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Overheating inboard

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blueflu

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"My port 305 FWC straight inbo

"My port 305 FWC straight inboard is running normal at idle but slowly cruises up over 200 deg after I reach about 15 mph. On both engines all the hoses, manifolds, risers and heat exchangers feel the same temp to the touch at running speed when the port gauge (which is a replacement gauge) reads hot. I replaced the raw water pump, back-flushed the entire raw water system, flushed the risers and manifolds, checked the tstat, removed and flushed the heat exchanger and checked the circulating pump. Whats next. Could it be as simple as a faulty sender. I've had several temp related issues since last year on this engine but it was running great this year until I fried a raw water pump then they all started again which is why I did the above. I'm positive there are no impeller pieces in the system. Shark season is around the corner! Could the risers be partially clogged but still feel the right temp?"
 
"Swap the senders between engi

"Swap the senders between engines, clean off any crud first, and see if the temp problem changes to the starboard engine and the port engine reads normal. If yes, get a new sender for both.

Guy"
 
"I didn't swap them today

"I didn't swap them today but I pulled the port sender and it looked brand new. I also pulled the raw water intake and outlet to the oil cooler hoses and flushed them AGAIN- both fine. I noticed that both sides of the raw water portion of the exchanger were the same temp, cool. Shouldn't the inlet side be cooler than the exit side which heats up as it cools the anti-freeze. I'm wondering if the exchanger is partially clogged. I'm going to swap the exchangers on Tuesday or Wed and check that. I'll post the results."
 
"Tony:

Stop guessing and bu

"Tony:

Stop guessing and buy a laser temp gun! Aim at the sender unit and read what's really going on. Okay? Not expensive.

Jeff

PS: If something is really hot down there, you can sweep the motor and exhaust system with the temp gun and see WHERE and WHAT is screwed up. Great tool."
 
I am in the process of borrowi

I am in the process of borrowing one but what will aiming it at the sender unit do aside from getting a reading there?
 
"Today I swapped the gauges, s

"Today I swapped the gauges, still overheating, swapped the senders, still overheating, then I took off the risers and extension bases and behold, almost half clogged. It ran at 2000 rpm at the dock for about 15 minutes at around 170 deg. whereas it just kept climbing up before. It's much better than before but I think it should still run cooler. I'm going to chemically clean the exchanger Thursday and see how that helps."
 
I just had to replace it last

I just had to replace it last week. I think I wrote that above. I picked up a piece of sea lettuce and fried the impeller and shredded the housing.
 
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