Cruisers that won’t cruise smoothly

Sometimes an existing vehicle that was produced originally with a sensibly sized engine compartment gets a powertrain upgrade that fills that engine compartment to the max.  One example of this would be when Ford decided to cram the Duratec V6 in the same place where that tidy little Vulcan Y block fit so well.  Granted, the Duratec has been a lasting engine design that runs like a champ, but it appropriates every available cubic inch of space in the powertrain compartment of the second generation Taurus.

The PT Cruiser and the VW Beetle are pretty much the same way, even equipped with their four bangers, and when you shoe-horn a Turbocharger in there, it makes things even tighter.

Retro vehicles became a hot item about 15 years ago, with cars like Ford’s reintroduction of the Thunderbird, the rebirth of the VW Beetle, the limited edition Plymouth Prowler, Chevy’s HHR, Dodge’s Challenger, Chevy’s Camaro and the venerable little PT Cruiser, which has been just about as popular as the Beetle.

This story is centered on a PT Cruiser that came to us from a regular customer who has owned several of these curvy little rides.  We’ve done everything from timing belts to radiator cooling fans to transaxles on PT Cruisers for these folks. This time, the problems the PT had were not so cut and dried, and the last thing I want to do is dump a bunch of high dollar work into a vehicle before I know for sure what’s needed.

Honeymoon Purchase
The son of a retired colleague of mine had purchased this clean little convertible PT while he was on a honeymoon trip with his new wife in Florida. They had been driving the car around for about five days sightseeing when it sprang a coolant leak, so they visited a shop down in Florida. They were told the engine oil pan would need to be replaced at a cost of $500, and the oil had been drained from the pan – the car had been driven in for service, and now, because of the oil pan problem, it was wrecker fodder.  This young owner was somewhat disillusioned as to how a coolant leak on a vehicle he had been driving for several days could morph into a $500 oil pan replacement. He placed a call to Mom and Dad, who took a trailer and spent 16 hours or so retrieving the Cruiser, which wound up in one of my service bays.

The first thing I noticed when I got it on the lift was a short ¾-inch coolant hose that had been replaced along with the new clamps. It seemed to me that during that hose repair the shop had noticed that the engine oil pan was sporting a rubber drain plug, which they might have dislodged while replacing that kind of hard-to-get to hose.  When they saw that the threads in that aluminum pan had been stripped out, they priced out an oil pan and the labor to replace it.  And, to be honest, I can sort of understand what they were thinking.  In this litigious society of ours, the last thing they wanted was for a customer to get a few miles down the road after their repair to have that rubber plug pop out and weld the engine together.  So they priced out the oil pan to protect themselves as well as the customer. That being said, a traveling customer will usually balk at a $500 estimate under circumstances of this kind. In other words, the shop didn’t actually do anything wrong, but when a customer goes in for a coolant leak and gets an estimate like that, especially when they’re eight hours south of home, they aren’t likely to pony up with half a grand to pay for something they aren’t sure about with the kind of family lifeline that was available.

In my service bay, the first order of business for us was to decide what could be done short of replacing the oil pan, and I’ve fixed problems like this before by installing one of those steel spark plug bushings and a 14 mm 1.25 thread pitch drain plug.  Usually, that is a permanent repair that works very well on an aluminum oil pan, but in this case, I made the mistake of having an inexperienced student operate the thread tap, and he didn’t understand the physics of turning a tap on its axis rather than recklessly yanking on it while cutting those new threads. Thus he made a mess of what would have otherwise been a flawless repair. Now the hole was too big for my original plan. This goes under the heading of “Why Teachers Get Gray.”

I called the parts store and ordered an 18 mm drain plug with the same thread pitch as an oxygen sensor, but that parts store couldn’t get a thread tap without my having to wait five days for it.

The next day, I took my own doggone thread tap to the shop from home (every mechanic should have one of these to fix the threads in O2 sensor holes), and I used it to bring that hole out to 18 mm. I then installed the drain plug for a good, solid repair, complete with a new oil filter and fresh oil.  We also noticed that, even with the engine idling, the oil light was on all the time, and they hadn’t complained about that, but I ordered a replacement sensor and the light was extinguished.  Problems solved, right?

Many Happy Returns
The son who owns this car lives about 100 miles to the north, and so, before delivering it to him, they drove it around for a few days and found that, while it ran cool most of the time, it would sometimes run warmer than others, i.e., a bit too far above the center of the gauge for their comfort.  I asked if the warmer times were happening in traffic or at the drive-thru, and they said they had noticed it on the highway but not in town. We did the cheap and easy and popped a new thermostat in, re-bled everything, made sure it was full of coolant, and sent them on their way again.

They drove it a few more days without incident, then headed off to the north to deliver it.  They spent a day or so up there while their son drove it around (they’re retired), and he made an 80 mph interstate run to another city, and on that trip he experienced some mild overheating, along with a flickering oil light.  And so the PT returned to us again. To begin, we replaced the oil sending unit again, swapping the original one out as defective, but not before checking to see what the actual oil pressure was. Even with the engine toasty warm and idling, the actual pressure was a comfortable 30 psi.

