The comments and items listed by Tegger are accurate and thorough.
For what its worth, in 1982 I had an old 1966 Dodge slant 6 that overheated.
I installed new "everything" in an attempt to fix it.
The problem was solved one day when I had the radiator cap off the new
radiator to check coolant level because of overheating, --- the sun was
shining at just the right angle to illuminate the inside of the new radiator
and the top of several of the tubes. The tubes in the NEW recently installed
radiator were plugged with small calcium carbonate pieces that had been
breaking off inside the block. This was due to the radiator cleaner I had
used when I first began. As mentioned the engine was old and had likely
been filled mostly with water that had a high mineral content.
I had the new radiator rodded and bought a sieve at the hardware store,
removed the stainless screen and made a funnel that would fit inside the top
return tube of the radiator, pointed end into the radiator. I made sure the
screen would not get pushed in too far (bent a few of the screen strands
back over the radiator tube and then pushed the hose back on. Later I made
one for a different car and just made the filter screen long enough to touch
the oposite side of the radiator.
At first I checked it daily and would remove all the little pieces of
calcium carbonate. As time went by fewer pieces showed up and after a few
months it was clean. I left the screen in and would check it every two or
three months just to be sure. I sort of remember leaving the screen
unchecked one time, and waited untill the engine began to run warmer than
normal
Though its not really necessary I have since used distilled water instead
of plain old tap water with antifreeze, in all my subsequent cars, about
15-20
I am 67 and rebuilt my first engine from a 1940 ford when I was 14 in 1956
but have not worked in the automotive industry, only on my own cars or
friends cars
Good luck- hope this might be of use
"Tegger" <inva
...@invalid.inv> wrote in message
...
> "nick" <ni
...@nmail.com> wrote in
>
news:-PGdnaoI_vnvAXzXnZ2dnUVZ_v6dnZ2d@earthlink.com: >> is there such s thing as a "..high performance thermostat.." (or is it
>> called something else) ?
>> just finished a total engine build, machined heads, all new internal
>> parts
>> have normally run without a thermostat due to increase in engine temp
> Then you have a deeper problem with the cooling system. Removal of the
> thermostat is masking that.
>> in case it matters, car is mazda mpv and asking at the dealer parts
>> depot just gets me blank stares.
> The cooling system is one automotive system that has remained fairly
> simple
> over the years, even as other systems have become hideously complex.
> Troubleshooting is easy.
> No modern Mazda or any other modern Japanese car should have ANY trouble
> exhausting engine heat with the standard OEM thermostat provided the rest
> of the cooling system is in proper shape. Do not try to do a bandaid fix
> with the wrong thermostat, but correct the underlying problem instead.
> This engine, like those in all modern Japanese cars, uses a high-flow,
> low-
> heat-transfer cooling system. Coolant is meant to speed through the system
> quickly, but not /too/ quickly. /Too/quickly means overcooling, excessive
> emissions, and severe engine wear. Not quickly enough means overheating.
> Check for these things (besides external leaks and a blown head gasket):
> - Evidence of actual overheating (need to rule out faulty gauge; infrared
> thermometer required)
> - Radiator that's internally plugged
> - Radiator with fins corroded away
> - Radiator with fins coated with gunk such that air cannot pass through
> - Radiator fan not operational, or starting up too late
> - Block water jackets that are silted-up due to incorrect coolant or
> insufficient fluid changes
> - Aftermarket thermostat (these are usually inferior to the OEM that comes
> with Japanese cars, which is usually the excellent-quality ND brand)
> - Water pump with loose impeller (don't laugh; I've seen this with
> aftermarket)
> - Aftermarket hoses, which can collapse under suction
> - Excessively advanced ignition timing
> - Excessive carbon buildup in combustion chamber (guess you've dealt with
> this by now).
> --
> Tegger
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