Catalina 34

General Activities => Main Message Board => Topic started by: abelovarac on April 19, 2022, 12:19:30 PM

Title: Replace Exhaust Riser?
Post by: abelovarac on April 19, 2022, 12:19:30 PM
Hello all!  I own a 1993 Mark 1.5 34 TR and have been reading about the need to replace the exhaust riser periodically due its tendency to fail at the most inopportune moment.  Since mine is 29 years old, and I have close to 2500 hours on the engine, I thought I'd have a look its condition.  After removing the insulation, I found what appears at first glance to be a solid riser with no visible leaks or cracks.  It's stainless steel with some rust around the elbow going into the manifold flange as well as the muffler, but as far as I can determine it seems pretty solid.  Not sure whether to go through the trouble of fabricating or buying a new one.  I am handy but don't have much experience with engines other than the usual maintenance.  Any thoughts from anyone who has more experience or a better eye for this?  Here's some pictures.  On the one showing the flange, note that I removed the top two nuts anticipating the possibility of replacement. The boat spent its first 18 years in salt water, but since then has been a sweet water boat on Lake Erie.

Title: Re: Replace Exhaust Riser?
Post by: Noah on April 19, 2022, 12:30:00 PM
Doesn’t look bad to me—a non-mechanic. I am guessing it has already been replaced previously. I don’t think the original was SS—at least on the 25XP engines they were black iron I believe.
Title: Re: Replace Exhaust Riser?
Post by: Ron Hill on April 19, 2022, 12:57:02 PM
Abe : Your exhaust riser looks pretty good to me.  I'd put the insulation back on it and then reinspect it in a couple of years again.  You have a very low number of engine hours for the age of the engine!! - which is why your riser appears in such good condition.  Always closely inspect the bends and welds of the riser!!

It looks to me that you have an M35 engine and the two top nuts that hold the riser to the exhaust manifold are missing! - or did you just remove them!?! 

Noah : FYI, The original C34s 1986 and into 1987 all had black pipe exhaust risers.  Catalina changed to stainless risers sometime during the 1987 production.

A few thoughts
Title: Re: Replace Exhaust Riser?
Post by: Noah on April 19, 2022, 01:49:05 PM
Good info Ron. Thx!
Title: Re: Replace Exhaust Riser?
Post by: Stu Jackson on April 19, 2022, 04:48:36 PM
I agree, looks pretty good.  Put those nuts back on the studs.  Before you start the engine.  Or you'll lose coolant.

Here are some tips for when you need to do this:

https://c34.org/muffler-exhaust-riser-replacement-2015/
Title: Re: Replace Exhaust Riser?
Post by: Ekutney on April 19, 2022, 06:28:30 PM
Agree with other comments’ looks in good condition.  I would suggest changing to the blue flexible hump hose, good way to reduce engine vibration transfer to the water lift muffler.
Title: Re: Replace Exhaust Riser?
Post by: abelovarac on April 19, 2022, 08:55:14 PM
Thanks for all your input!  I wondered whether it had been replaced as well - looked pretty good for all those years.  Glad to hear 2500 hours is not that much - I didn't have any reference to judge.   I did take the nuts off the flange just to see if they came off easily and they did.  Won't forget to put 'em back on. I guess it goes along with that old saying - if it ain't broke, don't fix it.
Title: Re: Replace Exhaust Riser?
Post by: Stu Jackson on April 20, 2022, 08:12:44 AM
Thanks for all your input!  I wondered whether it had been replaced as well - looked pretty good for all those years.  Glad to hear 2500 hours is not that much - I didn't have any reference to judge.   I did take the nuts off the flange just to see if they came off easily and they did.  Won't forget to put 'em back on. I guess it goes along with that old saying - if it ain't broke, don't fix it.

