What temperature?

[GregH]

Ok, let's see if I have this correct...

-The engine prefers to be about 180-190F
- for raw water cooled should be below 160 DUE to potenial precipitates at higher temp

Since I'm sailing in the Great Lakes, running at the higher 180-190 range is preferrable yes?

[Sam]

I have an early model 1966 A4 with early model thermostat and it always run at 140 F w/ Lake Michigan water. Every few years I might suck up some debris by the dock and the short 3/8 cooper tube from the water pump to the intake gets a little clogged and the temp moves up to 160 -180 F. I remove and clear the tube and gently run a coat hanger wire in and out of the respective engine intake water jacket, reassemble and it's back to 140 F.

[GregH]

Up Until Aug/Sept was running with Thermostat and no bypass valve. Engine was typically 180-185F. This is in lake Ontario waters that may get up to 70F in the peak of summer.

Switched over to no thermostat and bypass valve and the temp doesn't even make the needle move, even fully open in bypass mode.

Going to toss the thermostat back in, in the spring and see if cannot get the temps back up and the gauge showing this to make sure the sender is working. Then we'll try things again.

IF... if I find the temp send and gauge are working fine and due to the cold lake I cannot get the temps up over 120, would it be valid to run with the thermostat in AND adjust the bypass valve so more goes through the block? I am assuming that once the thermostat opens, it does block the bypass 100%

[JOHN COOKSON]

IF... if I find the temp send and gauge are working fine and due to the cold lake I cannot get the temps up over 120, would it be valid to run with the thermostat in AND adjust the bypass valve so more goes through the block? I am assuming that once the thermostat opens, it does block the bypass 100%

Yes, this is what I do.
Each RWC engine is a bit difference due to the amount of corrosion in the water passages and other factors that affect water flow such as pump output and so on.
My particular engine is happy with a thermostat and a bypass value wide open. The restriction provided by the thermostat and the (wide open) bypass valve + pump output + amount of water passage corrosion ++ all balance each other.


TRUE GRIT

Edit: Do an acid flush and get the water passages as clean as possible.

[Capngeo]

Well, I’Ll be

[Capngeo]

An interesting thing:

Out of the blue the A$ acted up. She would rev up and sound great between 600-2700 rpm, but ingear all i could get was 5.5 K at 1300 RPM. Advancing the throttle over 1300,and she's run rough,and sounded like she was really struggling...so I backed off. I put my hand on the block and something didn't feel right.

[Capngeo]

FLIR view of A4

a few more photos

[Administrator]

Aside: One of the images includes a great shot of the proverbial UHS.

Bill

[Ando]

I just got back from the club. A member on this forum had a problem with his C&C 29, she had markedly reduced water discharge with lots of steam; Temp between 160 and 180. His son is visiting from 1000 miles away and they wanted to go out....so I went right down to see the problem.

1. Checked the water intake...clear.
2. Pulled the cover off the impeller to see if it was intact...it was fine.
3. Removed the thermostat...stuck closed.

Mine RWC (with bypass open) fluctuates between 145 and 175 at idle and I have a brand new thermostat from MM. I assumed the reason it fluctuates is bc the valve opens and closes? You think it would be safe to close the bypass and run it cool for the season and track down the blockage in the winter?

[JOHN COOKSON]

Could be the temp sending unit.
The last time I took my temp sending unit out I found two problems: (RWC engine)
The sending unit was coated with a hard water type scale. Lime away and a tooth brush removed it.
There was a lot of KRAP in the sending unit port. I threaded a nipple into the port, hooked a piece of tubing to it, started the engine and blew it out.

Could be a wiring problem sending unit -> gauge.
Disconnect the present wire and run a temporary jumper wire sending unit -> gauge and see if anything changes.

More if I think of anything else.

ex TRUE GRIT

[Surcouf]

one question for you guys: I usually run my engine "lightly". I was "trained" by my father, who was defining acceptable rpm for multiple hours cruising as pretty low, and I may be running now my engine unnecessarily low...

When I run my engine "my way" for a couple hours hours on a day without wind, pushing the C27 at 4.5 knots, I barely get 130F. I was assuming that I had an issue with my thermostat, or that I had installed it wrongly (dissassembled, re-assembled, no change)

Yesterday, I ran the engine "a little harder" for one hour, facing winds of 20-25 knots, seas a little chopped but nothing crazy bad, still going 4 to 5 knots; and temperature came to stabilize at 150-160F.

Does that mean that the thermostat is actually working fine, but only when I runs the engine harder? Or should I have 160F even at low rpm after a certain period?

Thank you

[edwardc]

Since the water up your way in RI is pretty cold (compared to the Chesapeake), this sounds about right to me.

My FWC A4 runs at 180 when under any throttle, but cools down to at least 155 at idle in neutral, even in the middle of the summer when our water is quite warm. Goes even lower in the early spring when the water is still cold.

[Ando]

Do you all think it would be safe to close the bypass and run it cool for the season and track down the blockage in the winter? Is there an issue with closing the bypass in other words?

[edwardc]

If you still have a thermostat installed, you should not close the bypass all-the-way. With the bypass closed, and the thermostat closed (as it would be when starting cold), there will be no water flow at all until the engine warms up. This can quickly overheat and damage the lining of the exhaust hose, and even melt a plastic waterlift muffler if you have one.

It's the reason the bypass exists in the first place.

It doesn't take much, but you must have some water flowing through the exhaust system to prevent damage. Years ago, Hanley did some experiments on reducing the exhaust waterflow, but I don't have the link handy.

[Ando]

Ok guys, RWC late model with overheating which I plan on tackling this weekend. A bit of background, I recently did a muriatic flush of the cooling system. Today, to prepare for this weekend's task of resolving the overheating (and hopefully to get a better idea where there might be a block in the cooling system) I got a laser heat gun and at about the 15 min mark pointed it at different points of the engine and these are the readings that I got.

Thermostat gauge went from 140 to 160;

Spark plugs were in the range of 180-185 (#4 being the hottest);

A bunch of points all over the head were around 160-174

Manifold was mostly cool (like 150 or less) so was the area around the thermostat housing and the water jacket plate was even cooler.

The connection from the manifold to the exhaust was very high (like 340)!

Does this point to the area of the blockage in the cooling system being at the manifold exhaust connection? Is that where I should start looking for the blockage? I read somewhere that that particular connection is a common problem area. All input appreciated. Thx in advance