[MR2] A high speed cooling problem

[Donald Chalfant]

I agree, If you didn't flush the system, including the coolant line plugs,
engine plug, and radiator draincock, you should. Then refill with nice 50/50
and BLEED THE SYSTEM thoroughly.  A tiny air bubble could be causing your
problem now. My assessment.
----- Original Message ----- 
From: "Byron" <autoxer at sbcglobal.net>
To: <felix at crowfix.com>
Cc: <mr2 at mr2.com>
Sent: Friday, September 11, 2009 11:27 AM
Subject: Re: [MR2] A high speed cooling problem


> Did your mechanic use a genuine Toyota thermostat or one from a local
> auto supply store? An aftermarket thermostat may be the cause of your
> continued overheating although after this many years and miles, it may
> be time to remove the radiator and have a shop clean it thoroughly.
>
> Byron
>
> felix at crowfix.com wrote:
> > My 86 MkI overheats, a little, on hot days on the freeway, and no
> > other time or place.  It maketh me nervouth.
> >
> > I bought the car new, it now has 423,000 miles on it, and in all that
> > time, the temp gauge has always been rock solid sitting just to the
> > cool side of center, just enough to see the top half or so of the
> > white center line.  The only time it has ever been elsewhere is (1) on
> > start, (2) when a coolant hose broke, and (3) one time when I thought
> > the alternator was on its last gasp and I drove in 3rd on the freeway
> > for 5-10 miles.
> >
> > Several months ago, on a hot California central valley day with A/C
> > going close to full blast, I noticed tha needle was just as far to the
> > warm side as it had always been on the cool side -- ie, not much, but
> > it had never done that before.  I slowed down some (80 to 70 or 65, I
> > think) and turned the A/C down to minimum, and the needle went back to
> > its usual position over the next mile or two.  Bummer!
> >
> > I had a 60K service coming up, so the local mechanic who has been
> > looking after the car for the last ten yeras or so replaced the
> > thermostat, and when the next hot spell came around, it seemed to make
> > no difference.  However, it also overheated more just driving up the
> > dirt road to home at 5-10 miles an hour (it is pretty bumpy), rising
> > to halfway between normal and max, but a friend noticed that the front
> > license plate had been pushed back all the way and was making it hard
> > for the radiator fans to do any good.  Straightened it out and no more
> > low speed over heating.  I am a bit puzzled by this, because it seems
> > unlikely that this was the first time in 23 years for that to happen.
> >
> > And it didn't cure the freeway overheating.  We had another few days
> > of 100+ and the same problem came back.  I pulled over, checked the
> > license plate, it was normal, and I proceded on my trip at 65 with the
> > A/C low, and it did not overheat again.
> >
> > There's plenty of coolant.  Oil looked fine last few times I checked.
> > I've looked several times to se if a plastic bag or leaves have been
> > stuck on the radiator, but nope.  When it is on the warm side, I think
> > I notice within a few minutes, and I do not continue at the same speed
> > and A/C setting, so I don't know how steady it is there, but it isn't
> > rising noticeably when I do notice, so any rise must be pretty slow.
> > I think it has just settled down at a new point, but I have no proof.
> >
> > One other thing -- sometimes there is an electrical smell coming from
> > the engine compartment when I get out to get gas and check the oil.
> > Not real strong, but enough that I notice it when peering down to put
> > the dipstick back in its tube (I ought to paint that sucker with glow
> > in the dark paint).  I do not know if I would have even noticed it if
> > I hadn't been worried about the overheating, so I don't know if it is
> > related or not.  By "electrical smell", I think I mean ozone, not the
> > smell of burned electronics but the smell from generators.
> >
> >
>
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