Operating Temperature with 160 Thermostat

[Hiker_00]

Went from No thermostat to the kit with the 160 single action and spacer during a head gasket replacement job. It just seems running with a thermostat is more sound. Well now I'm confused.

Previously I never saw temps above 160 and mostly low 130+. Now she pegs out at a solid 180 and drops to 160 during idle. I'm running in very cold New England Atlantic water.

I have a wide open ball valve and restriction valve before the therm housing.

These swings in temp are a new feature. Is this working as designed? Reading old posts says clearly 160 is the point were salt precipitates out of seawater. I don't want any more junk clogging up ports than I all ready get from my RWC setup. But then again, 180 seems common and much close to the upper limits of safe operation.

Thanks in advance,

Tim

[Mo]

With or Without T-stat.

I will give my personal opinion on with or without. You are likely correct with your observations and that seems to be the ball-park. I've been asked to look at 2 overheated engines this season within the harbor. Both owners were and still are adamant about running with a T-stat citing information received both on this site and others. Both of those cases were t-stat related.
My honest opinion is that if you run your RWC with a T-stat get used to watching the temp like a hawk and also be prepared to do a repair while underway.

No T-stat and by-valve installed, open 1/2 way, has afforded me trouble free operation since buying my boat and installing it in 2007.

[ndutton]

Something's amiss. You should not be running that hot with RWC and at those temps salt crystal formation has likely already occurred. How is the water flow out the exhaust? 180° is a great running temperature but not with salt water for the reason you mentioned. I'd do a few things:

• Perform a Salt-Away™ treatment
• Perform an acid flush
• Open the water jacket side plate and muck out the cylinder gallery
• Replace the pretty machined elbows with cast ones and look for obstructing debris in the process
• Close the bypass valve for maximum cooling. Once things are under control, adjust to your liking.

[Dave Neptune]

Rwc

I'm with MO, however I have been running without a t'stat since 1984 and have never "over-heated". The few times in these years that the temp has risen (160 ) and a tweak of the bypass valve did not cool her off it was time for a flush! I have acid flushed my engine twice since then! Not bad for a lot of use and almost 30 years now. BTW it is getting time to flush again in the next couple of years or so.

I will say that running at 160~180 is a bit better for the engine, but I have not been down for 29 years of running at 130* and the engine is original except for 1 exhaust valve I replaced when I bought her, oh yes the engine was frozen tight then too!

Dave Neptune

[Hiker_00]

Side Jacket water plate was off when Head Gasket and new studs happened Dec '12. Very little gunk in there. Lots of water out the transom. Puling water during commissioning from the 5 gal pail was strong and as expected. New seals on pump shaft too. (Good oil pressure and 90 lbs on all 4 cylinders tested with a cold engine and no run time)

It really seemed the right move to replace the Thermostat studs with the longer ones and live a life of choice and freedom from the old days. It just seems I've done the wrong thing by buying this spacer and thermostat. I still don't understand the design. Runs at 180, idles at 160 with 50deg RWC.

Just lanched the for the season. I don't have long hours of run time to really understand the issue but this is pretty clearly a change.

Never have done a Salt-away but have done yearly water flushes and acid flushes. NO history on my engine of running hot ever.

Thanks for the feedback.
Tim

[ndutton]

Try closing the bypass valve fully and see if there's a difference in temp or flow.

[romantic comedy]

It sure seems like there is a lot of water going past, thru the by pass.

Have you closed the by pass, and sent all the water thru the engine?

[JOHN COOKSON]

Most likely adding the thermostat added restriction to the flow through the engine so now more cooling water is going through the bypass and not the engine.

As mentioned the solution is to open the passages through the engine and restrict the bypass.

TRUE GRIT

[marthur]

You may wish to adjust the valve to add a little back pressure to the system, that would increase the flow through the engine. My understanding is that you should be able to keep the temperature of your engine around 170 with this kit.