You're welcome.  All those years also is dependent on use and engine hours.  2500 is pretty good.  Dave Davis, a past Commodore, once tried to start recording failure times, but they were all over the place.  The top two nuts almost always come off easily, it's the bottom one that's a real bear.  My linked tech note article discusses that issue and MTBF on mine.  Good luck.
Title: Re: Replace Exhaust Riser?
Post by: Ron Hill on April 20, 2022, 01:38:51 PM
Guys : Stu is correct, that bottom nut is a BEAR.  Just make sure that you soak it with Blaster/Penetrating oil and you use a 6 pt socket!!

A few thoughts
Title: Re: Replace Exhaust Riser?
Post by: KWKloeber on April 23, 2022, 02:43:28 PM

Doesn’t look bad to me—a non-mechanic.


The answer, of course, is to use the hammer test
Tap along the entire riser and at welds using a small-head ball peen hammer or a tack (upholstery, not sailing) hammer to sound for thin spots that may be near corroded-thru from the inside and not visible on the surface.  Not wailing on it, just tapping to sound it out (just like sounding out a hull or deck.)   Pay special attention to the condition of the injection wye which is typically the first to go.
Title: Re: Replace Exhaust Riser?
Post by: Sailing Sirona on April 23, 2022, 10:31:45 PM
Wish I were in the same boat (so to speak)... I just recently started getting exhaust smell in the head and cabin, and investigated two days ago and found an exhaust leak where the raw water injection nipple meets the main body of the riser (and on the other end the threads of the rise at the exhaust flange are pretty rusted away)... looking like I'm going to have to replace the riser - so I've been reading all of the relevant posts over the last couple of days.  A couple of questions:

1) Any place other than Catalina or CD to buy the riser, or any point even spending much time looking? (I was talking to a Marine supply store near me on Vancouver Island, so asked, and they seemed to think there wasn't much option other than ordering from the US, from Catalina or CD)

2) Anyone had any luck with using automotive exhaust weld and/or tape as a temporary fix (i.e. until i can get a full replacement riser, flange, gasket, hump hose and do the full job)? --- kinda dreading the whole process.
Title: Re: Replace Exhaust Riser?
Post by: KWKloeber on April 23, 2022, 11:09:37 PM
Steve

One option is to make up a heavier wall and longer-lasting riser using schedule 80 stainless pipe nipples and fittings.  Lower cost as well!
Title: Re: Replace Exhaust Riser?
Post by: Stu Jackson on April 24, 2022, 09:38:48 AM
>>>>>>>>>>>>>>>>

1) Any place other than Catalina or CD to buy the riser, or any point even spending much time looking? (I was talking to a Marine supply store near me on Vancouver Island, so asked, and they seemed to think there wasn't much option other than ordering from the US, from Catalina or CD)

2) Anyone had any luck with using automotive exhaust weld and/or tape as a temporary fix (i.e. until i can get a full replacement riser, flange, gasket, hump hose and do the full job)? --- kinda dreading the whole process.

1)  Making up your own.  The Old Projects & FAQs (https://www.c34.org/faq-pages/faq.html) have some ideas:

https://www.c34.org/faq-pages/faq-exhaust-pipe.html

2)  The nipple is where they usually go bad.  Yes, muffler tape will tide you over.  From the 101 Topics:
Westerbeke Nipple Source  https://www.westerbeke.com/Product/NIPPLE/299693
Title: Re: Replace Exhaust Riser?
Post by: Ron Hill on April 24, 2022, 10:41:12 AM
Steve : The nipple weld is usually the first thing that goes bad!!  I've written this up a number of times but here it goes again : 

The factory used wire reinforced hose to go from the anti syphon valve to that nipple. That stiff hose transmits all of the engine vibrations right to that nipple weld!!  Change that hose to a softer nylon reinforced hose.  I also recommend a stake weld on the inside of the riser to reinforce the outside weld.

If you haven't changed to a Hump hose (riser to muffler) now is the time to do it - That softer hose negates the engine vibrations to the fiberglass muffler inlet!!

