Heat exchanger install

[Tiki91]

Installing older heat exchanger on my 5.7 with dry joint risers all the hose connections make sense except I don’t know what to do with the two upper hoses coming off the risers. Any ideals or just tee them into the lower manifold hoses.phots attached .

 

[Bondo]

Ayuh,..... Welcome Aboard,...... Ya shouldn't be puttin' an exchanger on a used motor,......

Crud in the motor will clog the uncleanable side of the exchanger in short order,....

 

[Scott Danforth]

unless the block is brand new, I wouldnt worry about a heat exchanger

the only way you can put a heat exchanger on a used block is as follows:
it was fresh water only its entire life, spending not a minute in salt water. brackish water, or high-mineral content water
you pull the motor apart, put it on a stand and mechanically clean the water jackets (I used a section of 1/4" steel cable on a cordless drill)
you completely re-plumb the motor

the heat exchanger you have wont work with the dri-joint manifolds anyway.

 

[Tiki91]

This is a fresh water boat with only a 180 hours .can I just remove and put plugs in the risers where the hoses were see photo.

 

[Bondo]

This is a fresh water boat with only a 180 hours .

Ayuh,..... That's 180 hours too many to convert now,.....

 

[QBhoy]

Waste of time. Not sure I’ve heard of one of these rusting right through the block...less hassle would be to change the exhaust and risers every 4/5 years if you’re fussy maybe ?

 

[kvkon]

Just put an exchanger on my 15 year old 4.3 MPI Mercruiser. Manifolds and risers are still raw water cooled. Runs cool, no issues after about 10 hours of run time.

 

[scoflaw]

Just put a seakamp CC system on my 20 year old engine RW cooled it's entire life and about 6 of those in salt. No problems after 70 hours this season. I will say there is a bunch of small brown particles floating in there and my block drains are plugged up, so I'll be flushing after the season is over. Runs dead nuts at 160* no matter what the speed

 

[Tiki91]

Thanks everyone but still don’t know where to plumb those upper riser exhaust hoses into. Which was the origin question.

 

[Scott Danforth]

you need to re-plumb your entire engine, you need a different thermostat housing in either case

if you are running a half system, the discharge of the HX runs into the manifolds, and then the manifolds are plumbed to the elbows and the water exits. the thermostat is plumbed similar to a car's system here.

if you are running a full system, the discharge of the HX runs to the elbows. a full system uses the thermostat as a mixing valve to regulate temp

however you cant clean the shell side of the heat exchanger, and installing a heat exchanger on a used motor means that you simply use the heat exchanger as a really expensive cooling system filter.

 

[scoflaw]

Depends if your HE is for a full cool or half. You will need the correct t-stat housing and depending on full or half you will need the right gaskets between the manifold and elbow.

 

[Tiki91]

This would be a half system. Engine block only.

 

[Scott Danforth]

with a half system, you still need a different thermostat housing and plumbing vs what came on the motor as raw-water cooled

for a half system

water inlet from drive thru PS cooler, thru fuel cooler to HX. then exit the two outlets on the HX thru the mainfolds to the elbows and out with the exhaust

engine side cooling is thermostat outlet to HX inlet. HX outlet to lower hose connection on motor.

fill line from the over-flow tank is teed into the lower hose.

vent lines from the back of the manifold go to the vent inlet in the deaeration section of the HX over-flow tank

your over-flow must have over 10% of your cooling system capacity for expansion/draw-down

However the discussions are futile since you have a used motor and you still need to pull the motor and mechanically clean the crud from the water jacket prior to installing a HX.

 

[Tiki91]

Thank you everyone since we are only fair weather boaters (May to oct store boat in winter on land)we will leave it as a raw water cooling system.flush out with fresh water.and if ever need a new engine would consider a HX at that point.thanks again I learned a lot.