merc 4.3 winterization drain plugs and overheat while fogging

uahub

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May 28, 2017
Messages
13
Engine SN: 0L063218, how many drain plugs do I have, I can only find 4, two each side for block and exhaust. Cannot find the supposed to be the easiest one on the front. Is it possible I may just have only 4 plugs?


Also I tried to spray fogging oil while engine is idle (temp is already in mid range), instead of killing the engine, the engine temp went up quite a bit and triggered the alarm. so I turned off the engine immediately. Is this normal? I found One black cable not connected to anything near the carb. I dont know if its related to the issue.

In last couple weeks, my boat stalled a few times while I tried to put it in gear from Neutral, or accelerate. I thought it was the bad fuel (2yrs from previous owner, I just bought it) or battery. I will also try to check the fuel line or fuel filter, or maybe the shift cable (all possible reason from my search online). But these will be done through the winter in garage.
 

Bondo

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71,310
Ayuh,..... Welcome Aboard,....... What's with the tiny font,..??
Why didn't you leave it at the default, so yer post can be easily read,..??

Ya know, most of Us tryin' to help ya are gettin' older,.....
You should be tryin' to help Us, tryin' to help you, rather than makin' it harder to help you,.....
 

Scott Danforth

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agreed, dont change the font

did you have the motor running on muffs when you were trying to fog it? if not that is one problem. you have toasted the impeller if you didnt have the muffs on

there are 4 drains on some 4.3's, and there is a 5th on some. the 5th would be to drain the thermostat housing area. its on the front of the intake manifold.

you also need to drain the PS cooler and its hose and the large hose going to the circulating pump

boat stalling going into neutral is an issue with the lower shift cable. either its out of adjustment, or if it cant be adjusted, it needs replacement.

stalling when trying to accelerate is normally plugged carb circuit or bad accelerator pump
 

uahub

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May 28, 2017
Messages
13
Thanks. Sorry there was an issue to post so I copied my post into a word document and pasted back, somehow the font became so tiny. The followings are quotes of my original post.
Yes. I had the muff on all the times. Don’t know why it overheated. Regarding to stall, I may have a stiff shift cable.
I couldn’t find any front plug so I opened the big hose in the front and pour in antifreeze until pink shows up at the drain and even at the return (after close the drain plugs).
Also tried to drain the PS cooler, but is there is plug or open a hose? Thanks

quote below:
Engine SN: 0L063218, how many drain plugs do I have, I can only find 4, two each side for block and exhaust. Cannot find the supposed to be the easiest one on the front. Is it possible I may just have only 4 plugs?


Also I tried to spray fogging oil while engine is idle (temp is already in mid range), instead of killing the engine, the engine temp went up quite a bit and triggered the alarm. so I turned off the engine immediately. Is this normal? I found One black cable not connected to anything near the carb. I dont know if its related to the issue.

In last couple weeks, my boat stalled a few times while I tried to put it in gear from Neutral, or accelerate. I thought it was the bad fuel (2yrs from previous owner, I just bought it) or battery. I will also try to check the fuel line or fuel filter, or maybe the shift cable (all possible reason from my search online). But these will be done through the winter in garage.
 

highfigh

Seaman Apprentice
Joined
Sep 1, 2018
Messages
39
Thanks. Sorry there was an issue to post so I copied my post into a word document and pasted back, somehow the font became so tiny. The followings are quotes of my original post.
Yes. I had the muff on all the times. Don’t know why it overheated. Regarding to stall, I may have a stiff shift cable.
I couldn’t find any front plug so I opened the big hose in the front and pour in antifreeze until pink shows up at the drain and even at the return (after close the drain plugs).
Also tried to drain the PS cooler, but is there is plug or open a hose? Thanks

quote below:
Engine SN: 0L063218, how many drain plugs do I have, I can only find 4, two each side for block and exhaust. Cannot find the supposed to be the easiest one on the front. Is it possible I may just have only 4 plugs?


Also I tried to spray fogging oil while engine is idle (temp is already in mid range), instead of killing the engine, the engine temp went up quite a bit and triggered the alarm. so I turned off the engine immediately. Is this normal? I found One black cable not connected to anything near the carb. I dont know if its related to the issue.

In last couple weeks, my boat stalled a few times while I tried to put it in gear from Neutral, or accelerate. I thought it was the bad fuel (2yrs from previous owner, I just bought it) or battery. I will also try to check the fuel line or fuel filter, or maybe the shift cable (all possible reason from my search online). But these will be done through the winter in garage.


These have a switch on the shift/throttle linkage, used to briefly kill the spark when shifting- mercruiser has clutch dogs, which are the reason these make noise while going from neutral to forward, reverse or whatever. If the cables stretch, the adjustment will no longer be correct. Disconnect the shift cable and shift it manually- if it works the way it should, adjust the cable.

