The venerable Mercedes OM636 aboard S/Y "Pagan" is officially a runner again after a complete top end recon / rebuild and the repair or replacement of most of the marinsation peripherals
And once she'd warmed up a bit and settled in, she sounded good! Better. in fact, than she ever sounded before
From memory ...
The head has been skimmed (requiring 8 thou taking off it which is a lot and close to the limit of the possible)
The valve seats have been recut
The valve stem tips have been reground to profile
All of the rocker arm faces have been sintered and reground to profile
The top face of the engine block has been lapped and the bores honed
The injectors have been sent away and serviced
The alloy cooling system elbows and mainfolds have all been replaced (they were corroded to within an inch of failure, every one!) as have the heat exchanger end caps (which were also on their way out)
The heat exchanger core has been re-soldered at one end where it was likewise on the point of catastrophic failure
The cooling water cap flange has been soldered back onto the cooling water tank (when we took the cap off, the flange came with it ... it ain't supposed to do that!!!)
The valve clearances have been set and the head torqued down but both will require re-doing once she's been run back in. Simon had to helicoil one head bolt and has his concerns about whether three others will go down to final torque without stripping (a nuisance but probably do-able without all the time, trouble and expense of taking the head of again. We shall see, it is what it is)
In the process, Simon has also fitted the new parallel glow plugs I bought about 8 years ago and bottled out of trying to fit for fear of the old crappy series glow plugs not coming out in one piece. My concerns were justified as it turns out given that it took Simon the best part of half a day on the bench in his workshop to get all four out and clean up the threads. If I had tried to fit them it would have gone Pete Tong in a big way!!! (As originally supplied, the OM636 had series glow plus with a dropper resistor giving a measly 1.5v across each plug. Hnece the engine needing anything between 30 seconds and 90 seconds of pre-heat to persuade it to start. The parallel glow plugs operate at nominally 12v and she needed about 5 seconds of pre-heat to fire up from cold after 9 months of being in pieces. I think that's a bit of an improvement)
And although not yet plumbed in until after we've given the cooling system a really thorough flush (as salt water had got in there due to the aforementioned dodgy bits on the cooling system), the take-offs for connecting the closed cooling circuit to the calorifier have been freed off (I couldn't shift them, it took a fair bit of heat on the bench to shift the one on the heat exchanger, the other is into an alloy cooling elbow we've replaced and was not coming out at all)
We took an executive decision yesterday that neither of us could live a moment longer with the bloody awful location of the raw water intake sea cock and strainer basket. It's the old fashioned small strainer mounted directly to the sea cock and it's at the aft end of the engine bay which is hard to get at with the boat ashore and would be an absolute nightmare to access if the intake got blocked in any sort of seaway or emergency situation. I've been planning to re-locate it to a better position ever since we bought Pagan in 2016 and it can wait no longer.
So the existing small bronze strainer is going and we're going to fit a new seacock under the galley floor connected to a decent Vetus basket strainer mounted at the forward end of the engine bay where it's easily accessible. As the existing seacock itself is perfectly serviceable and I like the notion of having a plan B in case the main intake gets blocked (which has happened to me twice), we're going to plumb the existing seacock to a T into the new raw water feed to that should the primary intake suck up a solid plug of weed we have a "get out of jail free" card to play
And we've also decided that whilst we're at it we're going (or to be more accurate Simon is going) to completely rebuild the raw water pump with new bearings, seals, etc. etc. It doesn't look in great nick externally to be honest and it's been pumping seawater around for 45 years so I doubt it looks any better inside! Makes sense to get it refurbished now rather than have it fail in a few years time in some remote part of the Scottish isles or summat
We've also examined all the other seacocks and to Simon's surpise and my relief deemed them all fit for ongoing service.
Simon is also quite keen on the fitting of a flexible shaft coupling and I get where he's coming from. It would without doubt be a good idea but I'm taking it under advisement at the moment as a possible for next winter
My to-do list before we can launch ...
Service all the seacocks
Replace the hull anode and remake the bonding connections
Replace the prop anode and grease the prop
Sort out the permanent wiring to the new glow plugs
Do something (temp or perm) about the dead battery charger
Replace the faulty bilge pump
Apply two coats of barnacle food (a.k.a. anti-foul)
I also, less urgently, need to rework the fuel delivery system plumbing and valve work so that we can properly switch between the port and starboard fuel tanks (it all got messed with whilst trying to diagnose what had gone wrong last year and we've currently got a lash up feed from the starboard tank only)
The head has been skimmed (requiring 8 thou taking off it which is a lot and close to the limit of the possible)
The valve seats have been recut
The valve stem tips have been reground to profile
All of the rocker arm faces have been sintered and reground to profile
The top face of the engine block has been lapped and the bores honed
The injectors have been sent away and serviced
The alloy cooling system elbows and mainfolds have all been replaced (they were corroded to within an inch of failure, every one!) as have the heat exchanger end caps (which were also on their way out)
The heat exchanger core has been re-soldered at one end where it was likewise on the point of catastrophic failure
The cooling water cap flange has been soldered back onto the cooling water tank (when we took the cap off, the flange came with it ... it ain't supposed to do that!!!)
