Winterizing 5.0 liter Volvo-Penta engines with raw

B

Blue Cruiser

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We have raw water cooled engines. Last year our mechanic removed the brass drain plug from the rear of each manifold (2 per engine) and removed the brass screw cap from the raw water drain hose (one per engine) which can also used to fresh water flush the engine. He placed the open drain hose on the engine room floor to drain water. Since each drain plug and drain hose properly drained he did not probe with wire. At the raw water pump he removed the top hose (inlet) and plugged it with a rounded 3/4"PVC cap, rounded side first into the hose, and re-installed the hose clamp. He then used a spare hose to hook up to the inlet side of the raw water pump to his five gallon bucket. He put three gallons of -60 degree F purple boat antifreeze into the bucket and had me run that engine until almost three gallons of antifreeze had been pumped through. We then did the same for the other engine. Brass manifold drain plugs and drain hose screw cap for each engine remained off until the spring boating season.

Why did he not start by warming up each engine so that a possible closed thermostat would not hinder the distribution of the antifreeze? Comments on this procedure would be appreciated
 
After thinking more about the winterization last year the boat was operated shortly before the mechanic arrived to start the process. Therefore the thermostat was open.
 
This year I watched our mechanic winterize our 5.0 liter Volvo Penta raw water cooled gas powered twin engines. He did not warm up the engines before winterizing. He removed the brass drain plug from the rear of each manifold (2 per engine) and removed the brass screw cap from the raw water drain hose (one per engine) which can be also used to flush the engine. He placed the opened drain hose for each engine on the engine room floor to drain the water. Since each drain plug and drain hose properly drained he did not remove the drain hose nor did he probe the openings with wire or nail. At the raw water pump he removed the top hose (inlet) and plugged it with a rounded 3/4" PVC cap, rounded side first into the hole to facilitate removal in the spring and re-installed the hose clamp to hold the cap in. He then removed the bottom hose from the raw water pump to drain the pump. He then re-installed the brass manifold drain plugs (two per engine) and he re-installed the brass screw cap on the drain hose (one per engine). He then connected a spare radiator hose with a right angle bend to the top (inlet) raw water pump where the inlet hose had been removed and capped. He connected the other end of spare radiator hose with clear hose to a spare bilge pump in the bottom of his five gallon bucket. He filled the five gallon bucket with 3 gallons of -100 degree boat antifreeze. The spare bilge pump wires had alligator clips to be connected to a boat battery if needed. While he watched in the engine room he had me run the engine at idle and occasionally with a little throttle to fun 3 gallons of antifreeze through that engine. We then performed the same procedure on the other engine. One engine did not draw the antifreeze from the bucket so he connected the pump wires with alligator clips to a boat battery. After running 3 gallons of antifreeze through each engine he then removed the manifold brass drain plugs and removed the brass screw cap from the raw water drain hose on each engine. He placed the drain hoses on the engine room floor and placed the 4 brass manifold plugs in a clear plastic bag on top of the port engine.
 
I havent had I'O's in many years but I don't remember going through that detailed of a process. If I recall, I put the muffs on the outdrive, ran the boat for 5 minutes and switched over the the pink stuff. Ran a couple gallons through and I was done. I don't remember taking out thermostats or plugs either. I did that for years and never had a problem. Was I lucky? I live in NY so it can get quite cold.
 
quote:
Originally posted by Anchor Management

I havent had I'O's in many years but I don't remember going through that detailed of a process. If I recall, I put the mittens on the outdrive, ran the boat for 5 minutes and switched over the the pink stuff. Ran a couple gallons through and I was done. I don't remember taking out thermostats or plugs either. I did that for years and never had a problem. Was I lucky? I live in NY so it can get quite cold.

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Maybe a bit lucky. Just running pink stuff through without first draining the block may not purge all the water, and diluted pink stuff doesn't protect very well. Using a refractometer would ensure protection.

When I had a boat that I had hauled for the winter, I would use automotive antifreeze to winterize the engines, collecting any runoff. In the spring, I would flush before splashing the boat, again collecting the runoff and disposing of it properly. The green stuff protects much better, so dilution was not an issue.

Now I leave the boat in the water over the winter, so I'm back to the pink stuff. I drain the heat exchangers, changing the anodes in the process, and run pink stuff through.
 
Sound advise. As it relates to te theromstat, how can you be sure it is open during the flushing process? Is it required to be open for full protection?
 
quote:
Originally posted by Blue Cruiser

After thinking more about the winterization last year the boat was operated shortly before the mechanic arrived to start the process. Therefore the thermostat was open.

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The thermostat is constantly opening and closing. There is no way to know for sure if it is open or closed. When I helped my son winterize his RWC Merc for the first time, I had him remove the T-stat first and then we ran antifreeze thru the engine using ear muffs.
 
quote:
Originally posted by Anchor Management

Sound advise. As it relates to te theromstat, how can you be sure it is open during the flushing process? Is it required to be open for full protection?

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I'd always give the engine a good flush with fresh water before winterizing, getting it up to operating temperature in the process.
 
Even if you run it up to temp, once the cold anti-freeze hits the thermostat, it's likely to close. I always thought that winterizing that way was a crap shoot unless you drain some mix from the block and test it.
 
quote:
Originally posted by Gregory S

Even if you run it up to temp, once the cold anti-freeze hits the thermostat, it's likely to close. I always thought that winterizing that way was a crap shoot unless you drain some mix from the block and test it.

