Inboard performance

[Randall Schmidt]

thx
I'll inspect the water heater and associated plumbing. I was thinking of getting a 5/8 to 5/8 connector and plugging both the hoses that go to and from the water heater into it in order to bypass the heater at the moment. Doesn't that seem like a reasonable troubleshooting step to you?

 

[Randall Schmidt]

since I'll probably be replacing the heater is there any advice on that? Probably just measure the dimensions so it will fit into the lazerette, as well as the capacity, I think it was 6 gallons

 

[Panta Rei]

I would not replace the water heater, It may be fine , just not connected properly. For a water heater not to heat water , the coils inside the heater that the engine coolant runs in would need to be clogged or not properly connected. No
need to purchase anything at this point. Can you please trace the coolant loop from the coolant pump on the forward side of the engine going around the port side of the engine heading aft. It may go into the coolant reservoir from there. Out the reservoir and possibly head to the water heater or the heat exchanger. From there it should go back to the engine block.
Often, the hoses to the water heater are tee'd off the hoses running to and from the heat exchanger with a valve to control flow.
Taking a few pictures may work well as other owners with the same boat may spot something.

 

[Randall Schmidt]

Good idea, I'll do that. I noticed the survey report said "the water heater was not hooked up and was noted by seller it did not work"
;;

 

[jssailem]

Randall
"Not hooked up" can have two meanings. My WH has an electrical side using shore power AC to electrify elements in the tank. Additionally, the WH uses the engine coolant running through coils in the tank to heat the water when the engine is operated. The coolant lines have valves to cut the WH off from the engine coolant. Check both systems to understand what was said in the survey.

 

[Richard19068]

Randall,

On your parts diagram in post 45 there is a hose (part #10 I think it says) going directly from the exhaust manifold to the heat exchanger. This is a fairly short hose. In my setup ( an M-18 in a 1985 O'Day 31 but the parts diagram is the same) instead of that hose going directly from the manifold to the HX it goes from the manifold directly to the water heater and then from the water heater to the the HX. That adds several feet of extra hose and the water heater to the system. If your setup is like mine, I think what you might want to try is replacing those long hoses from and to the HX with the "stock" short piece from the manifold to the HX. That is, just remove the ends of the existing hoses from the manifold and the HX and insert the short "stock" piece. You don't need to order the special hose, just get a proper length and diameter hose from your local supplier. This should be easy (other than catching the coolant that will run out) and will take the water heater out of the question. Of course your plumbing may be different than mine. On re reading some of the above, it looks like this is essentially the same as you are proposing in your post 81 above. I hope I am not confusing things.

Good luck.

 

[Randall Schmidt]

thanks Richard,

I'll see if I can try that, I was about to as if I were to pull the hose of the water heater if that meant I'd need to drain the system first. Your message implies I would, or at least I'll need to catch coolant coming out of that hose. Connecting 2 hoses by the WH that sits up high may involve less draining then removing the HX hose to reroute it which is a slight plus for the connector option but that option I can see would less efficient from a cooling perspective.

 

[Richard19068]

Connecting 2 hoses by the WH that sits up high may involve less draining then removing the HX hose to reroute it which is a slight plus for the connector option but that option I can see would less efficient from a cooling perspective.

Plus doing it that way leaves more hose in the system and that hose is higher in the system. Both of those things make it harder to bleed / burp out the air. I think it is the high spots that create the trouble.

 

[Panta Rei]

Plus doing it that way leaves more hose in the system and that hose is higher in the system. Both of those things make it harder to bleed / burp out the air. I think it is the high spots that create the trouble.

WH is up high....... Interesting. I agree with Richard but anything to get the WH out of the equation will help. So the coolant loop goes from the pump to the reservoir then the WH then to the HX then to the engine block.
No tees in the system. AND the water heater does not heat water.

 

[Randall Schmidt]

I was told WH does not work by seller. The bathing water is bypassing the WH unit altogether. The coolant flow is just as you described. All I need is an 11 inch long 7/8" hose to bypass the WH and connect the reservoir directly to the HX. That is an odd size hose that WM does not stock so I'll have to order to try that out. I do not want to cut one of the 2 brand new hoses recently installed connecting to WH. So, for now I connected the To and From coolant hoses routing to the WH and plugged them together in a generous loop avoiding any kinking. Before doing this I felt the hoses while warming her up and found hot hose to WH and cool hose from WH. After bypassing WH the old From hose is somewhat warmer but not as much as the hose coming off of the reservoir - as expected. I found a few tiny leaks in coolant hoses and tightened them down. I used the bleed valve on the tstat top with a hose loaded with coolant to displace bubbles and add more coolant. Did this twice after messing with WH hoses to create a bypass. My new temp gauge seems accurate until we get to operating temp (180 thermostat) at which time it reads higher than the digital temp gun I point at the tstat housing. The gun shows 170 - 185 and the gauge 200. Finally my gun reading reaches 193 and I see some blow by and shut her down, managing to bleed off some air still and add fluid. Next step might be another iteration of this and and get a new temp sending unit and to try the method where we pour coolant into the top tstat housing hose. Also may do a compression test. Your continued thoughts would be appreciated.

