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Deadly entropy with rusting vehicles

Saturday, May 1, 2010 - 00:00

The first time we saw this 1997 F150 was nearly six years ago, and it was a high mileage vehicle even then. The instructor who owns it originally had taken it to an independent shop because it had lost oil pressure, and that shop removed the engine, replaced the rod and main bearings and charged the owner $1,500. Eight thousand miles later, his oil pressure slid below the safety margin again and he returned to the same shop, only to be shown the door - they wouldn't work on the truck any more. So he went to another shop, which tackled the job, claiming they had found a lot of parts installed backwards and hitting him with a $1,700 bill. What they did is a mystery, but another 8,000 miles went by and the engine lost oil pressure again.

Well, this time around, the owner came to me and asked if we would be willing to take this problem child on. We did.

The 4.2L had worn out cam bearings, but for good measure he agreed to let us rejuvenate the major rotating assemblies (crankshaft kit, cam bearings and a new oil pump). We didn't remove the pistons from their holes at all.

Four thousand miles went by before the crankshaft broke right smack dab in the middle. I called the parts store and the counterman told me that crankshaft had no warranty; interesting that none of us (including the parts guy) knew this when we bought the kit. Go figure. Well, the parts store agreed to warranty the crankshaft and whatever else needed replacing. We did a full blown overhaul on that engine (the block had to be line bored because the broken crank distorted it; the new crank wouldn't spin when we torqued the main caps).

Another full set of bearings and the truck has been in the wind for about 30,000 miles, but it sprung a coolant leak right after a January cold snap. Figuring the repair would be quick and easy, the owner carried it to a shop in the town where he lives and that shop quoted him a $1,000 estimate, claiming all of the freeze plugs needed to be replaced. He thanked them for their time and paid their diagnostic fee, then brought the truck back to my automotive department.

Entropy – Early Stages

A fine gentleman I know has a daughter who has been overseas for a year or so and when he finally decided to drive her 2008 Honda Element, he was somewhat alarmed at the sounds that were coming from the rear brakes. Because the Honda was under warranty, he took it to the local dealership, where he was told he had abused the brakes by riding the pedal (he virtually always uses cruise control, thus he couldn't be riding the brakes the way they claimed he had), and then they told him that the Element would need $950 worth of brake repairs.

Because his other daughter is enrolled in my automotive program, he called me to request a second opinion, and I told him we'd be glad to have a look at it.

This was extremely interesting to me. Another friend of mine drives a Honda and when he took his SUV in to that same dealership for an oil change, they promptly told him his brakes were worn out and that he would need more than $400 worth of brake work. When I asked if he had noticed any noises or odd pedal sensations he didn't get a second opinion, he just made an appointment and paid them to rebuild his brakes. After our experience with the Element, it became apparent that he may or may not have needed that work.

A thorough brake inspection of the 2008 Element at my shop revealed front brakes with almost no wear at all, but the rear rotors were somewhat compromised by rust, which was the source of his noise. Why the front rotors didn't rust the way the rear ones did is something of a mystery, but we removed the rear rotors to examine the park brake shoes, which looked practically new. We then mounted the rotors on the lathe and worked them over with the 3M refinishing pads we use to establish the non-directional crosshatch pattern when we do machine work. We washed the rotors with hot soapy water, dressed the barely worn brake pads with a file, added some CRC Disc Brake Quiet to their metal backing plates, and reassembled everything.

As it turned out, those simple repairs were was all the Element needed. The Element drove like new again, and my advice to my student's father was that somebody needed to put a few miles on it every week.

Entropy – Courting Disaster

The GMC referenced in our title was shiny black, a 2003 Sonoma with a small enough number on the odometer wheel to really get a prospective buyer's attention, even with its $8,000 price tag. My friend Connie had been driving it for a few days (her boyfriend owned it and it had been sitting fallow for months), and she figured the grinding sound the brakes were making would go away after awhile. Well, the sound didn't go away - as a matter of fact, it got worse and then all at once she lost just about all pedal and managed to limp from wherever she was to the front door of my shop at the college. We do just about all her work.

With the pedal as weak as this one was, there was no point in driving the truck. The first thing we noticed was that the brake fluid reservoir was almost empty, and it's a foregone conclusion that the fluid didn't just evaporate out of there. Well, with the truck in the air and the wheels removed (the inside of the right rear tire had been soaked with brake fluid), we discovered that the Sonoma had blown that caliper. The pads had worn extremely thin (odd for 39,000 actual miles) and had actually allowed the piston to exit its bore. That's where the fluid went.

