Several years ago my 92 RMW went off to the boneyard, and a little piece of me died. The motor was still strong, transmission rebuilt, but the salt had taken it's toll over the years and the rest of the car was showing every one of it's 400,000kms.
Flash forward about 4 years.
My son has a 91 K1500 Heavy (ie: K1500 with K3500 suspension, etc. -- strange factory option, but I digress) plow truck. The engine has been used and abused, and was generating a smoke screen that would hide a battleship. We tried new valve guide seals, which reduced the following cloud to destroyer proportions. He talked to the owner of the aforementioned wrecking yard, who claimed he still had my old motor in storage.
Now personally, I had my doubts that a) the motor was still around a wrecking yard after 4 years and b) that the owner would remember who previously owned what car that stored engines came out of, however, circumstances proved me wrong and we found indisputable evidence that this was indeed my old motor.
My son prepped the motor with new gaskets, timing set, valve seals, etc. and the wrecker bolted it in. He was impressed with the new-found power, but soon noticed a coolant leak that turned out to be a cracked right head. The wrecker supplied a replacement head, it was prepped and swapped in. Soon after, my son noticed the indicated oil pressure was extremely low -- in the red at idle in gear. The wrecker dismissed the concern, suggesting it was a faulty gauge or sensor, since the engine didn't knock.
I suggested it was a simple thing to tee in a mechanical gauge to check the sensor; he did; the gauge was right: oil pressure was about 5-7 psi at idle in gear when hot. Not good.
We bought a new pump, jacked the engine off the mounts, dropped the recently cleaned pan and discovered considerable evidence of metal sludge in the bottom -- including flecks of brass. Fearing the worst, we decided to check the bearings. #5 big end was convenient and the Plasti-gage showed the clearance was still in spec. But to my horror, when I pulled #7, I found shiny metal swarf inside the journal oil passage drilled into the crank. I am talking 1/4" long curled bits of ferrous metal that I am convinced were peeled out of something by a drill bit. They are somewhat brittle, so I think iron rather than steel. My son suddenly remembered seeing the wrecker clear out the passages of the replacement head with a drill after it was installed, but these were way too big to get past the pick-up screen so I still have no idea how they could possibly get inside the crankshaft. I figure they had to have entered via the oil cooler lines or oil filter housing.
Anyway, surprisingly there was very little damage. Some bearing shells showed evidence of embedded metal particles and/or wear but most of the journals were untouched. The exception was the #1 main, which had some light scoring, about 1 thou deep. Not good, but with snow in the forecast and the wrecker no longer returning calls, I lightly stoned the journal, blew out all the crank passages, flushed the oil cooler, removed and flushed the filter adapter and generally cleaned everything I could get at, chewing up 2 entire rolls of shop towels in the process. We installed a new set of std bearings, lubricating everything with GL90 gear oil. Primed the new pump with the same, disconnected the injectors, cranked it over to fill the crankshaft journals and crossed our fingers.
She fired up with no noises and decent pressure (15-20 psi at idle when hot). All was well.
A day later, pushing a 7' plow blade, the plastic radiator drain decided to leave. By the time he noticed and shut it down, it was getting mighty warm under the hood and the oil pressure was down to 10 psi at idle. Changing the drain necessitated disconnecting the oil cooler lines and removing the radiator. On reassembly, one oil cooler line was dripping at the adapter. This truck uses the push-in quick connect style fittings, with a plastic retainer sleeve and an o-ring to seal it, so he pulled it apart and installed a new o-ring. Then he pulled it apart again and stacked on a second new o-ring. It still leaked. Today he bought a new fitting (adapter, o-ring and retainer). He couldn't feel the "click" when he pushed the line in, but it seemed secure, he couldn't pull it out and it didn't leak even after 20 minutes of idling. Oil pressure was back up to 20 psi at idle.
Driving down the road, the oil pressure dropped to 0 when the line blew out of the fitting. I headed off to rescue him and it took two of us pushing on that darn line to get it to "click" into place, so I understand now how it could happen. Anyway, fearing the worst, we poured in 3 quarts of oil to replace what was lost and fired it back up. Somehow it seems to have survived yet again. Oil pressure is back up at hot idle, with no ominous noises emanating from under the hood.
If the LT1 is a thoroughbred stallion, the L05 is a Clydesdale. Or a cat. I haven't decided which.
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Mon Nov 11, 2013 11:20 pm
