About heat exchanger

[newskipper]

Hello everybody,<br /><br />I have bought a 4-years old Bayliner 2859 (Mercruiser 7,4). All four years, she was in fresh water only but now she will go into salt water and will be used in salt water only. The engine has raw water cooling and the mechanic recommends installing a heat exchanger. <br /><br />The manufacture does not install heat excanhagers and as far as I know makes the engines corrsion resistant to certain extent, which leads me to the question: is it really that important to have a heat exchanger? <br /><br />Will there be any serious damage to the engine if I use it 100 - 120 hours per year without the exchanger? Not sure how long I will keep the boat.<br /><br />Thank you.

 

[WillyBWright]

Re: About heat exchanger

After the first few months of use, installing closed cooling became a tough option. That block is rusted inside now and the rust will flake off and clog the heat exchanger on a fairly regular basis severely limiting it's ability to allow enough water to pass for adequate cooling. The only way to get it all out is to dismantle the block and have it thorougly cleaned. In most cases, that's not much of an option either.<br /><br />Closed cooling in saltwater is vital to the longevity of a motor. Just like in a car, the coolant prevents corrosion (rust) from forming. Saltwater corrodes the internal cooling passages much worse than freshwater, but freshwater corrodes them too. I'm afraid that after 4 years without protection, the closed cooling option really isn't an option anymore. Frankly I'm dismayed that a mechanic made that recommendation. Kinda makes me question his qualifications (unless he's not a Marine mechanic and doesn't know any better, or is speaking theoretically).

 

[Bondo]

Re: About heat exchanger

Will there be any serious damage to the engine if I use it 100 - 120 hours per year without the exchanger? Not sure how long I will keep the boat.<br />

I'd go ahead,+ Install the H/E...... Freshwater run motors Don't Rust anywhere near the amount of a Saltwater cooled motor..... I don't think the alarm that Willy raises is warranted......<br /><br />It's got Nothing to do with the amount of Run-Time........ Even when the boat is sitting, the Saltwater is Rusting your motor Away..........<br /><br />The Expence will be Recoverable when,+ If you decide to Sell................<br /><br />Personally, I think you'd be Nuts to Not install the Closed System....................

 

[newskipper]

Re: About heat exchanger

Thank you!

 

[newskipper]

Re: About heat exchanger

Hello everybody,<br /><br />Thank you for the previous advice. Could you please advise whether there is any practical difference between Mercury, Orca and Seakamp heat exchangers? Or it is the same stuff under different names?<br /><br />Thank you!

 

[WillyBWright]

Re: About heat exchanger

Never had any experience with aftermarket systems. None of the shops I've ever worked for would accept that job on a boat beyond the first season, freshwater or not. Since you're obviously going to do it one way or another, it would be wise to install two gauges, a temperature gauge and a water pressure gauge. If it starts to clog and get hot, they'll tell you before it's too late. Overheat alarms are nice, but sometimes the damage is already done when they finally sound. Naturally, gauges are only useful if you keep an eye on them. I should add that you should be prepared to do frequent coolant changes, at least at first. The coolant is going to get real cruddy real quick the first several hours. Ask your mechanic to flush the motor real good before installing it. He should run it with the block and manifold drains out to get the sand and rust flakes that are already in there outta there. If you've ever drained a motor for winter, you'll know what I mean.<br /><br />Addendum: I lied, I did work for a shop that would do anything on any boat, charge an arm and a leg, and never stand by it. I think I was able to stomach about 6 hours, then I was outta there. I'd mention the place, but his wife works for an ambulance chaser. Her husband is a regular client judging by the number of court cases with his name on them.

 

[waterone1@aol.com]

Re: About heat exchanger

Newskipper,Sorry that I can't offer a suggestion on which aftermarket exchanger to go with. I did want to throw in my two cents worth in favor of installing a heat exchanger system. Salt water tears up engines far worse than fresh water ever could. It would have been ideal for your engines to have them since day one, but since that isn't the case....install one now ! Yes, you most likely will have to clean it out a time or two....ok, maybe three, but the long term benefits will be worth it.

 

[qystan]

Re: About heat exchanger

Newskipper<br /><br />I have a 89 5.7L raw water cooled run in saltwater all its life but flushed after each use, which at max is 2 or 3 days each go. I hear from mechs that the block is really tough and has never been a real problem with corrosion but the cylinder heads do see a fair number developing cracks. Merc is really an idiot to have raw water cooled engines. <br /><br />Personally, I will fit a FW system.<br />1. The rust flakes that come off regularly clogs the exhaust, risers, thermostat and do nothing but give u maintenance work.<br />2. Kepping corrosion at bay is always best. With the bits constantly falling off you never know when its time. Why live with this variable?<br /><br />The only reason I have not fitted one is the same Billy and its really too old to be able to ever get the cooler to stop clogging.

 

[newskipper]

Re: About heat exchanger

Guys, thank you so much!

 

[newskipper]

Re: About heat exchanger

Thank you everybody for the advices.<br /><br />Willy, do I understand right that since I have temperature and water pressure gauges install in the dashboard, I do not need additional on the engine?<br /><br />About “coolant changes”. How should I check its condition – just visually or there are some tools to do that? How often would you suggest: per trip; every 5/10/15 hours? <br /><br />I have chosen the Merc. stuff. Instructed the mechanic very thoroughly but anyway I have no means to check what he is actually doing. <br /><br />Thanks.

