454 temperature issue - bravoitis?

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TBarCYa

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I replaced the impeller and the thermostat and still seem to have a cooling issue. I pulled the hose from the pump to the thermostat and I get water but when I was out today it ran hot - about 200. At idle it doesn't seem to climb but it didn't drop either however when I got back to the dock I hooked up the hose to flush the system it cooled down almost immediately. The hose water shouldn't be much cooler than the bay but the hose connector is between the gimbal and the pump. Am I on the right track thinking that it's probably a restriction in the lower unit or gimbal? When I hooked up the hose on the trailer I had plenty of water coming out of the lower unit so I thought it was good but maybe not? In the meantime I'll try connecting a hose from a thru hull to the pump and see if the cooling issue goes away.

Thanks
 

tpenfield

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A good & quick way to check . . . with the boat out of the water. . . would be to remove the inlet hose and angled barb fitting from the inside of the transom assembly. You will be looking for a powdery corrosion mess that has squashed the inlet hose fitting.
 

TBarCYa

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I'm hoping to make it until February ish without pulling it again but I guess if I can't get the cooling sorted out I'll have no choice.
 

TBarCYa

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It's looking good for making it to February before I have to pull the boat from the water.

In the hose from the drive to the raw water pump there's a T with a section of hose with a fitting for attaching a garden hose. This is what I used to run the boat on the trailer. Apparently, the last time I ran it on the trailer when I disconnected the garden hose I took the shut off valve as well so the hose was open and sucking in air and therefore not getting enough water to cool the engine under load. Reinstalled the shut off valve and closed it and the cooling problem is gone!!

Had the boat out of the marina yesterday for about a half hour and she ran good. Initially she wouldn't get up on plane but I added some fuel using the mixture screws and was able to get her to 24mph pretty easily. Tonight I'll be setting the timing (because my timing light is a piece of crap and isn't bright enough to see during the day) after which I'll tweak the carbs a little more and hopefully have a good running boat. Still plenty of work to do, but the engine and drivetrain seem to be solid.
 

HT32BSX115

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Am I on the right track thinking that it's probably a restriction in the lower unit or gimbal? When I hooked up the hose on the trailer I had plenty of water coming out of the lower unit so I thought it was good but maybe not? In the meantime I'll try connecting a hose from a thru hull to the pump and see if the cooling issue goes away.

Thanks
Maybe.

Another place to check with a 454 is the oil cooler. Previous impeller disintegration fragments and certain other debris will likely end up in the oil cooler.

Mine was so completely clogged that I had to pick the pieces out using needle-nose pliers!

No amount of "back" flushing would dislodge them!

Cheers,

Rick
 

TBarCYa

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Thanks Rick. I checked the cooler and was able to get it clear when I replaced the impeller. Looks like the problem was sucking in air through the flush fitting.
 

tpenfield

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You might not have any other issues to worry about. Even a slight air leak on the suction side of the pump will really mess things up.
 

TBarCYa

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We had her out again yesterday and ran it pretty hard with absolutely NO temperature issues at all. Looks like the problem is solved!!
 
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