Simple overheating diagnosis

[transit360]

Mainly what I'm trying to diagnose is whether or not I'm
getting proper coolant flow through the radiator. I was a little
surprised to be able to lay my hand on the center of the radiator
and have the tank scalding hot. Is that normal?
The bus mainly gets a little hot when I'm running the A/C, and
it was about 80 degrees yesterday here, and I'm on the interstate
running. It was steadily slowly climbing towards 205. I can park the
bus and it comes down within minutes to a normal operating temp of
around 185.
That's why I'm gonna get a temp gun, to confirm what my gauge
is saying with accurate shots of the engine.
I don't think it's the thermostats, but could be I guess. I'm
thinking more along the lines of some clogged passageways INSIDE the
radiator or worn water pump. So any input on how I could diagnose
those would be great.

Steve
'79 GMC RTS 6V71


--- In WanderlodgeForum@yahoogroups.com, "mrdonut12"
<mrdonut12@y...> wrote:
> Based on what you've said, I'd replace the engine thermostat
> before I did anything else. That's a "baseline" repair to start.
> Until you do that, you're just guessing. They're cheap and
> they wear out.
>
> George Witt
> 81 FC 35
> Lincoln, Nebraska
>
>
> --- In WanderlodgeForum@yahoogroups.com, "transit360"
> wrote:
> > I'm working on an RTS (taking a break from my 2 Bluebirds),
> > however my question is general and not specific to just one bus.
> > How can I tell if I'm getting proper flow of coolant
through
> > the radiator? I will be purchasing an infrared non-contact temp
gun
> > (where is the best place to get them?), but for now, I am
collecting
> > advice on radiator dynamics.
> > I got the old bus to operating temp, but while driving I
> > notice she gets little hot. I checked the radiator when I got
home
> > and on the outside I put my hand on it and was NOT hot to the
touch.
> > The tanks on either side were super-hot. I shut the bus off and
felt
> > the inside (towards the engine), and the top of the radiator was
> > warm, not hot, and the bottom was hotter. What does this tell
me?
> > I did find on hot spot on the lower part of the radiator,
and
> > after looking contributed it to being clogged with oil and dirt.
The
> > rest of the fins looked good. What's the best way to clean the
fins
> > in the radiator?
> > My fan is working great, coolant is good. Any suggestions
on
> > diagnosing a worn water pump? Just looking to get this thing
running
> > as cool as possible. Thanks.
> >
> > Steve
> > '79 GMC RTS and 2 '98 Bluebird QBRE's