Otwell heater question

[1crosscut]

Curious as to the purpose of the small opening at the top rear of the manifold.

[Joe K]

This for use in the summer when your firewall valve is closed.

The alternative is to remove the manifold entirely and replace it with your "summer" manifold.

My Otwell is minus the auxiliary opening.

You want to arrange for some sort of "tightness check" on the gas side of that manifold. Otwells are notorious for in time developing a leak which bypasses carbon monoxide directly to the passenger compartment.

Other brands/arrangements don't suffer quite so much in the failing and are readily checked.

Joe K

[1crosscut]

Thanks Joe. Basically a bypass to help prevent hot air squeezing past the firewall valve.

[The Master Cylinder]

That's for adjusting the amount of engine fumes entering the cab.

[JoeCB]

There should also be a plate to cover the intake scoop end. At least mine has a screw hole that would indicate that.

Joe B

[1crosscut]

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Joe mine doesn't have a hole in the intake area. Leaving it open along with the rear bypass I think would help with keeping it cooler in warm season driving.

I taped off the manifold ports today and filled it with water. No leaks into the heater side of it.

[JoeCB]

Dave, no sign of a intake "stopper" , maybe an engineering change with the addition of the up- facing het relief port. My Otwell has no relief port.

Joe

[1crosscut]

I bet your are right. Yours is probably an earlier model.

[verdirick]

Just FYI, I simply take the heater door out and block it off with a baby food jar and replace it and in addition open the relief door for summer touring. always is a pain to replace the heater door, but goes with the territory. At least quicker than changing out manifolds.

[verdirick]

Baby food jar LID