I've noticed recently that the shelf above the exhaust is really getting hot. I suspect the factory installed insulation above the exhaust pipe has seen better days. Does anyone know what type of insulation to use in that particular application? I'm assuming it's nothing too special.
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Mark Swenson
Everett, WA
Hull #1016, unnamed
On our 87 there is just the standard exhaust wrap. 2 or 3 layers and a small heat shield screwed to the bottom of the plywood cover.
Plans are to add sound insulation to the inside of the box as well.
Ross & Joanne
Wavelength
Saint John NB
RKYC
C36 #658 TR 1987
Our boat has the fiberglass tape wrap which I have replaced one time since getting the boat. The metal heat shield on my boat is wired over the insulation itself, rather than attached to the box. I think attaching to the box would be better as the shield vibrates and abrades the fiberglass tape stuff, making a mess of itchy dust all over the engine compartment if I don't vacuum it out from time to time.
If there is some sort of high-temp tape you could wrap over top of the fiberglass insulation just to trap the loose fibers this would be a good thing.
Jason V
Vancouver, BC, Canada
Mark,
You are correct. The insulation is nothing special.
Jason,
I think the PO reversed the insulation on your exhaust. I think most MkI's came from the factory with metal mesh next to the the exhaust pipes, and then fiberglass tape wrapped over that. You can go to just about any automotive store and get exhaust wrap. I think it's used for hot-rodding and custom exhausts (or at least it used to be! :-)
Tom Sokoloski
C36/375IA Past Commodore
Noank, CT
Agree. That's what I put on mine - from Advance Auto Parts, as I recall. I think I had a post on it a while back if you want me to find it for you.
Heads-up that it still smells a bit if I run at high cruise RPM for 30 min or more, but it seems to have no other ill effects. I was told that the fiberglass just needs to "burn off" a bit and then it will settle down nicely. Still waiting for that to happen.
A race car mechanic told me to wet the tape before installing, so it will shrink as it heats - sort of like shrink-wrap. I did so, and that worked out well for me.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
If there is room you may want to consider putting a heat sheild on the bottom of the shelf as well. A simple piece of metal, stainless preferably with some spacers between it and the wood to allow some airspace between the wood and heat shield will greatly reduce the heat transfered to to wooden cabinet. This is in addition to the exhaust wrap not in place of it.
If you are seeing much steam coming from your exhaust, you should check that your mixing elbow is not clogged with salts as this will reduce the water flow in the exhuast and cause the system to run hotter.
Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas