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43 stbd riser HOT

M

moondrifter

Regular Contributor
"2000 4.3 Alpha gen II . Used

"2000 4.3 Alpha gen II . Used in fresh water only since new. Trolling/fishing. It idles for hours just fine. 700hrs
Today something smelly in engine comp. Not electrical, not oil.
I found the riser on port side was real warm.
The riser on stbd was hot. Could not hold hand on it.
Engine temp 160 as always. Ran well.
I have seen this situation here before but recall the solution. Thank You
Carl"
 
When was the last time the imp

When was the last time the impeller was changed? Risers and manifolds need cleaned or replaced. Heavy idling at trolling speed allows faster buildup of mineral deposits in cooling passages reducing water flow.
 
Impeller was changed 4years ag

Impeller was changed 4years ago. (Sieria)
The engine temp is at 160 degrees.
Thought a bad impeller effected low speed operating temps.
 
"changed 4years ago"

"changed 4years ago"

It's overdue since it has taken a set a long time ago.

"Thought a bad impeller effected low speed operating temps"

It is; sufficient water to cool the block but insuficient water flow to cool the exhaust manifolds and risers.

Do the impeller first and see it it cures the heat issue. Change the T'start as a PM measure. Use a Merc. OEM.
 
"Changed the impeller/kit &#40

"Changed the impeller/kit (merc).
Stbd manifold still hot hot. Just before pulling that manifold, I pulled the hoses to the manifolds while running. This was to compare flow to each side. Flow was the same. Opened the petcocks on the manifolds, each side had the same flow. Then the hot side cooled down just like the port side.
I'm confused but it is fixed.
Thanks Guys. This is the best site period!!!Carl"
 
"Carl-
Let us know if it stay

"Carl-
Let us know if it stays fixed. I have the same problem, and it's really strange- sometimes it gets really hot for a while, then it cools down for a while, then it gets hot again. I'm at a loss here."
 
""Opened the petcocks on t

""Opened the petcocks on the manifolds, each side had the same flow. Then the hot side cooled down just like the port side."

Perhaps some rust and scale buildup was limiting some flow. Time to send your exhaust manifolds and elbows to the radiator shop for a good cleaning."
 
"Guy. Good idea. One mechanic

"Guy. Good idea. One mechanic said "Just take a screwdriver and poke the holes clean. I like your way better. The manifolds have to come off anyway, if the new pump can't keep it clean.

Mike. Loosen the hoses that feed the manifolds.At the thermostate. Have them ready to pull off when the engine gets up to temp.Tape a piece of cardboard to the alt to block any splash. Pull the portside hose watch flow. Pull stbd. and compare flow. Remember what Guy said "Enough to cool the engine but not enough to keep the manifolds cool. The water goes thru the engine first. If it comes back i will post."
 
"In my quest to solve my one h

"In my quest to solve my one hot riser, I was told of flushing the cooling (fresh water)system with rust inhibitor/preventor.
How is this done?
Can I mix it in my antifreeze? I winterize using the merc seminar method of pouring specific ammounts of -100 into each hose at t-stat."
 
Carl:

Is your FWC engine bl

Carl:

Is your FWC engine block only? How old is the antifreeze? Is there a jelly like scum around the fill cap and overflow tank? Time to flush and drain it out if the scum/jelly is there. Then refill w/quality 50:50 premix. Rust inhibiters are included in the fresh antifreeze.
 
Guy
FWC only. The anti freez

Guy
FWC only. The anti freeze is the -100 from Boat US used only for storage over winter. Thanks for all the help. It's running great. Them thar salmon best watch out!!
 
"Changing the pump.and running

"Changing the pump.and running it 3,000 rpm under load. The riser was blown out by the new found pressure. Your advice was right on. My Water goes thru the motor then to the riser. With the reduced volume the water was unable to cool downstream."
 
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