A few thoughts
Title: Re: Replace Exhaust Riser?
Post by: ewengstrom on April 25, 2022, 06:14:32 AM
This is what was left of our original riser.....obviously it had been bad for some time and I could tell there was an exhaust leak in the engine locker.
I measured carefully and ordered the stainless steel parts from a plumbing supplier and assembled it myself. (Ferguson Plumbing Supply)
Total cost was just over $100.00 in early 2020.
Luckily the nipple weld assembly was reusable,  it appears it was made from bronze or brass and is virtually perfect.
Title: Re: Replace Exhaust Riser?
Post by: Sailing Sirona on May 12, 2022, 08:31:16 PM
>>>>>>>>>>>>>>>>

1) Any place other than Catalina or CD to buy the riser, or any point even spending much time looking? (I was talking to a Marine supply store near me on Vancouver Island, so asked, and they seemed to think there wasn't much option other than ordering from the US, from Catalina or CD)

2) Anyone had any luck with using automotive exhaust weld and/or tape as a temporary fix (i.e. until i can get a full replacement riser, flange, gasket, hump hose and do the full job)? --- kinda dreading the whole process.

1)  Making up your own.  The Old Projects & FAQs (https://www.c34.org/faq-pages/faq.html) have some ideas:

https://www.c34.org/faq-pages/faq-exhaust-pipe.html

2)  The nipple is where they usually go bad.  Yes, muffler tape will tide you over.  From the 101 Topics:
Westerbeke Nipple Source  https://www.westerbeke.com/Product/NIPPLE/299693

thanks for all of the input - has taken a while to get parts, and to have a local welder build a new riser for me, but finally got it today (needless to say, once I had the old one out and unwrapped it was clear that it was done).

Speaking of wrapping - the old riser had 2 layers of fibreglass wrap, and under those a layer of fibreglass "fleece"... it was a lot.  I've got a 2" X 50' roll of exhaust wrap, which I'm thinking should give me 2 layers (with overlapping).  Any input on if that is likely to be enough heat protection? overkill?  Thanks.
Title: Re: Replace Exhaust Riser?
Post by: Ron Hill on May 13, 2022, 12:28:07 PM
Steve : Just remember to replace the stiff wire reinforced hose from the anti syphon valve to the riser nipple with a nylon reinforced hose.

It looks like that stiff hose and the riser itself transmitted all of the engine vibrations right to the nipple area cracking it!!  The stiff wire reinforced hose from the riser to the muffler inlet didn't help!!

A few thoughts
Title: Re: Replace Exhaust Riser?
Post by: Sailing Sirona on May 15, 2022, 09:09:16 AM
Thanks Ron, and all.

I did change to a silicone hump hose and the hose from the vented loop to the injection nipple.  Installation of the riser took some time yesterday, but I got it done...

However - after reinstalling the heat exchanger (and replacing the 7/8 hoses) and refilling the coolant, the engine is overheating.  I have read multiple posts about how to burp the system, and followed the advice there... I filled through the 3/8" hose from the thermostat reservoir until I had coolant flowing from the nipple there.  After running a short time, the engine was up over 180.  I tried other fixes... I ran the engine with the cap off, and opened the petcock on top of the thermostat housing; I throttled up to between 2500 and 3000 RPM a few times (as was getting some bubbling at the petcock). 

I also re-did the fill from the hose to the water heater loop, just in case I hadn't gotten it reconnected quickly enough and had introduced some air there when I filled it.  (I don't have a fluid pump right now as I lent mine out, but I'm pretty confident the water heater loop is fluid-filled... was a good stream coming from the nipple, and we got the 3/8 hose on there quickly).

Was still up to about 200 degrees when I stopped trying yesterday. 

