Otwell heater question
 

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

Re: Otwell heater question
 

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

Re: Otwell heater question
 

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

Re: Otwell heater question
 

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

Re: Otwell heater question
 

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

Re: Otwell heater question
 

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.

Re: Otwell heater question
 

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

Re: Otwell heater question
 

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

Re: Otwell heater question
 

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.

Re: Otwell heater question
 

Baby food jar LID