Diagnosing and repairing high-mileage vehicles

Aug. 1, 2017
The ones that just keep on givin’ sometimes need help.

Those of us who have been in this industry a long time can remember when a vehicle was pretty much used up at the 100k mark. Odometers “rolled over” after 99,999. I read somewhere that in the 1930s, most engines needed rebuilding every 10-20K miles. Technology has certainly improved, and there are more than a few brands out there that can rack up some stratospheric odometer numbers with very few debilitating problems along the way.

When I worked at the dealer, we saw more than a few Ford pickups and Jeep Cherokees with 300-400K miles. The folks with Jeep Cherokees would keep the one they had driven hundreds of thousands of miles and buy another one. A few years back, my department was given a 1997 Pontiac Grand Prix with 250k on the clock and it still runs like a new car, even though the interior trim has aged to the point of coming apart in places.

This is one of those stealth problems — one of my guys had replaced the radiator in this high mileage Ranger, and since the lower radiator hose clamp had seemed okay, he re-used it. What he couldn’t see was that this clamp wasn’t quite long enough — the screw was only holding a couple of slots, and they gave way one day about six weeks after the radiator was replaced and dumped the coolant.

Some of the customers’ vehicles we work on in my department are low-mileage cars only a couple of years old, but we spend a fair amount of time on older ones. This time around there are several jobs to discuss; the most recent one we did yesterday. It was a high-mileage 2010 Ford Edge that had developed a serious transmission cooler leak after hitting a dog, and she had driven it until it was six quarts low on fluid before realizing that there was some serious dripping going on. As a side note, while it was on the lift, the lift itself breached a hydraulic hose and started leaking, and we had to fix that too – my contention is that that the transmission leak on the Edge was contagious. That one got a transmission cooler and the six quarts of replacement juice and the lift got $200 worth of new hydraulic hoses. Two crises dealt with in tandem.

Another recent one was a 2004 Trailblazer that rolled in with really high miles, an engine skip and a $450 estimate another shop had given her to fix that skip. They had proposed those $13 apiece Iridium spark plugs and a whole set of new coils. Well, this gal is a single mother and rejected that estimate out of hand. We pulled the codes, found a misfire on the No. 1 hole, did a compression test for good measure, then put a set of platinum plugs in there and a single coil.  For grins, we also polished the headlights, which had taken on the color and cloudy opacity that might be compared to dirty lemon juice. And yeah, we don’t charge labor, but why does a vehicle that old need the most expensive plugs and a whole set of coils? There is such a thing as pricing yourself out of a repair.

The Avalanche

The Avalanche

A lady called me one week while I was off during a break and asked if I’d have a look at a 2003 Mazda B3000 she had sitting on the curb in front of her house. The story on that one was that it was her son’s truck and that it had failed to start one night in a parking lot and they had tried to jump it off with no results. Figuring it was a bad starter, they simply parked it (strange, I know, but that’s what happened). It had been sitting there for three months when I opened the hood, noticed that the battery had been removed, connected my 30-lb. jumper cables, and fired it up. Faux jumper cable connections on crummy battery cables can de-rail a DIY diagnosis of a no-crank in short order. The B3000 ran like brand new and even had cold air, so she washed it and got it ready for a quick sale. A couple of weeks later it failed to start at the car wash, but that turned out to be a tripped inertia switch – somebody must have slammed the door or kicked it or something. But during the three months the Mazda was down, she had sold the boy her 2004 Chevy Avalanche and had bought herself a newer truck.

Now her son reported that the Avalanche, which boasted 268,587 miles, was leaking power steering fluid, and she wanted to know if we could check that out. I agreed, and when the truck arrived, we discovered that it had a dreadful engine oil leak that made the power steering leak look like a minor drip. It was odd that he was more concerned with having to add a half a pint of power steering fluid once a week than he was that the engine was bleeding oil to the point of what could be an early death. When I asked him how much engine oil he was having to add, it turned out to be a quart every two or three days. Yet the first thing on his mind was the power steering leak, probably because it’d whine and get his attention and he was tired of that. Squeaky wheel gets the grease, I suppose.

