Broke down - Freshwater Coolant Pump Model and Source

[Stu Jackson]

Breakin Away, try it now.

Thanks, Stu, I look forward to trying it. But I'm going to hold off on entering any credentials until the website security issue has been explained: http://c34.org/bbs/index.php/topic,10100.0.html

From Dave this morning:


Still need to find some time (few more hours) to take another crack at
the mediawiki plugin to support SMF/BBS user login... apparently it's
not easy to get them working and I don't want to break either the wiki
or bbs with a bad config.  (feel free to remind me about this in a few
days / week or so)

[Breakin Away]

Breakin Away, try it now.

I tried again. Same result - it says no user by that name. I still think that someone should try creating a new userID to see if you can replicate the issue.

The website is also still not secure.

[Breakin Away]

I'm starting to figure out how I'm going to flush, clean, and replace my freshwater cooling system this spring.

...I can easily drain coolant pulling the hose off the Hx, but my access may be way easier than yours.  I have also drained using the engine petcock (which Ron doesn't like) but I've never had so much as a drip from it....I have a nice place to disconnect/drain the lower hose, but I don't think the B series is as convenient.  Pic to follow.

Yes on both counts: My access to the HX coolant hose is very poor, and the lower hose from the water pump is segmented into a very short rubber bend, then a metal section. There's no benefit to pulling it off like Stu suggests, because it's not long enough to route it to a pail. In addition, note that the hot water heater for the MkII boats is located in front of the refrigerator, making for a significant low point where the fittings are virtually inaccessible, so draining that loop is going to be tough.

These key differences make draining and refilling the M35B on the MkII boats very different from what's been documented here for the M25 on the MkI boats. M35B does not even have a drain petcock, it has a plug behind the oil filter that is very hard to access. Before I start posting ideas for your comments, do any of you owners of the newer boats (MkII with M35B) have any suggestions on how best to drain the old coolant from the M35B motors, and then refill?

[Breakin Away]

As I said before, I am trying to figure out the best place to open up my cooling system to drain/flush/refill it. I'm having a little trouble figuring out the flow pattern through the pump. I'd like to know where is in and where is out. It's not totally straightforward because there are three ports on the pump.

First, you've got the little "return tube" on the top of the pump (as it's mounted on the motor). Since this is called a "return" (and looks to enter at a suction point behind the impeller) I assume that this is an inlet.

Second, you've got the large-diameter barb on the bottom, and leads back to the HX. Since this is off-axis, I assume that centrifugal force causes water to flow out from this barb.

Third, you have the opening in the gear cover onto which the pump attaches. From the angle of approach, it appears that the impeller is pulling the coolant through here.

So am I right that there are two inlets and one outlet?

I would guess that the two inlets result because the outlet water is split between what goes through the thermostat (when it's open) and what bypasses the thermostat (when it's closed). I assume that the little "return pipe" inlet is the part that bypasses the manifold instead of going through the thermostat to the manifold. Of course, this water does not go direct to the return feed, it first goes through the hot water heater loop, then back to the return pipe.

Is all of this description correct? My boat is covered in ice and snow right now, and it's not safe to go down and trace all the lines. But this is what it seems like from memory and from looking at photos of the motor and the schematics in the parts manual.

This is important to me because I'd like to know the suction points where I might be able to connect some tubing with elevated feed vessel to suck the new rinse/coolant into the cooling system. I'm also interested in places I might apply air or water flow to flush out the motor without it running. As I mentioned before, some of these points of access are different on my M35B vs. the M25, so not all the prior descriptions work for me.

[Stu Jackson]

BA,

Do these photos help? 

Start on reply #12, page 1

http://c34.org/bbs/index.php/topic,4588.0.html

[Breakin Away]

Same ones I was already looking at. Thanks anyway. Am I right about pump in and pump out and the other stuff?

[Jim Hardesty]

As I said before, I am trying to figure out the best place to open up my cooling system to drain/flush/refill it. I'm having a little trouble figuring out the flow pattern through the pump.

Did mine couple of years ago when changing hot water heater.  Easy to do.  Coolant change not water heater.  Main problem was catching the draining coolant, just need to find the right pan.  I also taped over the limber holes under the engine to keep the little spilled coolant contained.  I didn't do it, but, don't think it would be too bad to let it drain to the bilge, with the bilge pump off, and collect it there.  And flush it well.
The Owners Manual gives decent explanation and instructions.  If you don't have the manual it's here.  FWIW my drain plug took a 9/16 wrench.
Jim

[KWKloeber]

Same ones I was already looking at. Thanks anyway. Am I right about pump in and pump out and the other stuff?

BA

a quick ans right now. More l8r if u have Q?s.

The pump pushes coolant INTO the block, so 2 ports are Inzies (one from Hx outzie and one from WH outzie.)

The other hose is thermostat outzie (on the block, not on the pump)  —> exh manifold Inzie.
The other hose on the Exh man is;  EM outzie—> Hx inzie.

So there's two parallel coolant loops.

Block -> tstat -> ExhMan -> Hx -> pump -> block
Block -> WH -> pump -> block.

