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Automania/Repair & Maintenance
AUTO QUESTIONS AND ANSWERS FOR WEEK 30
by Bob Hagin
Q. I have a 1988 Ford F-150 with a 302 engine. Presently the odometer is at 162,000 miles. At 137,000 miles I had the truck serviced to change the water pump and the technician recommended that a new timing chain be installed. I had it done but shortly thereafter I noticed some pinging or spark knocking. In the next year, I had the timing checked and set on two different occasions. The spark knock is minimal now and I only hear it when I give it full throttle. I know it can't be good for the engine. I've been using one particular brand of gas lately and get the best results with it. I talked to a Ford service manager and she said that my truck was designed to run on 87 octane gas and because I had been using 93 octane, there is probably a residue build-up on top of the pistons and other engine parts. She suggested I stay with the higher octane gas.
A. Check to make sure that the advance on your ignition system isn't advancing too far. Clean the timing marks really well and then check the initial timing (engine idling, vacuum lines disconnected). Then begin to run up the RPMs. The timing should advance more and cease at a predetermined number of degrees. With the engine still at this higher RPM, reattach the vacuum lines and check the timing marks. It should read a little higher again. On an engine with that many miles, there could be other problems like the vibration damper on which the timing marks are located coming apart or the distributor being reinstalled incorrectly. There are methods of cleaning carbon from cylinders without removing the heads, but you can't pour a water/brake fluid mix down the air intake anymore for fear of damaging the engine management system. It takes sophisticated shop equipment or a valve job to do it right.
Q. I recently bought a 1973 Datsun 240Z. It runs but is badly in need of some major engine work. Is there a repair manual I can buy that would give step-by-step instructions on how to overhaul this engine and the transmission? I've never done any repairs on autos but I can usually figure things out if I have a book that explains what to do.
A. One of the main problems in doing a major repair at home is a lack of the right tools to do the job and a covered area to operate in. An engine rebuild can be a big undertaking for a pro much less a neophyte so you'll need a car port at the very least and hope for dry weather. The lack of tools may be the biggest problem since professionals use a tool box that contains thousands of dollars in hand tools they've acquired over the years. There's a "how-to" book on almost every subject but most assume a basis of common knowledge. A book on cooking assumes that the cook knows his way around the kitchen and most auto overhaul manuals assume that the mechanic has had some experience in doing major work on vehicles. Even basic tools are expensive and if you buy cheap ones, you'll wind up breaking them and skinning your knuckles. Most auto parts stores sell shop manuals published by Haynes Publications, Chilton Manuals and several others. But don't buy one that covers a bunch of different makes and models. They're too general and tell you enough to get into trouble but not enough to get out.
Q. Our '94 Dodge Ram 4X4 pickup with an automatic transmission has a ringing noise coming from underneath when I'm accelerating at around 30 MPH. I've checked under the truck and can't find anything loose.
A. According to a recent factory bulletin, the problem is in the driveshaft of certain models built in '94 and '95. The recommended cure is to replace the entire driveshaft with one of a later design. There's some other minor parts that have to be replaced along with it but check with a Dodge dealer first. I may be covered under your warranty.
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