Coolant Conundrum/Exhaust Riser Replacement [Master Thread]

[Prairie Schooner]

Galvanic Soup
I'm mostly focused on actually completing this project, but a quick report from the field . . .

Like the rest of us, I've made an effort to eliminate mixing metals in our system, especially less noble metals. The folks at Universal were a little less persnickety. I think both of these housings are some sort of aluminum alloy. In the t-stat cover assembly I count: aluminum, brass, copper, steel, and stainless steel.

 

[Eddie 169]

It's interesting that you point this out, Ken. I hadn't given it much thought. It's basically like what we got with the boat, but with some history. When I rebedded the strut in 2022 we ended up having a mechanic pull the engine, put in new mounts, reinstall it and align it. With a late start we only had two months with the boat. Heading to our winter yard at the end of the season a lot of commotion in the engine bay announced that the riser pipe had broken. An emergency call got the mechanic to come and repair it. It's possible in the rush he used whatever pipe was handy, longer.
View attachment 52578

I confess that I have basically considered the engine a necessary evil and not paid more attention than minimum maintenance required. That, and when I hire a professional I'd like to assume it's going to be good to go. (re: the pipe breaking two months after he reinstalled it ) In about 2009 the PO had the top end of the engine rebuilt and at some point he installed the new alternator bracket. It's possible that during those he changed the riser setup from something that looked more like what you had. Comparing the poor photos I have of the previous set up, this pipe does look taller.

View attachment 52579
Current configuration. Could this create a problem? Should I get a shorter pipe? Rethink this entirely and isolate it with a hump?
View attachment 52580

I'm reluctant to make radical changes. I'll be forever grateful to @klb67pgh for acquainting me with Chesterton's Fence.
What kind of arrangement to you other M25 owners have?

 

[Eddie 169]

The extra stainless parts came in today. I decided to stick with the height. It adds some extra anti-siphon qualities (in my current understanding) and I was going to build a brace anyway. The schedule 40 fittings looked plenty strong to me but we special ordered the sched 80 nipples.

View attachment 52651

I had a question my mechanic took out my riser that Westerbeke that was in my M25. He built a riser pipe and then wrapped it. I was a little reluctant at first because I was concerned about backflow, but he assured me that this was a great configuration and actually an improvement. I still have my original Westerbeke riser. Do you think I should go back to the original? I haven’t had any problem so far but I was worried about rough seas and water backflow flowing into the engine and killing the engine.

 

[Kenneth K]

Do you think I should go back to the original?

What makes you think the Westerbeke riser is better?

Unless you post pictures on both, there's no way we can make a judgment.

 

[Eddie 169]

Thanks for your comment and reply. I will take some pictures when I get back to the boat, which is in Marina del Rey. I’m currently not there. Not sure the original Westerbeke is better but it had a check valve I’m assuming to prevent backflow

 

[Eddie 169]

I’m really just concerned about backflow in rough Sehs, which I’ve hit a few of those so I will try to get some pictures soon when I get back to the boat in Marina del Rey

 

[Prairie Schooner]

I had a question my mechanic took out my riser that Westerbeke that was in my M25. He built a riser pipe and then wrapped it. I was a little reluctant at first because I was concerned about backflow, but he assured me that this was a great configuration and actually an improvement. I still have my original Westerbeke riser. Do you think I should go back to the original? I haven’t had any problem so far but I was worried about rough seas and water backflow flowing into the engine and killing the engine.

I've seen quite a few posts of systems built out of pipe only. IIRC, they all had some sort of vent. As Ken says, photos would be really helpful.

 

[Christian Williams]

My riser appears to be a simple pipe section, with fitting for heat exchanger exit hose.

It's a tall "U" and feeds direct via a 2" hose to the water-lift muffler.

Back flow in the long exhaust hose (from stern to muffler} would have to defeat first the high loop in the long exhaust hose, then the muffler, then the "U" of the riser. There is an anti-siphon valve in the hose between the heat exchanger and the riser.

The design has travelled many miles in all conditions with no issue.

 

[Prairie Schooner]

I've seen quite a few posts of systems built out of pipe only. IIRC, they all had some sort of vent. As Ken says, photos would be really helpful.

I should have said "raw water injection point", and that loop, as Christian describes, should have a vent.

 

[Prairie Schooner]

COOLANT SYSTEM FLUSH
Because the coolant system had been filled with salt water, this was a critical step for the rebuild process. Because we were on the hard I did it as @Captain Pete recommends, using a submersible pump and a bucket. In a compulsive fit, I decided to make a video about the flush process.

