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How cold is TOO cold for a raw water cooled 5.7?

No heater on either engine.

And thanks, Diver Dave. My oil pan usually reads about 125 with the infrared thermometer gun, and the oil filter reads 130 or so. Not sure how that translates to ACTUAL oil temperature, but I’m getting pretty consistent readings between 120 and 160 all over the engine (with the gun), so I guess I’m probably okay, unless I’m missing something.
 
I wonder if a bypass would help stabilize engine temps? Basically that is all a heater circuit does put a fotting on the intake manifold and another on yhe heater port on the circ pump. That allows water to flow through the nlock until the thermostat opens. Whats happening is the thermostat opens too far and then closes back down quickly. It wouldnt be that much maybe $20 2 brass nipple adaptors two hose clamps and a chunk of heater hose. Might be worth a shot?
 
I’m not too familiar with the whole bypass valve thing, apart from what I’ve read on this forum. I wouldn’t mind trying it, but my concern would be diverting additional water flow away from the exhaust. I already have a lot of steam coming out of the exhaust when I’m on plane.
 
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Give them a good backflush if it helps just plan on replacing them. What does the service schedule say about the oil coolers? Start at the water intakes and work your way to the raw water pump looking for any blockage.
 
One more area to consider. I had steam from the exhaust last year on my port engine. It had OK flow, but seemed a little less than the starboard engine. A couple weeks ago, I was de-winterizing by reinstalling the impellers in the Sherwood raw water pumps. I noticed the cam in the port pump was considerably smaller, due to erosion of the bronze, than the starboard side (I replaced the starboard cam a few years back). I installed a new cam and my steaming went away (based on one day of using the boat). I think the old worn cam was not squishing the water out from between the impeller's vanes as effectively as the new one does.
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Good Morning
My engines both 350's straight raw salt water cooled also in Southern California. 1966 Californian express. Engines are unknown origin matching 1970 blocks. I've owned the boat 12 years. I have 143 degree thermostats on the engines. Needles never leave the seat of the temp gauge which are at 125 degrees. Have changed the senders years ago with no effect back then. Heat gun shows 140 to 145 degrees at the block under the 2 center exhaust ports, and 114 degrees at the end of the exhaust elbows where the exhaust hose connects. Boat runs great. Change the oil December and June regardless. Start up twice a week in my slip. Warm up 15 min then engage into gear for about 30 seconds to spin the shafts and lubricate packing. Engines idle for hours on end just fine when in the fishing grounds.
 
jclays said:
Good Morning
My engines both 350's straight raw salt water cooled also in Southern California. 1966 Californian express. Engines are unknown origin matching 1970 blocks. I've owned the boat 12 years. I have 143 degree thermostats on the engines. Needles never leave the seat of the temp gauge which are at 125 degrees. Have changed the senders years ago with no effect back then. Heat gun shows 140 to 145 degrees at the block under the 2 center exhaust ports, and 114 degrees at the end of the exhaust elbows where the exhaust hose connects. Boat runs great. Change the oil December and June regardless. Start up twice a week in my slip. Warm up 15 min then engage into gear for about 30 seconds to spin the shafts and lubricate packing. Engines idle for hours on end just fine when in the fishing grounds.
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Hi socal buddy...your engines and routine sound almost identical to mine. I also have twin raw water cooled 454s that were original in 1976. My best guess from paperwork on board shows last overhaul in 1998ish. My engines start and run superbly and also idle forever without skipping a beat. I run the engines in the slip at least once a week and I also go into forward and reverse tied up just to keep stuff loose. Have owned 1 year...so far so good. I am in Cabrillo Way Marina in San Pedro. 19 miles from island.
 
DJR said:
........................... A couple weeks ago, I was de-winterizing by reinstalling the impellers in the Sherwood raw water pumps. I noticed the cam in the port pump was considerably smaller, due to erosion of the bronze, than the starboard side (I replaced the starboard cam a few years back). I installed a new cam and my steaming went away (based on one day of using the boat). I think the old worn cam was not squishing the water out from between the impeller's vanes as effectively as the new one does.
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Very well explained! :)


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