Looking at the '00 FSM it states that the 4.7L thermo is
closed below 195F. This may seem high, but read on.
BUT, it only blocks 50% of the flow to the radiator
when closed. I don't think many thermos work this
way which results in more accurate regulation
according to the FSM.
The 50% cutoff is symmetrical in the sense that when
closed (while the radiator gets 50% of its flow),
the bypass gets 100% of its capacity (used during
warm-up). And when open, the radiator
gets 100% of that branches capacity while the bypass
flow is reduced by 50%.
The bypass in the 4.7L does not circulate through the
block like a typical setup. It circulates through galleys
in the timing chain cover. From what I read, it seems
that the effect of this is that during warmup, the galleys
help warm up the fluid faster, and after engine is warm
they help cool it (being at the front of the engine in
the fan flow etc). Since heat flows from hot-area
to cold -area, this makes sense. Running the bypass
through a part of the block that can transmit heat either
back into the block, or into the air is minor genius. The
heat in the bypass will simply go in the direction that
is 'coolest'.
This differs from 'normal' where either branch is either
all the flow, or none (pretty much).
If I have time later I'll type in the pertinent section,
or maybe someone else will.
Anyway, it seems fairly obvious that one should be
careful modifying/replacing the 4.7L thermostat; at
least to the point of replacing it with one the functions
the same way, just at a lower temp.
Marty
'00 4.L CC auto
MALDBNSF@aol.com wrote:
> Cooler Tstat has been a HOT subject around here lately, What is the stock temp. in the 4.7 and what is the next step down? Two more quick questions, I live in TX (Fort Worth) and it doen't get cold here (not like RI where I moved from) Can a eng. be over cooled? and what is the min. running temp. for the 4.7?
>
> Thanks
> Don Mallett
>
> > Boog,
> >
> > Did you give any consideration to a plug one heat range cooler (5223)?
> Any
> > thoughts on this? When I am workin' my 4.7 hard I have noticed some
> pinging.
> > Only when the engine is really running hot though.
>
> Drop in a cooler Tstat, should take care of that.
>
> Jon Smith
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:51:22 EDT