensible ceiling anyway.

So, while more (in fact SOME) acceleration would be nice (my van does not so much 'accelerate' as 'gather momentum' ), and hauling up hills with less loss of said momentum and forward motion would be welcome.... I'm just going to take the easy way out and live with it!

That said... I love that fact that there are still clever people out there doing stuff like this.  I hope all the time, effort and money spent pays the OP back in miles and smiles - its well earned.


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## dometick

i had a automatic Hymer Mercedes S660 which had had a TB turbo retro fitted to the original OM602 engine

i loved that hymer, but with the turbo it gave me barely 13 miles to the gallon when i know a normal 602 engine gives over 20mpg

went to germany to follow the world cup in '06 with it, and over 1200 miles later proved that it really did give me 13! :-(

i sold that 660 with much regret due to the MPG, and got a non turbo version, that gave me, and still gives me, 20mpg +

i couldn't tell any difference between the performance either, both can get to 70 and hold it there on the motorway (most of the time!)

what i have noticed over the years is that the engine seems to return the same MPG whatever driving you're doing


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## Deleted member 967

We have the S700 on the 410D Transporter Chassis.  Same OM602 naturally aspirated engine. 1992

2 year ago while working below the inlet manifold the fitter that does our services, said the vacuum pipes although looking good were soft and needed replacing.   He did this and there was a vast improvement in the performance, although I still opted for the crawler lane.

This year in Spain we lost our servo assistance.  Rock hard brake pedal and no engine stop.   The vacuum (exhauster) pump had failed.   We had a new pump fitted 450euro plus fitting and what a difference it made to the vehicles performance.  I was able to overtake lorries going up hill and had watch my speed to keep within the limits. As well as assisting the braking the pump has a second function of speed regulation in the fuel pump and powers the engine stop.

Another S700 owner also found that replacing his vacuum pipes made a great difference to the performance of his newly purchased vehicle.  That vehicle had been a hire vehicle and was decommissioned because the fitter couldn't find the diagnostic plug and therefor couldn't diagnose why the performance had dropped off. 

Both of these jobs are not easy, due to location, but well worth it.


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