still running warm

[handball]

this is a follow up on my mercruiser engine problem. It is a fresh water cooled 350 chevy that has started off the season running 170 degrees and has gradually increased the temp to about 195 @ 3000 rpms. I have installed a new water pump, checked the water intake under the boat, cleaned the screen, checked the heat exchanger found it to be clean.just made a trip up the hudson and found the temp to increase as the hudson was over 82 degrees. would like to go at least 32oo rpms but the temp. heads up towards 200. Is it possible that a thermostat could cause this problem? Also I have checked the rises temperture and compaired them with the port engine, you can hold your hand on the port rises, but the starboard engine rises are a little to warm to keep your hand on to long. water flow out the exhausts seem similar. This is a new boat for me and do not know when the rises were changed, the last owner said recently but did not say when.<br />Does anyone know how to tell whether this is a problem on the fresh water side or on the salt water side? The manifolds are also fresh water cooled.As new rises cost $130 each and looks like a lot of work I would like to be sure they would cure the problem.Both engines have about 800 hours do not use oil and otherwise run perfect. This is a straight inboard installation.Any input on this problem would be greatly appreciated.

 

[akriverrat]

Re: still running warm

pull hose off exit side of trans and oil cooler/s and check if flow is restricted. usually it would take severely overheated engine to make raw water cooled risers to hot to handle if raw water side working right.

 

[magster65]

Re: still running warm

A thermosthat could cause that. Sometimes they get 'sticky' and don't open all the way... or close. They're cheap so I'd change them. Try pressure testing your systems to locate any coolant leakage, if there are none then start looking at the raw water side. Your riser job isn't that difficult either. Risers have raw water run through them so it's generally accepted that if you get 5-7 years from a set they've served you well. Pull them off and have a look inside the manifolds, you'll be able to see what's going on.

 

[crazy charlie]

Re: still running warm

HB,I would take off the warmer riser and either clean it out or replace it.Also check the manifold while you are at it.You said you changed the water pump.There is a water pump in the engine block at the pulleys and also a pickup water pump at the strainer. charlie

 

[handball]

Re: still running warm

Thanks a lot for the replys fellows. I bought a new thermostat and will be installing it today.unfortunitly I dont know how old the rises are as I only bought the boat this march.I wanted to back flush the tranny cooler but it is in a really tough place to get to and I have trouble seeing it with a mirror and a trouble light in order to get the hose off , the other end is easy as it is on the main heat exchanger.I took off the brass plug in the top of the riser and managed to easily run a wire thru the riser into the exhaust hose, the wire came out clean with no sign of rust on it. I think my next step would be to remove the risers and try to clean out the passages. What is the procedure for doing this? I understand some drain plugs must be removed to drain water first from the risers, also if I do this I guess I should first buy new gaskets or can the old ones be used again if a sealer is used .If I pull the hose off the main exchanger that comes from the tranny cooler my guess is that a solid stream of water should come out and that might be another thing to try as I really cant get to the tranny cooler to back flush it.Another thing I noticed recently was after a run my overflow container had completly filled up I guess this confirms the hot guage reading.

 

[ed hobbs]

Re: still running warm

I don't know about the Merc - I have an OMC - but there is probably a drain plug at the lowest spot on the manifold to drain the exhaust. And use new gaskets - you don't need any leaks