I have a problem on a 2000 Malibu LS with the heater. We replaced the
thermostat, the heater worked fine for a couple of weeks. Then the
engine overheated, the thermostat was replaced again, and now, no
heat. The gauge is running slightly under 180 degrees, which is a bit
too cold for a 195 degree thermostat. IS there something we are
missing causing the coolant to bypass the thermostat and heater core.
I have tried to find a heater control valve in the heater lines, but
do not see one there. The vent seems to be working from cold to hot
under the dash, but no hot air?
We are thinking that it might be a clogged heater core causing some of
the trouble. Problem: Where is the heater core, and how much of the
dash has to come apart to get to it to replace it? Can it be flushed
and have decent results, or is replacement the only option. We assume
that replacement will be a time consuming project, so any help with
other solutions will be appreciated.

Thanks in advance

Heater blowing cold is a sign of low coolant.
Are you sure your coolant is full?
Also, the 2000 Malibu has a known problem of
coolant leaking from the intake manifold, could
be the reason your coolant is low.

On Tue, 25 Nov 2008 15:02:21 -0500, "Russg"
<russgilb (AT) MUNGEsbcglobal (DOT) net> wrote:

while, but stopped again, after replacing the first thermostat. Now,
the engine overheats. This car belongs to my secretary who has a son
who knows more than most about everything, so I have to be a bit
careful of how I approach solutions. I have only been doing repair
work commercially from age 16 to around age 30, then part time since.
I am 53. I know that a lot of computer systems cause malfunctions, and
this car has a bad sensor in the intake, but, I still do not see this
causing a heater problem.
The son wants to replace the radiator and heater core next, and that
was the reason for my question earlier. I suggested flushing, and was
told that it had been done already. I do not know if he has an idea as
to how to do it, but. I did ask if he put the thermostat in backwards,
and was told rather nastily that he knew how to put a thermostat in.
(Apparently not too well, as replacing one on this car for him is an
all day job)
So, here I am, trying to help someone who needs help, but the biggest
and best thing she could do, is to keep her son from under the hood.
As that is impossible, where is the heater core? Any ideas as to how
big a job it is to replace or how much of the dash has to be
disassembled to remove and replace it?
Give me an old Chevy with a 235 in it any day!

"Steele" <> wrote in message news:
The heater core being 'stopped up' wouldn't cause
the engine to overheat. There are several things
that can cause the engine to overheat, low coolant
the most obvious. Bad thermostat, leaking head
gasket, faulty water pump or belt maybe too.
Hope you get your answer.

home from work, The guage situation sounds like a simple sending unit
malfunction, and may be related to a check engine warning of P0113,
sensor malfunction. The mechanic son has something ordered, that I
don't believe will solve anything, but, he is the mechanic.
As for the overheating, I do not believe it is doing that, but the boy
is going to flush the radiator today to check that.
I'll check the coolant from time to time for her, as I do not believe
the mechanic is capable, and if it continues to lose volume, I'll
check further, then. You said the intake was bad about gaskets?

snip
leaks to the outside, as opposed to into the intake ports.
I haven't heard of head gasket leaking coolant into
the combustion chamber. Some 'Bars Leaks Heavy
Duty' can fix the intake gasket leak.
Leaks that get into the combustion chamber, you can
smell coolant at the exhaust.

I think you should stop talking to him and suggest to her that she take it
to a good service shop. Old service procedures don't work in todays computer
controlled high tech engines. If he hasn't destroyed the engine yet he is
heading that way.

"Steele" <Ironandsteele (AT) hotmail (DOT) com> wrote

I quit talking to him before he opened his mouth. She is sending him
to mechanic's school, since he knows so much about engines. I forgot
more yesterday, than the kid will ever know, and he is unwilling to
learn. That is what is wrong with most of today's kids.
\What you say about high-tech engines is correct to a point, but basic
knowledge is still basic knowledge, whether high-tech or not.
The shop she finally took it to is about as full of geniuses as he is,
and they are still playing with it...I think it is a shop project. So
far, they have replaced all hoses, the water pump, head gaskets,
intake gaskets, the radiator..Sooner or later, they will find it?

On Fri, 05 Dec 2008 11:22:23 -0600, Steele <Ironandsteele (AT) hotmail (DOT) com>
wrote:

Well, I was wrong. They had not replaced any gaskets, as a 'chemical
test' had revealed that all gaskets were ok.. Guess what? The shop put
yet another thermostat in it and pronounced it ready. It made it to
about 6 miles from the shop on the waay back home and started running
hot again. This time, a lifter was also pecking, and all the oil was
out of the engine. I put a quart in it and quietened the lifter a bit,
but the heat was still running too high on the guage. A real shop, or,
more real than the other ( I wouldn't take a bicycle to either shop to
have air put in the tires successfully) looked at it this morning, ran
a compression test that was "unnecessary" as the chemical test had
revealed no leakage, and the #3 cylinder is leaking. We hope it is a
gasket, and not the head.
For those of you who try local shops, be careful, all are certainly
not the same. I do most of my work personally, and trust very few.