Overheating after freshwater conversion

fc3 said:
You mean suggestions other than pulling that system off and going boating? The boat is six years old. Installing closed cooling is darned near pointless. The only good it's doing is keeping you from wasting a lot of gas by going for boat rides the past few weekends.
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Yes, other suggestions please.

The engine was 6 years old but with only 16 hours on it. It's unlikely you'll find a newer '04 260 DA anywhere. Heck boat still had plastic on parts of it from the factory when I got it. I just want to do my best to preserve my investment (if you can call a boat and investment) and take good care of it.

Can you 100% guarantee that I won’t still have the problem after I take off the exchanger?

If we run out of options it’s coming off, but not with out a fight.

Thank you for your opinion though

Sincerely,
 
Personally, if it were me I would pull it off now and then test it again. If the problem goes away then for sure it is the FWC system and you have concrete proof to take back to the company who sold you the system. Maybe the heat exchanger itself is inadequate or somehow constrictive.

Dave
 
Dave S said:
Personally, if it were me I would pull it off now and then test it again. If the problem goes away then for sure it is the FWC system and you have concrete proof to take back to the company who sold you the system. Maybe the heat exchanger itself is inadequate or somehow constrictive.

Dave
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Et tu Brute? :smt001 I just left a message for and sent an email to my contact at Monitor Products the heat exchanger manufacture. Lets see what they say.

There has to be something easier to test, try or check on the freshwater side before ripping out the exchanger, no?
 
Nope, that's my suggestions and I'm sticking with it. My previous boat was a 26' with a single 350 CID V8, Alpha drive, and raw water cooling. Never flushed the engine except for at the end of the season during winterizing. Bought it new in 1987 and traded it in 1999. Never had an engine problem I saw it a few years later. The next owner wasn't taking care of it, but he said that it was still the same engine.

Closed cooling is nice. But I don't think it is worth as much down time as you've experienced. Hope your mechanic isn't charging you by the hour.

Best regards,
Frank
 
If there's a design flaw that's not flowing coolant through the engine properly there's nothing you can do. Maybe at some point you should throw in the towel, remove it and send it back.
The proper Mercruiser kit isn't looking so expensive now I bet...
Sorry you're having all this grief... your mechanic is probably starting to have bad dreams about your kit too! :lol:
 
Hornblower said:
There has to be something easier to test, try or check on the freshwater side before ripping out the exchanger, no?
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As far as the closed cooling system itself goes, you said your mechanic tested the fresh water temperature going into and out of the cooler itself and that looked OK. One question I would ask your manufacturer is what kind of temperature rise should you see (input side to output side)? After all it isn't called a heat exchange for nothing meaning the temperature of the fresh water should be higher coming out of the cooler. If that is within specs you have no other choice than to go back to your original setup and see what happens. If that fixes it then I would ask for a refund if it were me and forget about closed cooling.

I have not had the experience Frank has had but what he says makes a lot of sense to me. The things that are attacked the most by salt water are your risers and elbows. Don't forget even in a closed cooling system these things still have salt water running thru them so it is no different than your original set up in that regard . So, only the engine itself has anti-freeze running thru it. And if you don't change the antifreeze regularly it becomes acidic as well and can cause corrosionl. And now you have added a heat exchanger that has salt water running thru it so it is one more thing to fail from salt water corrosion and need replacing. Risers. elbows and manifolds, likely need replacing about every five years in a salt water environment. That heat exchanger may or may not last any longer either.

Dave
 
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I don't agree Dave, at least with the Mercruiser FULL FWC cooling kit, the block, exhaust manifolds and the 3" (3" in my case) risers have coolant running through them. Only the elbows have salt water running through them.

The Mercruiser heat exchanger is made from phosphor bronze and has a proven long life in hot salt water. The only problems I have seen with the heat exchangers have been no earthing causing electrolysis (earth straps need to be installed) and getting plugged up with sand and mud.

As I said in my post above, the heat exchanger I'm running was for the 350 (5.7l) and now it is cooling a 383 CID. My temperature gauge never goes over 170 no matter what the throttle setting, but I do admit that if pull the throttle off suddenly down to idle, the temperature will climb to 200. That said, I have never had the alarm go off.

The reason I went for FWC was purely economics. A set of manifolds, 3" risers and elbows are in the $3000+ range here in Australia, and you are lucky to get 3 years out of them here in tropical salt water. Where as the FWC kit cost me just under $1100. I expect the life of the manifolds will be now the same as the block. Elbows, I can import them from the USA for $140 all up, where manifolds from the USA draw $500 in freight each. (I guess it is the weight)

I would say there has been a design fault or Steve has the wrong HEx for his motor. I think I would be going for a refund and if FWC is required, I would go for the Mercruiser kit. I know it works.
 
Chris............I do stand corrected on my comments concerning the manifold risers and elbows. I looked up the kit he used on Monitor's site and it says the following:

COOLING SYSTEM TYPE
Full system: Engine block and exhaust manifold on fresh water system. Exhaust elbows remain on raw water system. System utilizes a new, unique, high performance heat exchanger, with built in, full flow, bypass control thermostat ensuring optimal jacket and exhaust manifold water flow under all operating conditions.

I assumed this system was a block only kit (which a lot of them are). Sorry.

Dave
 
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Hi Dave, I just read your previous post again, I missed a few of your points, getting tired, it's 1AM Sunday morning here.

I guess I'm always sus of things that have the claim
"high performance heat exchanger,
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Usually the parts are made out to be better than they really are !

