1991 Four Winns Freedom 190 4.3L OMC and Cobra Outdrive Engine Operating Temperature

e016188

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I have a 1991 Four Winns freedom 190 with a 4.3L V6 and OMC cobra outdrive. I noticed over the weekend the temperature gauge on the dash is running a little hotter than in years past. The temperature gauge in years past has always run at about 150F. This last weekend the temperature gauge was running up to 180-190F. I did check the rubber impeller in the outdrive and it is in good condition. I did change the impeller last year. I did not change the impeller this year. Is the indicated change in temperature an indication of the need to troubleshoot the cooling system?
 

southkogs

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Yup, time to start lookin' at it. I'd actually go ahead and change that impeller to see what kind of result that gives you. If that doesn't improve things, might check the water flow up to the thermostat and make sure you're drawin' water in.
 

Gary H NC

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The impeller may look fine as all in one piece but do the fins pop out straight when out of the housing? If not it needs replaced.
I have seen cheap ones not last but a season or two...
How long has it been since the thermostat was changed?
Then you have exhaust manifolds to think about too...
 
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e016188

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Jun 16, 2009
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Hello, I purchased and installed both a water pump kit (sierra pn 18-3348) and thermostat kit (sierra 18-3653) in the boat last week. I have replaced the water pump impeller every summer since I have owned the boat and this year decided to buy the water pump kit so I replaced the housing, housing o-ring and impeller base plate and gasket. A note. I find application of quicksilver 2-4-C grease makes installation and position of the rubber impeller much easier. The thermostat was a reasonable simple replacement. I did notice corrosion in the thermostat housing. I put the boat in the water this last weekend and watched the temperature gauge to make sure the motor didn?t run hot. The indicated water temperature was rock solid steady at ~ 70-72oC with the engine at idle speed. I?m guessing the water temp ran to and stayed at the thermostat actuation temperature of 160oF. I did run the boat up to ~30 mph for a few minutes and noticed the temperature gauge ran up to I think ~ 80-85oC. I don?t believe 175-185F is excessive water temperature? As noted earlier, I just don?t recall the temperature gauge up this hot in recent years. I did purchase an OEM manual a few years ago as suggested on the iboats forum. I pulled the water hose from the transom bracket at the thermostat housing last night to observe the water head as directed in the manual. I performed this test with a garden hose and muffs in my driveway. The manual denotes ?specified idle rpm?. I simply moved the drive/shift lever to the idle position with the drive disengaged. I believe the tachometer indicates ~750-800 rpm with the shift level at the idle setting. I?m not sure if I had the correct engine speed? I did hold the hose level with the engine intake spark arrester. I don?t think I saw 2 to 4 inches of discharge head as noted in the manual. I think I saw just at 2 inches or a little less than 2 inches. Have I performed the discharge head flow/pressure test correctly? I will start some of the other manual recommended troubleshooting/investigation work tonight. ? I will check to make sure the drive inlet screens are clean. ? I will remove the pivot housing drain screw to make sure I?m not losing water inside the pivot housing. ? I do have the oil cooler in the water supply line between the transom bracket and thermostat housing. o If I find the oil cooler dirty/plugged how do I clean? o As noted earlier, I did find what appears to be significant corrosion in the thermostat housing. I think just many years of use.
 

e016188

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Hi Gary,

I believe the fins on the new impeller were much stiffer than the impeller I removed.
 

lakenormangal

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Sep 6, 2014
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The impeller may look fine as all in one piece but do the fins pop out straight when out of the housing? If not it needs replaced.
I have seen cheap ones not last but a season or two...
How long has it been since the thermostat was changed?
Then you have exhaust manifolds to think about too...

As a newbie with a 4.3 Cobra, this subject is of interest to me, as I am currently investigating an overheat issue. Rookie question, what happens if the fins don't pop straight when the impeller is removed from the housing? Does it not move the water through the unit? I take it if the fins are not stiff, they don't move the water effectively enough?

My boat overheated bigtime very quickly last weekend. The details on in a post elsewhere on this forum. I thought it was the impeller, but it's hard to tell as the heat damaged the impeller and housing. I bought a new impeller, housing, liner and gasket. Should I also replace the impeller base plate and that gasket?
As for the age of the impeller, it was replaced 3 years ago and the boat has seen a lot of hours since then. No idea if it was aftermarket cheapie. The parts I bought were OEM as far as I know.

