Overheating

[vabiker23518]

I lit off my 1977 Columbia Sunday (6/2) and it started right up! I opened the raw water valve and verified the exhaust was "batching" water....it was.
Happily, I ferried some equipment from the dock to car. Upon return, less than 4 minutes the temp was buried at 220! Again, verified the raw water and batching...temp was not coming down so I turned it off. I took the raw water line off and the valve was not blocked...had good flow.
Last fall, when winterized, it was running well and temps never exceeded 180. The only change I made was to replace the 5/8" raw water line with a 3/4" thinking the extra volume would help the cooling. I SUSPECT the raw water pump is unable to keep the supply hose full and while it is getting some raw water, it's not getting enought to adequately cool the engine. I didn't have time to swap out the brass fittings and old hose, but will as soon as I can. Does anyone have any other ideas?

[vabiker23518]

Forgot to mention its FWC

The engine has fresh water cooling (FWC).
Wayne

[JOHN COOKSON]

If the heat exchange idea doesn't work out check the thermostat. It may be stuck closed.

TRUE GRIT

[sastanley]

what about the fwc pump? it may not be circulating the antifreeze to the HX.

Do you have one of those infrared thermometers? You can shoot it at the hoses & HX and see if the water coming out of the HX to the engine is cooler than the water going in. Also confirm that the raw water coming out is hot.

[marthur]

One other possibility is an obstruction in the FWC circuit. On my RWC boat that obstruction came from an old impeller blade. It had failed on the PO and after three years or so of my ownership a piece dislodged and blocked the flow of water.

Good luck!

Mike

[edwardc]

+1 on what Mac said. Impeller bits that break off tend to get lodged in downstream elbows in the plumbing.

[vabiker23518]

A little status update

Went to boat after work and changed out the raw water line for the old. The engine is still overheating, which leads me to believe its the impeller, as most have mentioned. Will order tonite and try to install this weekend. Thanks for your inputs!

[vabiker23518]

Plot thickens

Received my new impeller from MM and went to boat to install today. The old impeller (4 years old) was intact with no missing lobes. Installed the new, but noticed the "cam" was not in place. Didn't find in bilge but....it's mostly a touch and feely situation under the engine. Figure I'll order one (ouch, they are $40 in the catalog!) and pray the old one didn't lodge somewhere in the cooling system. While there, figured I'd take off the Tstat housing and check it out. I've owned this boat for 8 years and never had to take it off as it runs a consistent 180 for a FWC engine. No Tstrat in the housing...just open! As its been running for years without it, I'm not going to lose any sleep or money over that bit!
Still, I'm hoping the cam isn't lodged somewhere it shouldn't be! More to follow after installing the new cam....

[Mo]

Something doesn't sound right there. The cam should be there or it was removed?????? ...and without the cam it shouldn't pump at all!

[vabiker23518]

Agree Mo...

Engine was working fine when winterized last October. Always stayed at 180 or less. This season, upon commissioning, it would just overheat. Raw water does not appear to be a problem, it batches and exits as should. But engine overheats within 2 minutes of starting...it's just not getting the anti-freeze it should. What are the odds it would fall off/get lost right between seasons?

[Mo]

Engine was working fine when winterized last October. Always stayed at 180 or less. This season, upon commissioning, it would just overheat. Raw water does not appear to be a problem, it batches and exits as should. But engine overheats within 2 minutes of starting...it's just not getting the anti-freeze it should. What are the odds it would fall off/get lost right between seasons?

NONE!...unless someone needed a part and took it. I haven't seen anything like that re: an engine, but I have heard of people stealing mast rigging parts (pins etc)...pisses me right off to hear it. Have a good look at it and ensure it is what you think.

[edwardc]

...Didn't find in bilge but....it's mostly a touch and feely situation under the engine. ...

You can get quite creative using a digital camera in macro-focus mode to get a look at places you can't cram your head into.

Something doesn't sound right there. The cam should be there or it was removed?????? ...and without the cam it shouldn't pump at all!

What if he's got one of the newer pumps with no separate cam? I went back through this thread, and saw no mention of whether it's an Oberdorfer or Moyer pump.

[Gary Stimmel]

Hope 2 help.

I lit off my 1977 Columbia Sunday (6/2) and it started right up! I opened the raw water valve and verified the exhaust was "batching" water....it was.
Happily, I ferried some equipment from the dock to car. Upon return, less than 4 minutes the temp was buried at 220! Again, verified the raw water and batching...temp was not coming down so I turned it off. I took the raw water line off and the valve was not blocked...had good flow.
Last fall, when winterized, it was running well and temps never exceeded 180. The only change I made was to replace the 5/8" raw water line with a 3/4" thinking the extra volume would help the cooling. I SUSPECT the raw water pump is unable to keep the supply hose full and while it is getting some raw water, it's not getting enought to adequately cool the engine. I didn't have time to swap out the brass fittings and old hose, but will as soon as I can. Does anyone have any other ideas?

Dear 'V'-U should probably inspect your water pump impeller. Assuming that
U have an Oberdorfer pump on Ur Atomic 4. I am speaking from an experience
here in Ohio last season. I had 4 of 7 teeth missing on my impeller.

Best wishes from the crew of "Sandalfoot", Port Clinton, Ohio.
Gary Stimmel, Capt.

[vabiker23518]

Good News

Received the new "cam shoe" for FWP from Ken yesterday, so stopped by and installed it today...and GREAT news...it resolved the overheating! After installation, started up and ran it at top RPM in gear, pier side tugging at the mooring lines. After 15 minutes, temp gage was sitting at 140! A great success.
What I learned: The culprit was the cam shoe. The old, replaced impeller had all its lobes...none missing. When I went to install the new cam, I determined the old cam was still in place! Yep, it was worn down, but not flat. (who would think that rubber impellers could cause so more wear on a bronze cam shoe?) Thought it was missing, but it was still in place. After removal and checking against the new, there was a noticeable difference in the height. After installing the new, and starting up, MERLION ran like a champ. Now, with a little cabin clean up, we're ready for sea (or the York River, whichever comes first). Thanks for your comments and suggestions...always a great resource! And Ken too!
Thanks, Wayne

[Mo]

Perfect...good show.