Steve wrote:
> pawn wrote:
>
> > (REPOST AFTER CRAP)
> >
> > Hi:
> >
> > Had a breakdown last night, I'm pretty worried about what might
have
> > happened, any advice or enlightenment will be greatly appreciated.
Here
> > is the sequence of events:
> >
> > - left work at about 7:00pm in very cold weather (-20C).
> >
> > - as I was entering the highway, my Jeep hesitated a bit like it
was
> > going to stall, but then ran fine.
> >
> > - within a few moments, the thermostat went through the roof, so I
> > pulled off the highway at the next exit. The coolant was very low
> > (nothing in the resevoir), so I bought a jug of coolant, topped it
up
> > (about 2 litres to bring it to the fill line).
>
> Did you fill the external reservoir, or did you open the radiator and

> add coolant directly to the radiator? If you just topped the
reservoir
> and did NOT add coolant to the radiator, its very possible that the
> engine was still stone-empty.
>
> >
> > - the only other sign of trouble to my untrained eyes was that the
rad
> > was still cold, and the heater was generating zero heat. No
apparent
> > leaks, steam, smell, etc.
>
> A sign of no coolant in the engine, or at least not enough to
circulate.
> The other bad thing that happens in that condition is that the
> temperature indicator will often read abonormally low until the
engine
> is SEVERELY overheated because the only way the sensor is heated is
by
> conduction through the engine block and heads, not through
circulating
> coolant.
>
> >
> > - tried it out again to see if the temp would come back down.
> >
> > - Still bad, so I pulled off the road. While trying to get back to
the
> > gas station, there were dieseling sounds and the engine ran very
rough.
> > I couldn't even get to the station before the engine stalled. The
> > engine *would* turn, although it was labouring. I thought better
of
> > trying to force it.
>
> By the time you hear dieseling sounds, the insides of the combustion
> chamber are red hot.
>
> >
> > - at this point there was steam in the engine compartment, and not
to
> > steer you in any particular direction, but it seemed to me to be
coming
> > directly out of the perimeter of the cylinder head.
>
> Steam or smoke? Could just be oil residue burning off because the
head
> was so abnormally hot.
> >
> > - had the vehicle towed to the only place open at almost 8:00pm:
Crappy
> > Tire. The vehicle is there now and I'm waiting to hear.
> >
> > My opinion is the head gasket is blown, and dumped coolant in the
> > combustion chamber(s).
>
> You don't say what engine, but it has to be either a 4.0 (most
likely)
> or a 5.2 if its a '95. Both of those engines have cast iron heads and

> cast iron blocks- you have to REALLY roast either one in order to
blow a
> head gasket. I'm not saying it didn't happen, and the fact that it
was
> making diesel noises is a bad sign, but I've seen both 318 (5.2) v8s
and
> 4.0 sixes survive overheating to the point that they sounded like
> 18-wheelers before.
>
> >
> > So, my questions a
> >
> > - Why? Does the fact that the rad stayed cool throughout mean
something
> > froze and caused this situation? Or is the root cause the
(possible)
> > blown gasket, thus the coolant followed the path of least
resistance,
> > i.e., not to the rad?
>
> It probably means either that, or that there was no coolant at all. A

> possible scenario is that a block freeze plug popped out and when the

> engine warmed up, everything drained as you were first beginning to
drive.
> >
> >
> > - What now? Given the high temp, possible contamination and
definite
> > laboured engine turnover, is something totally pooched at this
point?
>
> If it was an aluminum-headed (or worse yet alumimum block and head)
> engine, then it would definitely be history. But given that its
either a
> 5.2 or 4.0, it may live many more years. It all depends on just HOW
hot
> it really got, and no one can tell just from a verbal description.
The
> fact that you didn't push it after it started rattling is a very VERY

> good thing.
>
> >
> > - What is the general procedure for fixing this? Is it possible
there
> > is no major damage? Can the (possibly blown) gasket be replaced,
the
> > engine flushed, the oil and coolant replaced and hope for the best?
> >
> Fix the coolant loss or freezing problem FIRST, and then see how it
> does. If there is a loss of compression or coolant in the oil or
coolant
> leaking at the head gasket, then the head will have to come off, the
> gasket be replaced, and the block and head checked for flatness and
> machined if necessary. The head should also be checked for cracking
at
> that time.
>
> WORST case is if it got hot enough to wreck the piston rings, in
which
> case it probably will not re-start because it won't have any
> compression. That should be fairly easy to rule out.

It may not be that scary. Sounds like a HG is indeed blown, but I like
the freeze plug theory. Might fake you out if you don't know exactly
what you're looking at.

I did almost exactly the same sequence in my '62 Studebaker one morning
- I just got up and decided I felt like driving an old car to work.
Pulled out of my driveway and headed off down the highway. I'd
apparently blown a freeze plug before I hit the highway, but I never
noticed because the road was unlit. Once on the highway, I could see
little wisps of steam following the car, so I pulled off at the next
exit. Once I dropped below highway speeds the engine got smokin' hot,
with the associated diesel noises. I replaced the offending freeze
plug (@#$%$^%& disc plugs - ended up using the screw in rubber type as
I was unable to get the disc type to seal reliably without pulling the
engine to set them) and changed the oil, and the car still has enough
power to roast the clutch, apparently

I have much respect for both the 318 and the 4.0, they seem to be just
as basically strong as a Stude engine, so who knows, this may not be as
bad as you think (of course, it could be just as bad as you think...
you do need to have it checked out)

nate