|Topic Review (Newest First)|
|10-28-2007 02:24 PM|
When i bought my Newport 6 years ago one of the first things was to have the heat exchanger cleaned and repaired. material from the pencil Zink can build up inside and residue that gets past the strainer will stick in there. I also replaced the thermostat. A mechanic that used to work for Capital Yachts in Harbor City indicated that the cooling system is critical on the engine.
One of the prior owners thought they new more than Gary Mull, boat designer, and put a different pitch of prop from the factory unit. The engine would not warm up, and left black soot all over the transom. Correct prop and bingo, problem gone. I now get 135 degrees upon leaving the harbor, 150 to 160 degrees at 2300 RPM.
Starry Night -Oxnard Calif
|10-06-2007 11:08 PM|
hello, after a quick search on dielectric grease I agree the never-seize is a much better choice....the dielectric being "non conductive"
Permatex Dielectric Grease is a silicone dielectric compound used to insulate, lubricate and protect electrical fittings. It protects against salt, dirt, moisture intrusion and stray current in electrical connections. Dielectric grease extends bulb and housing life of navigation lights, masthead electrical connections, trailer lighting and harness or any electric connections exposed to moisture and the elements. Prevents voltage leakage around any electrical connector thereby insuring a strong spark in high energy engine ignition systems.
|10-06-2007 10:45 PM|
Stenn, dielectric grease is a good idea when you don't want conductance. The outer threads on the sender should have a dab (SPARINGLY!) of never-seize, which is metallic and conducts to ensure a good ground to the block.
Temp senders are all just variable resistors. The manufacturer, or any good shop manual, can tell you exactly what the resistance of that sender should be at any given temperature, so you can test the sender by putting an ohmmeter on it and then putting it in a pot of water brought up to boiling, and watching the resistance versus the temperature (on a cooking thermometer).
Typically...a sender for a 12V system will have a resistance around 20-40 ohms on "READY TO BLOW!" and 200-240 ohms at room temperature, engine unused and cool.
Any other way of testing these senders, besides an ohmmeter with the factory specs, is just guessing. (Which is sometimes good enough.[g])
You can also be getting a false reading because the wire leading to the sender is corroded or not making good contact. Anything that reduces the voltage going to that sender (bad contact, corroded wire, poor crimp, bad ground, etc.) is going to make it read incorrectly. Often when you think you've pulled the sender and cleaned it--you've really fixed a loose or dirty wire that was contacting it, etc.
|10-06-2007 08:39 PM|
Stenn, after cleaning electrical connections its a good idea to coat with Dielectric to help prevent future corrosion problems. I use that stuff for everything...from lubing heads to coating water pump gasket's before assembly...good stuff
Drew, as a side note....I have a raw water cooled 3GM Yanmar and the high temp. alarm is set for 140 degrees..
|10-06-2007 04:23 PM|
You might get and use an infrared temperature gauge. They're not that expensive any more. Reading on the exhaust manifold should be roughly equivalent to the boat gauge. Not being able to stand on the engine cover sounds too hot to me.
Is your sending unit in the thermostat housing or on the front of the engine. Mine used to be on the front of the engine and I moved it to the mounting point supplied on the side of the thermostat housing. It seems like that would be a more accurate reading point.
|10-06-2007 02:33 PM|
Universal 5411 operating temps low?
I had/have the same problem....it's odd....
I say "had" because when I first got the boat a year ago (Newport 27-S MKII), the previous owner mentioned it never got hot enough, according to the temp gauge...but the engine ran just fine otherwise.....
...so I used a wire-brush tip on a Dremel tool, on the sending unit, both it's electrical connection on the outside and the lug on the end of the wire, and it's inside surfaces that contact the water..., polished all mirror-shiny, and presto, immediately got 140 degrees on my temp gauge....and that lasted about 6 months.
But a year later, it's back to not registering any more than 120 or so. I haven't taken the electrical connection apart yet to look at it, but I can't imagine it's dirty and corroded, the engine compartment is nice and dry and clean...only thing I can think of is the sending unit's fouled inside...but it actually looked pretty clean the last time I removed and cleaned it, so I'll be surprised if that's it.
The engine gets plenty warm enough....I can't stand barefoot over the exhaust manifold on the engine hatch in the cockpit for too long because it gets pretty hot (just on that edge of the hatch cover), and I'll actually get warm water out of the sink after running a couple of hours, so I know the engine's hot enough....
....maybe I just need another sending unit for this 24 year old one (I presume it's the original, but don't actually know), or the temp gauge itself?
But I'll try polishing the sending unit's inside surface again and report back.
|08-27-2007 12:25 AM|
OK, final comments on this issue.....
I was prepared this weekend to modify the thermostat to close off some of the bypass holes on the top when I discovered something very interesting/disturbing. I found that someone in the past had put a washer in the very bottom of the thermostat housing - which is the exit point of the thermostat housing to the recirculation line. Why they did that I'll never know. But it turns out that the thickness of the washer and the diameter of the thru hole effectively meant that the bottom of the thermostat was sealed against the washer in its closed position - there was no way that cooling water was going to the recycle line - even when the thermostat tried to open - yikes!
I removed the washer and behold - back in business with noted temperature rise during the first 20 minutes of operation on the temperature gauge. That included less noted water output from the exhaust on start up - presumably since more water was allowed to exit the recirculating line instead of being forced out the exhaust. I never got up to 140 degrees where the thermostat opens but that's OK with me. I figure if I'm operating from 120 - 140 degrees normally, I'm good.
Anyway, I'm closing the book on this issue for now but will continue to monitor. Thanks to all who offered their comments and thoughts.
|08-22-2007 11:34 AM|
Is the part number on the thermostat itself, the same one on the parts list? I've had wrong parts shipped in "right" boxes before.
Be careful about the manual restricting--consider that to be a "get me home" patch. There's still something WRONG and no telling what other damage it may do (now or at some future point) if you don't track it down and correct it.
I think every cooling system thread eventually comes down to the same line: You need to put eyes and hands on the entire cooling system, from intake to exhaust, and follow through every inch of it. Someone, somewhere, may have added in a hot water heater (incorrectly rereouting plumbing) or tapped a line, or SOMEthing, and sadly there's only one way to find out what and where: Go spelunking.<G>
|08-22-2007 10:52 AM|
Yes, thanks, I do have that manual and have studied the circulation system diagram. I replaced the thermostat from a 5411 parts list manual - it fit perfectly in the housing and I think it is impossible to put in backwards.
I may be relegated to studying the part itself and figuring out a way to restrict some portion of the bypass.
|08-21-2007 10:02 PM|
Do you have a copy of the engine manual showing how the engine cooling system should operate?
I'm not sure if the thermostat could be installed backwards and if so, would that make the engine run too cool or very hot?
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