My guess is that the thermostat has seen better days. Get a replacement that has a small hole in it- this is called 'fail-safe'.

Make a Winterizing rig so you can draw anti-freeze through the raw water pump- it will lubricate the impeller, fill the oil cooler and if done correctly, it will get into the whole engine.

The following would be a great way to handle winterizing boats if you have friends who might want to do this in a much easier way, share the cost and get it done far better than pouring the anti-freeze into a hose.

When I worked for a boat dealer, I bought a large plastic Rubbermaid tub that held about 50 gallons and had a barrel of anti-freeze that was rated for -90 F. Since I was working on stern-drives and ski boats with direct drive, I needed to be able to supply the liquid through the muff or a hose that connected to the intake side of the raw water pump of the engine. I used a bilge pump to provide pressure at the water inlet of the stern-drives and dipped the 1-1/4" hose to the direct drive engines into the tub- a good impeller will draw it into the engine quickly and it was an easy way to determine the condition of the raw water pump, or find that the oil cooler was clogged.

Run the engine on the anti-freeze, not water. Once the thermostat opens, run it for another 30 seconds, fog it and shut it off. There's nowhere for water to hide when it's being cooled with anti-freeze and you don't need to disconnect any hoses, remove the thermostat or any of that stuff. We had a refractometer to check the burst temperature, but if the anti-freeze hasn't been diluted by water from too many engines, there should be no reason to worry. A good way to avoid dilution is to drain the block before starting the procedure.

If you get a group together to buy the supplies, you can save a lot of money.
 

harringtondav

Commander
Joined
May 26, 2018
Messages
2,480
A property drained engine doesn't need antifreeze. I filled the block with antifreeze the first few years on my new boat "cause I was anal. But stopped for 20 years, and have had no problems.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Messages
51,399
These have a switch on the shift/throttle linkage, used to briefly kill the spark when shifting- mercruiser has clutch dogs, which are the reason these make noise while going from neutral to forward, reverse or whatever. If the cables stretch, the adjustment will no longer be correct. Disconnect the shift cable and shift it manually- if it works the way it should, adjust the cable.

My guess is that the thermostat has seen better days. Get a replacement that has a small hole in it- this is called 'fail-safe'.

Make a Winterizing rig so you can draw anti-freeze through the raw water pump- it will lubricate the impeller, fill the oil cooler and if done correctly, it will get into the whole engine.

The following would be a great way to handle winterizing boats if you have friends who might want to do this in a much easier way, share the cost and get it done far better than pouring the anti-freeze into a hose.

When I worked for a boat dealer, I bought a large plastic Rubbermaid tub that held about 50 gallons and had a barrel of anti-freeze that was rated for -90 F. Since I was working on stern-drives and ski boats with direct drive, I needed to be able to supply the liquid through the muff or a hose that connected to the intake side of the raw water pump of the engine. I used a bilge pump to provide pressure at the water inlet of the stern-drives and dipped the 1-1/4" hose to the direct drive engines into the tub- a good impeller will draw it into the engine quickly and it was an easy way to determine the condition of the raw water pump, or find that the oil cooler was clogged.

Run the engine on the anti-freeze, not water. Once the thermostat opens, run it for another 30 seconds, fog it and shut it off. There's nowhere for water to hide when it's being cooled with anti-freeze and you don't need to disconnect any hoses, remove the thermostat or any of that stuff. We had a refractometer to check the burst temperature, but if the anti-freeze hasn't been diluted by water from too many engines, there should be no reason to worry. A good way to avoid dilution is to drain the block before starting the procedure.

If you get a group together to buy the supplies, you can save a lot of money.

the small hole in a thermostat is a vent hole

fail-safe is a trademarked motorad thermostat and they do not make a marine version.

Stant makes most of the marine thermostats.

sucking up AF without draining is the fastest way to a busted block. you still have to drain prior to adding antifreeze.

mercruiser, volvo, PCM and Ilmor specifically call out to drain prior to adding any antifreeze for a reason. insurance does not cover a freeze busted block

thermostats dont open long enough to get the water in the block exchanged for antifreeze unless your under load for a period of time. it would take running in a tub about 20 minutes to guarantee AF in the block
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,454
Make a Winterizing rig so you can draw anti-freeze through the raw water pump- it will lubricate the impeller, fill the oil cooler and if done correctly, it will get into the whole engine.

Only works IF YOU DRAIN EVERYTHING FIRST
 

JASinIL2006

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Feb 10, 2012
Messages
5,738
The following would be a great way to handle winterizing boats if you have friends who might want to do this in a much easier way, share the cost and get it done far better than pouring the anti-freeze into a hose.

