[Shotimes] SLO overheating in winter weather: possible culprits? Hey, it's on topic!

[Paul L Fisher]

Is the top radiator hose getting hot? Sounds like the system needs to be
'burped'. On a SHO, you just take off one of the little coolant hoses going
to the intake and run the engine until a little coolant comes out. Don't
know much about the SLO motors. 

-----Original Message-----
From: shotimes-admin@autox.team.net [mailto:shotimes-admin@autox.team.net]
On Behalf Of Koper Jim
Sent: Thursday, February 05, 2004 8:58 AM
To: shotimes@autox.team.net
Subject: [Shotimes] SLO overheating in winter weather: possible culprits?
Hey, it's on topic!

My brother's 1993 3.8 SLO (129,000 miles) has overheated twice recently in
sub-freezing weather. In the course of my troubleshooting this week, I have
installed a new thermostat and gasket, upper radiator hose, radiator cap,
fresh coolant and, in back in the summer of 2002, installed a reman
waterpump and serpentine belt, and lower radiator hose. Car has original
heater core, radiator, and hoses (except those mentioned above).

The temp gauge will climb slowly to middle of the gauge (where it typically
registered before this overheating began). My brother said that he observed
the gauge spiking into the hot range and then seeing steam pour out of the
engine compartment (it was coming from the T-stat housing/gasket area).

There is NO heat coming through the vents, even after idling for 15 minutes
and verifying that the T-stat has opened (upper hose is warm).

There is no evidence (leakage or bearing noises) that the water pump is bad.
Serpentine seems OK for 1.5 years of age.

Last night I turned the engine off while the gauge was in the middle, but
the engine was still starting to steam (similar to when spilled oil burns
off). I wanted to avoid replacing the T-stat gasket for a third time! It
continued to steam for 10-15 minutes.

Could the pump be bad already? Any quick way to verify if the pump is
good--perhaps peering down the filler neck to check flow?
Could the radiator be on its last leg or (shudder...) the heater core be
clogged? The heater core inlet hose was sort of warm (after 10 minutes of
idling) but the outlet hose was cold, so I am beginning to suspect a clogged
core. There is no evidence of a leaky core (no antifreeze smell or residue
on the inside of the windshield).

I am considering back flushing the core only (removing both hoses at the
core and putting garden hose to core outlet to determine flow-through).

Say it is a bad radiator--wouldn't I still be getting heat through the
vents? I've got a new rad ready to install, but am not convinced that would
resolve the problem.

There is no evidence of head gasket damage, something the 3.8s are famous
for. Don't wanna get to that point either!

ANY suggestions or advice? I'd love to resolve it this weekend! Thank in
advance.

Jim Koper
92 SHO red/black
138,000
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