gas and temperature gauges

[JOHN COOKSON]

With corrosion on the housing, I don't think my Holley T-stat, when fully open, is seated with a good seal. So it is likely allowing flow thru the bypass when it should be diverting the flow thru the engine.
I hope to eliminate this potential issue of excess flow thru the bypass with the new t-stat housing.
And even if the new housing does allow me to dial in the operating temps, I might still opt for the Moyer bypass kit. I like the redundancy and the additional control it affords.

Your analysis in paragraph one is right on the money.
I don't like to under cut Moyer but all you need is a ball valve in the bypass hose to balance the water flow through\around the engine - probably available locally. With a valve in the bypass you have positive or active control rather than passive control of the amount of water going through the bypass.
Don't know if it has been mentioned previously but this would be an excellent time for an acid flush.

TRUE GRIT

[joe_db]

Or you can do the Indigo thermostat.
The ball valve is the cheapest thing.

Your analysis in paragraph one is right on the money.
I don't like to under cut Moyer but all you need is a ball valve in the bypass hose to balance the water flow through\around the engine - probably available locally. With a valve in the bypass you have positive or active control rather than passive control of the amount of water going through the bypass.
Don't know if it has been mentioned previously but this would be an excellent time for an acid flush.

TRUE GRIT

[romantic comedy]

MMI has a cute little ball valve.

[Vermonstah]

Update on RWC engine running hot

My boys were looking for gift ideas for Father's Day, and I was pleased to receive a shiny new Moyer thermostat housing.

So, I installed the new housing and then re-ran similar tests under load as above. Essentially, I was testing my (secondary) theory that the old housing had corrosion, to the extent that excessive flow was passing around the t-stat when the t-stat was fully open. Turns out, this was NOT the case and I observed essentially the same temps as above with t-stat installed: 140 at Idle and 180 at Cruise. I didn't think this was going to be the root cause, as I did not think the housing had corroded substantially in one off-season. But I have a shiny new housing and I have seen elsewhere on this forum strong recommendations for the Moyer housing.

So, I moved on to my primary theory: that the timing was off, possibly considerably. Some might recall from another thread that over the winter, I had to tear down the alternator side of the engine to access the aft drain nipple which sheared off in the block. To do so, I had to remove the distributor which was uncharted territory for me. I suspected that I might not have replaced it correctly. Why did I suspect that? Because I inadvertently moved the rotor during re-install. Why did I do that? Because I am an idiot fumbling around in uncharted territory. I needed the assistance of a good friend who has been extremely helpful in mentoring me on the care and maintenance of my A4. So, he brought his "tune-up" bag and made a mooring call out to my boat. Using his timing light, we determined that the timing was considerably advanced, by at least 10 degrees, possibly as much as 12. So, we dialed in the timing and she immediately idled much more smoothly. Then when we took her out to test her under load. After warming up, she pegged right at 170 degree at cruise. When I pushed her to WOT she warmed up to 180° and then quickly cooled back down to 170 at cruise.

So, advanced timing seems to have been the root cause of my elevated operating temp. And rough idling.

She is back to running strong and smooth.

Thanks to all for their helpful counsel.

[JOHN COOKSON]

I didn't reread the thread. Have you tried clamping the bypass? You might be able to get the temp down even further by restricting the bypass.

TRUE GRIT

[Vermonstah]

I didn't reread the thread. Have you tried clamping the bypass? You might be able to get the temp down even further by restricting the bypass.

TRUE GRIT

I have run tests with the by-pass clamped off, as well as removing t-stat altogether. Without the t-stat, I can get the temp down to 105 under load. But she runs rough at that temp.

My objective was to identify the root cause of 10 degree increase in temp at cruise from last season. I believe I have done so, with the advanced timing.

Now, I could install the Moyer by-pass valve with confidence and set the cruise temp without masking another problem.

But, the thing is, that Ken at MMI will not sell me their bypass valve. He says that MMI believes that the RWC engine with the original Holley t-stat at 170 degrees at cruise is right where it should be.

And hard for me to argue, my plugs have never looked better!

[roadnsky]

...But, the thing is, that Ken at MMI will not sell me their bypass valve. He says that MMI believes that the RWC engine with the original Holley t-stat at 170 degrees at cruise is right where it should be.

V-
FWIW, I run in fresh water (Lake Mead) and have the Holley.
My typical cruise temp is 165-170°

[Vermonstah]

V-
FWIW, I run in fresh water (Lake Mead) and have the Holley.
My typical cruise temp is 165-170°

Jerry - the feedback is much appreciated. Given the pristine condition of your A4, your performance numbers contribute to setting the gold standard for the rest of us.

Two questions for you:

If you push her beyond cruising RPMs, do you see the temp climb, say as high as 180? I don't make a practice of pushing my engine beyond cruise, just want to collect some additional performance data if / when I ever need to get a little more from her.

Are you RWC or FWC? I cannot recall which. I ask because I seem to recall that many on the forum subscribe to higher operating temps for FWC.

Thanks again,
Brian

[roadnsky]

Jerry - Two questions for you:

If you push her beyond cruising RPMs, do you see the temp climb, say as high as 180? I don't make a practice of pushing my engine beyond cruise, just want to collect some additional performance data if / when I ever need to get a little more from her.

Are you RWC or FWC? I cannot recall which. I ask because I seem to recall that many on the forum subscribe to higher operating temps for FWC.

Brian-
First, thank you for the kind compliment.

I'll answer question #2 first. My vessel is RWC (lake water)
FWC engines like to run at 180°

As far as question #1... today's sail was a perfect example/answer...

This afternoon after a great day of sailing, the monsoon thunderstorms kicked up.
I was 16 miles from the marina.
Winds on the nose at 35-40K. Fetch waves at 3-5 ft.
Motoring at 2000 RPM (normal cruise is 1700) the temp was 170-175°
Hope that helps.