It's about as entertaining as watching someone do their taxes and my voice induces slumber. I'll save you the six minutes with this recap:
- A coolant pump dummy was used for better flow.
- Thirteen flushes, most with a complete drain of the system in between.
9 with tap water
1 with Barnacle Buster
1 with tap water
2 with distilled water

When I started the BB cycle it occurred to me to put a strainer on the return end. I wish I'd done this from the outset. I'm sure I was sending some particles back into the system. That said, I was surprised at what came out. Lumps of mushy crystal, blue rubbery stuff, and a little disc of plastic. I'm glad I did so many cycles. The ports used for in and out, as well as direction of flow, were switched several times over the process. In retrospect, I wish I'd used some baking soda in the tap water rinse after the BB.

- - - - - - -
I'd gone back and forth on which of TRAC's products to use, Barnacle Buster or Descaler. In a closer reading of the company literature the BB is for salt water exposed systems and DS is for fresh. Normally I would have used the DS for cleaning out our 'fresh' water/coolant system. Since our engine had salt water infiltrate the coolant, I decided to use the BB.

- https://www.trac-online.com/products/descalers/tracs-descaler
- https://www.trac-online.com/products/descalers/trac-ecological-barnacle-buster

I chose these products largely for their claims of ecological friendliness. But I think BB is mostly phosphoric acid.

I've come to the conclusion that it's not a good idea to let boat parts soak in Barnacle Buster for very long periods. I discuss this in greater length in post #13 of Christian's excellent thread
- https://ericsonyachts.org/ie/threads/e38-heat-exchanger-blockage-resolved.22057/post-180610

 

[Christian Williams]

I found the video to be fast moving, with good character development (yours) and the necessary surprises. The blue blob a very nice touch.

Most notable, after multiple times entering your constricted spaces to set up pumps and buckets over extended periods, i find my joints don't hurt at all and there is no blood on my elbows and knees. I must be getting better at this stuff.

 

[Nick J]

I'm envious of how much room you have behind the engine. What kind of water heater do you have?

 

[Sean Engle]

We've got oddly fluctuating coolant levels and composition and I can't figure out what's going on.

...

Have any of you had a similar experience? What could it be? What is some other evidence I can be looking for?

I know when my heat exchanger rotted out some of the symptoms were like you were describing. It was dropping water out from the coolant side into the raw water side and the coolant kept disappearing... I put in a new heat exchanger and that was the end of it (and $500).

 

[Prairie Schooner]

I'm envious of how much room you have behind the engine. What kind of water heater do you have?

It's an Isotemp Slim. The PO put it in.

It may not be as much room as it looks, though, Nick. The muffler, heat exchanger, and riser/mixer were all out. And, the 'normal' lens on my iPhone is still wide angle. This is a shot with the .5 wide angle of all the parts in. No room for a bucket any more.


More details shots to follow, in time.

 

[Sean Engle]

That's what I put in also. Great little heater...

 

[Nick J]

That's way more room than the Kuuma 6 gal I have now. Not much you can do about the plumbing, but I think thisis something to add to the list. Thanks for sharing. Awesome work getting your coolant system cleaned out!

 

[Captain Pete]

Nice Job Jeff. And nice to see her floating!

 

[Kenneth K]

More details shots to follow, in time.

Funny, I have that same section of exhaust hose sitting up in my garage. I keep waiting for it get up and install itself, but so far, no luck.

 

[Prairie Schooner]

HEAT EXCHANGER INSTALLATION



Thanks to comments earlier here and in other threads I no longer felt constrained to mounting the HX to the bell housing as before. I considered mounting on one of the side bulkheads, but the arrangement of ports on the new unit would have meant adding many feet of hose to the system. The new location is in the same orientation as before but about a foot aft. A few hoses had to be only a little longer. Basically, it's some wooden mounts and a piece of angle iron. A key component of this is the stainless mounts which even have silicone liners.


The hangers are easily strong enough for just two to support the full weight of the HX but the contact welded nut is a possible fail point so I put in three. Once everything was in I realized I should have put the starboard-most mount a little more toward center. As an afterthought, I clamped a piece of silicone hose to the coolant hose as a chafe guard.

There are at least two advantages of the new location. One is the substantial added weight of the 3" HX isn't cantilevered off two bolts into an aluminum bell housing. The other is I have much better access to the transmission dip stick. In the 35-3 there is a removable panel in the quarter berth, which is on port. There was easy room for the riser/mixer. More details of the project to follow.

 

[Loren Beach]

The other is I have much better access to the transmission dip stick.

Based on my experience with having to unbolt and move aside the HE to check the dip stick, this is a huge improve improvement. (The basic Kubota engine is marvelous, but I was often offended by some of the 'marinization' that Universal/Westerbeke did for peripherals like this.)