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 Post subject: W50 high heat
PostPosted: 22 Nov 2016 09:40 
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Skipper

Joined: 24 Sep 2013 09:20
Posts: 393
I've read everything I can on the forum and also the tech section about trouble shooting. Couple of questions for advice. Before we left cruising, I noticed temp gauge creeping above 180 if over 2000 RPM. So, before we left, I checked the impeller, removed the raw water pump, inspected, checked flow, back flushed the raw water circuit as shown in tech section, inspected the heat exchanger (didn't appear bad and also when flushing pump and circuit didn't notice any bad sediment or blockages coming out. all was normal), replaced the engine belts (retensioned and no slipping that I can see), replaced a couple of hoses that looked worn, scraped out exhaust elbow and seemed free of obstruction to begin with, changed out zincs, put everything back together making sure to line up cap on heat exchanger, cleaned raw water strainer, removed hose and pumped salt deposit remover and fresh water through system, flushed with fresh water and left with fresh for a week. When we left cruising, it seemed a little better, but temp still seemed to rise ever so slightly above 180 if I went over 2000/2200. Read on forum some saying that they have to run between 1800-2000 mostly and thought maybe that was just me too.

Now, a month into cruising, I look down one time and see the gauge near the mark between 180 and 230 (guessing this is 200 since the gauge seems to count by 40 with a mark in between each 100, 140, 180. not sure why it jumps to 230). Never seen it that high before. I was running between 2000 and 2200 fighting current out of Naples, FL. Reduce RPM, temp comes back down to 180 or just over. I haven't tested to see if temp holds steady under 200 if continue at 2200 to 2400 because worried about damage.

Question:
Are these temps bad or just a little higher than normal? Is over heating anything over 180 or is over heating when alarms start going off and temp is climbing without signs of stopping?

Some other observations:
Water temp at exhaust is hot. meat thermometer read about 150 holding it in the stream best I could although couldn't hold my hand there easily due to heat.
Water flow at exhaust is about a gallon in a minute at 1200 RPM (engine RPM, not necessarily pump RPM) measured by holding a container. I have the Sherwood pump. It doesn't appear as water is gushing out like crazy, but I can't tell any more and also can't find any reason that it would be diminished flow. Anyone know if that is the correct rate?
Water hoses going into galley hot water heater get hot making me think I flow there and nothing to suspect an air lock.
No noticeable leaks anywhere.
Nothing visually wrong with my expansion tank cap.
I haven't checked or changed thermostat or coolant yet, but I have absolutely no leaks in that system that I can find. Correct level has stayed the same for years. I know I am due a coolant change, but from what I've read the old coolant won't affect it's cooling properties. Can I check the thermostat without draining the coolant? (I'm at anchor and would like to keep things simple at first if possible).
I haven't jumped in the water yet to check for obstruction of the intake, but I just had bottom scraped and the guy said it looked good, and I do have flow. Just not sure if its the right flow.
I even added a little oil since I've got nuisance leaks but dip stick has never shown low.

I'm at anchor and don't want to start pulling everything apart...yet. Can anyone read all my info here and tell me what I might be dealing with...if anything? How do you know if a raw or fresh water pump has gone bad? Visually nothing looks wrong when they run and no strange noise or anything. Please ask away if any questions about things I may have left out.

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Zach Duncan
SV Holiday
Hull# 280


 
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 Post subject: Re: W50 high heat
PostPosted: 22 Nov 2016 09:43 
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Skipper

Joined: 24 Sep 2013 09:20
Posts: 393
One other thing, no idea of my prop specs, but this is a new issue with the same prop that I used to run at 2500 for many many hours and not go over 180. Only difference would be more weight in the boat since we are now loaded down for cruising.

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Zach Duncan
SV Holiday
Hull# 280


 
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 Post subject: Re: W50 high heat
PostPosted: 22 Nov 2016 14:10 
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Skipper

Joined: 24 Sep 2013 09:20
Posts: 393
Thermostat removed, here is the inside of the housing. Looks pretty good to me, I guess this is a sign of things being generally good in the fresh water circuit. Tested thermostat in water. Began to open at 180, but not fully opened until higher temps. Found a spare on the boat from previous owner (looks new) seems to open at same rate.


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Zach Duncan
SV Holiday
Hull# 280
 
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 Post subject: Re: W50 high heat
PostPosted: 22 Nov 2016 15:02 
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Skipper

Joined: 16 May 2009 08:06
Posts: 236
In my opinion, anything over 180 is an indication of a problem. I should clarify by saying that I never run above 1800 and I don't think I get much above 2000 at wide open throttle. I think my prop is a bit large but I have over 6,000 hours on the engine, it starts up just fine and it doesn't smoke or anything (watch what happens this spring now that I have committed that to writing!).

