Change of exhaust elbow on KAD 300

About Time

About Time

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Hi,

I am about to change the exhaust elbows on my twin KAD 300. It seems one of them is full of rust and partly blocked so air cannot flow freely from turbo unstable pressure about break in point (2700 RPM).
The boat is in water ... Is it wise to change the elbows with the boat in water or should I better get her out of water before I do this ? It seems an easy fix ... few bolts and clamps,
Just not sure how deep the sea water stands in the outlet pipes.... worry about water intrusion.
It is a Windy 37HT.
Better safe than sorry :)
 
I did mine in situ / afloat on a S/Skr Porto 35 , they are above the WL .
The real horror comes looking down at the “ horn “ it’s rim will be rotten as well . Might need some bodge gasket sealant to reattach the rubber bellows back to the corroded horn rim once you have removed it ,

Dont know Volvo use such crap metals?
 
Interesting .... I thought the exhaust pipe was bolt mounted to the transom and that the big anode on the DPG (290) transom should protect the pipe too... I see why the elbow is rotten as this part is exposed to sea water but has no anode to protect (due to the rubber bellow between pine and elbow). Thanks for the input though.
 
No problem changing elbow in water .
They don’t generally stop exhaust gas flow , it’s the raw water flow that gets restricted , look up inside and you will see the outlets , a screwdriver can clear them , then submerse in neat brick acid will dissolve the smaller rusty bits.
 
As mentioned... no problem changing in the water (on my boat anyway, Cranchi Smeraldo 37)

My elbow was fine (fresh water).

Only thing to mention is that I needed to use exhaust assembly paste between the turbo / elbow when putting it all back together.
 
Corroded top of alloy exhaust horn.
Think Volvo Penta did do a "repair" kit to kick that particular can down the road so that next owner has the joy,delight and howling expence of removing and replacing that alloy exhaust horn.
It consisted of a little sleeve or collar that was bonded. ie glued onto the top of the coroded horn to allow the hose clamp to grip tightly.
Part No 3581114
Did the job on one of my outdrives and it certainly lasted long enough to flog the boat to a new owner.
To replace the horn you need to remove the bolts securing it to the transom assembly.
They are almost impossible to get at ,even by Volvo Penta standards , and will almost certainly be corroded.
On my boat it would have meant taking boat out of the water and moving the engine forward.
 
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The part number I have is 3581115 which is the 4 inch kit for the exhaust horn - when I spoke to the volvo dealer he said there was 2 kits the other being smaller diameter.

jon
 
Yes - Paul is correct - The chap on the phone to me when ordering said he thought the smaller kit was for the earlier kad versions.
As a side note Paul did you fix the exhaust horn whilst the boat was in the water ?? just thinking of the water line.

Jon
 
volvopaul said:
No problem changing elbow in water .
They don’t generally stop exhaust gas flow , it’s the raw water flow that gets restricted , look up inside and you will see the outlets , a screwdriver can clear them , then submerse in neat brick acid will dissolve the smaller rusty bits.
Click to expand...
How long would suggest submerging the elbow in brick acid for ?
Jon
 
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