New Live aboard with OM636

[CraigandHan]

Morning all,

Wasn’t sure which topic to put this in however considering my plans with the misses to up and leave in 2 years I might as well do it here.

My partner and I are currently under negotiations with a sailboat where we have put a deposit down subject to survey and any major issues.

The surveyor has come back with two points rigging due to it being original although tested and the fact it has the original engine. The rigging is not a big problem to us as, it is something we would budget for prior to leaving. I.e use it to gain confidence and re invest in rig prior to us setting off.

the main problem is now that although the owner brought it to our attention when first negotiating it was the original engine,, and told us the fact that it had been rebuilt circa 2015 and had roughly 1000 hours on the clock, and doesn’t miss a beat we were all set and I was not too worried due to the belief of the owner and his care and love he has put into his sailboat.

Then the surveyor the other day gave us back his report and now stressed that due to the engine age even if it’s working now we need to budget on the fact of needing a new engine.

I have been up most of the night weighing up all this in my mind and realistically I don’t think the owners will negotiate further as the boat as described although 40 years old is in good condition, and has been loved. We have a small deposit down on the boat to secure it through Covid subject to the survey.

The original engine is an om636, was tested by the surveyor and held it at WOT for some 20 minutes, he did note the engine did get hot at some 110 degrees but this was at WOT for 20 mins, and returned to running temp once revs subsided. He noted nothing else in toward an engine, except a little bit of hunting once. One of our plans is to do the french canals out to the med when we leave in the future, knowing that, this will be purely engine led.

the problem is this sailboat is on our budget, I mean our budget knowing what boats do and will need, however, realistically a re engine is not in this.

Im realistically looking for some advice and options on what to do. Knowing that the owner is, on payment, sailing the boat with us back across the channel to where we reside, saving us money on finding someone and have, been extremely accommodating through this process.

cheers

c and h

 

[Kelpie]

Did the surveyor actually do an engine condition report? Most don't, in fact most will not even run the engine in my experience. So his recommendations regarding the engine could just be an opinion.
You can get more detailed testing done, e g. compression check or oil analysis.
If there's nothing actually wrong with the engine, then what will likely end its life will be if spares are unavailable.

 

[CraigandHan]

Kelpie thanks for the reply and it is sound advice, I do get this and they are just recommendations and considerations for purchase, it’s just the phone call that he said he would not even take the engine across the channel due to it being that old, however his report still states that it all appears fine apart from the odd oddity
The survey was as follows:

Run-up
The dials were obscured by UV crazed acrylic
Engine started easily from cold.
Some black soot ejected initially but after warming, generally no undue smoke/steam noted from the exhaust.
The alarm extinguished on start up
The gears engaged easily (with exception of the button issue)
The cooling water primed initially and on subsequent start-ups.
Trial
There was some hunting of the engine at low revs initially
There was some run away of the revs (i.e. well over tick over) at tick over when initially berthing the boat
The engine was run for some 20 minutes under wide open throttle (WOT) – after warming up
The temperature reached 110oC (i.e. too hot) on the dial
The revs reached 2200 rpm
No vibration noted. The oil was re-checked – no emulsification.
Recommendations
A Service Agent or suitably competent engineer should further professionally check the engine address / advise on the findings (in italics). (ASP) (as soon as practicable)

 

[Tony Cross]

Many surveyors are remarkably poor at engine surveys. They tend to err on the side of caution to cover themselves. Since you're clearly concerned I would get a competent marina diesel engineer to take a good look at it.

You might also get a length of dowel and use that as a sounding rod to your ear to listen to the internals of the engine (the bearings etc) as it's running. A compression test of each cylinder would also be an excellent idea.

I would also find out how easy it is to obtain parts for this engine. Fuel pumps, injectors, impellers, filters, etc. etc. If it proves quite difficult to source common spares now then that's likely to get more difficult with time and that would concern me some.

 

[CraigandHan]

Hi tony,

thanks for your input, I’m not necessarily worried, I just feel a bit caught between wanting to believe the owner and no reason not to, and the surveyors remarks,

I must admit I’m just at a big loss and on the other hand do not have the money to keep forking outfor marine engineers on top or already surveyors, lifts etc etc

 

[Yngmar]

Those old Benz engines have near legendary reliability, durability and can be repaired forever. They're also not picky about their fuel. Parts are available anywhere in the world, as they were widely used in small trucks, light industrial machinery and agriculture. They're not necessarily original parts though. I wouldn't worry too much about it and just carry a sensible set of the common spares, service manuals and start familiarizing myself with the beast.

That said, when going cruising, in my opinion it's always wise to have a reserve budget for any sort of big unexpected expense, which depending on the boat may be around 5-15k, so you don't end up stranded when the rig does fall down or the engine spontaneously turns into a hunk of scrap. Unless the backup plan is to call it quits in that situation and go back home.

Sounds like your new boat might be a Reinke, they were mostly fitted with marinized (heat exchanger) or keel cooled OMs of various sizes, often second hand ones.

