C310 overheating

Mar 27, 2016
26
Catalina 310 NAS Pensacola
My 2004 C310 Universal M25XPB temp climbs to 200+, takes about 20 minutes. R&Rd thermostat, coolant level OK, raw water screen and HX seem ok, Sherwood impeller OK, raw water output starboard aft seems OK but not alot. The only thing left is engine water pump. Is there a way to check that? Thank you!
 
Mar 27, 2016
26
Catalina 310 NAS Pensacola
Don, thank you for the quick reply. Have not attempted R&R exhaust elbow. I assume I would decouple from coolant reservoir (with attendant loss of coolant) and inspect for clogging?
 
Sep 25, 2008
7,076
Alden 50 Sarasota, Florida
Correct. Depending on how many hours on the engine, the elbow is the most likely suspect to cause a flow restriction thereby increasing engine temp.
It may be a water pump issue too but checking the elbow is easier to check/eliminate.
 
Mar 27, 2016
26
Catalina 310 NAS Pensacola
I will study how to take elbow off manifold, thank you! I noticed the HX didn't seem particularly wet either end. I am thinking of replacing Sherwood with Oberdorfer. It will be a while before I get back to boat...very much appreciate your comments and will post resolution.
 
Mar 27, 2016
26
Catalina 310 NAS Pensacola
Paul, I removed the thermostat & ran it straight through, results as reported. Put spare thermostat in later, same (original thermostat checked out ok in hot water test). I've only had this boat a few months and I've never really observed much water from the exhaust, just sputtering (I can hear it & observe a few drops at high rpm). The Sherwood pump had a great deal of play in the pump drive shaft when a mechanic checked it a few months ago. I bought an Oberdorfer and when I get a couple of barb fittings I am going to change pumps. I didn't see a lot of evidence of raw water in HX when I removed end caps.
Thank you for your comments!
 
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
The first thing I would check based on your description is that the coolant is air bound. You can search old posts and there see description of how to properly bleed the system.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Been doing auto mechanics for a while now and I've never seen an engine coolant (anti) pump not pump. They leak but there is not much chance of the impeller not turning and pumping anti around the engine. They get air locked when the thermo does not open though. The best way to check the thermo is to pull it and boil it in a pot of water. Use a candy thermometer to check when it opens and that upon pulling it from the water it closes also.
The most common cause of a slow overheat is low raw water flow with the exhaust elbow being the most common culprit.
 

paulj

.
Mar 16, 2007
1,361
Catalina 310 Anacortes,Wa
Hogdriver
"I bought an Oberdorfer and when I get a couple of barb fittings"
Make sure they are bronze fittings.

paulj
:hook2:
 

SFS

.
Aug 18, 2015
2,066
Currently Boatless Okinawa
@paulj - is that the engine in your boat? I had no idea engine access was that easy in any boat around 31 feet.
 
Mar 27, 2016
26
Catalina 310 NAS Pensacola
Yes it is pretty well laid out. I will use that hose for flow check. I need to learn more about exactly how the raw water /manifold work together and how to remove the elbow. Just disconnect from manifold & exhaust hose output?
Bill thanks for your comments...I have a 67 Austin Healey that keeps me busy also... The boat systems are what I need to learn. I appreciate everyone's comments!
 
Mar 27, 2016
26
Catalina 310 NAS Pensacola
The Catalina 310 is a superb design by Gerry Douglas. He observed larger boats that only had a couple onboard and designed it for the causing couple. It is a wonderful boat!
 

paulj

.
Mar 16, 2007
1,361
Catalina 310 Anacortes,Wa
Just disconnect from manifold & exhaust hose output?

Yes....will not take long for an answer. The water will start flowing as soon as engine is running.

paulj
:hook2:
 
Mar 27, 2016
26
Catalina 310 NAS Pensacola
Right, thank you, one has to be ground down a bit for clearance, I've ordered a straight fitting also. Unfortunately I have some commitments and It will be another week or two before I get back to her but I will let you all know how this turns out. Very much appreciate the comments...it is amazing how much I've learned from everyone!
 
Mar 27, 2016
26
Catalina 310 NAS Pensacola
So I finally got some boat time & put everyone's thoughts to the test. Pulled the hose off the exhaust elbow... no raw water! Removed Sherwood pump...gears inop. Replaced with Oberdorfer...runs like a champ, 165 degrees, 15 degrees cooler than before she started overheating.
Many thanks to all for sharing your experiences & ideas!
 

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