Another guy running hot.

[Laker]

First ; Full disclosure. A few years back I pulled my Afour , made a lot of improvements , and hung out on this forum a lot.

4 years of flawless function allowed me to become a slacker. My maintenance became sloppy ; I barely kept up on the forum.

On Independence day my Afour stopped making water. I let her cool , limped back to the marina , and got on the phone to Ken. When I pulled the water pump I was relieved to see that the impeller blades all seemed to be in the pump housing. New inpeller , new grease , she started batching water like a champ. Problem solved - or so I thought. The first time I ran under load the temp rose to 200-205. Not good.

Good water discharge tells me that there is no significant blockage. I am sorry to say that I cannot testify to the temp reading on the old original gauge prior to the pump failure. The gauge is hard to see given it's location ; I am prone to opening the galley counter and doing a visual and sniff test periodically. When showing 200 nothing smelled hot.

Should I try removing the thermostat? Worst case scenario is running too cool. How cool is too cool? I think I know where I can borrow an infra red heat sensor. Where on the engine , thermostat housing , or hoses should I look for heat readings?

Any input will be appreciated by this negligent Afour operator.

Hoping to power a few miles to anchor off of Whistling Straits '

Laker

[JOHN COOKSON]

R U raw water cooled?
The theromstat may not be working and stuck closed. Try removing it. If you have good water flow through the engine the temp will drop.

TRUE GRIT

[Mo]

http://www.moyermarine.com/forums/showthread.php?t=9195

Post number 4 in above thead. That's how I've been running...no issues and she's never failed me in rough weather either when I had it opened up whatever she could give. The excess fuel usage that was supposed to happen doesn't, my plugs have never fouled, ...I'm using just over half a gallon an hour. I also use 15w40 diesel oil.

I bought water pump seals for that engine last year and haven't even had to put them in yet. The thing just runs on and on, I do my checks and maintenance and that is it.

[Dave Neptune]

45 years and still ticking!!! No t'stat for 33 years now, just the bypass valve.

Ditto Mo.

Dave Neptune

[ndutton]

Because of the design of the late model raw water cooling system with the bypass loop, you'll still get full flow out the exhaust with poor flow through the block (as John Cookson said) so good flow out the exhaust is not necessarily a sign all is well.

[hanleyclifford]

Often the cast iron thermostat housing will corrode to the point that the by pass loop will not close. Have a look inside. You may have to consider the replacement housing offered in the on line catalogue. Or you could lose the thermostat and install a manual by pass valve, also available from Moyer Marine. Personally, I like losing thermostats - especially on RWC engines.

[Laker]

Mr. Cookson - Yes , raw water cooled.

I plan to work on the engine tonight. I will report back.

Laker.

[Mo]

FWIW, an infrared thermometer is "golden" on the boat. They are on sale here in Canada for $24 this week at Princess Auto...the blue one. You could buy it on-line...very same one I have.

Once you really know what your temps are truly running at the peace of mind is just wonderful...that piece of kit is so cool.

After hours of running without T-stat expect 108 F at head, 140 or so on block within a few minutes...and if you run the engine for hours on end around 156 F...opposite side of block from carb side will be cooler due to no manifold heat interferance. My base pan, oil pan...156 after hours of running.

Last week I ran the engine at one point for 7 hrs straight...checked with Infrared about every 2 hrs ... I sit at the back of the boat and the gurgle of exhaust is automatic listening...if it stopped I'd miss the sound.

This by no means supercedes a working gauge...but it is a very nice secondary check. I have no doubt you will sort this out and carry on with worry free operation.

[Laker]

Well , here we have it.

I troubleshot flow restrictions as best I could and came up with no evidence. I then removed the t-stat housing ; nothing amiss there , and removed the t-stat. Started the Afour , water discharge plentiful. The various temps topped out after 15 minutes of running under load (tethered in the slip) , but I ran 35 minutes for good measure. I simulated hull speed as best I could.

The results:
Temp. gauge : 140 , when I went full throttle it came down to 130f.
Head , opposite exhaust manifold : 120

Head , near manifold , varied from 130 to 180 , depending on location
Thermostat "turtle" , 100
Block , below temp sensor , 120
Block , near carburetor , 125
Oil pan , 101
Rear manifold discharge nipple ,125
Base of standpipe , 105

All in all I am pleased with the results of running without a thermostat. I can live with 140 ; that is MUCH better that 205! I should have procured an infrared thermometer a long time ago. I am now hooked.

I think that we may power right past Whistling Straits and go overnight to Manitowoc.
Thanks for the support to all , CK

[Mo]

Great...have a good trip.

Now that you have the T-stat out ensure you run with hotter plugs...there's two parts to this. I think Dave Neptune uses the recommeded MMI hot plugs and I use NGK XR4's which are a tad hotter again.

Also, I back my boat into my slip so I can stand on the dock and get a sniff of the exhaust. If you get the rich smell back off the mixture screw a little bit at a time until you tweak her in there. With my engine, if I start the boat with the choke and push it immediatly it will stall. When I wait 15 seconds and push it in she's good...as I mentioned earlier, just over 1/2 a gallon an hour cruising.

...small tweaks...

[JOHN COOKSON]

Not To Rain On The Parade Here

All in all I am pleased with the results of running without a thermostat. I can live with 140 ; that is MUCH better that 205! I should have procured an infrared thermometer a long time ago. CK

IMO you are still running a tad hot at 140* for a RWC engine without a thermostat.

I suggest you consider:
1) An acid flush.
2) Installing a valve in the bypass. A valve in the bypass will give you positive control over the engine temperature.

TRUE GRIT

[hanleyclifford]

4 years of good operation, raw water cooled while a thermostat slowed down your flow and probably plugged some passages thus creating a preferential flow thru those remaining open so as to allow continued nice flow at discharge. Acid flushing might help. I would switch to a bypass loop to regulate temperature,

[Laker]

Ok , Parade rained on , but only light showers ,nothing to cancel the event.

It looks as though an acid flush and a bypass valve are in my future , but I am still happy to be released from confinement to the dock.

Thanks for the tip on the possible need to adjust the carb. When starting cold I need to clear the choke almost immediately , so I may be a bit rich. And - I will buy a set of NGK XR4's.

Now I need to decide if we should go for a short cruise this weekend , or anchor off the PGA at Whistling Straits. Tough call ...

Thanks again.

[Mo]

IMO you are still running a tad hot at 140* for a RWC engine without a thermostat.

I suggest you consider:
1) An acid flush.
2) Installing a valve in the bypass. A valve in the bypass will give you positive control over the engine temperature.

TRUE GRIT

With all due respect John, 142 is the norm and that is what it is. The trick is to warm the combustion chamber and not allow the carbon buildup and use hotter plugs. I've been running like this for years and ask anyone that knows me, including coast guard, this boat will go and if your diesel fails it will show up as well. If he took temps close to the plugs it's hotter....but the surviving A4's in use...think about it...I have one question...how often to we hear of RWC engines with no T-stat and a by valve overheating. I'm all for progress but when the simple cure is the simple cure....I'm sorry, I don't care how many letters are after the name.

[Mo]

PS...she will run around 140 with the by pass as well but will warm to 159 when running hours on end...and of course the block will absorb and retain some heat. Question is: how hot is the block really when the sensor at the head is putting out 180-200 F....