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Mercruiser 4.3 port elbow hot

M

Michael33

Member
Hey all !

New member here. Long time boat owner, new to I/O boats always had outboards. We bought a 2006 Bryant 190 with the mercruiser 4.3 with 240hrs. Has an Alpha one gen 2. Really clean boat that’s been kept inside. The motor runs great, me and my son changed the oil and the fuel filter last weekend. The port elbow is running 60-70 degrees higher than starboard. Port elbow staying around 160 and starboard around 100 Verified with temp gun. Temp gauge on dash stays between 160-175 depending on how hard it’s being run. Any suggestions on what might be going on? I’ve ordered a new water pump kit and a circulating pump and thermostat, also have ordered plugs and wires. Just want to go thru it so I know what I’ve got. Would a failing water pump cause one side to run hot ? Also way less water coming out of port exhaust at transom. The only service records I have are new LU installed in 2016 and gimble bearing and bellows replaced at same time, and yearly oil changes. We also got A new battery and the alternator is putting out around 14 volts.

Thanks Michael.
 
One exhaust elbow will always run a bit hotter than the other, it's jut the way water flows. Running on a muffs with a garden hose can also see more heat because the hose cannot provide the same amount of water a lake can. Don't run it above 1500 rpm on a hose
 
AllDodge said:
One exhaust elbow will always run a bit hotter than the other, it's jut the way water flows. Running on a muffs with a garden hose can also see more heat because the hose cannot provide the same amount of water a lake can. Don't run it above 1500 rpm on a hose
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Thank you for the response, yes it’s pretty much the same rather it’s on the hose or at the lake. We’ve had it out three times in the last 10 days. Figure it won’t hurt to change the water pump since I don’t know when it was last done, just trying to figure out if I actually have a problem or not or if this is normal operation.
 
The water pump impeller is regular maintenance....as are the exhaust elbows (though usually at much longer intervals)...
 
makomark said:
The water pump impeller is regular maintenance....as are the exhaust elbows (though usually at much longer intervals)...
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OK, well waiting on parts to show up, gonna tackle the water pump thermostat tuneup. See where it’s at after that, figured worst case scenario is I could take off the port elbow and take a look.
 
Can you take a picture, upload here,.
Showing thermostat housing with hose routing?

1. are there two hoses, one for each, going to elbows and is there two hoses one for each going to bottom of exhaust manifolds?

Or is there only two hoses going to bottom of exhaust manifolds?

It not uncommon for someone to have connected one side in reverse.

Do you see steam rising when on the water from exhaust?
 
kghost said:
Can you take a picture, upload here,.
Showing thermostat housing with hose routing?

1. are there two hoses, one for each, going to elbows and is there two hoses one for each going to bottom of exhaust manifolds?

Or is there only two hoses going to bottom of exhaust manifolds?

It not uncommon for someone to have connected one side in reverse.

Do you see steam rising when on the water from exhaust?
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I have a total of six hoses leaving the thermostat, housing, one big hose on starboard for the circulating pump that goes to another large hose that goes back to the intake, two hoses is going to the bottom of the manifold and two hoses going to the elbows. I haven’t noticed any steam on the lake but honestly, it’s hard to see because it has a big swim platform, I was getting some steam out of the port exhaust tube at the transom, running it on the hose big temperature difference between the water coming out of the port side versus the starboard side Also a lot more flow coming out of the starboard side
 
Hers a pic
 

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looks like dry joint mans and risers, sometimes during service the gasket gets installed wrong/reversed. One gasket is one hole restricted and one hole full flow, It matters with a cold system or a warm system
 
Bt Doctur said:
looks like dry joint mans and risers, sometimes during service the gasket gets installed wrong/reversed. One gasket is one hole restricted and one hole full flow, It matters with a cold system or a warm system
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Ok thank you ! Will see how it’s doing after water pump and tune up !
 
I dont have a manual for that year and model.

The two hoses on top close to throttle body look weird to me. That bend in the hose on older models typically went to the bottoms of the manifolds and the straighter hoses went to the elbows.

If someone has a cooling system image showing hose routing that may help!!
 
kghost said:
I dont have a manual for that year and model.

The two hoses on top close to throttle body look weird to me. That bend in the hose on older models typically went to the bottoms of the manifolds and the straighter hoses went to the elbows.

If someone has a cooling system image showing hose routing that may help!!
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That would definitely be helpful, I thought the same thing why is there such a sharp bend in those two hoses it seems unnecessary. I looked up the part number that is on that hose and it says it’s no longer available. I can’t find it anywhere.
 
AllDodge said:
That one is setup with check balls in the top hose
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Yes, I have ordered the replacement balls and springs. I plan to swap all that when I put in a new thermostat, I ordered a 160° thermostat because that’s what it says it should have, and that’s also what the owners manual says from the guy I bought the boat from. It says that’s what it came installed with.
 
Check ball ports go to elbows

Also when replacing the spring and balls, make note of the lenght of screw from nut end to end of screw. Hopefully thats still original. You dont want to much spring pressure on the balls.
 
kghost said:
Check ball ports go to elbows

Also when replacing the spring and balls, make note of the lenght of screw from nut end to end of screw. Hopefully thats still original. You dont want to much spring pressure on the balls.
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OK, got it, thanks for the tip. I wondered how much pressure or how tight those are supposed to be. What’s the word on these thermostat housing do they usually hold up pretty good, nothing visibly leaking. It appears to be original, new ones are pricey, about 400 bucks and difficult to find.
 
AllDodge said:
They are not that tight. They were used to send more to manifolds when thermostat was closed

When Stat opened the hot water would exit past the check balls to elbows

Your cooling system
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I thought it was the opposite,

When Tstat is closed, maximum fresh water pressure exists thus opening the poppets to elbows. Fresh cold water to both elbow and manifold. Once Tstat opens the engine water mixes with fresh going to manifolds. Elbows I thought always get fresh cold water....
 
So those two hoses that go to each elbow are item number six in that diagram do they not make those anymore? I cannot find them anywhere? I thought about replacing both sides just in case the port side was starting to collapse or restricting flow because I don’t understand why there is such a sharp bend in it, the part number in the diagram is the same part number that is on the hose that’s currently on the boat, the parts diagram does not show that hose having that sharp bend in it it just has a gentle curve. I don’t know if that is an accurate drawing of it or not.
 
kghost said:
I thought it was the opposite,

When Tstat is closed, maximum fresh water pressure exists thus opening the poppets to elbows. Fresh cold water to both elbow and manifold. Once Tstat opens the engine water mixes with fresh going to manifolds. Elbows I thought always get fresh cold water....
Click to expand...
yes that is correct water is feed with thermostat to elbows to cool exhaust, when thermostat is open hot water comes up through manifolds then out elbows. I can only assume some water passes the balls when thermostat is open as they use restrictor gaskets vs the fully open with this design.

either way if too much flow of raw water goes to elbows engine will overheat
 
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