RWC & no thermostat guys

[Dave Neptune]

Well guys I have benn contimplating this change for quite a while and finally did it. I have stated that when running without a t'stat that the bypassed water influences the temp sendor because there is no baffle, like the t'stat itself to keep the warm block and the cold bypassed water from mixing in the housing area which is also where the temp sendor is. I have run with the bypass valve for over 27 years now and was never really happy with how the temps adjusted and I blaimed it on the housing and sendor location. I have also wanted to do the "Tom Hatch common sence" fill from the bottom switch, this was not for control at all just a better way to fill the manifold.

What I have done is to plug the housing where the "bypass" water enters and reroute it to the manifold for mixing there instead. This eliminates the mixing in the housing and I now have far more control of my operating temps. I can run warmer and I also have far less heat rise after shutting down and rechecking the temp. I have now run this configuration for 18 plus hour and three 5 1/2 hour motoring trips to the island. I have set it for ariund 135 at 2200 RPM cruise and it idles at around 120. I can now run over 160 if I wish but I do like to run cool to keep the cabin temp down. Also in this configuration I can see temp rise within minutes of start up which was not the case before.

I know this is not considered proper as far as temps are concerned but now I can run warmer with far more control and the responce in temp change when adjusting is far more responsive.

This gives me far more confidence in the actual operating temp of the block and better control as the reading is far more accurate without the "cold" water mixing with the blocs warm in the sendor caavity.
I'm now open for hits and further opins from the forum, have at it guys!

Dave Neptune

[hanleyclifford]

Hi Dave, It would seem that your preferential flow is thru the by pass, a good thing in the case of RWC. I would keep an eye on the close nipple under that 90, especially if it is brass. You have a lot of angular momentum working on it, what with the weight of that valve etc. I actually had one break off in the casting once; lucky I had the pipe tap with me.

[thatch]

Dave,
Since there's no thermostat involved, I would consider your approach to be an improvement over the "stocker" configuration of just placing a control valve between the side cover "T" and the thermostat housing. Everything looks good as far as I'm concerned.
Tom (also no thermostat)

[sastanley]

t-stat Q's

Dave, looking good!! What's the blue thread goop? Does it smell any less putrid than #3 Permatex??

Tom,
What kind of temp are you seeing with FWC & no t-stat?

The Bay water temp is in the high 80's this time of year (88.7°F this weekend) and I am pushing ~190°F on my temp gauge at high cruise RPM (2,000 or higher) I believe this is primarily due to my slightly undersized HX, but at $35 from ebay it was a steal. When not pushing the motor so hard (~1,800), it eases back to 165°F. At idle, 145°F. When the engine is working overtime due to a dirty bottom/prop, I am seeing numbers perilously close to 200°F. I don't like the gauge readings way up there!

I am wondering if I might be able to expect lower operating temps with the t-stat removed? Additionally, the installed Moyer bypass kit, which allowed noticeable changes in temp readings when RWC'd, now provides no control on the readings I am seeing at the gauge.

[thatch]

"No short answer here"

Shawn,
When I did my FWC changeover I made some major flow improvements to the system. These included enlarging the side cover plate hole to 1/2" ntp, changing the hose fittings to better flowing "plumbing style" fittings and doing a thorough acid flushing of the system. These changes were made after discussing, with Tom Stevens at Indigo, the limited pressure ability of the "Johnson circulation" pump. When I installed the system innitially I elected to leave the thermostat out just to keep "that" element out of the equation. Since the ocean temp in my area tends to stay in the 60 to 70 degree range I have found that I can keep my engine temp below 150 degrees. I generally have my block bypass valve set at about 1/2 open.
Tom

[sastanley]

Tom, Thanks..I have made those same modifications as well, after the advice received from you and Neil. I have the larger opening in the side plate, and cast instead of machined fittings, and no hose barbs.. I used 3/8" npt pipe nipples instead of hose barbs to keep the ID as wide open as possible. All of my hose is at least 5/8" also, except the bypass which I think I kept at 1/2" since we are trying to restrict flow there anyway.

I do not seem to have any problem circulating antrifreeze with my Johnson pump..I have it between the HX & the engine block, so it has the cool side of the coolant (coming out of the bottom of the HX) coming thru it, and then off to the be injected via the sideplate. After getting thru the engine & manifold, it heads to the top of the HX, and that is where I have a visual on what's just come out of the motor as I see it shooting coolant around the top of the HX with the cap off in what appears to be plenty of volume, and until recently I had a clear strainer which easily showed me the antifreeze flow (see my recent post in Captain's Confessions for more on that.)

