93 Fox overheating

I diagnosed my overheat problem, hot upper hose cold lower hose, as a stuck
thermostat. I pulled the coolant pump and replaced the thermostat. After
roadtest: radiator heated up, lower hose heated up, fan came on, fan shut
off, no overheating. My wife drove to work (12mi) no overheating. On the
way back overheat problem is back. Is it possible that I got a bad part?
What a pain to redo this repair!

Doubt the thermostat is bad. When it started overheating on the way
home from work did the fan come on?

Is coolant(yes 50/50 antifreeze and water mixture) circulating out the
overflow hose back into the reservoir?

Need more info

I don't think the fan came on because the lower part of the radiator stays
cold. If I remove the reservoir cap then there is coolant recirc. The new
thermostat fixed the problem and the system functioned normal, but not very
long.

You have to check to see if the coolant is still in the system.
Did the heat on the inside of the car fade to cold? If so I would suspect
low coolant level.


"foxstreetblues" > wrote in message
lkaboutautos.com...
>I don't think the fan came on because the lower part of the radiator stays
> cold. If I remove the reservoir cap then there is coolant recirc. The new
> thermostat fixed the problem and the system functioned normal, but not
> very
> long.
>

If it sits in the driveway and idles how long does it take to overheat?
Does the fan come on?

I'm leaning towards a bad water pump.

Yeah but he gets plenty of heat on the inside of the car so I would rule out
the water pump.
I would also guess he has not had the heater recall either. I don't
recommend the recall in areas that get cold. <g>

I am thinking that the fan is not coming on, or there is no air flowing
through the radiator.
Maybe the radiator fan switch is bad, or the fuse, or the wiring, or the fan
motor itself.
He has a new thermostat but I would ask if the radiator does get hot or not.

"Simplstupd" > wrote in message
ups.com...
> If it sits in the driveway and idles how long does it take to overheat?
> Does the fan come on?
>
> I'm leaning towards a bad water pump.
>

It will overheat within 5 minutes. Again the lower part of the radiator
stays cold so the switch doesn't close and fan doesn't cycle. The thing
that bothers me is that a new thermostat fixed it but only for a short
time.

Did you use any 'stop leak' in it?
Are you sure that there is plenty of coolant/water in it?
You might want to take off the top radiator hose and fill both the engine
and the radiator that way.

BTW 5 minutes is mighty quick for your engine to overheat if there is
coolant in it.
How is the heat inside of the car?
If bad:................
Possibly low fluid level or bad water pump.
If good:..................
Might be another bad thermostat.
(I have seen a thermostat that was stuck open by it's bleed hole device) Of
course in your case the thermostat is stuck closed. :-(

And then it could be an engine problem like cylinder head gasket, or maybe
cracked cyl. head.

"foxstreetblues" > wrote in message
lkaboutautos.com...
> It will overheat within 5 minutes. Again the lower part of the radiator
> stays cold so the switch doesn't close and fan doesn't cycle. The thing
> that bothers me is that a new thermostat fixed it but only for a short
> time.
>

In article outautos.com>,
foxstreetblues > wrote:
>It will overheat within 5 minutes. Again the lower part of the radiator
>stays cold so the switch doesn't close and fan doesn't cycle. The thing
>that bothers me is that a new thermostat fixed it but only for a short
>time.
>

its either the water pump, the thermostat stuck, but I will bet for a blown
head gasket or cracked head. been there. sold the car




--
Eduardo K. | To put a pipe in byte mode,
| type PIPE_TYPE_BYTE.
http://e.nn.cl | (from the Visual C++ help file.)

foxstreetblues wrote:
> I diagnosed my overheat problem, hot upper hose cold lower hose, as a
stuck
> thermostat. I pulled the coolant pump and replaced the thermostat.
After
> roadtest: radiator heated up, lower hose heated up, fan came on, fan
shut
> off, no overheating. My wife drove to work (12mi) no overheating.
On the
> way back overheat problem is back. Is it possible that I got a bad
part?
> What a pain to redo this repair!

You might want to pull the thermostat out and throw it in a pan of
water on the stove. Is it closed when cold? Does it open before the
water boils?

You might have a bad thermostat. If the thermostat checks good (testing
it in a pan of water on the stove), then I would check the water pump.
While you have the thermostat housing off, try turning the impeller in
the pump with a screwdriver. Don't push hard enough to break it, but if
it spins easily, then the water pump is a problem.

I'm also a little suspiscious of the head gasket. With the engine cold
(like after sitting overnight), start it up. Rev it a little (not high,
maybe 1500-2000 RPM's a couple times) and shut it off. Now, listen
carefully as you release the pressure cap. Do you hear hissing as
pressure escapes? If the system pressurizes when it's cold, then you
have combustion pressure (and heat) leaking through a failed head
gasket.

--

Racer X
1984 VW Jetta Diesel GT
1992 Mazda Miata (looks OK for a car that's been hit by an 18 wheeler)
1994 Caravan (OK, maybe it's a keeper, but I still want a VW Caddy)
1995 Ford Escort (may it rest in pieces)
1983 VW Rabbit GTI (ITB racer)
1988 Mazda RX-7 (maybe for sale, make offer)
1992 GMC Topkick (portable garage for racecar[s])