If it's not keel cooled the heat exchanger may be the main source of trouble, so I'd have a good look at that.

 

[CraigandHan]

Yngmar, thanks for this audition, the problem is I seem to have two different type of people, ones saying re engine, others saying they are long living engines and last a life time,

budgets are always there and so are loans but it’s more about what I do about purchasing a boat in this condition. It’s a discus out of interest to you,

could you develop a bit more about the heat exchanger problem?

 

[grumpygit]

Hi tony,

thanks for your input, I’m not necessarily worried, I just feel a bit caught between wanting to believe the owner and no reason not to, and the surveyors remarks,

I must admit I’m just at a big loss and on the other hand do not have the money to keep forking outfor marine engineers on top or already surveyors, lifts etc etc

This is a "How long is a piece of string" question.
Even if you got an engine surveyor I very much doubt he would give you an opinion on the internals of the engine except in what you already know, it's starting easily so you can assume the compression is good, 20 minutes of WOT is a reasonable test, the hunting will probably the governors in the inline diesel injection pump . . . .but at the end of the day it's still a very old engine although a robust one and parts are available but not as readily.
Rebuilt or overhaul is a very loose description and if it can't be backed up by any paperwork I would reject it as an unknown quantity and go on the initial assumption that sooner or later it will have to be replaced.
We don't know what yacht it is and how much it gets used, I don't know what others think but a 1000 hrs since 2015 seems rather a lot for a sailboat.

 

[CraigandHan]

Grumpy,

Totally understand this and it is a piece of string question. Granted the engine will while I have it at some point, will need an engine replacement, the deal is whether I am able to deal with this and how soon. That is the problem. I guess asking on here is the reason everyone does, for advice.

 

[grumpygit]

Those old Benz engines have near legendary reliability, durability and can be repaired forever. They're also not picky about their fuel. Parts are available anywhere in the world, as they were widely used in small trucks, light industrial machinery and agriculture. They're not necessarily original parts though. I wouldn't worry too much about it and just carry a sensible set of the common spares, service manuals and start familiarizing myself with the beast.

That said, when going cruising, in my opinion it's always wise to have a reserve budget for any sort of big unexpected expense, which depending on the boat may be around 5-15k, so you don't end up stranded when the rig does fall down or the engine spontaneously turns into a hunk of scrap. Unless the backup plan is to call it quits in that situation and go back home.

Sounds like your new boat might be a Reinke, they were mostly fitted with marinized (heat exchanger) or keel cooled OMs of various sizes, often second hand ones.

If it's not keel cooled the heat exchanger may be the main source of trouble, so I'd have a good look at that.

Generally a correct analogy, could be a Westerly maybe?

 

[CraigandHan]

Generally a correct analogy, could be a Westerly maybe?

a Discus!

 

[grumpygit]

Grumpy,

Totally understand this and it is a piece of string question. Granted the engine will while I have it at some point, will need an engine replacement, the deal is whether I am able to deal with this and how soon. That is the problem. I guess asking on here is the reason everyone does, for advice.

We all take this risk buying a second hand boat. I remember my boat purchases, the engine question is always at the back of the mind.
As far as I can remember this engine finished in road vehicles late 70's early 80's but spares are still out there.

 

[CraigandHan]

Some thinking to do!

 

[Yngmar]

could you develop a bit more about the heat exchanger problem?

Same as any other heat exchanger: They're sitting around full of corrosive seawater and eventually tend to get a hole eaten through, often near the end fittings where the tube stack is seated. You can compression test them to check they haven't already got a pinhole somewhere and/or take off the endcaps for visual inspection. Both may be inconclusive! Repairs are difficult but possible.

This is not originally a marine engine, so it will have been marinized by someone - that means there's not a standard heat exchanger model for them, but I think Bowman ones are common in UK boats. It's a good sized engine for that Westerly.

Given the above, I did some googling, and found several used OM636 engines for under £2k, one even is marinised and at a glance looks in pretty good shape: Mercedes OM 636 for sale UK, Mercedes boats for sale, Mercedes used boat sales, Mercedes Engines For Sale Mercedes OM636 42hp Heat Exchanger Cooled Marine Diesel Engine - Apollo Duck

The heat exchanger itself is available as new part for £1120 (if you think that's expensive, look up a Volvo one): Heat Exchanger Manifold and Header Tank MB180

As a drop-in replacement of the same model engine is not difficult to do yourself, the maximum risk to you is around £2k, so that gives you a number you can take to the negotiating table or add to your emergency budget if you decide to take on the boat. Hope this aids your decision!

 

[CraigandHan]

Same as any other heat exchanger: They're sitting around full of corrosive seawater and eventually tend to get a hole eaten through, often near the end fittings where the tube stack is seated. You can compression test them to check they haven't already got a pinhole somewhere and/or take off the endcaps for visual inspection. Both may be inconclusive! Repairs are difficult but possible.

This is not originally a marine engine, so it will have been marinized by someone - that means there's not a standard heat exchanger model for them, but I think Bowman ones are common in UK boats. It's a good sized engine for that Westerly.

