Self Healing Head gasket??

[troot]

I found this group after buying a '99 OBW with 117K. Boy, I have
learned alot. After reading about the dreaded HG failures I felt that
it was only a matter of time before problem would raise it's ugly head.
Sure enough, after 300 +/- miles of trouble feel cruising the temp
gauge headed north about 15 miles away from home on the way out of
town. I was very lucky to be ale to pull right off the road and into a
gas station. The left side of the engine bay was soaked and there was
coolant dripping. I could find no leaks and topped up the overflow
with about 1 1/2 qt. of water. I opened the air valve and did a quick
purge. The temp gauge ran back up ,but settled down after running at
idle for several minutes. Unable to get a tow, I drove home at 45 mph
with the guage reading normal. I spent today cautiously driving around
town and made several runs at 65 mph. The gauge (and sensible engine
heat) is perfectly normal. Now the clues. I did find a very slight
film on th coolant and when I first got the car I cleaned a small
amount of blackish residue off the sides of the overflow.. No
oil/water mixture in the sump. No sweet smell in the exaust. No
regular bubbles in the overflow.
When a head gasket fails can it re-heal? Do the symptoms come and go?
I'm I barking up the wrong tree? I will have the coolant checked for
hydrocarbons, but thought I'd ask here for some insight. Thanks in
advance for any input.
dave c

 

[Carl 1 Lucky Texan]

I found this group after buying a '99 OBW with 117K. Boy, I have
learned alot. After reading about the dreaded HG failures I felt that
it was only a matter of time before problem would raise it's ugly head.
Sure enough, after 300 +/- miles of trouble feel cruising the temp
gauge headed north about 15 miles away from home on the way out of
town. I was very lucky to be ale to pull right off the road and into a
gas station. The left side of the engine bay was soaked and there was
coolant dripping. I could find no leaks and topped up the overflow
with about 1 1/2 qt. of water. I opened the air valve and did a quick
purge. The temp gauge ran back up ,but settled down after running at
idle for several minutes. Unable to get a tow, I drove home at 45 mph
with the guage reading normal. I spent today cautiously driving around
town and made several runs at 65 mph. The gauge (and sensible engine
heat) is perfectly normal. Now the clues. I did find a very slight
film on th coolant and when I first got the car I cleaned a small
amount of blackish residue off the sides of the overflow.. No
oil/water mixture in the sump. No sweet smell in the exaust. No
regular bubbles in the overflow.
When a head gasket fails can it re-heal? Do the symptoms come and go?
I'm I barking up the wrong tree? I will have the coolant checked for
hydrocarbons, but thought I'd ask here for some insight. Thanks in
advance for any input.
dave c

You could have a sticking/bad thermostat and/or a bad radiator cap. a
plugged o'flow bottle tube, a crack in the radiator tank etc. are other
less likely possibilities.
Could the residue you saw have been some stop-leak type subsatnce the
previous owner had used?

I dunno

Carl

 

[Dmitriy]

Call your subie dealer, give them your VIN and ask if the coolant
conditioner service has been performed.

Alternatively, go register on my.subaru.com, and it will give you all
that info.

 

[Edward Hayes]

From my experience HG leaks do not heal themselves. I agree with Carl,
that a sticking thermostat could be the culprit. The top radiator seal
has also been suspect as has a bad radiator cap or cap seal. As
mentioned the "cooling system conditioner" is a must and will usually
take car of coolant weeping.

 

[AS]

Agree with Carl, and in particular i lean towards the thermostat.

 

[troot]

Thanks for the input! The thermostat is on the short list of
possibles. The cap and over flow bottle are in very good shape and
seem to be fine. When the system went south, I had a sudden loss of
coolant, not a weeping leak. Not seeing any further leaking. My guess
is that the system blew out the coolant via the overflow. I wish I had
paid more attention, but I was stressed about over heating the engine.
I don't remember the over flow cap being displaced or the rad cap being
loose, just losts of coolant every where. It wouldn't hurt my feelings
one bit to have to replace the thermo instead of the head gaskets.
Regarding the coolant conditioner. When I cleaned the over flow bottle
I got less than a nickle's worth of material . It was black and had a
hard , but rubbery feel. However, I thought that the conditioner was
used to address the HG problems in the later ('00 +) series of the 2.5
motors, mine is a '99

BTW the Soob dealer reports that they only do about 3-4 HG jobs a year
??? This is a fairly large dealership in Newport News VA. Maybe
folks go else where??

Dave C

 

[Dmitriy]

http://forums.nasioc.com/forums/showthread.php?t=488157&pp=25

99 is included.

Call the Subaru dealer and have them check if the service was done.
Actually, first look for a sticker in the engine bay, on the radiator
support beam, that would say "coolant conditioner... blah blah".. the
sticker might be all worn out (it is on my car) but you should still be
able to make it out.

When the HG was bad in my RS, the coolant level would drop pretty
quickly...

 

[CompUser]

@i3g2000cwc.googlegroups.com>,
(e-mail address removed) says...

When a head gasket fails can it re-heal? Do the symptoms come and go?

No, and yes.

I had a 2.5L straight 4 Cherokee that
intermittently showed sudden overheating, then
would run fine for 2-3 months without a hitch,
over the better part of a year. After one "hot"
session, I found the mocha-latte deposit in the
oil fill cap. That's my experience, and I'm
stickin' to it.

 

[bj]

if there's black gunk in the overflow its oil...keep your eye on the
heat gauge ....i've read many reports which stated the HD lasted for a
while...keep the rpms down and it may keep goin..

only 4 hd's a year?....don't believe 'em

thermostats do go...but the black stuff is a concern

 

[Dmitriy]

if there's black gunk in the overflow its oil...keep your eye on the
heat gauge ....i've read many reports which stated the HD lasted for a
while...keep the rpms down and it may keep goin..

only 4 hd's a year?....don't believe 'em

thermostats do go...but the black stuff is a concern

Agreed. A bad thermostat won't cause there to be oil in your coolant,
and 'mocha latte' in your oil pan...

 

[Edward Hayes]

Black gunk in the overflow is also caused by someone using
water-wetter in the coolant.

 

[Carl 1 Lucky Texan]

Black gunk in the overflow is also caused by someone using
water-wetter in the coolant.

And I think he said black - not tan or brown, and a 'nickel's
worth',no mention of a 'film'. Heck, that could be trash from factory
assembly.

I dunno

Carl