How to Switch to Antifreeze Cooled Engine

[scatgo]

I just took a fast look at a 19sixtysomthing Sea Ray boat in great condition. It has a new 301 engine with very low hours. Unfortunately the water in Long Island Sound is like battery acid so I would like to switch it over so the seawater never sees the inside of my engine. I know I will need a heat exchanger and maybe different exhaust manifolds but clueless for the most part. any help on how to deal with this would be extremely appreciated. Thank You.

 

[Bondo]

Ayuh,...... What's a 301,..?? A 3.0 liter,..??

Ya can't, for various reasons. add freshwater coolin' to an already used motor,.....

 

[achris]

If the engine has been operated in any salt water during the last 50something years, you would be very ill-advised to fit a heat exchanger. Salt has already leached int the metal of the engine block, head and manifold. A heat exchanger will have more problems than it's worth.

I just checked the salinity of Long Island Sound (27-32g/L), same as most other part of the world. You'll be fine.

Chris.......

 

[racerone]

??--he said ----That the engine was new / newer with low hrs I believe.

 

[tpenfield]

Yes, how new and how low hours. 301 engine?

I guess 'we' need more information/clarification.

@scatgo - tell those people on LI to stop pouring battery acid into the water .

Generally speaking, once and engine 'sees' salt water for any length of time, enough rust and scaling can occur inside the engine block and manifolds to make it a BAD candidate for a closed cooling system conversion. Pretty much a judgement call on your part. I've done a closed cooling conversion on an engine that had 700 hours in FRESH water without issue. (but don't tell anybody )

There are closed cooling conversion kits ($1K ish) from SeaKamp, Orca, and maybe a few other companies. If you do the conversion I would recommend a flush of the engine/manifold cooling system with an oxallic acid solution, followed by a baking soda solution, and then fresh water purge. It will get rid of as much rust as possible.

 

[Scott Danforth]

if your motor was fresh water only, there may be a chance, however you do need to pull the motor out get it on the stand to clean out the cooling water passages

if the motor was ever in salt water, too late, rust is already forming on the insides of the block, and those rust flakes will come loose and plug the heat exchanger

whats a 301?

 

[matt167]

He says 1960 something Searay... A 301 is a Pontiac engine, which Pontiac was used in some marine applications, but not the 301 I don't think. I bet the boat originally had a Pontiac 350 or something and a 301 was dropped in to get it running. 301's can be had for free as they are generally worthless.

However this boat should be considered for fresh water only, with manifolds and things that are made of unobtanium. And then it's probably an OMC drive as well

 

[Lou C]

Even if used in salt water with raw water cooling you can get 15 seasons or more without major engine problems in the Long Island Sound region. Yes ideally closed cooling is best for longevity but I ran my old 4.3 in salt from 2002 to present; replaced heads in 2017 (cracked) due to an overheat back in 2013; at that time the block was still fine but the cooling passages in the cyl heads were getting eroded from salt water cooling. So I put a set of reman heads on the old short block and it’s still fine. So my guess is as long as you change manifolds & elbows when needed and figure on a top end overhaul at about 15 years of use you can make a raw water cooled cast iron engine last. Surely if I repower with a new engine I’ll put a half closed system on it. Things to watch for are water in the oil. An oil analysis picked up sodium in the oil (salt water) suggesting that the HGs were starting to leak. This was a year before the HGs actually blew, and 2 years after the original overheat. Ironically the engine ran fine with cracked heads from 2013–2016 till the HGs blew.

 

[Buzzsaw420]

He says 1960 something Searay... A 301 is a Pontiac engine, which Pontiac was used in some marine applications, but not the 301 I don't think. I bet the boat originally had a Pontiac 350 or something and a 301 was dropped in to get it running. 301's can be had for free as they are generally worthless.

However this boat should be considered for fresh water only, with manifolds and things that are made of unobtanium. And then it's probably an OMC drive as well

Ouch, some of us do like our OMC’s. Cheers.

 

[tpenfield]

whats a 301?

It could be a 302 with a bent connecting rod

 

[76SeaRay]

A potential problem (voice of experience based upon my Mercruiser Alpha One) making the switch to closed cooling could involve changing the exhaust pipes as well as the manifolds as the angles and position of the exhaust might change. Just a heads up....

 

[Reserector_]

Y'all are viscious! Why not give the OP the benefit of the doubt. A 301 is a Pontiac engine, and I have had the pleasure of owning one in a '79 Olds Delta 88 that was still running strong with 200K miles on it when I sold it.
No reason to doubt that it was used in a boat that I can see.
We can also give the benefit of the doubt concerning the low hours. That could be fresh water time by previous owner for all we know.

Now, why would one not be able to convert to a recirculating system and successfully flush the system with one of the chemical flushes that descale and derust automotive blocks? I have used such products on neglected vehicles with great success.
Once flushed, the recirculating coolant would contain anti-corrosive agents.

Maybe I am being overly optimistic, but I clicked on this thread hoping to read ways that it COULD be done.

 

[Rick Stephens]

Y'all are viscious! Why not give the OP the benefit of the doubt. A 301 is a Pontiac engine, and I have had the pleasure of owning one in a '79 Olds Delta 88 that was still running strong with 200K miles on it when I sold it.
No reason to doubt that it was used in a boat that I can see.
We can also give the benefit of the doubt concerning the low hours. That could be fresh water time by previous owner for all we know.

Now, why would one not be able to convert to a recirculating system and successfully flush the system with one of the chemical flushes that descale and derust automotive blocks? I have used such products on neglected vehicles with great success.
Once flushed, the recirculating coolant would contain anti-corrosive agents.