I'm going back today to keep trying to find the issue (perhaps try again a couple of times to open the system and run the engine at elevated RPMP) - but any ideas of why else I might still have an air lock (or other potential issue), or other steps to try?

thanks.
Title: Re: Replace Exhaust Riser?
Post by: waughoo on May 15, 2022, 09:51:52 AM
I had a pretty good air bubble in the hose from the heat exchanger where it runs under the exhaust manifold and then to the lower part of the coolant pump.  A solid wiggle there helped me get all the air out.
Title: Re: Replace Exhaust Riser?
Post by: Noah on May 15, 2022, 10:57:17 AM
I am NOT a mechanic. But once upon a time, when changing coolant, I ran my engine at higher RPM, a bit past “temperature comfort level (200+?)” with the coolant cap loose/open, and the air ran itself out of the system after a few minutes. You might consider this, depending how brave you are.
Title: Re: Replace Exhaust Riser?
Post by: KWKloeber on May 15, 2022, 01:17:01 PM
Make sure the Tstat is opening.  Is the hose hot to the exh manifold?

Good return from the Hx?  Hot water in the 7/8” hose to the coolant pump?

Are you getting good seawater flow?  Hot water in the hose to the injection wye?

The coolant pump can get an air lock but it sounds as if you have coolant circulating.

You can eliminate one variable by disconnecting the WH hoses and inserting a short bypass hose, then reattach once you know the beast is cooling properly.

We have a particular issue w/ the plumbing on the C30 mk-I due to the WH location and burp similar to how Noah describes.  Leaving the pressure cap off we run up the rpm for a while; idle down. Repeat this pumping/surging several times to bubble air out of the pressure cap while topping off there.
Title: Re: Replace Exhaust Riser?
Post by: Sailing Sirona on May 15, 2022, 04:54:21 PM
Thanks - ran through some of these to further isolate the issue... including removing both WH hoses and creating a short bypass loop - definitely had good flow from the pump.

In any case - third time was the charm... I managed to borrow a 12V fluid pump, and put a lot of coolant through the WH loop (there was air coming through for quite a while for some reason), then reconnected and that got it.  I ran the engine, including under load, at the dock for over 1/2 hour, and never did quite get to 160 degrees.

I was finally able to check how the exhaust riser replacement was working, which was the whole point, and was very discouraged to see a pretty good coolant leak onto the area of the aft port engine mount.  Thankfully, though, it doesn't look like it's from the exhaust flange, but from the fresh water return hose connection on the Hx... ran out of time today, but will go back to tighten and confirm that tomorrow (and also investigate why, after running the engine for as long as I did today, I didn't have hot water... ).

thanks again for the suggestions
Title: Re: Replace Exhaust Riser?
Post by: KWKloeber on May 16, 2022, 04:33:54 AM
Steve,

Did you check the Hx end cap for a leak?

“Our” problem is that our WH sits high in the cockpit sail locker so air accumulates there and is difficult to move out of the high loop.  From what I understand about your hoses they run down to the sole then up to the WH?  So that could create the same sort of air trap.  Air fights like heck from “going down.

How long was the WH hooked up w/ engine running after purging that loop?
Title: Re: Replace Exhaust Riser?
Post by: Noah on May 16, 2022, 08:39:53 AM
Ken-the OEM C34 water heaters are under the galley sink at the same height or lower than the engine. The hose run under the sole and then rise up slightly (8-10 inches?) to the heater.
Title: Re: Replace Exhaust Riser?
Post by: KWKloeber on May 16, 2022, 09:16:15 AM
Thx Noah.  Our “up” is probably not much more than that.  The hoses enter at the bottom of the locker, basically just above hull level (slopes up from the engine of course.)  So I’d think they are comparable.  Your engine connections are higher than ours ( stuffed underneath a seat height) Tthe mk-II WH was moved onboard and lowered.  I’d think any “up” pocket could potentially be problematic.

In our wheelhouse we don’t have the tips to fill/hand pump that loop but would be a good thing to add.
Title: Re: Replace Exhaust Riser?
Post by: Ron Hill on May 16, 2022, 02:46:39 PM
Steve : To "burp" (get all the air out of the Water Heater line) I disconnect the WH return line (from the thermostat) and connected in a small hand "PAR pump".  Then pumped fluid (into the open reservoir on the engine) until all the air is out of the line and just fluid is coming out!!  Then reconnect the W heater hose line back to the thermostat.  Easy as that!!  :thumb:

A few thoughts

Title: Re: Replace Exhaust Riser?
Post by: Sailing Sirona on May 16, 2022, 03:51:35 PM
thanks guys,

I had lent my hand pump out (of course, just when needed it), but a borrowed 12V fluid pump did the trick - I was surprised by how much air it pushed through, and I must not have been getting it all just by pouring into the raised 3/8" hose from the Tstat reservoir.

