The Murphy Builders Site

One mistake on my previous email. I have a double pass radiator, not a
crossflow.

Mike
044SR

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Mike
Kimball
Sent: Tuesday, August 08, 2006 8:41 PM
To: Rebel Builder's List
Subject: [rebel-builders] The V8 saga

I went for a long engine run today under new conditions.

1. Head gasket no longer a problem.
2. I put the 160 degree thermostat back in. (Not sure why I got such a
cool one.) At the suggestion of a friend I drilled a #40 hole in the
thermostat. He said it would help get rid of trapped air. Seemed to make
sense.

Observations:

1. Hearing a sort of chattering sound that seems to be coming from only one
side of the engine. Used a mechanics stethoscope to try and isolate it. I
had already reset the valves after hearing valve tappet sounds on earlier
runs. This sound was different. I still could not isolate the sound.
2. Coolant started coming out of the overflow while only showing 11 psi on
the gauge. Oil temp steady at about 200. I never saw any coolant temp.
Sensor is hooked up, wire looks good. No idea why I'm not getting temp on
the gauge. At least it took a lot longer for this to happen. About 15
minutes or so. The radiator fan was running when the coolant overflowed.
The fan is on at 180 degrees.
3. After the engine had cooled down and no coolant out of the overflow
observed a continuous drip, drip, drip from the bottom of the timing chain
cover. Followed it. I swear it looks like it is coming from the lower bolt
that holds the timing pointer on to the timing chain cover. How can that
be?! I could find no coolant stream above that.

I decided to proceed with my plan for the day. I mounted the prop. Reran
the engine for a short time. The chattering seems to be gone. Gear
backlash in the PSRU while under no load? I couldn't hear that with my
stethoscope earlier. With the prop on perhaps the resistance holds the
gears against one side eliminating the backlash? I had not heard the
chattering on earlier engine runs so why now? Maybe a tiny exhaust gasket
leak that sealed itself on the last run with the prop? Exhaust gasket leaks
can sound like all sorts of other things.

Question: I have a crossflow style radiator which would normally have the
inlet above the outlet. In my installation the inlet and outlet are at the
same level. The radiator is mounted roughly horizontal with one side higher
than the other. The inlet and outlet are on the high side. Would this
cause problems?

Mike
044SR




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2. Coolant started coming out of the overflow while only showing 11 psi on
the gauge. Oil temp steady at about 200. I never saw any coolant temp.
Sensor is hooked up, wire looks good. No idea why I'm not getting temp on
the gauge. At least it took a lot longer for this to happen. About 15
minutes or so. The radiator fan was running when the coolant overflowed.
The fan is on at 180 degrees.

If I really have 11 psi, then I really have 180 degrees coolant. That is
coolant temp coming out of the engine and the pressure sensor at what I
figure is an average of system pressure mounted in a 5/16 vent line
pretty much midway between outlet and inlet pressure. If your pressure
is really 11 psi at the cap then the cap is leaking but of course the
pressure will vary several psi in various places when the pump is
running. It should be the same everywhere (except for minor gravity
effects) when you shut down the engine. Don't know what your gauges are
or where the sensors are located but my EIS did need tweaking
(calibrating) for most of the sensors. You've probably done the boiling
water thing with the coolant sensor?

I decided to proceed with my plan for the day. I mounted the prop. Reran
the engine for a short time. The chattering seems to be gone. Gear
backlash in the PSRU while under no load? I couldn't hear that with my
stethoscope earlier. With the prop on perhaps the resistance holds the
gears against one side eliminating the backlash? I had not heard the
chattering on earlier engine runs so why now? Maybe a tiny exhaust gasket
leak that sealed itself on the last run with the prop? Exhaust gasket leaks
can sound like all sorts of other things,

FWIW I found that I needed a second opinion on some of the noises. I'd
get concentrating on something and not hear something else. Fortunately
most of my minor noises went away when the prop was mounted ;) Guys
frequently use something like 1200 rpm minimum idle speed with a psru.
One interesting thing is that with my setup, the Warp drive prop blades
occasionally vibrate forward and aft at least an inch below about 1400
engine rpm. That can be seen while watching for blade tracking.

Question: I have a crossflow style radiator which would normally have the
inlet above the outlet. In my installation the inlet and outlet are at the
same level. The radiator is mounted roughly horizontal with one side higher
than the other. The inlet and outlet are on the high side. Would this
cause problems?

Mike
044SR

I don't totally understand your rad setup and my memory of your previous
posts is not good. Some guys have needed a continuous vent line on the
rads. My rad is 6" in vertical size. It is mounted horizontally with
water flowing in and across the bottom then up and back across the top
and out. The outlet is 3 or 4" above the inlet and I welded it on as
high as I could get it on the end water tank. It has no air pocket
issues. Conventional advice was that the inlet should go above the
outlet, as you mention, but I did the opposite. I wanted to make it easy
for vapour to escape and it has worked fine. I did not want a situation
where water flow was trying to push an air pocket downward and I didn't
want to trap air in an end tank.

Ken




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