Fresh Water Cooling

[kwoolard]

I installed a freshwater cooling kit from San Juan Engineering yesterday. The kit was number MC-321, a full system (block and manifolds). As I installed the parts I filled everything up with antifreeze to help prevent large air pockets forming. When done installing I filled the heat exchanger with antifreeze and started the engine on the muffs. I ran the engine for approximately 10-15 minutes and the temp would not get over 140 degrees. I have a 160 degree thermostat installed, which has a couple of 1/8" holes drilled into it. It was the thermostat that came with the kit. Are these two 1/8" diameter holes allowing enough bypass water into the heat exchanger to keep the engine cool enough without having to open the thermostat?

 

[Don S]

Re: Fresh Water Cooling

No need to fill each part seperate, but you do need to have the engine either level or the front raised to prevent air bubbles. Those holes in the stat let the air out, not bypass coolant. But if you have the front of the engine low, it will trap air in the block and not circulate.

 

[kwoolard]

Re: Fresh Water Cooling

I had the front of the engine high when filling the block and the heat exchanger. I am confident I have all the air out of the system. Unless it takes the engine a long time to reach operating temp or the T-Stat failed open, I can't figure out why I can't reach operating temp on the muffs at idle.

 

[45Auto]

Re: Fresh Water Cooling

My boat with the Mercruiser factory freshwater cooling also runs about 140 at idle on the muffs. It runs at 160 once it's in the water and moving. I just figured that it removed enough heat from the water flowing through the manifolds and risers to keep it at 140 with no load on it.

 

[Don S]

Re: Fresh Water Cooling

If all the air is out, then it just might not run 160 at idle, like 45 says. I have seen many that don't. When you put them in the water and actually put a load on em, they will warm up. Probably run about 180? with block and manifold both being cooled.

 

[kwoolard]

Re: Fresh Water Cooling

That's good to hear....I'll have to see what happens under load.

 

[95yj]

Re: Fresh Water Cooling

I have the same exact kit on my new 5.7L with the 160? thermostat. My temp gauge on the dash reads 175 at idle, (muffs or floating) and climbs to 195 while cruising. That's about what the boat ran before with the old motor and raw cooling. Knowing the accuracy of gauges on boats, both our boats are probably doing about the same thing.

Nice kit. Went on without any issues once I got the store to send me a 321 instead of the 314.

 

[Don S]

Re: Fresh Water Cooling

195 is too hot for an enclosed engine compartment.

 

[kwoolard]

Re: Fresh Water Cooling

95yj, sounds like you might have a weak water pump in your leg. I agree with Don, 195 is too hot, especially if you have a 160 stat installed.

 

[HT32BSX115]

Re: Fresh Water Cooling

I have a similar (full) system I installed before I put the 454/Bravo in my Four Winns.

I think it came with a 160 T-stat. It warms up very quickly!

The temp RARELY deviates from about 170* I don't think it's ever gone above about 180 on the gage. (which is probably well within the error of the gage)

Just make sure you still winterize by draining the low spots in the raw system. Your power steering, oil cooler, and raw side of the heat exchanger along with the exhaust elbows still have raw water in them. I just had the "muff" draw about 2 gallons of 50/50 all thru the system running at idle. WIth a large wash basin below the drive you can actually let it circulate a little.


Cheers,


Rick

 

[Don S]

Re: Fresh Water Cooling

One other note on using full systems with an Alpha drive. Merc states that you must use an engine mounted pump instead of the one in the drive. Especially if you are trying to cool the manifolds with AF.
In the Merc kits, they use a pump like the ones used with the 454's and Bravo drives and a thruhull fitting for water pickup.

 

[kwoolard]

Re: Fresh Water Cooling

I have heard different opinions on using the leg water pump for a complete system. Most have stated that the Gen II pumps provide enough flow to properly cool the fresh water.

Looking at the coolant flow (fresh water) in my new set up, I would think that the temperature would have to reach at least the thermostat temperature, unless the circulating pump is pulling some bypass water through the heat exchanger. Would it not?

 

[95yj]

Re: Fresh Water Cooling

I have heard different opinions on using the leg water pump for a complete system. Most have stated that the Gen II pumps provide enough flow to properly cool the fresh water.

I've seen the same thing in a lot of places. The Gen I and pre were the ones that need a engine mounted pump. The Gen II's are supposed to pump enough water to do full cooling. San Juan actually states this also.

 

[Don S]

Re: Fresh Water Cooling

My information came directly from Mercruiser, and it's also stated in the Mercruiser closed cooling system instructions.
Mercruiser also installes engine mounted pumps on their factory installed closed cooling systems on engines with Alpha I Gen II drives.
So where did you guys get your information from.
(Of course SJ says that, they don't sell the pumps.)

 

[kwoolard]

Re: Fresh Water Cooling

It could all depend on the design of the heat exchanger. Mercruiser may use a heat exchanger with fewer raw water tubes than San Juan, thus needing the increased flow through the heat exchanger.

My information mainly comes from people on this board that have installed these aftermarket systems utilizing the Gen II pumps.

Has anybody installed a San Juan full system that used the Gen II pump and did not provide enough cooling capacity?

 

[95yj]

Re: Fresh Water Cooling

(Of course SJ says that, they don't sell the pumps.)

I don't disagree that SJ may not be the best source of info here since they are just selling kits, but their technical staff seems to be pretty knowledgeable. In addition, when I was talking to them about buying the kit, they stated I would need an engine driven raw water pump. Then when he found out I had a Gen II, he informed me that the the II's provided better cooling and I would be OK without adding the pump.

Now on that note, IF I was in the market to install a belt driven pump, what do you do with the impeller and water supply from the Gen II? Do you just reroute the Gen II water supply back out through the exhaust, do you plumb it into new system and let it "help" supply water, do you plug it and forget it or do you remove the impeller and plug it?

 

[kwoolard]

Re: Fresh Water Cooling

I have run the engine in the driveway on the muffs twice since installing the freshwater kit. The day after each run I removed the heat exchanger cap and noticed the coolant level had dropped, both times. It probably took about 10 ounces to fill it back up, but I was wondering if on new installs if this is normal due to air in the system or if I have a potential problem.

I haven't noticed any sweet smell of the exhaust or water in the oil or in the bilge. I have checked every clamp and fitting for leaks and everything looks good. Just wondering where the coolant is going.

 

[Bondo]

Re: Fresh Water Cooling

Ayuh,.......

How Long did you run it,..??...

10oz.s Each Time,..??..... Or Total..??..??

I don't really see a Problem yet........

 

[kwoolard]

Re: Fresh Water Cooling

I ran the engine about 15 minutes each time. And after each time I had to add about 10 ounces.

 

[kwoolard]

Re: Fresh Water Cooling

One thing I noticed and this may be where the coolant in the heat exchanger is going. My expansion tanks inlet line, where the clear hose from the heat exchanger connects is sitting at a level lower than the fill neck on my heat exchanger. I guess what could be happening is when the engine warms up the coolant expands and flows out into the tank, but since the tank is lower than the fill neck, the fluid cannot get back into the heat exchanger. You think this could be why I was losing coolant in the heat exchanger?