This cover provides insight into the source of a leak. When we popped it out of there and found oil in the bell housing, it was a no-brainer that the rear main was the biggest leak.

Well, we went after the oil leak first – it was dripping off the bell housing, but since that’s the lowest place, the leak might be coming from the pan gasket, the oil filter adapter or the intake. The bell housing was dry on the outside leading up to the intake, and it didn’t look like the oil pan was leaking (which these love to do). We looked closely at the oil filter housing before popping the small round cover off the underside of the bell housing, and through that hole, we found engine oil puddled in there, pointing to a rear main seal. We would attack that first, proposing the rear main, a torque converter seal and an oil pan gasket just for grins, since GM was kind enough to put a crossmember under the oil pan and make that part of it an easy fix.

My guys plowed into that one, and we were extremely happy it wasn’t one of those later model GM platforms with the stainless steel exhaust fasteners. Whoever came up with that idea should be chastised harshly. You can’t cut those stainless nuts with a torch and heating them doesn’t help either. But I digress.

The Explorer

This 2008 Explorer had been in who knows how many times for oil changes. The instructor who drives it makes a 120-mile round trip to work and back, and once a couple of years ago she came in with a bad engine vibration due to a busted cooling fan and two full-grown dead cats lying in the bottom of the fan shroud.  On another trip, the pulley ring of her harmonic balancer had slipped back toward the engine so that the belt was riding on the naked rubber part of the balancer, and the crank sensor was being machined away by the misplaced pulley. We saw two of those slipped 4.0L balancer failures that same week and haven’t seen another one since.

This 2008 Explorer had been the equivalent of 10 trips around the world before the spark plugs were finally replaced, but it still ran like a champ.

On a humorous note, we decided on one trip to check the fuel filter on the Explorer, which was almost completely blocked. I used that for an object lesson as to why it’s always a good idea to check the fuel filter on a high-mileage vehicle. There was a time when Ford required the filter replaced every 15K on trucks. Later when I was changing the oil on my 2007 Taurus I decided to check the fuel filter and it was just as bad as hers was.

On the last oil change, I suggested we have a look at her spark plugs and it turned out that they were the originals – with 238,000 accumulated miles, and this one was still running great with not so much as a flicker from the MIL. The plugs had the paint spot on the tip and on the way out they did that heavy-duty squeaking ancient spark plugs do when they’ve been in there forever. Furthermore, the business end of those plugs was textbook worthy.

The Suburban

About the time we got the transmission out of the Avalanche, a high-mileage 2004 Chevy Suburban came rolling in with an engine skip that turned out to be on cylinder 4. This one was blessed with the trusty old 5.3L, which I like because of the camshaft-in-the block, but even without the overhead cams and all those nylon sliders and tensioners, this engine isn’t without its problems. Camshaft lobes wear down and head gaskets blow. When we pulled the plug out of the misfiring cylinder, there was a piece of ceramic that had been cracked and shucked off the center electrode sheath by some catastrophic mechanical event (that according to the Denso chart anyway), and that cylinder had no compression. A cylinder leakage test fingered the exhaust valve, and I wondered if that chipped-off piece of ceramic might be stuck in some valve carbon holding the valve open, but it would seem to have been hammered to bits and spit out the back, because that’s what usually happens.

We won’t know until later this summer what happened on the 2004 Suburban to cause this, but the cylinder it came from has almost no compression at all, and since the mileage is so high we’ll probably stuff an engine in it.

The prevailing question I had was what had caused the spark plug’s ceramic to fail in the first place. Were there detonation or preignition events that cracked and damaged it or what? They had to go on a trip and opted to drive it that way, but in the coming month we’ll stuff an engine in that one – the cool thing is that we can upgrade to a 6.0L if we want to because the 4.8L, 5.3L, and 6.0L are plug-and-play engines.

