[Supras] Auto Trans & Oxygen Sensor Questions

[Bigmacz28 at aol.com]

Have a 89 that went 304K before rod bearing gave up. Don't know other  
history about the car. Oil changes etc....That's when I got it. Replaced with  JDM 
engine. Guy said he was the second owner and got the car with about  160K.
 
I had the same problem you did on a 88 but torqueing the head down again  
didn't help. Car ran good just some bubbles coming out the radiator after  
turning the engine off and would loose coolant over time. I did a leak down test  
and three cylinders were doing it. Compression was 170 in all! Car ran  good! 
The leak was only one way. No coolant in cylinders or oil. I  replaced the 
engine with rebuilt one last week. After taking the engine apart  the head had lots 
of pits around the water channels, next to the cylinders and  the block had 
some trenches around two out of the three cylinders in question.  The head is 
scrap. The block is at the shop for cleaning and decking. The range  I have 
seen is between 115K & 145K. That's about six total and I have two  others I 
haven't looked into yet but both are in that mileage range.
 
Joe Mac
 
Tucson,Az
 
 
In a message dated 5/14/2008 10:27:32 A.M. US Mountain Standard Time,  
wellner.christian at navy.mil writes:

Studioartist,

I wish 300K was possible with the  original head gasket.  Mine
went at around 120K.  When I replaced  it, I noticed the block deck was
trashed.  Head gasket must have been  leaking for at least 30K miles
before it let go.  I had only spent  $1500 for the car & hadn't planned
on rebuilding the engine (other than  the head gasket car ran fine and
looked good).  So I just stuck on a  new head gasket and crossed my
fingers.  Two weeks later, I started  hearing the famous gurgling sound
from the dash (heater core) telling me  that the new gasket had started
leaking.  Needless to say, I was  pissed......  So, I got out the torque
wrench, and torqued all the  head bolts (in sequence) to 85 ft-lbs.  What
did I have to loose  ?  The "trenches" in the block deck looked like they
were deeper than  the allowable milling limit.  Anyway, its now been
about 100K miles on  the same head gasket.  As long as I let the car
fully warm up (temp  gauge needle about half way up) before I touch the
throttle, it uses no  coolant !!!  Power is still reasonably good.  If I
remember  correctly, the gasket is blown on #3 and #4 cylinders.
Now,  if I can just get the auto trans to stop shifting from
first straight to  fourth.......
Really would like to know if anyone has made it  to 300K miles
without rebuilding the engine bottom end.  Trans  internals should last
this long if fluid is changed.  Since all 7Ms  blow head gaskets, there
probably isn't a 7M Supra around that hasn't had a  valve job.  When I
had my head off, I had two valves ground, and all  the stem seals
replaced.  The new stem seals at 120K changed the oil  consumption from 1
qt every 700 miles to 1 qt every 2500  miles.

Thanks, Skip
'86  MA70


---------------------------------------------------------------
Original  Message
Date: Tue, 13 May 2008 19:43:26 -0700 (PDT)
From: LN  <studioartist at yahoo.com>
Subject: Re: [Supras] Supras Digest, Vol 53,  Issue 16
To: supras at supras.com
Message-ID:  <489860.95412.qm at web30406.mail.mud.yahoo.com>
Content-Type:  text/plain; charset=us-ascii

If you can get 300k miles on stock head  gasket it would be a first.
Mine went to 135k then it was gone.  Hope  that answers  it.



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