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Cooling MacSkier
4/18/16 afternoon
Ran the boat with the aft manifold gaskets preventing water from exiting
in the "side slots" of the "lower loop." Temperature went to 200F within 5 minutes.
4/18/16 evening
Removed thermostat. Ran engine. Temperature went to 200F within 5 minutes.
4/19/16 evening
Tested (cold) water flow in both "lower loops." Functions as expected.
Re-routed (reversed) water in lower loop. Thermostat out. Temperature gauge stayed
on cold peg after 5 minutes of running.
Hard to explain. Why the difference?
XX
Click above for larger images.
Future --
Intend to use "bucket method" (next photo) of supplying water in driveway. All previous driveway runs have been made with garden hose simply shoved in the "pickup" hose. Not the best way to operate, IMO. Will use this in future tests:
Click above for larger image.
Hi Grant
Hope you have about 5 gpm available from your garden hose, to keep the bucket full because that should be about what your pump will draw at 1000 rpm or so. At least that's been my experience.
Ken
Ken,
- Ran the first test on the bucket -- this afternoon -- in the rain.
- Monitoring a bucket of water in the rain isn't at the top of Phyllis'
enjoyable pastimes.
- It was easy to stay ahead of the garden hose at 1000 rpm;
level dropped at a reasonable rate at 2K.
- Today's test was with no thermostat, flow in "lower" manifold
from back to front, side slots blocked. The gauge did not move
a bit -- stayed on peg.
- Busy with other things today.
- Tomorrow, first test will be with thermostat installed.
- Expecting results will be "too hot." (That was correct.)
- Then I'll open the "lower loop" a bit near the aft manifold cap.
First, opening drain petcocks. (Temps rose slowly to 200, making me think opening side slots will solve the problem.)
XX
Click above for larger images.
- Then, punching 1/2 inch holes in aft gasket "side slots." (Skip this, open "slots" completely.)
- Theory being that letting hot water escape will replenish the
engine's "loop" with cold lake water.
Plan to re-install thermostat and test run again. ( rain delay )
It ran hot -- 200F within 5 minutes.)
If temperatures are not good, will run engine with lower loop drain petcocks open, simulating
holes cut in gaskets' "side slots." If this works, will cut probably cut holes to permit more hot water to escape aft end of manifold to lake. This did "work." i.e., slower temp rise makes me think opening slots is the way to go.
4/21/16 -- Installed new "aft" gaskets with "side slots" opened. Ran on bucket for 11 minutes with water flow reversed thru "lower loop" in exhaust manifold. (per PCM diagram)
Thermostat in, I opened up the "side slots" in aft manifold gaskets.
Ran for 11 minutes at 1000 - 2000 rpm (so as not to "overdraw" the bucket.)
The temperature gauge did not move.
(Unlike this afternoon, running 5 minutes with
petcocks open, temp to 175F, then slowly up to 200F.)
Considering possible future use of 130F or 140F thermostat. (Still a possibility, but certainly not needed this evening.)
XX
Click above for larger images.
BTW -- looked at my photos of the
77 Skier.
(It has the later exhaust manifolds, etc., so no help with MacSkier.)
Click above for larger image.
(Dwg. shows "lower loop" blocked from
exiting exiting manifold.)
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