The valve clearances have been set and the head torqued down but both will require re-doing once she's been run back in. Simon had to helicoil one head bolt and has his concerns about whether three others will go down to final torque without stripping (a nuisance but probably do-able without all the time, trouble and expense of taking the head of again. We shall see, it is what it is)
In the process, Simon has also fitted the new parallel glow plugs I bought about 8 years ago and bottled out of trying to fit for fear of the old crappy series glow plugs not coming out in one piece. My concerns were justified as it turns out given that it took Simon the best part of half a day on the bench in his workshop to get all four out and clean up the threads. If I had tried to fit them it would have gone Pete Tong in a big way!!! (As originally supplied, the OM636 had series glow plus with a dropper resistor giving a measly 1.5v across each plug. Hnece the engine needing anything between 30 seconds and 90 seconds of pre-heat to persuade it to start. The parallel glow plugs operate at nominally 12v and she needed about 5 seconds of pre-heat to fire up from cold after 9 months of being in pieces. I think that's a bit of an improvement)
And although not yet plumbed in until after we've given the cooling system a really thorough flush (as salt water had got in there due to the aforementioned dodgy bits on the cooling system), the take-offs for connecting the closed cooling circuit to the calorifier have been freed off (I couldn't shift them, it took a fair bit of heat on the bench to shift the one on the heat exchanger, the other is into an alloy cooling elbow we've replaced and was not coming out at all)
We took an executive decision yesterday that neither of us could live a moment longer with the bloody awful location of the raw water intake sea cock and strainer basket. It's the old fashioned small strainer mounted directly to the sea cock and it's at the aft end of the engine bay which is hard to get at with the boat ashore and would be an absolute nightmare to access if the intake got blocked in any sort of seaway or emergency situation. I've been planning to re-locate it to a better position ever since we bought Pagan in 2016 and it can wait no longer.
So the existing small bronze strainer is going and we're going to fit a new seacock under the galley floor connected to a decent Vetus basket strainer mounted at the forward end of the engine bay where it's easily accessible. As the existing seacock itself is perfectly serviceable and I like the notion of having a plan B in case the main intake gets blocked (which has happened to me twice), we're going to plumb the existing seacock to a T into the new raw water feed to that should the primary intake suck up a solid plug of weed we have a "get out of jail free" card to play
And we've also decided that whilst we're at it we're going (or to be more accurate Simon is going) to completely rebuild the raw water pump with new bearings, seals, etc. etc. It doesn't look in great nick externally to be honest and it's been pumping seawater around for 45 years so I doubt it looks any better inside! Makes sense to get it refurbished now rather than have it fail in a few years time in some remote part of the Scottish isles or summat
We've also examined all the other seacocks and to Simon's surpise and my relief deemed them all fit for ongoing service.
Simon is also quite keen on the fitting of a flexible shaft coupling and I get where he's coming from. It would without doubt be a good idea but I'm taking it under advisement at the moment as a possible for next winter
My to-do list before we can launch ...
Service all the seacocks
Replace the hull anode and remake the bonding connections
Replace the prop anode and grease the prop
Sort out the permanent wiring to the new glow plugs
Do something (temp or perm) about the dead battery charger
Replace the faulty bilge pump
Apply two coats of barnacle food (a.k.a. anti-foul)
I also, less urgently, need to rework the fuel delivery system plumbing and valve work so that we can properly switch between the port and starboard fuel tanks (it all got messed with whilst trying to diagnose what had gone wrong last year and we've currently got a lash up feed from the starboard tank only)
So hopefully, boatyard willing, we'll be back in the water in about a month. Then it'll be some fairly intensive engine running in including at least two complete flushings of the freshwater cooling system and an oil change. We also need to get the standing rigging properly set up - it never happened after it was replaced two years ago due to the ongoing issues with diesel bug and then the head gasket failing on the engine - and sort out the mess that the running rigging is currently in
Then we've got a bit of a hiatus due to Jane's work schedule before maybe, just maybe, actually getting to go for a local cruise in August. September, like July, is a total bust and by the time Jane has time off work in October it's probably going to be the end of a very short season
There's a lot to then do before next year, mainly electrical stuff. I know what charger / inverter we're going to be fitting and I've jsut got to decide on where the new domestic battery bank is going (I can only squeeze two batteries into the current location and I want to increase the capacity of the battery bank by at least 50%, preferably doubling it). I think I know what I'm going to do with that but it means some wood butchery in the port cockpit locker
And I think I've finally got a workable plan for fitting a half decent amount of solar power but more (much more!) on that anon
Oh and I'm also in the early stages of designing and making all new cockpit gratings. I've got the space and the tecnhology at home to do that and I've finished the design work. I just need to order and collect the rough sawn Iroko planks I need and crack on with it. They might not be done for this season so in the next couple of weeks I'll nail some decking timber over the existing frames as a temporary solution
Boats eh? It never, ever, stops
And finally ... aplogies for the lack of pics and/or video. Even though I was just the oily rag apprentice assistant to the master engineer that is Simon "Engines" Dunn, I'm knackered! And it all got a bit intense yesterday afternoon as we were rapidly running out of time as I had to be away by no later than 7pm. I made it, just!
Amd finally # 2 ... it is hard to put into words the overwhelming relief and joy Jane and I are feeling at the present moment. There's no ducking the fact that going for a rebuild of the OM636 was a gamble which might not have paid off. It was entirely possible that we could end up two or three grand out of pocket and still not have a serviceable and, above all, reliable, engine. Without a doubt, a nice shiney new Beta 35 would have been the preferable option but financially it was a complete non-starter. We simply couldn't afford it (and given that the current market value of a W33 in good order is not much more than a new engine would have cost, it's debatable whether it could be justified even if we could). Even a suitable second-hand engine would have put a severe crimp in our financial plans potentially committing Jane to another year in work before we get to sail away and live the dream. We're not out of the woods just yet but the signs and portents are extremely promising.