I may experiment and try the t-stat off just to try and maxmize the coolant flow. I like the hotter temps the engine is running at, & she is sounding better than ever, but 195°F is a little too hot I think, and getting at the edge of my comfort zone..I'll have to see if the bypass valve makes any noticeable change in antifreeze flow as well..have not checked that, but as previously mentioned, it doesn't change the gauge temp at all.

Dave Neptune, sorry for the slight hijack

[Mo]

Dave,
I worked the beast the other day and could walk in and hold my fingers on the head and side of block. Noted it warmer on lower portion of the block, and although I was able to hold my fingertips to it, the heat was considerable more.
Temp reading was 130...but my true test is my fingers on the head and block.

Changed the oil today and did a maintenance plug check...plugs were perfect. Fuel used was 10 gallons for 12 hrs. I really had not noticed the engine heat after shut down until you mentioned it...mine warmed up after shut down as well. Looking very seriously into this setup you have going on.

The thing is that I like to feel that head warm and not hot. The hotter plugs I'm using keep the combustion chamber clean. I pushed her in 12 footers the other day (5 hrs) and I didn't really trust the guage...so I moved the step, sat on it and did my finger test...the boat was punching through at 4 to 5 kts with it on the nose. Steadily slowing to 4 when her bow dug in and up to 5 going over. I don't have a tach but I figure it was 1/2 throttle...not working it full out at all.

How much did your temp rise following shut-down and do you think it was an ominous situation.

[Dave Neptune]

Some anwers

Shawn, the blue stuff if "Leak Lock", I think by Chem-Tech. I have seen it used by many marine yards and gave it a try a few years back. I have been using it since. It is a thick goo like the liquid teflon but the stuff sort of sets but does not harden. Works well on NPT and "straight pipe" too.

Mo the temp rise is not a big concern as it is mostly the core heat the engine operates at while to cooling water is carrying away what it can. Before the mod the temps were showing cooler and when checked after shut down rose higher. Now instead of 30~40 degrees of rise I get around 20. I think most of the diferance is the mixing in the housing just does not yield an accurate temp reading of the block water alone. I too use the touch method and now the block seems to be more even as far as temp distribution and the housing feels like the rest of the head and block not cooler than the rest.

Hanley, yes the fitting is a weak link however I am thinking of moving the entire "wye & valve assembly to the bulkhead for stregth and to give me back my good access to the carb side of the beastie.

The goal I am attempting by this is nothing more that a more accurate temp reading of the "block's" water before introducing the bypassed cold water. One of the pluses is better control because what you see on the gage is the temp of the cooling water and the rise gives you the core temps which should be higher as that is the heat being carried away.

Dave Neptune

[Administrator]

...the blue stuff is "Leak Lock", I think by Chem-Tech. I have seen it used by many marine yards and gave it a try a few years back. I have been using it since. It is a thick goo like the liquid teflon but the stuff sort of sets but does not harden. Works well on NPT and "straight pipe" too.

Dave:

I've got a persistent leak where the PVC (?) hot water hose exiting from the water heater meets the hose barb at my Honeywell mixing valve. Do you think this stuff might do its magic there?

Bill

[Dave Neptune]

Not sure

Bill, not sure what your trying to seal. Is it the pvc to the barb? or?
Is the PVC the spiral wound hard soft stuff?

I have the blue on all my straight pipe thru hulls and that is what sold me on trying the stuff. It has not leaked yet and I use a lot of on hydraulic and coolant fitting around the shop.

Dave Neptune

[Administrator]

The leaky connection is the soft, clear potable water hose to barb.

Bill

[Dave Neptune]

Will check

Bill, not sure it is rated "potable", will check.
I have had trouble with a kink in a hose clamp not sealing before. If the barb is OK perhaps a fresh cut on the hose if you have enogh for that without having to run new line. Might just try a fresh clamp, I've had that work on thinwalled lines more than once.
Are you sure it is the barb/hose connection that is leaking and not the barb if it is threaded in?

Dave Neptune

[Dave Neptune]

Don't know

The "Leak Lock" is made by Highside Chemicals (39503) and I can't read the back anymore. Perhaps the info is "on-line".

Dave Neptune

[Al Schober]

Hey Dave,
Just looking at your original pics - what's that hose attached to the cap on your oil filler? Where does it go?

[Dave Neptune]

Hose

Al, before I installed the PCV kit I installed the "vented" cap. The hose runs to my exhaust fan intake and terminates about 2 feet inside. I run my fan whenever the engine is running and that way the blowby was pumped over the side via the fan and not just eminating through the cabin and stinking things up. Once I installed the PCV I just plain ole didn't bother removing and probably won't.

Dave neptune