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

[Paul Nimz]

One thing I always do when flushing is to observe the t-stat operating with
the upper hose off the radiator.  I fill the system with water and with a
slow trickle on a garden hose I keep the radiator filled as the engine
idles.  When the t-stat reaches it's designed temp you can watch it open and
close.

If you are getting no heat out of the heater, the core is probably blocked.
You can disconnect one of the hoses, remove the radiator cap and try to
either blow air of water from the garden hose through it.  If the core is
open then you will get either air or water out of the radiator cap opening.

My bet though is it is clogged as well as the radiator.

Paul Nimz
'97 TR
'93 EG mtx


----- Original Message ----- 
From: "Koper Jim" <jkoper@frankgates.com>
To: <shotimes@autox.team.net>
Sent: Thursday, February 05, 2004 8:58 AM
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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