Atomic 4 running too cool..why?

[twofreddy]

Engine running with a load on it around 105 degrees, after I took out the t-stat and put in the valve to control water through the bypass. But it does not make any difference whether I have the valve completely open or closed. It is still around 105 degrees. Isn't the valve supposed to allow control of the water so that the engine can be brought up to temperature?

[Dave Neptune]

Yes it should at least change the temps. Possibly the "bypass" line is actually clogged or partially so and that would render the valve pretty much ineffective.

What temp water are you running in? I ran without the t'stat a long time and whenever I adjusted the valve the temp would start to change in a minute or two.

Check the bypass just to be sure it is clear.

Dave Neptune

[twofreddy]

Thanks Dave, the bypass is clear. new hoses etc. I did run the valve back to a stern lazarette where I can adjust the valve while looking at the temp gauge. Could it be that a run of hose that long is to much for the water pump? the water temp is about 72 degrees

[Dave Neptune]

I think the long run of hose would work just like a restriction due to the additional friction of pumping through a longer hose. Shouldn't bother the pump though.

I ran in 70 degree water and ran the engine between 125 & 135 under load and a bit cooler after idling for a while.

Dave Neptune

[JOHN COOKSON]

What was the temp before you took out the thermostat? A properly operating thermostat will restrict or slow down the flow through the block just because it is in the flow. Restricting the bypass will force more water through the engine and the engine will run cooler. If the engine is running too cool with the bypass wide open the only solution is to increase the flow through the bypass. This would be hard to do unless the bypass clogged or otherwise restricted somehow.
You are RWC I presume?

TRUE GRIT

[twofreddy]

Thank you John for the reply. Dave was making the same comment about the bypass being blocked. Is it possible to have an "air lock''in the bypass hose . And if so would that create the same situation as a blockage?

[roadnsky]

Could it be that a run of hose that long is to much for the water pump?

How long do you estimate that hose run to be?

[Administrator]

Half-inch diameter hose has roughly 0.24 psi of friction loss per foot. Five-eighths has 0.07 psi per foot. A traditional MMi pump wouldn't know the difference, within the range of lengths we're presumably talking here.

You're not using an electric pump, right? That's a whole different ballgame.

Bill

[tenders]

Is there any sign of life on your temperature gauge? 105° sounds like the dead/leftmost position on the gauge.

My engine has the bypass blocked off completely and runs warmer than that.

I would suggest confirming that there is a clear path from the bypass through the valve, without a kink in the hose, etc.

But unless the engine is frequently run for hours at a time, the engine is likely to run cold most of the time no matter what you do. For that reason I would also suggest abandoning the complexity of the adjustable bypass valve, and just plugging the bypass altogether.

My bypass has a bolt stuffed into it, which blocks 95% of the flow. The engine runs cold and I always run the suggested amount of MMO in the fuel to head off sticking valves. If the engine ever gets warm I know something is wrong.

This stuffed-bolt decision was made by my engine rebuilder in 1993, before the Internet, before Moyer's expertise was well-circulated, and before Moyer prevailed on Victor Gasket to produce an aftermarket A4 head gasket. In those days, the replacement head gaskets were made of paper, rather than the original asbestos, and they failed regularly when the engine overheated. Thermostats and thermostat housings were also largely unavailable, and people didn't understand the logic behind the weirdo A4 thermostat, so a lot of engines were not properly set up...all of which made overheating a frequent and incredible inconvenience of A4 ownership. So, COOL WAS COOL.

Moyer's head gaskets were the beginning of a huge upgrade to the A4 owner's user experience, but even now I see insufficient benefit to the additional complexity of the bypass valve.