<letterman@[EMAIL PROTECTED]
> wrote in message
news:4t0c24l7e7nqkrtvamjt81p1gpqbbf68el@[EMAIL PROTECTED]
> On Sat, 10 May 2008 10:19:11 -0700, "Ted Mittelstaedt"
> <tedm@[EMAIL PROTECTED]
> wrote:
>
> >
> ><letterman@[EMAIL PROTECTED]
> wrote in message
> >news:c7sa24t7uae8p8pva60tcpb7he3uf3549i@[EMAIL PROTECTED]
> >> Last fall I bought a used 1990 F150. It ran fine all winter. Now
> >> we're getting warmer weather, and after I drive the truck for a half
> >> hour or so, it refuses to turn over, or turns over so slow it's
> >> rediculous. Once the engine cools, it starts right up.
> >>
> >> This is a fuel injection 5 liter engine with manual trans.
> >
> >starter. Make sure the starter isn't right next to a hot manifold, if
> >it is there should be a heat ****eld.
> >
> >Ted
> >
>
> Is the starter prone to turning slow when it gets hot? Why?
> Every electric motor I have ever known work at most any temperature,
> not considering the load on them, like air compressors often trip the
> breaker in very cold weather, but that's because the compressor oil is
> thick.
Electric motors work fine up to around 300 F or so. Much beyond that
and you start having problems with the lubrication in the bearings not
working, unless the bearings were designed for high temperatures and
are internally lubed with high temp lube or some such.
Exhaust manifolds close to the engine run at around 1200 F. (think, what
is the temp of fire?) They put out a lot of infrared energy. If your
starter
is right next to one, and it is close to the exit point of the exhaust
g*****
in the engine, the radiant heat from the manifold is enough to heat the
starter
a lot past 300 F, to the point that the bearings lose lube. Once that
happens
too many times the bearing races start to fail. When things cool down the
starter turns a bit easier.
Usually you see these problems when people put headers on a vehicle
since the header pipes run a lot hotter further away from the engine, if
they don't wrap the headers or put in a heat ****eld. But some vehicles
also have the starter located close enough to where they need a heat
****eld and the factory puts one on.
It's not uncommon for amateurs changing out a starter to forget to put
the heat ****eld back on, and since everything works fine for a while they
figure the ****eld wasn't doing anything useful.
Ted
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