In general, your temperatures don't seem terribly high for the T-stat you have installed. They may be undesirable for a salt water RWC motor, but not unusual. Remember that the 160 degree thermostat is not going to open until the coolant temp reaches 160 degrees or so. In an earlier thread, Don Moyer has said that "Operating temperatures in late model Atomic 4's are prone to wander from 160 to 180 depending on power setting, temperature of the outside raw water, and the condition of engine cooling jackets."

For lower temps, you could always install a 142 degree thermostat. There are single action 142 degree t-stats available, but Moyer Marine currently lists the dual action 142 degree T-stat which is a little pricier.

Good luck,

Mike

[Hiker_00]

Will try to dial the temp down with the ball valve. Without a thermostat I could never get close to 180. It would never really go over 150 - more like 130. It's hard to remeber, I'll have to look at my log book to see if there are notes.

So mayber this is the best of situations with a higher thermostat and the ball valve to balance the temp for the best operating temperature which, by my research is 170 in a RWC late-model engine.

Also, the convential wisdom of the Forum is that salt preciptates out of seawater at above 160. How is this seen? I get black flakey gunk that gets flushed out during pressure flushes that happens with or without a thermostat.

I'm still wondering why I peg on 180 with a 160 Thermostat. Back presssure is my best guess. Will report back after some testing.

Tim

[Ball Racing]

One other thing to ponder is gauges.
I went thru 4 differnt brands of gauges last year to find one that read "right".
Both electrical and mechanical guages.
I now have the racing people Auto Meter brand mechanical gauges.
They seem to be the most accurate of what I have tried.

So, yes you should be seeing a increase in temp, but maybe your gauge is giving a false reading, maybe 10 degrees or more + - and if you right at the verge of the salt thing that could be the deal maker or breaker.

If your current gauge is always consistent, thats great, just need to learn if it's accurate, and if not, learn if it reads high or low so you will know your baseline.

[JOHN COOKSON]

Does your temp gauge read higher than 180?

If the gauge reads only to 180 and you are pegged on 180 you really don't know hot the engine is running.

TRUE GRIT

[Hiker_00]

I think the gauge is correct. There's not be a reason to doubt it to here. I really hate adding another variable to the mix. It seems the idle temp at 160 on a 160 Thermostat is telling. It has not gone below that so far. I suppose it could be 20 deg low but that would mean last 4 years of running at rediculously low tempatures -100, 110.

Yes the Tempature gauge reads past 180. I think the top is 220. I don't remeber having an idle tempature when running on no Thermostat and 1/2 ball valve. The gauge in the past would grow as the engine warmed up and stay there. Now it builds to 180 and will drop fairly quickly to 160 at idle. Maybe this is all the way it's supposed to be. It's new to me.

Maybe the new pump shaft seals have solved a issue I didn't know was there?? This year during commissioning, the garden hose could not keep up with the water demand of the pump sucking the bucket dry.


Finally, is this salt thing a real threat to the health and welfare of our A4 fleet?

Tim

[Hiker_00]

In the 11-24-12 posting on the Head Removal Rabbit Hole case on this site, I wrote:

"Never have overheated in my ownership. Engine runs cold 140 or so in
Northern New England cold water."

That was no thermostat and 1/2 ball valve.

I didn't know quite what to expect by adding a thermostat. This is very interesting.

Tim

[ndutton]

I know you're trying to rationalize this away but lemme tell ya, when my engine was RWC the gauge rarely went past 110° and I had a 140° thermostat and no bypass valve. Even though I was running in Southern California (typically 57° - 68° water temp) I'm sure the engine thought we were in the Arctic or something.

As for that salt thing, I've seen it first hand. A friend's Hunter 31 with a 2GM Yanmar with FWC started overheating. First it was once in a while then it became more frequent to the point it could no longer be put off. His HX tube bundle and cast mixing exhaust elbow were so crystallized they looked like a geode inside. I don't know how any water got through there.

I suspect the initial overheating was due to factors other than the salt crystals. I think they formed as a result of the elevated temps to aggravate the condition. It's very possible they initially formed in the exhaust elbow impeding raw water flow.

He pulled everything apart, rodded out the HX and had a radiator shop tank the elbow. No problems since (but in truth the boat doesn't get out much anymore).