Overheating - Found thermostats corroded and dropped in water jacket

[robmcconnell]

Hi All

I have a 2001 mercury 140hp V6 carb model.

It's started overheating this season running up to 170 on the gauge and occasionally hitting 220 before dropping back to 170 again when speeding up. Telltale was running fine.

First thing I checked was the thermostats and found that the body of the thermostat had corroded and dropped into the water jacket, see picture of the remaining part. I have orders two new ones to fit next week. The local boat store said I needed to track down the parts that had dropped into the water jacket, this would mean removing the cylinder head covers and new gaskets. What do you think, do I need to do this and will they be in the water jackets that run around the cylinder heads or would they have worked their way somewhere else?

I replaced th impeller last season and I have checked its condition and the gasket, it seems fine. I have also checked for blockages in the hoses that feed the heads and they are fine.

I actually had another problem where the engine would not drop back into neutral and was revving but I think this is control or throttle cable related. I wil post this question under another thread but thought I would mention it in case it was linked in any way.

Cheers
Rob

 

[wired247]

First off what do you have? There is no 2001 140 HP carb model V6 unless its a jet in which case the rest of us would call it a 200 HP. In any case you need a new water pump impeller, possibly a poppet kit and you absolutely need to pull the heads and clean the "extra" parts out. It'll cost you $50 for the gaskets and TTY head bolts are good for one, maybe two at the most additional torque cycles so you shuldnt need those. . .

 

[robmcconnell]

Hi Wired

Sorry I should have said I am in Australia, the engine was probably rebadged for export as a 140hp. Probably a 150hp V6.

So I should removed the cylinder head covers and clean out the water jackets. Does the water cycle through any additional chamber. My engine has the fresh water flush fitting next to the telltale and this seems to have a large hose running to a connection to a section between the two banks of cylinders. See photo of head enclosed.Apologies for my description, its been a while since I worked on an outboard.

Cheers
Rob

 

[wired247]

If the thermostats fall apart , and they frequently do, the pieces are going to end up in the cylinder case under the heads. Your temp spikes have me thinking the water pump is bad. Those should be changed every couple of years.

 

[robmcconnell]

Hi Wired

I just pulled the poppet valve and I will order a new kit for this. I will order the two cylinder head gaskets and a new impeller. I may as well do the lot while I have it apart.

Thanks very much for your help, I will let you know how I get on when the parts arrive next week.

Cheers and happy new year.
Rob

 

[Dukedog]

Now that's something ya don't see here in tha States! CDM motor with plain jane heads. All tha "electronic" motors here have 0-ring type head and "tall" blocks....Old dawg learned somethin' today. Thanks for tha pics and good luck with it...