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Hot exhaust manifold

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richp

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"Have a 1987 Carver 32' wi

"Have a 1987 Carver 32' with two fresh water cooled crusaders 270hp. One of the exhaust manifolds on the port engine runs 45 degrees hotter than the others. I have removed ,cleaner and made sure the proper gaskets were installed,still runs hot. Any idea what the problem could be?"
 
The water is not getting out t

The water is not getting out the back of the riser to the exhaust. The holes in the riser where the water finally mixes with the exhaust must be plugged. Pull the riser and spray water in with a hose. It should blow right out the back.

Jeff
 
"It appears one manifold is ge

"It appears one manifold is getting more flow than the other. Since they have hoses that basically route the flow from the same place on the thermostat housing and end the flow at the heat exchanger, not much to go wrong. I'd check the hoses themselves on the hot side for interior delamination."
 
"rich:

you didn't say w

"rich:

you didn't say what you removed and cleaned, so here's my guess. assuming you have the infamous IR thermometer, if you measured the exhaust outlet (riser), follow what Jeff suggested. I'd add if one riser is plugged up, change both on that engine and keep a close eye on the other engine; it won't take much longer for those to plug up.

If you measured the manifold itself, especially along the sides, away from the riser, go with Dave's suggestion."
 
"I removed the manifold from t

"I removed the manifold from the inlet hose to the exhaust exit . Today started the motor and both exhaust manifolds we running about 140 at idle using a IR thermometer,could there have been a air pocket that bleed out?"
 
"Air pocket, perhaps. When fi

"Air pocket, perhaps. When filling my heat exchangers with new coolant, the exh. manifolds are the last items to fill up. Also, if the engine was not fully warmed up for the test, there is very little water flow thru the manifolds in a FWC setup. They can heat up pretty good up until the thermostat opens, and flow starts thru the manifolds."
 
How hot should the manifolds b

How hot should the manifolds be. Ive wondered about mine. Ive had the boat almost 3years never had the manifold off. I doubt if the previous owner has. Shot the manifolds (raw water cooled. No risers old style crusaders with elbow) after idling 1/2 hr. Temps where 113-115 degrees. 145 at the exhaust ports at the head.
 
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