Exhaust Riser Time Bomb

I would think that, at least sometimes, the problem would reveal itself more gradually than a sudden failure. If corrosion inside the elbow caused restriction of the water flow, it would result in overheating. Not good, but one might be able to get home at very low speed, where a high rate of water flow was not needed. Maybe?

I had such a problem on a 2-cylinder Yanmar in a sailboat many years ago. I had noticed what appeared to be reduced water flow, but foolishly convinced myself it was "normal" until the high temperature warning went off. (I sailed home and re-started the engine only to get into my slip.) The local repair shop told me to use Muriatic Acid to dissolve the corrosion. It worked fine, and I used the boat for many years afterwards without further issues.

Was I just lucky? Is Muriatic Acid a viable treatment?

-- John H
 
My manual for the Yanmar 4JH3-DTE 125 HP in our 2007 R25 says to check the riser bi-yearly or every 2000 hours. It does not say when it should be replaced although I have read once every 4 years.
 
I'm familiar with both David Pascoe and hydraulic lock. David surveyed our Crealock 37 when we were shipwrecked in Pensacola by Hurricane Opal. He knows his stuff. I’ve seen David's comments about injecting the water on the "upstream side" since I used to occasionally browse his site. We have owned boats with the water injected both "upstream" and "downstream". Obviously "downstream" is much to be preferred. I looked to see if he had reviewed Ranger Tugs before we bought ours (he hadn't). Hydraulic lock cost us an automotive engine one time. Neither event was very much fun, but I did like David and have recommended his site to lots of folks over the years.

I had gone out and looked at our engine this morning before my earlier post. Our 3YM30s are built with the water injection on the "up" side, of course. I believe that with the hose routing on our engine that leakage into a corroded mixer would be minimal. There would be little or no drainage by gravity and the engine would be running if pressurized water were present. There might be some expansion as the raw water stopped moving and warmed up a bit, but even that would be low. I wonder if running the hose up the port side of the riser with a direct shot from the raw-water source to the mixer wouldn’t essentially reduce the leakage to just about nil. But I suspect there was a reason for it to be routed as it is now, especially since manufacturers won't use 18 inches of hose if they can get by with 8.

I will inspect my riser/mixer periodically, of course, as I am always on top of routine maintenance, but I don't expect that worry over it will give me nightmares.

From the pictures in the manuals it appears that the "L" shaped mixers would be considerably safer but I don't expect one could be retrofitted to our engine compartments. I suspect that at a minimum the house battery would have to go. I wish I had my hands on one to see how it might fit. I don't suppose Yanmar makes an "L" mixer with a 90 degree bend on the end. Too bad, since cast iron is so easy to produce in some pretty imaginative shapes. Has anyone ever looked into converting to the "L" version?
 
Its not that simple. There is a minimum drop requirement for the Vetus exhaust. The Ranger engineers decided that the U type riser is required. The 21 simply doesnt have enough bilge depth for an L type mixer.

If you really want to eliminate the problem entirely then I would consider engineering a dry exhaust and a keel cooler.

If this exhaust system as found on a 21 is maintained while not the best it is reliable if watched.
 
Engine placement in the R-21 (EC models as well) seems to be a bit too low to use an "L" type mixer. I think the "u" is needed to create the neccessary "break" well above the water line. I checked on my '05 R-21 and the top of the "u" is a few inches higher than the exhaust outlet at the starboard side near the stern. (used a cheap laser level..not easy with the boat in the water). The stern "squats" when under way so that difference would increase. I also have a drain plug at the bottom of the waterlift muffler.
If you have an R-21, perhaps it would be a good idea to remember to dis-connect the water injector hose if you find that the engine needs to be cranked for long periods?...just don't forget to put it back if it finally starts! Also don't assume that because the fitting is on the "up" side of the "U" that it sprays there, I think the exit for the cooling water is on the "down" side. It is only a serious problem if the corrosion perforation is on the "up"side and you need to crank the engine a lot... I'm not trying to minimize the seriousness of the potential threat...just saying you've got time to shop for the best deal on parts and/or labor. Know the normal temp characteristics of your engine..if it starts to run a bit warmer than usual, check the mixer when you check the heat exchanger for corrosion and crud...the labor and hassle of trying to clean/patch/de-crud the old elbow isn't worth it...put on a new one if it is suspect.

Over the years I've owned 3 boats that had this (or "GM" series engines)...never had a problem with the mixer in any of them (sail or power)...maybe I'm just lucky.
 
Slackwater are you in freshwater?

The failure I am describing gives you no warning at all. The engine wont heat up.

