6packers,
I need help. It's only 4 days till the TRF summer party, and suddenly
I have big problems.
The car is overheating in a big way. Here's what happened today: start
up from cold, no problems. Car runs great, turn the choke full off
within a minute and she runs smooth. Oil pressure is around 80psi.
Drive through town, stop and go, car around 1/2 on temp gauge. Hotter
than I usually see. Stop at a light for about a minute, car creeps up
to 3/4. But then I pull away and she cools back down to 1/2. Okay, I
figure everything is cool. Drive down a highway for about 15 minutes,
temp still at half, oil at about 70psi, cruising at 65 in 4th
(overdrive not working - electrical problems that aren't related to
this). Stop to get on PA turnpike. Temp gauge creeps up to 5/8, but
cools back down once I'm up and running. I am on the turnpike for a
total of about 45 minutes. The car is at 1/2 and 70 psi at the
beginning of the journey. After 15 minutes, temp starts creeping up.
By the end of the turnpike leg, temp is above 3/4, oil pressure down to
45, constant cruising at 60-65 mph the whole time, no traffic or stop
and go.
Stop to pay toll. Car gets up near red on the temp gauge. Car no
longer showing ANY oil pressure at idle up to 1500 rpm. Once I get up
and going again down another 4 lane highway, she cools a bit to a
little over 3/4, oil pressure is at 30-35 psi, constant 50-60 mph
cruising.
The car did this same thing on Friday. Today before setting out, I
changed the thermostat, and checked timing. I usually set static
timing at 10 BTDC (because the engine is souped up, 9.5 compression,
triple stombergs, header, etc). I run no vacuum advance or retard.
The timing was showing 14 static, so I moved it back to about 9. The
timing chain is pretty shot, very noisy, etc. But the car runs fine,
smooth, no overheating for about half an hour of driving.
My thoughts are that either 1) centrifugal advance isn't working
because maybe the weights are stuck or rusted up, will check this
tomorrow night with a timing light 2) crack in head (please no!!) which
opens up as engine warms up and then lets exhaust gas into the water
jacket, or 3) head gasket is blown and letting exhaust gas into water
jacket.
The car used to run great, never got over 1/2 on temp gauge, usually
ran at 1/4-3/8 even in 95 degree temps. The car then sat for about a
year. Drove it to my new home in PA from Michigan over Memorial day.
Car ran fine at first, but did this same warming up thing after about 4
hours. However, temp didn't get as high as today, perhaps because
ambient temps were much lower (May 60s rather than today's 85 degree
temps). I haven't driven it much at all since bringing it down. One
drive was about 45 minutes on back roads on a nice day, temp got up to
about 3/4. Other drives have been shorter, temp doesn't go over 1/2.
This Friday and today's drives were about 1hr15min each, of sustained
highway cruising.
I tend to think it's not a blown head gasket, because the water doesn't
get hot right away. Also, at first the car gets hot but then cools
again during typical stop/go traffic at lights and such (warms up at
lights, but cools back down after moving again). It's not until I
drive for a longer period of time that the problem really gets bad. I
don't know much about the cylinder head cracking problem, but have
heard that this happens on TR6s sometimes. For those of you who have
experienced first-hand or through others, does this sound like what's
happening to me? My theory is I have a small crack that doesn't open
up fully until enough time goes by, then it opens and allows heating of
the water jacket. My other theory is that the centrifugal advance is
not working, thus running very retarded at cruising speeds and
overheating the engine. This I will check tomorrow after I buy a
timing gun at Sears.
Please help! Any advice would be very much appreciated. Hopefully
it's something relatively simple, otherwise it looks like I'll have to
show up at TRF in a rice-burner (Honda Civic). I fear I may be thrown
out of the place!!
Tim Holbrook
1971 TR6
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