The ’98 F-150

One of my colleagues owns an F-150 he inherited from a relative, and we got one of those laundry list requests – the fuel economy had dropped off, the passenger side power window wouldn’t work, the transmission needed servicing, the intermittent wipers were intermittent, and, of all things, the Check Engine light didn’t work – and he wanted all of it fixed. A lot of people “fix” the MIL by covering it with a picture of somebody or by installing a piece of tape blocking the view of it, but this one had a breach in the wire between pin 2 on the PCM and pin 13 on the bulkhead connector, so we did an overlay on that one and brought the MIL back to life. Several of my people worked on that problem because it was a great troubleshooting and repair exercise in electrical systems, and it was a bug I didn’t plant.

This ’98 F150 had a laundry list of issues, the least likely of which was the inoperative check engine light.  We ran an overlay between the PCM connector and this bulkhead connector and got the light back online.

For a truck this old, that re-operational MIL might be problematic, because now, if the truck had issues of which he had previously been oblivious, he’d be swinging by regularly to have those issues handled. After we replaced the spark plugs, the passenger-side window regulator, the PRNDL indicator and the Combination Switch, the truck had no starter operation, and we tracked that to the big C172 connector near the battery – one of the students had begun disconnecting that connector, gotten side tracked, and left it that way. In the end, that F-150 rolled out with no codes and no illuminated MIL, which was something of a surprise on such a high miler.

The hunting truck and a Nissan

The Toyota pickup on which we had used head gasket sealer came back in for a timing belt and a water pump – it still wasn’t leaking coolant any more, not even from the water pump, but the bearings in the pump were rattling, and so we stripped it down and did the kit thing – belt, idler, tensioner, water pump, etc. After we filled it with coolant and fired it up to do the final burp-out, I saw coolant leaking from the rear of the engine and discovered a head gasket breach that was trickling coolant down the bell housing. Whether he’ll want to redo the head gasket sealer or replace the head gasket remains out with the jury, but he opted to take the truck and use it for a while, keeping a check on the coolant level. His prerogative, I suppose.

The Toyota hunting truck revealed this leak after we did a water pump and a timing belt.  It was a tough shot to get, but in the real world you can see coolant trickling from under the right cylinder head. This stain told the tale.

Then there was the 2000 Nissan Frontier with an A/C belt squeak after a few minutes of at-idle A/C operation. This was condenser airflow-related because the head pressure started out normal and slowly climbed until the compressor had to struggle. Checking for radiator and condenser fin blockage, we rinsed them out with soap for good measure but to no avail. When we put a fan in front of the condenser blowing through it, the pressures normalized, and when we tested the fan clutch by heating the bimetal spring, it never got any stiffer, so we fixed that one with a fan clutch.

At first the only thing we saw in the power steering area was this tantalizing drip (left photo) but as we ran it for a while we began to see power steering fluid dripping from between the master cylinder and the Hydroboost unit – and so it got one of those.

Finishing up the Avalanche

The power steering leak on the Avalanche was the last thing we tackled on that one. It wasn’t leaking from the pressure hose as we had figured. It was dripping fluid from the hydroboost unit, and so it’d need one of those babies to close out that job. We got one from the parts store, swapped it out, refilled everything, used the vacuum bleed cap I built to purge the air, I charged out the parts, and we put that one on the yard. Oh, yeah, we polished the headlights on that one too, and the whole truck looked better. “It’s the little things,” as one customer told us. We do what we can to breathe new life into those high milers, and it felt good to be done with another one.

Sponsored Recommendations

Best Body Shop and the 360-Degree-Concept

Spanesi ‘360-Degree-Concept’ Enables Kansas Body Shop to Complete High-Quality Repairs

ADAS Applications: What They Are & What They Do

Learn how ADAS utilizes sensors such as radar, sonar, lidar and cameras to perceive the world around the vehicle, and either provide critical information to the driver or take...

Banking on Bigger Profits with a Heavy-Duty Truck Paint Booth

The addition of a heavy-duty paint booth for oversized trucks & vehicles can open the door to new or expanded service opportunities.

Boosting Your Shop's Bottom Line with an Extended Height Paint Booths

Discover how the investment in an extended-height paint booth is a game-changer for most collision shops with this Free Guide.