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That might happen if the thermostat were upstream of the engine block. It's not. The antifreeze is warmed by the engine block before it reaches the thermostat.
 
If that's the case in raw water cooled engines, then why does a thermostat continually open and close and not just stay open once it reaches operating temperature?
 
quote:
Originally posted by Gregory S

If that's the case in raw water cooled engines, then why does a thermostat continually open and close and not just stay open once it reaches operating temperature?

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I believe it does stay open. How have you observed it opening and closing?
 
They definately open and close. I realized that when after an 8 hr boat trip, my thermostat failed in the open position and I couldn't maintain a temp higher than about 120 degrees. Not what I would have expected after the engines had been running at 150 degrees all day. Once thermostat function was explained to me it made sense. Cooling water bypasses the block until the block water is hot enough to open the thermostat. In cool/cold water the thermostat will periodically close to assure high enough operating temps. It's exactly as CWMS described above.
 
Thanks Gregory. I'm glad someone actually understands how a T-stat works. That it is constantly opening and closing to maintain a set temperature. Leave it open and the engine will never warm up. keep it closed and you cook the engine.
 
I have seen many suggest to warm up the engine before pumping in the antifreeze, but I 100% agree with CWMS that you never know whether the thermostat is open or closed and you risk cracking the block.

I have always drained all the water out of the engine first. I never trust those little petcocks on the side of the block that people say to run a piece of wire through. I take them totally out so I can use a screw driver and break up any sediment that has migrated to that hole. This way the water drains through a 1/2" hole vs. an 1/8" and again there is no question whether or not the majority of the water has been drained. Then I remove the thermostat and reinstall the water neck. I stick my 5 gallon bucket on the swim platform, fill it up with antifreeze, fire up the motor, and watch the engine suck it down. On my 7.4L Volvo it takes about 6 gallons of pink before it comes out the exhaust. I usually have to put an extra one in the bucket while it's sucking it down. I also fog the motor while the pink is going in and just shut it down once it comes out the exhaust.
 
quote:
Originally posted by cwms

Thanks Gregory. I'm glad someone actually understands how a T-stat works. That it is constantly opening and closing to maintain a set temperature. Leave it open and the engine will never warm up. keep it closed and you cook the engine.

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Well, you apparently don't understand how an engine thermostat works. An engine thermostat doesn't constantly "open and close" as in "snap open, snap closed" like a thermostat controlling a home heating system is either "on or "off." It will open partially depending on the temperature of the coolant. The point is that running cold antifreeze through a hot engine is not going to result in the antifreeze not getting through the block.
This is due to the way an engine thermostat is designed with dissimilar metals in contact that expand and contract at different rates.

Drop an engine thermostat into boiling water and watch it slowly close as the water cools. (Which I just did, by the way, to confirm my point.) If it "opened and closed," your engine temperature gauge would constantly fluctuate. Cold water passing through the engine block is not going to reach the thermostat at a temperature that will cause it to completely close. This will be confirmed by taking the temperature of the water or antifreeze flowing out of the exhaust when running the engine on earmuffs. Or simply feeling it with your hand. It will be hot.
 
Nobody said it was all or nothing. Your experiment doesn't explain what happened in real life. So, you're saying that once the thermostat is open, it stays that way? That it won't partially open or close, allowing cooling water or anti-freeze to bypass the block and go right out the exhausts? Your perpetuating the myth that a lot of boaters have that once they warm the engine up, they are good to go by running a couple gallons of anti-freeze thru. They have no idea what the thermostat is doing at that time. That's why smart people pull the thermostats out before they run the anti-freeze, or drain the blocks first.
 
Capt. Rick, I'm not saying you are wrong on the partial opening, but totally agree with Greg on this. Why risk how open or closed the T-stat is when it only takes a few minutes to remove it. Once out there is no question whether or not the AF is running thru the block.
 
quote:
Originally posted by Gregory S

Nobody said it was all or nothing. Your experiment doesn't explain what happened in real life. So, you're saying that once the thermostat is open, it stays that way? That it won't partially open or close, allowing cooling water or anti-freeze to bypass the block and go right out the exhausts? Your perpetuating the myth that a lot of boaters have that once they warm the engine up, they are good to go by running a couple gallons of anti-freeze thru. They have no idea what the thermostat is doing at that time. That's why smart people pull the thermostats out before they run the anti-freeze, or drain the blocks first.

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Sorry. When you said the thermostat "closed," I thought you meant that it closed. And I never advocated not draining the engine block. (See previous: Just running pink stuff through without first draining the block may not purge all the water, and diluted pink stuff doesn't protect very well.) And I did not say it doesn't partially close (see previous: It will open partially depending on the temperature of the coolant.)

Yes, some cooling water will bypass the block. But if you drain the block and then refill it while it's still hot with antifreeze, there is no need to remove the thermostat. I will grant you that if you prefer not to work on a hot engine, it would be advisable to remove the thermostat. I never have, and in 30+ years of boating I've never had a problem. Maybe "most boaters" don't know what the thermostat is doing, and I have an advantage because I do. So be it.

I'm declaring this a dead horse for my purposes.
 
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