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Automania/Repair and Maintenance
AUTO QUESTIONS AND ANSWERS FOR WEEK 14
by Bob Hagin
Q. I bought a very clean and well maintained 1983 Toyota 4X4 pickup truck with a 22R engine, five-speed transmission and 101,000 miles on the clock. When I first drove the truck, I noticed that it had a vibration that felt like a tire out of balance but the owner told me that the transmission would soon need work. I bought it and had the transmission replaced but forgot to tell them to replace the clutch assembly so they only replaced the throw-out bearing along with the gearbox. The new transmission works well but it still has the vibration. I've checked with several shops to see of the vibration could be caused by a misaligned flywheel or an out-of-balance clutch and they all said it was not too likely. I also tried to find out if the flywheel could have been put on in such a position that it could be out of sync with the original factory balancing. The vibration occurs even when the car is parked and the engine is revved up with the transmission in neutral.
A. My personal rule of thumb is to never pull a transmission without at least removing the clutch to check for faulty or worn out parts, especially if there's a problem with vibration. Since labor is very expensive, it's false economy to not spend the extra half hour to check it out. Too many other things could be wrong such as mismatched or missing crankshaft and/or clutch bolts or missing alignment dowels all of which could affect engine operating balance. The flywheel can be put on in several rotational positions and must be marked before removal to make sure it goes back together in the same location. Your best bet it to pull the box, clutch and flywheel, rebalance the flywheel and install a new clutch assembly. At 100,000 miles, you can't be sure of what repairs were done without having the complete service history.
Q. I have a question regarding the use of snow tires as a year-around thing. As long as snow tires are grooved so as to channel away water and prevent hydroplaning, is there anything wrong with using snow tires all year long?
A. I always like to bring in experts on questions like this so I called the PR folks at Bridgestone. I was told that snow tires have a softer compound than general-purpose or even all-weather tires so they will wear out much faster. Having deeper grooving will also reduce the cornering power of a snow tire since the tread has more "squirm" to it on dry pavement. They tell me that a set of snow tires used exclusively in an area like yours will last about three winter season since the tread depth should not be allowed to diminish by much more than half in order to get the best "bite" in the snow. I asked them about noise but was told that modern snow tires don't make much noise on pavement.
Q. We have a nice, garage-kept 1983 Winnebago with a Chevrolet 454 cubic inch powerplant and a 4 KW Onan generator. Since the demise of leaded fuel we have been adding a lead substitute when we refuel but adding the lead substitute is inexact. The bottle says to use one bottle per 10 gallons of gasoline but we hardly ever refuel in increments of 10 gallons. We guess at it as best we can. Is the lead substitute necessary for either engine?
A. The best folks to consult on questions on the use of unleaded fuel are those that made the units. I'm sure that fuel requirements for both are in the owner's manuals that came with them. The use of tetraethyl lead in gasoline did two things: it raised the octane rating to prevent ping and knock on high compression engines and "cushioned" the valve-to-valve seat contact on engines with relatively soft valves and seats. Neither of your engines have these problems and un-leaded gas is available at 97 octane so you're safe in dropping the octane booster.
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