And you brought up the exhaust manifolds. The manifolds on my boat have been repaired and they seem fine, no leaks. Is there something else I should be looking for?

The boat goes into the shop tonight for head gasket replacement. I'm still not sure exactly why it overheated like that.
 

Gary H NC

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Hi Lake Norman Neighbor!
It will still move water but not enough to keep it cool....3 year old impeller needs to be changed.
The wear plate can be reused if it is smooth without grooves worn in it. Some models you can turn the wear plate over and use the other side.

I wish I would have seen this sooner as I work on Cobras and have done many manifold and impeller changes for 50 an hour labor.
Why do you think head gasket? Manifolds can leak internally and cause issues too..

If they were repaired due to freeze cracks I would be very suspect of them too...
 
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lakenormangal

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Hi Lake Norman Neighbor!
It will still move water but not enough to keep it cool....3 year old impeller needs to be changed.
The wear plate can be reused if it is smooth without grooves worn in it. Some models you can turn the wear plate over and use the other side.

I wish I would have seen this sooner as I work on Cobras and have done many manifold and impeller changes for 50 an hour labor.
Why do you think head gasket? Manifolds can leak internally and cause issues too..

If they were repaired due to freeze cracks I would be very suspect of them too...


Well, we pulled the heads off yesterday and sure enough both head gaskets were blown. We spent the morning, cleaning all the head and intake gasket surfaces, and checking the cylinder walls, which look real good. Turned the motor over by hand and it moves easy, nice and smooth the way it should. The heads are going to the machine shop this weekend and they are being checked over.
The bellows look good, not melted at all. So hopefully it didn;t fry any seals in the cooling system. From the time it was started up until it was turned off, it ran less than 10 minutes. Maybe just over 5 minutes.

Here's the story on the boat, my brother/best friend bought it 3 years ago. It needed a motor and outdrive. He's a very good mechanic and has an automotive repair shop here. He has some experience with boats, he's build a few over the years. He was planning on keeping the boat forever and did everything the right way with the rebuild. He had the exhaust manifolds repaired and there was no problem with them. The boat ran like a champ for the past 3 years, give the throttle a pump, turn the key, it fires right up and runs smooth as silk, every single time.
No problems what so ever.
Once he got into Lake Norman he got boat envy and bought a larger boat, a Baja. He sold me the little Sunbird for exactly what he had into it. I've done pretty good with it, got the shifter stuck in between gears once ( I learned better how to shift it and it hasn't happened again). Hit a rock with the prop last year, changed the prop and it was good to go.
Then right at the end of last season, the alternator went out and fried the battery. Got a new alternator and battery last year but the guys were lazy about hooking it up. Usually we winterize by running the outdrive in a tank of antifreeze and then pulling the drain plugs on the motor. But with the boat not running due to the alternator, we just pulled the engine plugs. At the time I did not know about pulling the plugs in the outdrive.

And the impeller plate looks to be in good shape, no grooves in it.



I have a custom paint shop here in Waxhaw and my bf has a an automotive restoration shop where they restore classic cars. So we are used to doing our own work and want to learn the right way to work on the boat.
Here's two examples of the kind of work we do. On the Firebird we replaced every panel on the car.
 

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Gary H NC

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Nice paint work!

On the winterizing issue...pull the brass plugs on the manifolds too...drain the block,hoses,ect..
Winterized many Cobras and air don't freeze...the running in a tank of anti-freeze is not the best way to do it.

Oh,Indian Trail myself...Ever hear of Fatman's Fabrication?

Here is some of our work....I help on the side..This truck was a 7 year build. Owned by a good friend of mine.
57.jpg
 
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lakenormangal

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Come to think of it we do pull the plugs on the manifolds also.
Nice truck.
I just wish I knew for sure what happened.
 

HT32BSX115

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Dec 8, 2005
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.......................... Usually we winterize by running the outdrive in a tank of antifreeze and then pulling the drain plugs on the motor. But with the boat not running due to the alternator, we just pulled the engine plugs. At the time I did not know about pulling the plugs in the outdrive.

And the impeller plate looks to be in good shape, no grooves in it.................


..........................Come to think of it we do pull the plugs on the manifolds also.
Nice truck.
I just wish I knew for sure what happened.
Winterizing that way will work just fine. [the AF is not necessary as long as you're still draining everything LAST, but it doesn't hurt a thing........] Head gaskets fail for a variety of reasons.........freezing temps are usually not one of them......
 
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