I also think that 1 gallon per minute is light and the exhaust water should not be too hot to hold your hand in. I suggest that you have some kind of obstruction somewhere. When mine exhibited the same symptom, years ago (decade actually), the culprit turned out to be a piece of engine zinc that was lodged in the syphon break. I have the Jabsco pump that is mounted backwards so you have to get in the quarter berth locker to change the impeller. It seems like the heat is getting into the raw water system, there just isn't enough raw water to take it away as fast as need be.


 
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 Post subject: Re: W50 high heat
PostPosted: 22 Nov 2016 17:51 
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Skipper

Joined: 21 Oct 2006 15:36
Posts: 268
Do you know the prop size and pitch? My boat came with a 2 blade 16 in x14in pitch. Think that may have been standard out of the factory. In my opinion it was way over pitched. I couldn't get the engine above 2500 rpm without the engine overheating. I reduced the prop pitch to 11 in, and now I've never had overheating. You may have the same problem if you never ran your engine above 2500 rpm with a lighter boat. I've also had my raw water heat exchanger a few times. Even when the hx looked good a cleaning also helped. Also, take out your raw water pump and check the discharge elbow for blockage. Found impeller fins jammed in mine.

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Jim Voelxen
Odyssey #191
Home Port: Osterville, MA


 
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 Post subject: Re: W50 high heat
PostPosted: 22 Nov 2016 20:24 
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Skipper

Joined: 24 Sep 2013 09:20
Posts: 393
Going to sea trial tomorrow after changing thermostat. If doesn't change, guess I'll start searching for obstruction. I'm only going about 5 knots or so at 1800 in most conditions. Upper 5s to 6 at 2000. Don't get to high 6s/7 until 2400. I don't know my prop size and pitch. Mine is a 3 blade that was installed within the last 5 years. Will it be marked on it? I just took the whole raw water system apart and flushed it about a month ago. No obstructions found, including all the places people are mentioning.

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Zach Duncan
SV Holiday
Hull# 280


 
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 Post subject: Re: W50 high heat
PostPosted: 22 Nov 2016 21:59 
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Midshipman

Joined: 15 Jan 2010 16:13
Posts: 54
I had similar problems with my W-50 a few years back. Tried many of the things you mentioned, including replacing thermostat, flushing system, replaced leaking raw water pump, belt tension, etc. Nothing seemed to help. Finally I bit the bullet and replaced the heat exchanger. A bit of grunt work involved as it requires removing the manifold too. But that did the trick. Can run now at 2400 rpm or better if needed and temp never goes above 180-190.


 
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 Post subject: Re: W50 high heat
PostPosted: 23 Nov 2016 15:37 
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Skipper

Joined: 21 Oct 2006 18:12
Posts: 325
I agree that 1 gallon per minute is not enough. Have you checked if the nipple where the seawater gets injected into the exhaust elbow is totally full sized and not partially blocked? I had to ream mine out with a drill bit until I finally changed my elbow a couple years later. A bit of blockage can put more back pressure on the system which would slow down the flow rate. Also check the water strainer and the outside for blockages.

Richard


 
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 Post subject: Re: W50 high heat
PostPosted: 24 Nov 2016 08:19 
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Skipper

Joined: 24 Sep 2013 09:20
Posts: 393
Found it. The short piece of hose between the heat exchanger and the oil cooler and the orifices it hooks to on the exchanger and cooler were gunked up. I hadn't changed that hose because it looked decent, was hard to access, and all other hoses, exchangers, and elbows had been clear when checked or replaced. Guess that hose had been there longer than everything else due to the difficulty in changing. Hose is changed, flow is increased, and I'm motoring out of Marco Island heading for the Everglades then the Keys next. Engine temps at 180 up to 2500 rpm. Happy Thanksgiving Tartan group. I'm thankful for all the help I get on this forum. Check out our cruise at www.funonholiday.com.

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Zach Duncan
SV Holiday
Hull# 280


 
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 Post subject: Re: W50 high heat
PostPosted: 26 Nov 2016 11:41 
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Skipper

Joined: 29 Dec 2006 09:38
Posts: 656
Good you found your problem. I recall that the oil coolerf on my old W50 was much more likely to gunk up than the main heat exchanger. The other thing I would alert the group to is the fact that exhaust elbows do not last forever and it is probably not especially good to delay changing them out if you are going out cruising. I recall taking mine apart before I had a problem and finding it about 50% blocked. I think I had about 3000 hours on the engine at that time. I attribute the early demise of my otherwise well-maintained W50 to my failure to change out the exhaust elbow earlier.
Ray Durkee
T37 #373


 
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