Date Posted:- Saturday - 07/ 2/11 - 9:06am Author: Paul M31 #106 NJ Subject: Exhaust temp is much lower than engine coolant temp In reply to:
Randall, Murre, M31
's message, "PVC it is...at least for now" on - Saturday - 07/ 2/11 - 12:09am
The only influence the 180 degree engine coolant tem has on exhaust temp is at the water cooled exhaust manifold. The (dry) exhaust is cooled somewhat there but definately not all that much. The real cooling happens at the raw water injection elbow where the exhaust gets mixed with seawater after it is done cooling the heat exchanger, oil cooler and tranny cooler. Then the exhaust gases literally pushes the raw water from the water lift muffler into the exhaust line to the through hull - well cooled at that time...
The only downside I see with where you propose to put the loop is that, since the exhaust line is sloped down towards the thru-hull, you will have standing water in that hose from then on when the engine is shut off - instead of the hose draining as was designed. With my system, all hoses drain - either back into the water muffler or overboard, once I shut off the engine.
But it should help you keep the ocean out of your exhaust manifold for now.
Will you be able to also put in some vacuum break?
Randall, glad to hear you could find the needed parts that easily. If I understand, you're going to put the loop aft close to the through hull. On my boat the PVC lift muffler is attached to the lower front side of the fuel tank, so the water that flows back into the muffler when I shut down is minimal (just the vertical rise to the underside of the cockpit seat.) Just make sure that if your muffler is lower than the loop your installing there won't be more water backing into the muffler than it can hold when you shut down. Hope that makes some sense? Mark