Maybe I am being overly optimistic, but I clicked on this thread hoping to read ways that it COULD be done.

The problem is the negative results are so common - negative being that it doesn't take much sand and scale to plug a shiny new HX. Been tried and tried.

If the motor is clean then there are no reasons not to convert other than number of digits in the cost.

 

[Lou C]

I doubt this is any Pontiac 301 engine, very unlikely to be ever used in a boat, if its a Ford/Merc I/O It could be a Ford 302, if an OMC same thing both used Ford engines then, in addition to GM, which could be a 302 (5 liter).
As far as putting a closed cooling system on a salt run inboard, you can't really understand how much corrosion there will be until you've run boats in salt. Fresh water you will never see this. Just an example, this is new vs 5.5 seasons exhaust elbow section of my old OMC manifolds....next is my old cyl heads with 15 seasons on them....

 

[Scott06]

Y'all are viscious! Why not give the OP the benefit of the doubt. A 301 is a Pontiac engine, and I have had the pleasure of owning one in a '79 Olds Delta 88 that was still running strong with 200K miles on it when I sold it.
No reason to doubt that it was used in a boat that I can see.
We can also give the benefit of the doubt concerning the low hours. That could be fresh water time by previous owner for all we know.

Now, why would one not be able to convert to a recirculating system and successfully flush the system with one of the chemical flushes that descale and derust automotive blocks? I have used such products on neglected vehicles with great success.
Once flushed, the recirculating coolant would contain anti-corrosive agents.

Maybe I am being overly optimistic, but I clicked on this thread hoping to read ways that it COULD be done.

I recently tried to clean the cooling jackets on my 65 Pontiac chasing some over heating issues. This was an engine that was rebuilt in early 90s (block hot tanked) has mostly sat over the years. I ran this product through it twice https://www.summitracing.com/parts/...MI8-XTq-PN9QIVBK_ICh2lwwUkEAQYAyABEgKzvPD_BwE
I did this twice flushing with water, refilling with water then running it for several days flush again and I know I didn't get it all out. Car does run cooler but its definitely not 100% clean.

The hard part was getting the scale out through the block drains which were 1/8 or 1/4" pipe plugs. With out taking out the core plugs and recirculating acid I don't see it being successful.

I've never run closed cooling but if I recall the passages in the HX are like 5/16 " or so? I would think even the rust inside a fresh water engine would be hard to remove.

 

[scatgo]

Yes, how new and how low hours. 301 engine?

I guess 'we' need more information/clarification.

@scatgo - tell those people on LI to stop pouring battery acid into the water .

Generally speaking, once and engine 'sees' salt water for any length of time, enough rust and scaling can occur inside the engine block and manifolds to make it a BAD candidate for a closed cooling system conversion. Pretty much a judgement call on your part. I've done a closed cooling conversion on an engine that had 700 hours in FRESH water without issue. (but don't tell anybody )

There are closed cooling conversion kits ($1K ish) from SeaKamp, Orca, and maybe a few other companies. If you do the conversion I would recommend a flush of the engine/manifold cooling system with an oxallic acid solution, followed by a baking soda solution, and then fresh water purge. It will get rid of as much rust as possible.

Less than 50 hours after he had the engine put in with new exhaust system. More info to come as I get it.

 

[Scott Danforth]

coming from a prior life were we built heat exchangers for Volvo Penta and Mercruiser (along with John Deere, Cummins, Cat and others).

the gap between the tubes in the bundle on a heat exchanger are between 0.02 inches and 0.040 inches depending on which tube size, and bundle spacing. the average is usually .031"

tube diameter is either 1/4" diameter with .020 wall, or 5/16" diameter with .028" wall. however the glycol side is the outside of the tubes inside the shell. some larger industrial heat exchangers use 3/8" tubes, however not the marine engines.

a typical rust flake is about .060" thick and about 1/4" inch by 3/16". these plug up the spacing between the tubes effectively plugging the heat exchanger on the side of the tubes you can not clean. no, you can not reverse water flow and flush.

the sand and rocks that come into the engine cooling system every time you run the outdrive into the muck is larger than .030" in diameter.

you can attempt to run a screen just after the thermostat and before the heat exchanger, however be prepared to overheat, wait 4 hours for the motor to cool down, pull the plumbing, clean the screen, then re-assemble while the wife is saying you should have called a tow

Less than 50 hours after he had the engine put in with new exhaust system. More info to come as I get it.

if the engine was run in freshwater only, you still need to clean the debris from the water jacket. this involves pulling the motor, putting the motor on the stand, pulling the heads, and manually removing the debris from the cooling passages. then sealing the motor back up

if the engine was run in salt water, dont even think of putting a heat exchanger on it. the damage was done.

 

[Reserector_]

OK. You'e starting to paint a picture. If I understand correctly, the sand and rust particles in a seasoned engine tend to clog the HX.
I still can't help but think that a new-ish block could be cleaned well enough, but you guys are the ones with the experience.

 

[Scott06]

Less than 50 hours after he had the engine put in with new exhaust system. More info to come as I get it.

One thing that seems to confuse some of us - please confirm what engine is in there you said 301, do you really mean 3.0 L as in three liter ?

 

[Scott Danforth]

OK. You'e starting to paint a picture. If I understand correctly, the sand and rust particles in a seasoned engine tend to clog the HX.
I still can't help but think that a new-ish block could be cleaned well enough, but you guys are the ones with the experience.

if the block is fresh water only, then yes, you can clean the debris (rocks, sand, small fish, seaweed, etc)

if the block has been run in salt, no.