The block was full of coolant, and even had the right level in the surge bottle, but we pressure-tested and double-checked everything. The fan was fine (no dark commutator segments during my roulette test, and it kicked off and on), and the engine temperature the whole time we were checking it and driving it. I reasoned with the customer that, since this one is a turbo, driving it at 80 might push some compression past the head gasket into the water jacket under extreme conditions, especially since the problem doesn’t happen at 65 mph but does happen at 80-plus mph.  My suggestion was that they drive it around for a few days to see if they could duplicate the problem at normal speeds, because we couldn’t, and I don’t drive 80 mph on any customer’s car. They agreed and planned to keep a close check on the coolant level, noticing any other patterns that might emerge.

In-Between Jobs
In the meantime, these same folks brought a 1997 Chevy Van with an A/C leak, and when we applied dye with the refrigerant charge, ran it for awhile and shot it with the black light, the compressor lit up like it was radioactive.  That one got a compressor, a new orifice, an accumulator and a gaggle of new O-rings. While the front registers were shoving artic air into those two seats, the rear unit still wasn’t cooling. It  probably needed an expansion valve and some flushing, but they needed to use the van, so we would address that when we were done with the PTs and they had time to release the van for awhile.

Another interesting vehicle we took in was a 2010 Diesel Jetta with 9,000 miles on it that belonged to an electronics engineer. He had driven the car into a deep ditch of water a couple of years earlier and it hadn’t started since. The car looks brand knew – it didn’t look like it had been wet inside – the carpet was pristine and there was no mud anywhere, but then, the car had been sitting in his yard for two years as a no-start. The interesting thing about this one was that he had replaced every controller he could get to with salvage yard units, and he had removed the radio because it had been wet as well. 

What that meant to me was that the Jetta had been chest deep to the driver on the inside of the car, usually the kiss of death for all manner of electronics.  Nothing would talk to the J2534 flasher or any scan tool, and when I called Joey Henrich at AE tools, he told me that nothing would talk on that Jetta unless a factory radio was installed. Further, if an aftermarket unit was installed, the scan tool would be fried as soon as it was connected.  I sent the Jetta’s owner in search of a replacement OEM radio, and that job wound up on hold.  We also had a percolating Caravan because of a Chinese radiator (see illustration) and a wire harness issue on a 2000 Ranger that had disabled the A/C.

Another ‘Happy’ Return
The next happy return on the PT happened when they discovered the coolant was low in the surge bottle, and when they tried to add coolant to bring it to the line, it went straight to the pavement – fingering a brand new breach in the surge bottle. Further, they had seen the oil light flickering again, and this was getting peculiar enough that I was wondering if the oil sending unit wire was shorted to ground, but we couldn’t locate a short. I did notice in passing, however, that disconnecting the unit seemed to cause that light to illuminate (sometimes), which makes normal diagnosis of a circuit like this kind of troublesome and misleading. That led to an Identifix search, which revealed that quite a few shops had seen flickering oil lights because of aftermarket oil pressure switches on Cruisers. Because we had to order a surge tank to replace the newly cracked one on that PT, we snagged a $25 oil pressure sender from Chrysler on the same order and swapped that pressure switch out again.

Then came the other PT Cruiser these folks own, this one a 2002 model hard top and they reported that they’d had to add over a gallon of coolant because it had tried to run hot like the 2005 Convertible had. But pressure test as we might, we couldn’t locate any leaks, and the cooling system was full, as was the surge bottle on that one.  I asked them about the last time anybody had checked the coolant and they couldn’t remember – said it had been months.  My prognosis was that it was probably seeping into one or more cylinders and making its way out the tailpipe over time. If coolant is leaving and there is no leak, that’s the only answer that makes sense.

Explanations and Scheduling
That postulation of mine led them to ask how the problem they were having with this PT differed from the other one, and so I shifted into teaching mode, and my answer was that the other one had a turbocharged engine and only overheated at high speeds. That would be, according to my hypothesis, a migration of the fire from the power stroke on at least one hole shoving heat past a compromised head gasket into the coolant.

This 2002 PT, however, was a different story. It would be seeping coolant into the cylinders rather than letting compression pass in the other direction. Just about engine guy has dealt with both these types of head gasket failures, but coolant migration into the combustion chamber with the engine running has always seemed counter-intuitive to me simply because of the pressure differential between the coolant passages and the combustion chamber.  My notion is that most of the coolant migration takes place as the engine is cooling, but that generally causes issues on cold startup, and sometimes they don’t have that kind of symptom even though coolant is being swallowed by the combustion chambers.

We ended that conversation with the agreement that they would monitor the 2002 Cruiser to gauge the rate at which the coolant was leaving, and that they would monitor the 2005 PT for overheating at normal speeds.  One way or another, both of those cruisers will probably need head gaskets, but that won’t happen until this fall, because the semester was at an end. Sometimes I have to kick the can down the

 road until the time is right, and both of these Cruisers can cruise until it’s time to do the work.