But all the rotors were badly pitted with rust, and if that wasn't enough, the frame and the front brake lines were, too. The shiny paint job was deceptively concealing a truck with an undercarriage that had seen enough road salt to make it look like a portion of the Titanic.

We sold a right rear caliper, all four rotors, a full set of pads and both front flexible brake lines, because the metal parts of those lines were so rust-compromised that we didn't want to risk disaster. The rest of the metal brake lines didn't look so bad for some reason, but the steel line leading to the HCU twisted off while a student was replacing the flexible hose. That was a peachy keen occurrence. The dealer didn't have one so I sent the line to the parts store, and he cut one of the ends off the line I sent and used a copper tubing union to marry the old line to the new one. Wrong!

What a lot of folks (including some technicians) don't realize is that brake lines have to be able to carry more than 2,000 psi, and it is insane to splice them with a copper tubing union. We replaced the flexible feed lines for exactly that reason. Calling the parts store, I berated my otherwise trusty parts guy and had him send me the right kind of fittings to splice a brake line. This was a dynamite learning experience for my guys. After we double flared the lines and used the right fittings, Frank busted his fanny duplicating the spiral loops on the replacement brake line (they allow the brake line to flex as the body and frame shift on the mounts).

The GMC is back in the wind with a good hard pedal, strong fluid piping, new pads and rotors, and a crisp new for sale sign on the window.

Entropy – Internal Attack

On the 1997 F150, we found one expansion plug leaking (front of the right head) that had rusted through, but just barely. Could some or all of the other expansion plugs be suspect? Sure, but they weren't leaking now, and the owner completely understood the fact that others could follow. We fixed that one expansion plug and pressure tested the cooling system to find the intake gasket leaking like a sieve on both sides. It was pouring coolant topside and into the crankcase, and with coolant running back and dripping from so many places right after a bark-busting cold snap it's no wonder the shop made a snap-click diagnosis and condemned all the expansion plugs.

Two students replaced the intake gasket, filled the cooling system, fired up the engine and even after the air was burped out it tended to slowly overheat in the service bay, but only with the coolant filler cap installed.

That being said, we used a pressure tester gauge as a tool to determine that there was no rapid pressure rise in the cooling system that would indicate head gasket failure, so the thermostat was replaced as an inexpensive first step, but to no avail. As before, with the cap removed it never heated above 220 degrees, but if they installed the fill cap it would slowly begin to climb beyond safe levels.

With the heater hoses getting hot right away, the water pump was ruled out. We removed the radiator and did a borescope inspection to find some pretty substantial clogging.

A replacement radiator ($160) was in stock at the parts store, and early the next day with the radiator in place and the cooling system burped we had a cool running F150 in the service bay (210 degrees), even at high rpm and with the cap installed. With the scan tool ECT readings and the instrument gauge in firm agreement, we thought we were done with the overheating problem – WRONG.

When we drove the truck on the road, it would spike up into the red (240 degrees) and it only took a few hundred yards for it to heat up. Yet we could stop the truck and it would cool down immediately. This kind of cooling system performance is downright spooky and just didn't make sense, especially because we had just installed a nice clean radiator. The two students who worked on this are real troopers – they never complained, nor did the owner, even though his repair bill was climbing into the red as fast as the temp gauge was.

When we removed the tanks from the old radiator, there were a lot of big rust flakes floating around in there (perfect for blocking flues), but we obviously weren't done. The only component that could produce that many large rust flakes was the water pump impeller, which is stamped steel on this unit, and it was there that we found the answer. The water pump impeller had separated from its shaft. Because the owner only drives the truck to work and back, which is less than two miles each way, there was no telling how long it had been since the failure occurred.

Entropy had launched a full-blown rust attack on all three of these vehicles, and while we could only partially reverse it, all three vehicles are back in the wind.

A white Ford and a black GMC – both non-drivable. VEHICLE: 1997 F150MILEAGE:190,547 milesENGINE:4.2L Engine 4R70W TransmissionCOMPLAINT:Leaks Coolant

VEHICLE:2003 GMC SonomaMILEAGE:39,304 milesENGINE:4.3L Engine 4L60E TransmissionCOMPLAINT:No Brakes

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