A perforation between the fresh water side and the exhaust side occurs. Then while the engine is NOT running the contents of the riser drain into the exhaust of the engine. Crank the engine and you hear a snapping clank sound of your block cracking. Voila hydraulic lock on cylinder number three.

I am reading on the internet about this engine. It seems that the little elbow fitting that hose is connected to on the 3YM engine is known to clog, slow the flow down and cause overheating. I dont understand how that can happen. Mine was clear. I noticed the replacement riser has a larger threaded hole for this fitting. I had to go get a bushing adapter. I also noticed the fitting was relocated from the side of the riser to the end of the riser. There must've been a problem for them to relocate the fitting and enlarge it.

I wonder if ranger could come up with a dry exhaust, keel cooler kit for us seawater guys. That could make a good boat great.
 
I think I can hear the tell tale tick-tick-tick of my exhaust riser getting ready to blow, all the way from the barn where I have Tugger Toy stored for the winter, almost 3 miles away. I guess I'll have to lay awake nights worrying about this until it either explodes or I have a chance to disarm it in the spring when we recommission the boat for next season. I just hope that no one is injured if there is an explosion..... 😱 😉

Eric
 
I've had several friends water lock an engine...all due to over cranking a reluctant motor. all were sailboaters. All knew they had "problems" starting for a long time (we got sails!). None resulted in a crack block or anything breaking (the starter motor just isn't that powerful..all that occurred is the motor couldn't turn over and needed a rebuild of the very old engines.

Where does the large volume of water in the mixer come from? The mixer's water jacket may hold a cup or 2 of water (if its removed, held upsidedown, and filled). In its natural state (inverted 'U") it doesn't hold much water. At worst it drains out whats in the "UP" half into the exhaust manifold when the engine stops running. The exhaust maniflod can hold more than that before the water might enter the valves. I don't think that the water held in the "UP" side of a mixer would be enough to water lock an engine by itself.
I could see a water lock occur if there is a perforation on the "up" side, and the engine is cranked long enough and water lock may happen sooner than expected ...that may be where the concern lies. I still maintain that if the riser is badly plugged it won't be doing it's job and the mixer and/or exhaust will get hot, probably enought to discolor it (after six years mine is still looking like new and cool enough to grasp after a day on the water). I'm in cold fresh water but it was used in cold salt water by the original owner for 3 years. The original owner may have changed the riser at some point, but he didn't mention anything...('cuz I bought it from his estate).

It's very common to see several changes in replacement parts from one year to the next that reflect ongoing improvements in materials and design (not always for the better). When you change your riser (mixer) I suggest that you may want use the new style.. end of problem? I've heard keel coolers are nice but not without their own set of maintenance issues. I'm not sure how they would fare in a launch and retrieve trailer boat like the R-21. Dry exhausts can be loud and can generate a lot of heat.

I think I'll stay with the present system, it works, it's quiet, it's on about a bazillion other boats. I'll still keep and eye on all my engine's systems as I always have.

As always, I recommend that anyone take what I say for whatever they want to think it's worth, and I take no offence if they think I'm full of ship. Only keep in mind... what is often reported as "huge" or "problematic" or "widespread" in some internet chat (not this group though), is often not the whole story, and may be from someone looking for warranty or validation for something they won't admit was self inflicted, or have some other agenda. I'm sure we've all read "reviews" on websites for things from cameras to house paint, where 8 out of 10 swear by it, one thinks it's a great product "for the price", and one says it blew his hand off and killed his dog.(but, it's same guy with the dead dog that is on every chat room, review page and comments forum there is).

If I was a bettin' man I'd go with the odds, that Yanmar's engineers know their stuff. (Oh yeah, and I wouldn't let the one handed guy with the dead dog borrow my boat. 🙂 )
 
Slack

I did what you said with the old riser that has been rolling around in the back of my pick up truck.

I filled it up as if the engine were running and then turned off. I flipped the riser over and no water came out at all. The engineers designed this part so it fully drains when the engine is switched off. So you are correct that a leak between the water side and the exhaust side while the engine is not running or being cranked is impossible.

A leak developing while the engine is running would be interesting. I wonder what symptoms would result.

Well anyways nothing good will come of a corroded riser. Mine was definantly restricted but I wont know if it runs any better yet until I get her in the water.

In my past life with a ford 302 and a Barr cast iron riser it was a real bummer. For all these boat engines it is always seems to be the marinizing parts that cause all the problems. Be thankful you dont have a V8 with risers and that gasketed surface.