Anyway, lets hope Steve gets it sorted. :thumbsup:
 
I just spoke to one of my mechanics, I actually have two, both great guys. They’re following this thread and they’re not ready to give up. “We don’t want to be defeated” is what one of them just told me. I don’t have the details about all the things they’ve tried since yesterday, but for sh*ts and giggles as I write this they’re hooking up the raw water pickup to the black water macerator outlet thru-hull. We’ll see if the larger less restrictive (1.25” I believe) plumbing will improve the situation.

I’m going to swing by the Marina a little later to get the scoop.

Thank you again for all your ideas, opinions and thoughts.

Here's the Monitor Heat Exchanger in question:
MonitorHeatExchanger.jpg
 
Stopped at the marina late afternoon on Saturday, my mechanics had connected the raw water pick up to the thru-hull used for the holding tank, but between sloppy weather from Earl on Friday afternoon and being shorthanded on Saturday they didn’t have a chance to test it. So on Sunday after spending the afternoon with the family on the hook in Moriches Bay at a nearby island and favorite clam bed (about 1.5mi from marina) I dropped off the wife and kids at the marina and I resolved to put it to the test.

It was about 6:30PM when I headed out, the tide was up, the wind died down and whitecaps subsided. To get the heat up from the 154 deg I started at, I put the throttle up around 4,500, when I reached 168 degrees (less than 2 min later) I throttled back to 3600RPM where for consistency I do most of my testing (and where I’d keep the throttle if I could actually cruise without issue:smt089). For those of you familiar with the area I headed west to Smith Point bridge about 9 Statute miles away.

The temp slowly climbed and hit 174 after 15 minutes and stayed there for another 10min or so until I reached buoy #2 just before the bridge. I came off plane and took only 10 seconds to lower the throttle to idle (600RPM). As expected the temp proceeded to climb but this time only to 190 degrees. I stayed there for about 3 minutes and then started to drop. All in all I’m thinking this was quite an improvement. Here’s the thing though, the bay temperature was 69 degrees. The last time I went that far about 4 weeks ago the water was around 82 degrees and at 3,500RPM the engine temp was 188 degrees and still climbing.

Since this issue has been going on for a while, when I’m on the boat if my eyes aren’t on the water they’re on the temp gauge. So I’ve come to understand that this setup is particularly sensitive to the raw water temp. What was different this time is that the engine recovered at idle speed with 69 degree raw water, without reaching 195+ or the temp alarm sounding.

The return trip wasn’t as impressive. I idled under the bridge, spun around to go back. Clear of the bridge I jumped up on plane and held her at 4000 RPM. The temp gauge quickly jumped from around 170 up to 185 degrees where it stayed for the 20 minute trip back to the marina. Correct me but I think 185 is nearly 10 degrees more than what you’d probably like to see?
I then came off plane taking a full 30 seconds to slowly reduce the RPM’s to idle. The temp climbed hit 195, the overheat alarm went off, I quickly put her in neutral, and raised the RPMs to 2,500, the temp dropped and alarm stopped in 3-4 seconds.
BTW 2,500RPM seems like a sweet spot for cooling.

So it appears that a thru-hull may help but clearly not enough to make it acceptable. I don’t know what else my mechanics have up their sleeves, or if Monitor Products can be of further help.

Any thoughts? :smt017

I should take a vote:
How many of you say I should yank the heat exchanger out?
How many say I should keep pulling my hair out and try something else? :smt021

I truly appreciate your help and support.
 
I feel your pain. I am having the same exact problem with my boat. 2006 240 Sundancer w/ 5.0 MPI Bravo III, 200 hours. I do not have a freshwater conversion. This just started at the end of July. Boat has been in and out of the shop since, and is going back tomorrow.

Here is the list of things done to date:
1. back flushed entire system
2. new raw water impeller
3. new pick up hose in outdrive
4. new raw water pump housing and another new impeller

Still no fix!

Please let me know when you get yours fixed and I'll do the same.

John
 
Temp sensor location!!!!!! get a temp probe non contact and do the readings. when you got your kit it should have had a pic of the system make a few copies to write on and probe temps and record them and submit to the company and you most likely find that temp sensor needs adjustment or relocation. I beleive someone else stated this.
 
Hey John yours sounds like a collapsed hose (rubber hose heat and a bend) not a good combination copper elbows are time consuming but great in fresh water systems.
sorry Hornblower I do not want to high jack your thread
 
I like the idea Chris posted if you're determined to have closed cooling. Get the Mercruiser kit. Mercury does engineer their stuff down to a price, but it generally works.
 
eman369 said:
Temp sensor location!!!!!! get a temp probe non contact and do the readings. when you got your kit it should have had a pic of the system make a few copies to write on and probe temps and record them and submit to the company and you most likely find that temp sensor needs adjustment or relocation. I beleive someone else stated this.
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Good suggestions but we checked them with the temp gun as I posted earlier in this thread "the gauge on the dash matched the temp at the heat sensor."
 
fc3 said:
I like the idea Chris posted if you're determined to have closed cooling. Get the Mercruiser kit. Mercury does engineer their stuff down to a price, but it generally works.
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I'm losing my resolve and I'm not as "determined" to be FWC. But I agree with you I don't know if the Mercruiser kit is the best or not, but you know it'll work.

Hindsite is always 20/20:smt119
 
eman369 said:
Temp sensor location!!!!!! get a temp probe non contact and do the readings. when you got your kit it should have had a pic of the system make a few copies to write on and probe temps and record them and submit to the company and you most likely find that temp sensor needs adjustment or relocation. I beleive someone else stated this.
Click to expand...

I had that issue on my 240 but this kit has the temp sensors in the original location still... although it does relocate the t-stat itself up to the exchanger.
Something's way off here... like they sent the wrong kit for wet joint exhaust and the flow pattern is disrupted... maybe not that but... I'm guessing now... thinking out loud.:huh:
 
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