Also confirmed my suspicion that the coolant leak I had was from that hard-to-reach 7/8" return hose on the back of the Hx (ironically, when I took the Hx off, I had disconnected that hose at the elbow at the front of the engine, and left it on the Hx to make it easier... but then decided to replace it with new).  Just glad it wasn't leaking at the flange.

Ran at the dock for about 45 minutes today and engine temp only got to just under 160, no leaks, and no real hot spots on the new riser -- looking alright.  I'm hoping to get out to give it a proper run tomorrow out of the marina to confirm everything is good before a planned 4-nighter this weekend  :D

photo is of the new riser just before I adjusted the wrap one last time and installed.
Title: Re: Replace Exhaust Riser?
Post by: KWKloeber on May 16, 2022, 04:10:31 PM
Steve

That’s purdy!!

That begs the question, are you getting hot water now?

Consider using ABA or AWAB hose clamps for any future work!

Bravo 👏 🙌 🎉 👍 👌
Title: Re: Replace Exhaust Riser?
Post by: waughoo on May 16, 2022, 04:36:16 PM
NOICE!!!  I am going to second Ken's suggestion on the better hose clamps.  I have seen a lot of hoses PRESSING through the serrations of the clamps that I decided to quit using them unless I had to due to inavailability.  That said, I wouldn't go in there and change them.  I still have some in my boat from before I decided to switch.  They will be just fine till I need to mess with those hoses again. 

Also wanted to know the answer about the hot water question.
Title: Re: Replace Exhaust Riser?
Post by: KWKloeber on May 16, 2022, 04:52:42 PM
>> T I wouldn’t go in there and change them.<<<

Actually (I didn’t want to throw out an arrow but) I would where subject to a wide temp swing (eg, Hx and exh.)
Even tho the hump hose may be more forgiving.

(Or use T bolts on the exhaust.)

I’ve seen broken M25 Hx mounting clamps due to the expansion (that’s why Seakamp supplies T-bolts for its M25XP Hx brackets.)
Title: Re: Replace Exhaust Riser?
Post by: Sailing Sirona on May 16, 2022, 05:38:14 PM
thanks for the notes on the clamps - I'll look at getting some.

In terms of hot water, I checked today and I had tepid water (definitely warmer than the cold)... I'm double check when I'm actually cruising and the engine temp does get a chance to get up to full op temp for a while, and enough time to heat the full tank.  Both of the hoses on the loop were hot.

When I turned on the water heater on the AC panel when I plugged in to shore power I got good hot water!
Title: Re: Replace Exhaust Riser?
Post by: KWKloeber on May 16, 2022, 08:43:03 PM
Steve

UltimateGarage.com is a reasonable source for ABA clamps w/o the marine tariff; and Steve’s a good guy. 

In BC you probably won’t see more than 160 (“get up to full op temp”) with the lower temp Tstat (freshwater boats can use the higher Tstat.)  It’s just a matter of transferring BTUs from a small flow to a big tank of water, and of course, depends on the ambient temp of the water! 
But at cruising rpm there’s greater volume of coolant (heatant?!) going thru the WH so the water remains in contact w/ hotter coolant throughout the length of the WH coolant coil.  In other words, say the input is 160 and after transferring heat the return is 130.  With high flow the input may still be 160 but the return might be 155 so each minute more BTUs are transferred to the water. (Those aren’t actual numbers! just concepts.)
Title: Re: Replace Exhaust Riser?
Post by: Ron Hill on May 17, 2022, 03:17:58 PM
Steve : On the M25XP engine, I found that you had to run the engine for apparx 30 minutes @ 160F to get hot water from the tap.

A thought