Look at this. Flow is identical on the B engines (about the only thing that is  )
Coolant flow UPDATED 5/10/18 Here

http://www.c34.org/wiki/index.php?title=Manuals
http://c34.org/bbs/index.php/topic,9871.msg75379.html#msg75379

Note u can actually print or save the corrected diagram to ur phone n take it to the boat; not just try to remember what was wrong on the orig drawing <wink>.

If you need, I can mark the flow paths on those photos of the B engines?

-k

[KWKloeber]

BA.

There's a major statement missing from the Ops Manual description of the closed system.

Thermostat

.....When the engine is first started the closed thermostat prevents coolant from flowing (some coolant is by-passed through a hole in the thermostat to prevent the exhaust manifold from overheating).

To prevent hot spots in the block, coolant also bypasses FROM the thermostat housing TO the coolant pump via a short bypass hose (between two small hose barbs at the base of the thermostat housing and the coolant pump.)  Catalina removes this short bypass hose and attaches the water heater hoses to those two ports.  This creates a continuous coolant flow through the water heater whether the thermostat is open or closed. 

As the engine warms up the thermostat gradually opens.

[KWKloeber]

BA:

see the 1st entry under engine cooling

http://c34.org/wiki/index.php?title=Diesel_Engine

[Breakin Away]

Thanks for straightening me out on all this. It's a lot to unpack, but I'm working my way through it. I'll have more questions in a few days.

Note u can actually print or save the corrected diagram to ur phone n take it to the boat; not just try to remember what was wrong on the orig drawing <wink>.

Actually there is no original drawing of the flow directions in the B-series ops manual - or, at least, I've been totally unable to find it.

This flow direction is actually somewhat surprising, because the impeller's rotation and angle of the passages sure made it look to me like the two larger ports would go the opposite direction. This was because in my head I had the motor and belt rotating counter-clockwise, in the wrong direction. The "clockwise when viewed from the front" direction (as stated in the B-series ops manual) makes all the flows go in the direction that you say.

Here's the dilemma, and the reason why I made this mistake: With a right-handed prop, the shaft needs to turn counter-clockwise (when viewed from the front) for the boat to go forward. Please tell me that the Hurth transmission reverses the shaft direction when in forward gear. Otherwise my head is going to explode. (My B-series manual actually doesn't explicitly say this, only saying "Transmissions turn Right Hand propellers" without reference to the engine's rotation.)

If you need, I can mark the flow paths on those photos of the B engines?

I see you added that to the Wiki. Thanks! But to pick nits, the B-series photos are a M35B, not M25XPB (which is nice for us MkII owners). The white sign on top, where you wrote in "From Tstat out" identifies it as M35B on the other side. (Check the other photo angles to verify.)

[Breakin Away]

I also taped over the limber holes under the engine to keep the little spilled coolant contained...

I actually kind of like that idea. Seal the pan and just let it it all drain in there, and come up with a way to pump it out of there before it overflows. Maybe a drill pump? I have a really nice electric oil extraction pump, but the antifreeze will be more difficult to dispose of it it's contaminated with oil.

The Owners Manual gives decent explanation and instructions.

I had seen those instructions but was struggling with how to get a container under the drain hole. Just letting it drain in the pan looks more straightforward.

Any ideas on how to purge the HW heater loop? Blow it out with a compressor?

[KWKloeber]

BA

Wb manuals sometimes leave things to be desired.  Tho they are a lot better than the old Universal Motors manuals (that e.g., reference a (tractor) 'radiator to cool the engine.')
I meant that the pix could be downloaded and taken to the boat.  Actually, the corrected M25/XP (ops manual) coolant diagram is accurate for the B series as well (as a schematic, that is.)

Engine coolant pumps (even autos) push coolant INTO the engine block.  Because hot coolant rises, the flow is OUT past the thermostat (top of the engine) and returns back to the coolant pump.

Prop rotation: check out the 1st and last 2 paragraphs on page 5 the Huth manual on the (bottom of) MANUALS wiki page.

Thanks for the heads up on the model, so noted and corrected. 
D'oh I hadn't looked down far enough in the pix to see the "35B" (or four injectors!!) and had my head around "A4 replacement" (for the C-30.). 

[KWKloeber]

<<Blow it out with a compressor?>>

Or a portable/refillable air tank, sm shop vac blowing or sucking that you adapt down to a smaller hose.

[Stu Jackson]

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Any ideas on how to purge the HW heater loop? Blow it out with a compressor?

It seems to me that "absolute" removal of all of the old coolant may not be necessary.  I would simply remove the two ends of the 3/8"/5/8" hoses to the water heater at the engine and blow through the highest one with a container under the other one.  You could even cobble together an extension hose on the lower hose and run it to a bucket/container.  Good luck, what ever you choose to do.  Once you've performed this successfully, it would really be appreciated it if you'd document it and we can add it to the "Burping Your Engine" post in Critical Upgrades and post it as a wiki.  Heck, make a tech note out of it, too.    Thanks.