Given the above, I did some googling, and found several used OM636 engines for under £2k, one even is marinised and at a glance looks in pretty good shape: Mercedes OM 636 for sale UK, Mercedes boats for sale, Mercedes used boat sales, Mercedes Engines For Sale Mercedes OM636 42hp Heat Exchanger Cooled Marine Diesel Engine - Apollo Duck

The heat exchanger itself is available as new part for £1120 (if you think that's expensive, look up a Volvo one): Heat Exchanger Manifold and Header Tank MB180

As a drop-in replacement of the same model engine is not difficult to do yourself, the maximum risk to you is around £2k, so that gives you a number you can take to the negotiating table or add to your emergency budget if you decide to take on the boat. Hope this aids your decision!

Yngmar, I cannot thank you enough for doing this research of your own back, I too have seen one of these engines which has made me feel a little better,

emails have been sent to Westfield as well. Thank you and to everyone else for the help and any further input!

 

[grumpygit]

Where Yngmar has gratefully done some homework for you may I give you another but costlier alternative which may be cheaper in the long term.
Take the gamble and run what you have for as long as it will, who knows it may be years yet, but have a separate engine fund pot. If the worst happens just replace the lot.
I can't see throwing money in dribs and dabs at an unworthy cause. A secondhand engine as suggested probably with less history that the one you may own plus a new heat exchanger along with whatever else it may need 2k+1.12k=3.2 + overhaul+ hassle+labour.
Take a look at new and s/h engines but do plenty looking and plenty homework that will suit you and of course your pocket,
As here for instance ://www.boatsandoutboards.co.uk/Boat-engines/inboard-diesel-for-sale
As Del Boy said . . . you know it makes sense??

 

[Bru]

The OM636 is indeed legendary as others have said

It's based on a 1930s petrol engine (believe it or not) and was in continuous production from the early 50s until the late 90s (and i think beyond under license)

It was used in Mercedes cars, vans and small trucks, the original Unimog, Thermoking trailer fridge / freezer units, plant machinery, generator sets and boats amongst other things

Parts are readily available, including the marinisation parts (mainly the aforementioned Bowman heat exchanger) and Manfred at West 4x4 up Liverpool way is a fount of knowledge and supplier of anything and everything you might ever need up to and including fully reconditioned part exchange engines

The 636 is virtually bomb proof and will pretty much run forever with due diligence and frankly the surveyor, unless he had specific reasons to doubt the longevity of that particular engine, was talking out of his bottom!

The downsides? It's not the most economical noise maker ever installed in the bowels of a boat. In our W33 (exactly the same hull as the Discus) if pushed hard, say battling down channel into the teeth of an F5/6, it will gobble up about 3.5l to 4l an hour (ouch) and cruising at 5 knots in decent conditions only improves that by a litre or so

Long and short of the matter is i wouldn't worry about the OM636. It's no more or less likely to cost you money down the line than an engine half its age or less (and parts are substantially cheaper than Volvo or, especially, Yanmar)

 

[elenya]

We have a 636 on our 40 year old yacht. Original engine and done likely 10,000 hours. Rebuilt 2008 and never misses a beat. If the 636 ever fails I will fit another 636.
Easy to work on motor and simple. Spares are easy to get as are replacement motors, Any motor is a punt as you don’t know what is going on inside. I like the idea of saving a bit as you go for a just in case fund.

 

[CraigandHan]

Elnya, yngmar and everyone else that has made an input thank you ever so much for your help. I think the main worry is this boat is just on budget, I do know the boating industry so know this budget has to stretch in the unlikely event of something happening, the problem is I have always fallen foul of “Sod’s law” and I’m petrified of it happening, especially with something like the engine. But, this boat, is just too good to pass up.

I have had a chat to the owner and it looks like, providing he accepts my next correspondence due to me writing it late, he has kindly lowered the asking price once again. With luck we may be the owners of a new vessel ?.

 

[grumpygit]

Elnya, yngmar and everyone else that has made an input thank you ever so much for your help. I think the main worry is this boat is just on budget, I do know the boating industry so know this budget has to stretch in the unlikely event of something happening, the problem is I have always fallen foul of “Sod’s law” and I’m petrified of it happening, especially with something like the engine. But, this boat, is just too good to pass up.

I have had a chat to the owner and it looks like, providing he accepts my next correspondence due to me writing it late, he has kindly lowered the asking price once again. With luck we may be the owners of a new vessel ?.

It looks as though you are going to end up with a very reasonable boat. Don't worry about "Sods Law" it never stops in one place and don't get petrified about the engine, you will take away the buzz of getting the boat.
In the past I have had a fleet of 3 vans and 2 cars with this design engine and they are sturdy devils. Just keep the oil and filter changed regular,
These as road engines often used go to 500k + especially if they have been serviced . There is a saying that regular new oil is a cheap spanner, in other words clean oil can prevents a major overhaul. Make sure to find out what engine oil it requires mineral, synthetic or semi. If it was overhauled in 2015 it could now be on a synthetic type instead of mineral.
Good luck with your dealings.