Heat exchanger install

I Want to put heat exchanger on my 5.7 mercruiser. got it figured out but don’t know what to do with the exhaust hoses to the risers?can I remove them and put a plug in the riser?see photo .Are the lower hoses enough for exhaust with a half cooling system? See photos.

Ayuh,...... Puttin' a heat exchanger on an already run boat motor won't work,.....

The crud already in the coolin' passages will plug the uncleanable side of the heat exchanger,...... it'll be junk in no time,.....

Tiki91 said:

I Want to put heat exchanger on my 5.7 mercruiser. got it figured out but don’t know what to do with the exhaust hoses to the risers?can I remove them and put a plug in the riser? see photo . Are the lower hoses enough for exhaust with a half cooling system? See photos.

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From what I see, you have exhaust manifolds with spacers/risers directly above them, and exhaust elbows directly above the spacers/risers.
You also have what is called a "dry joint" system.

Your new heat exchanger is equipped with a single "spent" seawater outlet that sends the spent seawater to a T style diverter/splitter fitting.
This T style diverter/spitter sends an equal amount of "spent" seawater to each exhaust manifold.


Your spacers/risers will need to be equipped with open gaskets (both under and above).

The single "spent" seawater outlet and T diverter/splitter fitting prevents the system from sending seawater to the manifolds and elbows individually!
You will feed the spent seawater to each exhaust manifold, where it will then move up through the spacer/riser (open gaskets), enter the elbow where it will eventually go out with the exhaust gasses.

Compare the above with the instructions that you received with the H/E kit.


As for installing a Closed Cooling System on a previously raw water cooled engine, yes..... there will be a few obstacles/challenges.
The largest obstacle will be previous rust scale coming loose and building up around the exterior of the H/E's tube bundle.....( I.E., the E/G (ethylene glycol) side. )
Rust scale in this area will eventually diminish the tube bundle's ability to remove engine heat from the E/G, possibly resulting in over-heating.


Suggestion:

After XX hours of run time, drain the heat exchanger and remove it from the engine.
Flush the E/G side with warm soapy water and dump the contents into a clean white 5 gallon bucket.
Repeat this!
Look for rust scale debris.
Neutralize the soapy water, and re-install.
Fill the H/E with the proper amount of coolant.
Purge any air from the system.


Run it, and repeat this process in another XX hours until you no longer see a threatening amount of rust scale debris.


This has been done successfully in the past.


Now when winterizing, you will drain the seawater side of the H/E and the exhaust system, along with any other components that require winterizing.



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What kind of boat? If it lives on a trailer, a closed cooling system is a waste of money. If it's a big boat that sits at the dock a lot, it's a waste of money. If the engine is more than a couple years old, it's a waste of money. If you have it in the water all the time and it's seawater or brackish, then it makes sense.
It looks like you've done your research, what benefit are you expecting from this installation? It is adding several points of failure and maintenance; proceed with eyes open.

Do you have pics of your engine? Serial number? This will help us know what you have.
The suggestion by Ricardo is not Mercruiser-specific...only generalization.

If you decide to go with a heat exchanger, try to find the kind with removable end caps. This will make your life a ton easier. This will let you clear obstructions either by simply opening up the ends and cleaning or in extreme cases you can run a cleanout rod thru the tubes from one end to the other.
Cheaper ones are simply brazed closed and if they get jacked up they're trash.

o2batsea said:

The suggestion by Ricardo is not Mercruiser-specific...only generalization.

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That is absolutely correct, and is why that was accompanied with:

Compare the above with the instructions that you received with the H/E kit.

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As for the comments about this being a "waste of money", that is not for any of us to say. If the OP wants to do this, has the budget and is prepared to take the preventative precautions, it can be made to work!

As for the H/E tube bundle interiors being serviceable, look closely at the ends of his H/E.
I see what appears to be the SJE style, center bolt, removable end caps.




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Bad idea! The exchange will clog with rust and overheat the motor. Trust me on this! Many have tried this and few have succeeded.

Jeff

Jeff, I must disagree with you.
Many have done this successfully.
However, the "KEY" is to do what I explained in my previous post #3.
It may require doing that two times.... perhaps three if there was a substantial amount rust scale.

Rick's correct. I modify my terminology to "useless spending".

Ita a mercruiser heat exchanger with both end being removable see photos.

Tiki91 said:

Ita a mercruiser heat exchanger with both end being removable see photos.

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Ayuh,..... 'n that only allows cleanin' the raw water side,.....

To clean the fresh water side, the bundle has to be unsoldered, 'n removed,......

.... and that only allows cleaning of the raw water side....

To clean the coolant side, the bundle has to be unsoldered and removed,......

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That is exactly why at XX hours (20, 30 etc), the Heat Exchanger would be removed and the E/G (ethylene glycol) side would be flushed out with hot soapy water and so on!

So yes.... if a person installs a heat exchanger on a previously raw water cooled engine, and then doesn't to this flushing, then sure, you're going to have trouble down the road!


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