When I worked for a boat dealer, I bought a large plastic Rubbermaid tub that held about 50 gallons and had a barrel of anti-freeze that was rated for -90 F. Since I was working on stern-drives and ski boats with direct drive, I needed to be able to supply the liquid through the muff or a hose that connected to the intake side of the raw water pump of the engine. I used a bilge pump to provide pressure at the water inlet of the stern-drives and dipped the 1-1/4" hose to the direct drive engines into the tub- a good impeller will draw it into the engine quickly and it was an easy way to determine the condition of the raw water pump, or find that the oil cooler was clogged.

Run the engine on the anti-freeze, not water. Once the thermostat opens, run it for another 30 seconds, fog it and shut it off. There's nowhere for water to hide when it's being cooled with anti-freeze and you don't need to disconnect any hoses, remove the thermostat or any of that stuff. We had a refractometer to check the burst temperature, but if the anti-freeze hasn't been diluted by water from too many engines, there should be no reason to worry. A good way to avoid dilution is to drain the block before starting the procedure.

uahub , DON'T DO THIS! Just drain your engine of all water. If you really feel a need to fill your block with antifreeze, pull the hose off the thermostat and pour AF down there AFTER you have drained the engine. Literally every Spring we see on iboats dozens (or more) posts about people that followed a procedure like that outlined above that resulted in a frozen and cracked block. Don't join their ranks!
 

uahub

Cadet
Joined
May 28, 2017
Messages
13
Much appreciated all replies!
Yes, I drained first from 4 plugs, couldn’t find the 5th. Then I pour AF into the big hose till I saw pink from outlet and drains. Next need to find the PS cooler. New to boat still trying to learn a lot. Thanks again.
 

Maclin

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May 27, 2007
Messages
6,761
When fogging, had you pulled the drain plugs first? If so, did you put them back in? Sorry, had to ask.
 

Scott Danforth

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uahub , you didnt answer the question on the overheat / muffs asked in post #3
 

highfigh

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Sep 1, 2018
Messages
39
A property drained engine doesn't need antifreeze. I filled the block with antifreeze the first few years on my new boat "cause I was anal. But stopped for 20 years, and have had no problems.

That's true, but many people try to fill the engine with antifreeze in a way that doesn't work.
 

highfigh

Seaman Apprentice
Joined
Sep 1, 2018
Messages
39
uahub , DON'T DO THIS! Just drain your engine of all water. If you really feel a need to fill your block with antifreeze, pull the hose off the thermostat and pour AF down there AFTER you have drained the engine. Literally every Spring we see on iboats dozens (or more) posts about people that followed a procedure like that outlined above that resulted in a frozen and cracked block. Don't join their ranks!

As long as the thermostat opens, this works- I worked for a fairly large dealer and they had been filling engines this way for decades with no frozen engines. I suspect the frozen blocks were due to impatience, more than anything. As I wrote, we used a refractometer to check the burst temperature of a sample taken from the block.

I have no problem draining engines, as long as the hoses are emptied, too. The instructions I gave were for those who DO want to use anti-freeze but it's not an absolute necessity. One good way to drain the engine is to pull the plugs and the low connections of the hoses, then drive the boat on hilly roads with a few bumps.
 

highfigh

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Joined
Sep 1, 2018
Messages
39
the small hole in a thermostat is a vent hole

fail-safe is a trademarked motorad thermostat and they do not make a marine version.

Stant makes most of the marine thermostats.

sucking up AF without draining is the fastest way to a busted block. you still have to drain prior to adding antifreeze.

mercruiser, volvo, PCM and Ilmor specifically call out to drain prior to adding any antifreeze for a reason. insurance does not cover a freeze busted block

thermostats dont open long enough to get the water in the block exchanged for antifreeze unless your under load for a period of time. it would take running in a tub about 20 minutes to guarantee AF in the block

I wrote "A good way to avoid dilution is to drain the block before starting the procedure.". We ran the engines on AF, not water. The thermostats open fairly quickly, but I'm not saying anyone has to do it that way- I was explaining how we did it for hundreds of boats every year without a problem.

I have seen a plastic rig for attempting to fill engines with AF that has a valve for selecting water or AF- I DO NOT like that thing.
 

Scott Danforth

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highfigh , defend bad practices all you want, however I personally know the engineering staff at Mercruiser and Volvo-Penta and Stant from my life designing heat exchangers. your process is wrong and not supported by the factories for a reason. Period.
 

uahub

Cadet
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May 28, 2017
Messages
13
sorry for the late reply. I ran the engine until it reached to the mid temp and did the fogging. Then I turned off the engine and drained the 4 plugs, water was hot! Yes. Muff was on all the time.
 

Scott Danforth

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so when did it overheat that you mentioned in post #1
 
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