Running warmer and possible exhaust leak

[noworries]

Before I replaced the sherwood water pump with the ode, the boat would cruise at 180F.
Now if I'm at cruise she creeps up to 190 or so... almost 200F.
Seems like I might be seeing steam in the exhaust.
We were cruising under power and the wife said the back cabin (which was closed) smelled like exhaust.
So my guess is that I've got an issue with my exhaust.
Another note is that I haven't replaced the zinc in the heat exchanger yet (had the boat a year... I know... I'm stupid)
So I'm guessing I've got a date with the heat exchanger and the exhaust riser?
I know a lot of people say the ode pumps less water, but I don't think the problem is lack of water.  I'm guessing I'm just seeing another problem sooner because the symptom isn't being masked as well anymore.
We've got two races before I'm going to start tearing in to anything.

[Jim Hardesty]

I would say that the first, easy, and most reassuring thing to look at would be the water flow from the exhaust.  I would not use the boat at all if I suspected an exhaust leak.  It's not that hard to check for and not finding a leak would be well worth the short time spent.
Jim

[Roland Gendreau]

When you are replacing the pencil zinc, remove the heat exchanger end caps and check for any debris that may be limiting water flow, such as pencil zinc pieces.

[Les Luzar]

Noworries,
I would also first observe the flow of water out of your raw water cooling system. You should observe and learn what this flow looks like on your boat when operating properly, so that you have a comparison in your mind. Also, does your temperature gauge indicate lower engine temps at sustained lower RPM? Or is the temperature higher now at low RPM's too, with your new Oberdorfer? Higher RPM's mean higher engine loads and this may affect engine temperatures with reduced raw water cooling flow. If your engine is running higher temperatures all the time, this may indicate a water flow blockage, either something sucked into your intake throu-hull, or perhaps a blockage beginning in one of your hose elbows. or an issue with your water pump (impeller, seals, etc).  A dock neighbor of mine with a 1996 C-34 Mk II had a new engine installed and within three years, his HX output elbow (on port side of HX) became completley clogged with calcification. It was amazing to me that this could happen so quickly. I would start with these things, and see what you discover.

[Stu Jackson]

 A dock neighbor of mine with a 1996 C-34 Mk II had a new engine installed and within three years, his HX output elbow (on port side of HX) became completley clogged with calcification. It was amazing to me that this could happen so quickly. I would start with these things, and see what you discover.

It happens.  I continue to suggest that you REMOVE your HX at least once every two years if not sooner.  Salt precipitates out on that port of the HX and blocks it up.

[tonywright]

I had the same symptoms this spring. Clogged heat exchanger. 4 hours of paid mechanic time to unclog! (Comes of being to too busy to do it myself, and how the heck do you access it on a MKII anyway?). One day I'll work out how to remove the box around the back of the engine in the aft cabin.

Tony

[Ron Hill]

No : You seem to go from frying pan to fire!

It is impossible to eyeball gallons per minute flow from the exhaust, unless it's only a dribble.  
I'd  recommend that you remove the HX and take it to a radiator shop and have them boil it out. Then contact Glen Mar Marine (800)282-0123 and get new end caps and gasket kit. re assemble and reinstall and I believe that your temperature problem will tone down.  
Not surprised at the steam as you are only a few degrees from boiling! Check as there are two different thersmostates - the normal (lower temp) is 160.

As for your exhaust leak it may be difficult to find.  Here's what I suggest:
First - inspect the exhaust riser where it attaches to the exhaust manifold.  I'm not sure if your M35 engine has the same setup as the M25XP or if it is like the M35BC engine??  See if you can find some black carbon streaks.  
Second - run the engine and see if the palm of your hand can detect any exhaust leaks from the riser attachment to the engine all the way to where it joins the short exhaust hose that enters the muffler. Especially look at the connections and the elbow bends (there are welds under the insulation).
Third - if you still smell exhaust - remove the insulation and expose the entire stainless riser.

Good Hunting

[noworries]

Thanks for all the info.

I know I'm getting water because the ode pump is cold to the touch, and it's splashing out the back.

It seems to me when we got the boat we cruised at 160F, and slowly over time it went up to 180F.  Now with the new pump it's 190F.

I'll pull the HX after the next 2 races and boil it out, replace the zinc, etc.  Thanks for the tips on where to look for the exhaust leak.  Hopefully it's not something major.

[noworries]

I was hoping I can get some advice from somebody who's done this already so I can buy some parts ahead of time (if possible).

I inspected the exhaust where it comes off the engine, but it doesn't appear to be leaking there, although the first bit of insulation is a different color then the rest.  Not sure if that's heat or water related.

I found something that definitely does not look right.  It appears that the dry exhaust comes off the motor and goes to the muffler, where it is mixed with raw water.  Where the wet and dry exhaust meet at the muffler I've got a large buildup of salt around the dry exhaust side. 

Is that part of the muffler or some other part?  My muffler is a black small bucket shaped device with the hoses going in to the top of it.


exhaust by No Worries 29, on Flickr

[Stu Jackson]

It appears that it could be a potential failure of the nipple, the stem off the main exhaust riser where the water enters.

[Ron Hill]

no : As Stu said you probably have a crack in where the stainless nipple (from the raw water HX) enters the stainless exhaust riser.

You'll have to remove the riser from the engine and detach it from the muffler.  I wrote a step by step Mainsheet article on how to remove and replace it - What to do and the parts needed.  There has also been many posts on this very topic.

You might get lucky and just need that nipple rewelded, but you won't know that until you remove the riser and strip back the insulation and inspect it. 

The nipple probably was over stress because of the stiff wire reinforced 5/8"hose from the vented loop to that nipple (engine vibration). 
Had you changed to a nylon reinforces hose like I recommended (critical updates), the nipple weld would not have fractured.   

A thought

[DaveM]

When my temp has slowly risen on my M25xp it has usually been a sign that my exhaust water injection point was closing from corrosion products.
Hope this helps.
DaveM

[Ron Hill]

Dave : Thanks for your thought, but the exhaust port on a C34 is about 8" above the water line when the engine is not in gear.  
It's under the water line when the engine is running in gear, but then it's blowing exhaust gas and raw water out of it!
I replaced my exhaust hose and the port after 23 years and had no buildup inside. Our size exhaust port is 1 1/2" inside diameter!!

Also I changed out 2 stainless risers on the old engine and there was no buildup in either stainless nipple.

[DaveM]

I think I understand?  My idea was that when I have constricted hole size through the water injection into the exhaust mixing elbow my engine temp runs a little higher even though I can't perceive any difference out of the exhaust stern port. My exhaust stern port is also above water at dead stop and below water at cruising speed. I am assuming the slow temp rise over years was the corrosion choking the elbow water flow. When I have replaced the constricted water injection pipe the temp goes back to normal right away. Am I missing something?

Goodwinds
DaveM

[Ted Pounds]

Dave,
I was just about to post that I think Ron misunderstood you.  But then you beat me to it.