 

[Randall Schmidt]

thx
that makes sense. I'll have to get a short hose to try it out. Meantime and eventually when I put in a new WH I'll need that circuitous route so it must actually/eventually work. maybe I need a few more air bleed iterations? How many is typical?

 

[Panta Rei]

Measure the temp of each hose as the engine heats up. The heat exchanger should be reducing the temp a great deal . You water temp at your dock should be in the 50,s or less

 

[Panta Rei]

What do you mean by "blow by"?

 

[Randall Schmidt]

I did 2 -3 more cycles of air bleeding and now she runs a cool 130. Cannot seem to get her up to normal operating temperature. Took her for a test motoring at 2800 RPM and she stayed a this cool temp. Cool is better than overheating but odd to me. Thoughts on this please?

 

[Randall Schmidt]

What do you mean by "blow by"?

Blow by was a new term to me. I heard it from the shop mechanic who was helping me in the past. There is an hose/pipe on the top of the motor. When she hits 200+ degrees smoke comes out of that pipe. He called it blow-by. You can google the term and find several definitions. Most indicate a sign of an engine with some real wear on it. Does this help? My cockpit is about to be ripped out for fiberglas work. That would be a good time to swap for new motor if I'm feeling rich and think I end up needing a motor. I thought I'd do a compression test but I learned my gauge for a gas motor will not work with a diesel due to the much higher compression. Also I got confused by the glow-plugs and what appear to be rigid piping above them. Not sure how to remove all that to get to to the cylinder for a test. Now that she's running cool I may not pursue this but have mixed feelings. Does anyone know the approximate price of replacement diesel motor/tranny installed? It is an M-12 Universal 10 HP no longer made. A 12 Hp westerbeke is a close fit but they just discontinued that model as well. I'm trying to get a price on one but dealer is not responsive.

 

[Randall Schmidt]

What I think I learned... (a) clean up the motor and underside to help detect leaks; )(b) check for leaks - I had a few loose hoses; (c) don't tighten clamps too much as they will break; (d) bleed and bleed and bleed iteratively; (e) cut the water heater out of the loop. I never quite got to the point of pouring coolant into the t-stat top hose but I hear that be simple and fast. I wonder how that helps bleed with a system of hoses that are above the motor that route to the water heater.

 

[Davidasailor26]

When she hits 200+ degrees smoke comes out of that pipe. He called it blow-by. You can google the term and find several definitions. Most indicate a sign of an engine with some real wear on it.

Blow-by often refers to combustion gasses "blowing by" the piston rings into the crank case, which is a sign of engine wear, but totally unrelated to your type of coolant overpressurization "blow-by". The fact that your engine runs smoothly and performs fine other than the (hopefully resolved) overheating suggests that it still has life left in it and shouldn't need replacement.

The items on top of the cylinders with the rigid hoses are actually the injectors, not the glow plugs.

As for tightening the hose clamps - you should be able to get them reasonably tight before they fail, certainly tight enough to prevent leaking unless they're badly corroded. I usually tighten them as tight as I can before it looks like hose rubber is starting to "ooze" into the perforations. Maine Sail would point out that the perforated style clamp isn't really the greatest. Search the archives and I believe you'll find his recommended alternative.

 

[Richard19068]

I did 2 -3 more cycles of air bleeding and now she runs a cool 130. Cannot seem to get her up to normal operating temperature. Took her for a test motoring at 2800 RPM and she stayed a this cool temp. Cool is better than overheating but odd to me. Thoughts on this please?

Fantastic. Congratulations, you've certainly had a frustrating time.

May be overly obvious but as I recall you may have removed the thermostat at some point. Did you put it back in? Other than that are you sure you have the correct thermostat? Or, maybe it could be stuck in the open position. Might try a new one or testing the existing one an a pan of hot water.

My 30 year old M-18 has a fair amount of blow by but still seems to be working fine. I put a crankcase breather filter on that outlet to keep the engine compartment a bit cleaner.

Not sure what you did about that short hose you said you needed to order from West Marine, sounds like you don't need it any more but you should be able to get an 11" piece of 7/8 heater hose from most any auto parts shop or online from Amazon or the like and avoid "marine" prices.

 

[Bill Roosa]

seen quite a few of these in the automotive world. Thermostats, when they get old, tend to stick open and closed at random intervals. Results in overheating and cool running. If you test the thermo in a cup of hot water it can even appear to work normally but if you test it through several cycles of hot and cold you notice it does not respond with the same opening at the same temp or sticks closed then opens rapidly or opens at too low a temp..... they are not that expensive so as a general rule if you had a temp problem and there was not an obvious reason like low coolant level or busted pump the replace the thermo.
FWIW

 

[Randall Schmidt]

Thx
replacing thermostat was my idea also. It is a new one though. I've put few in during this difficult period. I tested this one before. Perhaps the overheating damaged it? if I pull it out I'll have to do the bleeding routine again which is a pain but I think I know how to do it now. Strangely just before bleeding the last bit of air out I watched with the laser heat gun and saw it go from 185 to 170 to 185 like it was working. The air pushed it to 190 when I got the last bit out. Probably should swap it and test it again but am dreading that as my boat to-do list is already extensive. Thanks to all of you who kept giving advice!