FIXED: '87 Suburban, help diagnose engine problems

On Sep 18 2003 (yes, that long ago) Una wrote:
>My 87 Chevy Suburban R20 (3/4 ton with all factory towing extras,
>gas 454 aka 7.3 L, TBI) has several perplexing engine problems.
[...]
>3. The Service Engine Soon light comes on within a few minutes
>of starting the engine, and mostly stays on. It sometimes goes
>off during trips, usually *after* climbing a steep hill. On my
>last trip, 4 hours each way, the light stayed off several hours
>at a time. DH used a paperclip to read the codes; the only
>code it gives indicates the O2 sensor complains of a lean mix.

That's a code 44, FWIW.


>I have now taken the vehicle to 2 mechanics to diagnose the SES
>code. Shop #1 charged me for 2 hours of diagnostics and changed
>the fuel filter. No other information! The guy at the counter
>didn't know who did the work, or what the findings were.

I guess it was more than they wanted or were able to take on,
but they chose not to say so. Because they were not up front
with me, they will get no more of my business.

>Shop #2, which has the vehicle now, will charge me for 2 hours
>diagnostics, and I got a phonecall from the mechanic. He said
>the compression test showed low pressure in *some* cylinders.
>My Q: which ones? His A: well, all of them really. My Q: how
>about the valve seals and guides? His A: they're okay. And the
>problem is the rings (how does he know?), and he recommends I
>get a new (not rebuilt) engine. He'll do it for me for $6,000.

This shop at least took a stab at the problem but they did not
get far with it. Instead they tried swap-parts-until-it-goes-
away, beginning with just about the most expensive part. Pass.


More than a year later, I found Shop #3, and Shop #3 fixed the
SES code 44. A previous owner had the transmission replaced,
in which job the wiring harness got pinched. So the computer
was getting garbage data from the O2 sensor. The fix: patch
the wiring harness. Cost: $180.

Of course, to *find* the source of the problem took hours of
work, during which many other problems were found and fixed
(mostly leaks: vacuum lines, gaskets, fuel injector), so the
total cost came to $1800, but that is money well spent! Shop
#3's compression test showed a nominal 140 (outstanding!) on
all cylinders. So I don't need that $6,000 new engine block.

This truck suffers rubber rot (no surprise given its age and
the climate here in New Mexico) so a lot of money is going into
replacing the gazillion hoses and tubes under the hood, as well
as all door seals...and the tires...and and and. But still it
is a good deal, financially. New, a 3/4 ton Suburban with the
functional extras this one has would cost $40,000. And because
depreciation has run its course, I feel comfortable driving it
where few people would risk driving an expensive newer truck.

Una