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Subject: TWL: RE: Exhaust overheat alarm sensor location on Lehman 120s
From: Joe Engel (joe@XXX.XXX)
Date: Wed May 01 2002 - 18:02:40 EDT
Highly recommended.
Joe Engel (toasted exhaust specialist)
-----Original Message-----
From: Rich Gano [mailto:rgano@XXX.XXX]
Sent: Wednesday, May 01, 2002 2:53 PM
To: TrawlerWorld
Subject: TWL: Exhaust overheat alarm sensor location on Lehman 120s
I recently mounted 160 degrees F alarm sensors (from Doc Freeman Marine)
on the exhaust elbows of my two Lehmans and Onan generator, and the one
on the stbd engine went off Sunday while at "battle speed" of 2100 RPM.
My normal operating range is 1600-1800 rpm, and I have had no alarms in
that operating range. Luckily wife was below to hear the bell because I
could not hear it from the FB. That problem was corrected last night
with an additional alarm buzzer on the FB. Had tried listening to the
bell at the lower station pier side without wind and crashing bow wave,
and it seemed loud enough then.
After being notified of the alarm, I shut down the engine
and found no obvious fault (all fluids ok and engine temp
gauge never exceeded 180F). Restarted, checked cooling
water flow at stern, and ran at moderate speed of 1200 rpm
for a few minutes until alarm light went out. Ran at 1900
and then at 2000 rpm for awhile with no alarm. As soon as I pushed to
2100, the alarm went off. NOW I noticed that the stbd engine's sensor
was mounted ALONGSIDE the raw water inlet on the exhaust elbow instead
of OPPOSITE the inlet, as had been done on the port engine. Water
hitting the opposite wall of the exhaust elbow makes a big difference in
temperature.
Loosening the sensor's mounting clamp and rotating it to the other side
of the elbow seems to have solved the problem of premature alarming.
Nice to have had an op test without a Joe Engel type consequence.
Luckily the wiring tube to the FB had enough room for another twinned
wire for the second alarm buzzer. Otherwise it's an all-day sucker of
disassembly/reassembly to get any more wire runs up there.
Rich Gano
CALYPSO (GB42-295)
Homeport Southport, FL
I'd rather be cruisin'
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