 

[newskipper]

Re: About heat exchanger

Hi,<br /><br />The mechanic started installing the heat exchanger to-day. I was a little in shock to see a sort of a small bronze intake installed onto the bottom of the boat for the sea water to get through the hole into the heat exchanger. <br /><br />It is probably OK but I feel like somebody drilled a hole in my skin ) Is it OK to install it this way?<br /><br />Thank you.

 

[WillyBWright]

Re: About heat exchanger

Does that have an Alpha drive? If so, you're water used to pump from the drive. That would be adequate for a small largeblock, but I can see where it might not be enough for a heat exchanger. They must need to mount a belt-driven water pump inside the boat. Now you'll have two water pumps. It's important to keep up maintenance on both. Obviously the new one to cool the motor, but the old one in the drive to cool the drive. There won't be any kind of warning if it goes bad and a bigblock on an Alpha can turn the gearlube pretty black pretty quick if the drive gets hot.<br /><br />Check the coolant once in awhile. If it's dirty, it'll be apparent. If orange antifreeze is used, it'll be a bit more difficult to tell cuz the green stuff turns downright ugly. I'd do it once after 10 hours on the motor automatically, then at the end of the first season, and as needed after that. The first time or two the heat exchanger should be removed and flushed thoroughly. The gauges on your dash are all you need.<br /><br />I Know what you mean about the hole. Whenever I rig a new boat, one of the first things I have to do is drill holes in it. Seems kinda counter-productive, don't it?

 

[yoced]

Re: About heat exchanger

I can't say much about the aftermarket heat exchangers, except on a personal note: I can tell you that Kathy and Clark at Seakamp are some of the nicest people you could deal with. This becomes important if you are doing your own work and need someone to talk to...

 

[Don S]

Re: About heat exchanger

The 7.4's did not come with Alpha drives in 96, they are all Bravo.<br />Why your mechanic put a thru hull pickup is beyond me. The drive pickups work fine, and is what is used on all the big blocks.

 

[newskipper]

Re: About heat exchanger

Thank you.<br /><br />It is a Bravo 2 drive. The whole is really confusing to me though it looks like that the bronze filter is a part of the kit, which porobably means it must be installed on the bottom. <br /><br />I do not see a single boat (among those sitting on dryland) having such a filter though and a hole. Could it be that it depends on the kit components?<br /><br />Could it be they are doing something wrong? I mean the hole.<br /><br />Thank you.

 

[Don S]

Re: About heat exchanger

I do not see a single boat (among those sitting on dryland) having such a filter though and a hole.

That is because it's not needed. As I said before, the Bravo pickup is plenty for the engine with FWC.

 

[newskipper]

Re: About heat exchanger

Don, thank you.<br /><br />Should I live with the hole or ask them to remove the filter and use the drive pickup? What is your opinion on that?<br /><br />Thank you.

 

[newskipper]

Re: About heat exchanger

Don,<br /><br />Mercury Marine and two their authorized dealers they refered me to upon my request confirmed that the hole is required for the engine working in the sea water. <br /><br />Thank you for your advice anyway.

 

[Don S]

Re: About heat exchanger

Then why are you asking all the questions if you already have the answers you want???? You even mentioned there were no other boats like that in the yard. So why suddenly does your particular boat need it when none that I have ever come in contact with need it?<br />I also work at a Mercruiser dealership. I have never seen any installation manuals, or service bulletins saying the thru hull water pickup is necessary.<br />Sorry, but I will not be going out and telling all the people I know with 7.4L engines and Bravo drives that have fresh water cooling, that they need to cut a hole in their hull for a water pickup. Nor will I tell the ones running the diesels, both Merc and Yanmar, that are using through the drive water pickup with no problems.

 

[newskipper]

Re: About heat exchanger

Don,<br /><br />First of all, I really appreciate your advice and desire to help. <br /><br />I did not have answers to the questions. I called to Mercury Marine and the dealers only after reading your reply. <br /><br />As for the boats in the yard, firs of all it is not a factor, is it? I met the mechanic who did the installation to-day afternoon and he was going to show me quite a number of boats with the same type of installation. It looks like I did not check this close enough, which I regret. But again, whether there are boats with this type of installation or not, it is not a factor yet.<br /><br />“I have never seen any installation manuals, or service bulletins saying the thru hull water pickup is necessary.” – I cannot dispute that but at the same time I cannot question opinions of various pros like yourself who were talking to me today. It looks like the opinions could be different. Probably the advice from Mercury Marine could be the most important factor.<br /><br />But it was convincing enough, which resulted into calls to two authorized dealers. Why not convincing? A lady over the phone could hardly understand my question. She wrote everything down and called me back 10 minutes later. Her advice did not sound convincing enough. I am not sure that she took into the consideration the drive though I advised her on that.<br /><br />Don, I cannot argue with you about technical part as I do not understand about the stuff. I only provided the opinions of the people I was talking about the issue. Sorry but I really did not mean to be offensive but I believe it would be not right if I would not have provided their feedback.