Cant a dry exhaust be made quiet enough? Ever ride the jungle cruise at Disneyland. Couldnt we do something like that?
 
I had yanmar in sailboat which I used nearly every weekend for almost 10 years.
Didn't know you were supposed to worry about the mixing elbow.
Never EVEN thought about it.
Never had a problem.
 
As I said earlier, I am pretty certain that a running engine would expel any water. After all, that is exactly what is happening with an "upstream" injection of water. The intake is obviously isolated, so no dangers there. The pressures of exhausting combustion products would preclude water entering the cylinders and would blow it "over the hump" and into the muffler.

As to marinization, it depends who did it. We had twin 150 hp turbocharged Ford Lehmans in our Atlantic 44. It had the water injected on the "downstream" side of the exhaust. Those engines were notorious for keeping mechanics broke. As someone else has said, that's where trusting the designers comes into play. All things good involve trade-offs. I suspect Ranger Tugs evaluated all the options and it is obvious they have come up with a pretty great product. Yet they are not so hide-bound as to refuse to make changes when it makes sense, e.g. the EC, and making that tree-catching folding mast go forward instead of to the side (unfortunately 1 year too late for me).

Would I change some things? Sure. Would all the rest of the owners buy one with those changes? That is another question altogether.
 
Yanmar's are very tough engines. I have done further research about my engine (4jH3-DTE-125HP) regarding the riser. It turns out the riser on this engine is very well designed and the chance is relatively small that you will get a hydraulic lock from it. However, it can happen. Even without the failure of the riser you can get hydraulic lock. For example, when my son was 3 he shoved a ball in the exhaust when I was de-winterizing the engine. When I turned on the water supply in order to start up the engine the water backed up into the cylinders and the engine would not turn over. It did not destroy the engine, as I said before Yanmar's are tough. In fact, as mentioned earlier, the starter appears to not have had enough torque to break anything. I ended up removing the injectors and cranking the engine to remove the water and then changing the oil a couple of times. It started up fine and was trouble free afterwards.

That being said, my reading also indicates that you should replace the riser every four years because corrosion doesn't care how many hours an engine has.
 
That story contains alot of humor but also says alot about how well the engines were designed. I still have several of my grandson's small toys in the kitchen air condition floor registers.
 
I dont think your good fortune was the reult of the YANMAR design. The engineers do not design engines for waterlock. If they tried to design for waterlock the tradeoffs would show up some where else.

Maybe you had enough water in the one cylinder that the crankshaft never got the momentum required to break something and the starter didnt have the power to break it. Or perhaps the diesel never fired a cylinder on the other two cylinders.

Either way congratulations on your good fortune that was almost several thousand dollars worth. Now if we all had dry exhaust and keel coolers we could stop talking about this riser, seawater pumps, strainers, and heat exchangers.
 
Perhaps it's time to ask all Tugnuts if anyone has ever water locked the engine in their Ranger,,,from the earliest R-21's, C-Rangers, Martini's (diesel version), 25', 27's 29's, from the late 80's to the present. I'd like to hear your stories, what caused it, how was it resolved. Has anyone ever changed/serviced their mixer/riser, what did you find as to condition? Where did you buy the parts and who had the best deal.

It also might be a good idea to start a new "subject" thread for this. One that won't have DHS put us on a "Watch List"...maybe "exhaust riser/mixer experiences" would be good. That way, all of the many instances of waterlock could be under 1 subject and easier to find on "search". We really should keep it to Ranger boats though, just so that it doesn't get clogged up with the many other boats we own(ed) that it also happened to. The experiences that would be especially interesting, would be the ones where the engine (that always started easily and had no other issues) locked up and cracked the block as soon as the key was turned.
 
I think the horse died......

Eric
 
But he was a good old fellow if you look at the number of riders he had and the number who actually placed bets.

I suspect the actual title attracted attention, but maintenance that affects big dollars does seem to be a topic of interest to a lot of folks. Right now, I am varnishing the interior, probably no interest in that at all. 🙁
 
Hey I thought this riser was the same as any other Barr time bomb riser on a marinized V8. Those truly are time bombs.

Ive discoovered since then that the Yanmar riser is better in that it doesnt hold water when the engine isnt running. I can tell you this about mine though., There were large chunkies of stuff popping off the walls and the exhaust side was restricted by at least 1/3.

Do what you want with your dead horse but I am replacing mine every 5 years.
 
Gonzo,
If your engine is still under warranty, you might want to consider replacing the riser/mixer after 500 hours/2 years. I don't think Yanmar would put the 500 hour/2 year requirement in their manual for the 3YM30 unless there was a reason.
 
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