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When I bought my ’83 Volvo 245 back in 1998, over a 100,000 miles ago, it seemed to have a kind of hitch in its gitalong. I took it back to the guy who sold me the car, who was also the mechanic for most or all of its existence. He made several upgrades, but the problem still existed; he finally told me that “some cars from this year just have that problem.”
Last winter I took the car in for a 30K service as well as a new timing belt. When I got the car back, it ran far worse than it had before. The hitch in its gitalong, which had never gone away, now seemed much worse. The mechanic (let’s call him M1) had put a gas treatment in the tank and I filled the tank. I didn’t refill the tank for several weeks, and just charged up the bad running to the gas treatment. When the car continued to run badly and now began to overheat, I brought it back to M1 and was told that the compression was over 190 in each cylinder. Their theory was that carbon deposits in the cylinders was raising the compression, causing preignition, which caused both the overheating and the bad running. They recommended I use some Marvel’s Mystery Oil and drive the car awhile.
I certainly did that. I drove from Colorado to Vermont by way of Memphis, using high test fuel and adding the Mystery Oil in every tank. No change. If anything, the bad running and overheating had both gotten worse. So, before heading west again, I consulted another Volvo mechanic in Vermont. They found a spark plug wire that wasn’t working and replaced it, as well as setting the timing up to 12 degrees BTDC instead of 10, in accordance with the info printed in the engine compartment. They also tried putting in a new air-flow sensor, but, while the car ran better because of the plug wire, it still had the hitch. They were stumped.
So I drove west, back to Colorado. When I got to Michigan, I decided to try something I’d been thinking about the whole way: If the problem was preignition, why not just advance the timing? So I carefully marked the spot where the distributor cap sits on the distributor so I could go back to 12 degrees if I needed to, loosened the bolt that secures the distributor, and turned the distributor to advance the timing. Unfortunately, as you may have noticed, what I needed to mark was where the distributor meets the engine body, so I couldn’t reset it. I got in the car, fired it up, and it ran great! The hesitation completely disappeared, the car had more power, and started getting about 32 miles to the gallon. True, it pinged on acceleration, but otherwise it started and ran great.
So recently I brought it back to M1 for an unrelated problem, but asked them to check the timing and compression. They still found the compression in the 190s and the timing was set at 28 degrees. They warned me that the pinging was destructive to the engine and reset it to 15 degrees. The car immediately went back to its old hesitation thing and my mileage fell from 32 to about 25 mpg. The car continued to overheat.
So I found Mechanic #2. He sold me the gas treatment 44K, which is designed to reduce carbon deposits. It made a significant difference, but the car still overheated and hesitated. So I had him check the radiator, which was plugged. He installed a new one and the overheating has disappeared completely. He tested the compression and found 130 across all four cylinders. The hesitation and bad gas mileage continue. So I think we can rule out the preignition theory. M2’s theory is that the fuel injectors are old and worn, which they undoubtedly are.
But the question is: Why would my advancing the timing have made the car run better, with more power and efficiency? That wouldn’t happen if the injectors were worn. Also, and this may be the more important question, why would this problem be so consistent for so long? If it’s the sign of something wearing out, wouldn’t it keep getting worse? And why would the designers of the engine make it run worse and with less effiency at the nominal timing? Could the timing belt be installed not only incorrectly but consistently incorrectly for the whole time I’ve owned the car?
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