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With an infrared thermometer I got the following temps from farthest cylinder to the one closest to the fly wheel. 135, 148, 152, and 164. Is this normal? What should I be getting for temps?
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That sounds about right to me. It makes sense that the aft most cylinder (#4) would be the cool one if your engine is a late model one that has the diverter fitting in the water jacket directing all the incoming water toward that cylinder first. I'm not sure exactly which years the fitting was configured this way, but my boat is a 77' and has it configured like that.
Qben Oliver -
Cylinder Head Temps
I went through this last summer, my first with FW cooling. At 1400 RPM tied to the dock, I measured (infrared) head temps from 150 F to 196 F, with a temp gauge reading of 160 F. At the same time, the outlet coolant from the manifold was at 125 F or so. My conclusion was that the temp sensor at the front of the head was more effective in measuring head temperature than water temperature!
Wondering about limiting head temps, I did a 'google' and found that the only folks really concerned about head temps are the ultralight aircraft folks. Their temperature of concern varies with their engine, but is 350F or higher.
I decided that head temp wasn't really a concern, and moved the coolant temp sensor to the exhaust manifold outlet.
AlComment
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Cylinder Head Temps
Al,
I've wondered about cylinder head tempas well. I partially dismanteled my fresh-water cooled A4 after a water injestion -> over temp -> blown head gasket incident last year. Since reassembling, I've been watching the temps very closely; finding the same as you - high cylinder head temps near 200F while temp guage reads 160 ish (under load). I can watch RPMS and baby the motor - but it doesn't seem correct. Perhaps others could measure thier head temps under load and see if we are the expections? I used the oven thermometer placed on the head for readings..Comment
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