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Running too warm?

jclays

Regular Contributor
Good morning
Almost one year ago this month I replaced my port side engine with a brand new base 350 marine engine long block. She's been running good but had not gone very far. Unfortunately due to my work load at the time she has only been started weekly in her slip but not really run out in the open. Her cooling is strictly raw water cooled (ocean salt) 1966 style. I did not change over when I replaced the port engine. At the time I could not afford to convert over 2 engines to a closed system. Anyway running at harbor speeds 5 mph the temp gauge reads 120 degrees. After running about half an hour at 2400 rpm 15-16 knots the temp gauge reads 180 degrees. I have the Crusader 142 degree thermostat. Is she running too warm?
Thanks
Jim.
 
maybe....

I'd check it with an IR gun before I declared anything needing attention.....the dash gauges aren't known for their accuracy.

I'd check the t-stat outlet, both manifolds (away from the exhaust ports), and the elbows....If you can do both engines at the same time, that would be useful data too....
 
I need to find a quality for salt water use thermostat. The ones that look like a stainless/brass mix get rusted up in about a year or so. With the stay at home quarantine I have plenty of time to spend in the marina. Ill remove the Tstat housing and check it out.
 
Found the trouble. Belt that drives the engine circulating water pump was damaged and loose. Bought a new belt and installed it however it starts running true after about a minute the belt twists/rolls over as it is running.
 
Found the trouble. Belt that drives the engine circulating water pump was damaged and loose. Bought a new belt and installed it however it starts running true after about a minute the belt twists/rolls over as it is running.

The pulleys may be out of alignment, or as suggested, one pulley may be bad and in need of replacement.

Back in my old high performance SBC days (mid to late 60s), we would use V belts that were weighted as to prevent them from rolling over.
 
Quality of t'stats... buy either an OEM t'stat or a Sierra replacement. To lengthen your t'stat ( and other parts that see salt water) life, flush your system with fresh water every couple of trips (ideally) every trip. This will require the installation of a marine grade T, shutoff valve, and a hose bib . The safest way to flush IMHO is to attach a short ( 3 to 4 ft) hose to the bib, put the other end in a 3 to 5 gal bucket and let a dock hose free run water into the bucket. Monitor the water level carefully, Running above idle engine RPM not recommended. Occasional use of SaltAway seems to help.
 
Replaced a pulley and used 1/4 inch spacer to extend out the pulley on the harmonic balancer. Seems to have worked it was out of alignment put new alternator with the new motor I installed. The new alternator mounting ears are thicker and the holes smaller than the original 1966 alternator. threw the belt alignment off.
Thermometer still reading 180 degrees even with the 142 degree thermostat. Heat gun at the hoses and thermostat housing reads 140 thru 145. Need to find a better location for the sending unit. Its at the bottom end of the log type crusader exhaust manifold below the #7 exhaust port.
Remember this boat is 100% salt water cooled no risers, heat exchangers. Salt water in thru the engine and out the exhaust. Log manifold to elbows, mufflers then out.
 
glad you got the belt alignment resolved....

On the sending unit, Never seen one on the exhaust manifold....usually on the t-stat housing or in one of the intake manifold passages....not surprised that the gauge shows hot....I'd look at relocation....
 
I wish there were provisions on the intake or the T stat housing for the sending unit. there is a Tee that feeds from the exhaust manifold to the T stat housing. One end is capped. I can try installing it there. It is the feed to the T stat housing. Feed comes from the top of the exhaust manifold to the bottom of the T stat housing. From there the Tstat opens up and water rises to the top of the T stat housing and exits thru a hose on each side to the exhaust elbows. Until the T stat gets hot enough to open the water exits thru the bypass pop up valve inside the top of the T stat housing to the hoses feeding the exhaust elbows
 
I do not see anything on the head itself however there is a brass threaded plug on the right side of the engine block (viewed from the rear looking forward) centered below the center exhaust ports but in the block itself.
 
in a car, most people use the drivers side head....that said, I would say either is viable and I would chose the one the has the better access...
 
Going to have to go to the boat and check the access. I think the manifolds will be in the way of the plug removal and temp sender installation. The block has a plug about half way down mid block looks like a drain plug for the water jacket on the block. Is this a good alternative?

Was looking online and saw some radiator hose adapters that had a bung for a temp sensor welded on. Cut the hose and insert adapter inline with the hose. Maybe this would be a good option? Installed in the hose that feeds the thermostat housing
 
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the drain plugs are usually lower than the freeze plugs...two issues with these - 1) size isn't big enough for typical sender unit & 2) location is on the 'cooler' portion of the cooling loop...in other words, it won't reflect what is going on up at the thermostat.

The adapter may work out best...

another option would be to buy the correct thermistor and make your own sender unit...lots more time than the adapter...
 
the drain plugs are usually lower than the freeze plugs...two issues with these - 1) size isn't big enough for typical sender unit & 2) location is on the 'cooler' portion of the cooling loop...in other words, it won't reflect what is going on up at the thermostat.

The adapter may work out best...

another option would be to buy the correct thermistor and make your own sender unit...lots more time than the adapter...

thermistor?
 
A temperature sending unit should be installed just prior to (i.e., upstream from) the actual location of the thermostat.

This will allow it to sense coolant temperature after it has gone through the cylinder block, around the cylinders and through both cylinder heads as it makes a return to the thermostat area.
 
thermistor?

Its the electronic component inside a sender unit....usually a bit bigger than a BB...with two lead....functions as a temperature controlled resistor but has a non-linear transfer curve...get the right one and a bit of thermally conductive epoxy and you can put the 'sender' anywhere you want...
 
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