New to me 1985 Carver 3697 Mariner with ch 350 Crusaders, raw water cooled. Always a fresh water lake boat best I can tell from records. Noticed port engine running very cold, barely 110 degrees in 82 degree water, and starboard slow to warm running up to about 125 after quite awhile. Service records from PO show that right after he purchased in 2017 he reported temp gauge (s) not working. Tech noted the gauges were working but “think thermostats have been removed”. Nothing apparently done to correct.
Went to port motor first and after a lot of work to break the housing (s) loose I found what appears to be the original thermostat. Brought it home and it was stuck slightly open. (Pressure relief valve, seat and spring In housing seemed fine). Put thermostat in hot water on stove and checked temp with a thermopen. It started opening at about 100 and was fully open at 110. Started closing about 100 but never fully closed, so causing motor to run cold. Problem solved, bought two new sierra kit # 18-3671 with 140 degree thermostats and gaskets. Discovered the water outlet gasket in the kit was not correct for the lower housing which sits on manifold. Got one at Autozone ( found that lot’s of parts cross reference for these motors to 1974 Corvette with 454) put it together and all good. Engine now warms to about 145 degrees quickly and holds right around 145 to 150 when running down Table Rock Lake. Did starboard engine yesterday and it now warms up much quicker and runs about same temp as port.
Questions:
After the fact (this morning) I discovered the marine version of the water outlet gasket from manifold to lower housing has a copper grounding rivet to provide continuity from upper housing to lower to manifold for temp sender. My gauge is working so I assume I am getting ground through the bolts. My question is I think the ground is all or nothing, either I get a ground or not, won’t give an erratic result. If that is correct I will just leave as is unless I lose the ground. Or should I just replace with the proper gasket?
Obviously the engine has been running cold for a long time, PO did not run much, only put 80 hours on it in six seasons. No clue how long it had been running cold before 2017. He had a survey done before purchase. Of course better for thermostats to default open than closed but wondering about any long term effects on motors from running cold. Oil looks good, don’t see any milky deposits from condensation when viewing through oil fill caps on valve covers. Anything I should watch for?
Also, did not replace the pressure relief assembly it seemed fine, worked freely, spring good. If I am correct this allows water to cool the risers when thermostat is closed in raw water systems?
Not quite related to topic, but port engine (LH rotation) has some “clatter” at idle that goes away about 1000 rpm. It’s not alternator, water pump, etc because before I replaced the belts I ran engine for about 45 seconds with belts off and noise still there. A couple of friends think it is the ”extra gear” for timing chain/camshaft for reverse rotation on this era Crusader. Any thoughts?
Sorry for the long winded post but trying to get all details out the first time.
Thanks, Ron
Went to port motor first and after a lot of work to break the housing (s) loose I found what appears to be the original thermostat. Brought it home and it was stuck slightly open. (Pressure relief valve, seat and spring In housing seemed fine). Put thermostat in hot water on stove and checked temp with a thermopen. It started opening at about 100 and was fully open at 110. Started closing about 100 but never fully closed, so causing motor to run cold. Problem solved, bought two new sierra kit # 18-3671 with 140 degree thermostats and gaskets. Discovered the water outlet gasket in the kit was not correct for the lower housing which sits on manifold. Got one at Autozone ( found that lot’s of parts cross reference for these motors to 1974 Corvette with 454) put it together and all good. Engine now warms to about 145 degrees quickly and holds right around 145 to 150 when running down Table Rock Lake. Did starboard engine yesterday and it now warms up much quicker and runs about same temp as port.
Questions:
After the fact (this morning) I discovered the marine version of the water outlet gasket from manifold to lower housing has a copper grounding rivet to provide continuity from upper housing to lower to manifold for temp sender. My gauge is working so I assume I am getting ground through the bolts. My question is I think the ground is all or nothing, either I get a ground or not, won’t give an erratic result. If that is correct I will just leave as is unless I lose the ground. Or should I just replace with the proper gasket?
Obviously the engine has been running cold for a long time, PO did not run much, only put 80 hours on it in six seasons. No clue how long it had been running cold before 2017. He had a survey done before purchase. Of course better for thermostats to default open than closed but wondering about any long term effects on motors from running cold. Oil looks good, don’t see any milky deposits from condensation when viewing through oil fill caps on valve covers. Anything I should watch for?
Also, did not replace the pressure relief assembly it seemed fine, worked freely, spring good. If I am correct this allows water to cool the risers when thermostat is closed in raw water systems?
Not quite related to topic, but port engine (LH rotation) has some “clatter” at idle that goes away about 1000 rpm. It’s not alternator, water pump, etc because before I replaced the belts I ran engine for about 45 seconds with belts off and noise still there. A couple of friends think it is the ”extra gear” for timing chain/camshaft for reverse rotation on this era Crusader. Any thoughts?
Sorry for the long winded post but trying to get all details out the first time.
Thanks, Ron
