Exhaust manifold overheat and blistered

[Big Al 66]

The exhaust hose on this Volvo Penta 3.0 is blistered. The boat was running hot last time out. I suspect a bad impeller. Would bad impeller cause the exhaust rubber pipe to blister like this? Is this a bad indication that it got dangerously hot or is this common and likely just needs impeller?

 

[alldodge]

Would bad impeller cause the exhaust rubber pipe to blister like this?

Yes, if there is not enough water going thru the exhaust to keep thinks cool the rubber will blister.

The impeller is always first thing to look at in these cases. The impeller is a maintenance item and should be replaced as required.

 

[Scott Danforth]

with water going thru the exhaust manifold and out the elbow, the exhaust gasses are cooled to about 220-250 degrees

without water going thru the exhaust, your exhaust gasses are 900 degrees

you need a new impeller and new exhaust hoses at a minimum. if the vanes of the impeller are gone, you need to find them

volvo recommends replacing the impeller every 2 years. they recommend pulling the drive to inspect the u-joints, alignment and bellows every year