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Automania/Repair & Maintenance
Auto Questions And Answers For Week 46 Year 2001
by Bob Hagin
Q. I have a 1993 Plymouth Voyager with 89,000 miles, which I bought new. My problem is that the engine developed an external pinhole in the coolant system. I first thought that the drip was from the lower hose connection. I replaced it and the drip continued but it was coming from above the connection. I thought possibly it was from a freeze plug so I went to a garage where the mechanic pressurized the coolant system and exposed the pinhole. He put in a product to stop the leak and removed the thermostat. Is there an inexpensive permanent repair or must the block be replaced? Because the block eroded internally, will the hole increase in size? How long will the solution the mechanic put in my radiator hold and what is the downside with using this type of sealant?
A. I'd try anything before I'd go to the monumental expense of replacing the engine block. The downside of a sealant in the cooling system is that it can congeal in small passages like the tubes in the radiator. In the early days of motoring, mechanics would dump a little corn meal into a leaking system to seal it up. I don't think removing the thermostat will help except to keep the engine from heating up as fast. In the past, I've sealed up some pretty horrendous block, head and transmission case pinholes with what used to be called epoxy-steel. I'm pretty sure it's still available but the surrounding area had to be very clean and the stuff put on very quickly. If the hole came from internal corrosion rather than a casting flaw at the plant, you haven't checked or changed your antifreeze often enough.
Q. My 1991 Ford Explorer 4.0-liter with 139,000 miles has what the mechanics say is a lifter or tappet noise. This started at 100,000 miles. At 102,000 miles, I had a quick-oil-change shop do their fuel injector cleaning program. Six hundred dollars later, a Ford dealer got the car running again. I religiously change the oil every 3000 miles and have never had to add any between oil changes. Several different mechanics have put in oil additives. They all say it is not hurting anything. At 130,000 miles I decided that I did not like the noise and asked for a price to fix it. They came back with a price of $1100 since the twelve lifters have rollers and cost $67 each. At that price, I said we should look at a new engine but first to check cylinder compression. It came back in the 210 to 215 PSI range. It didn't need a new engine so now I just listen to the click. What do you think of the situation?
A. Lifter noise can be caused by a couple of things. In the case of a hydraulic lifter, the hydraulic mechanism can either collapse or it can become stuck in a low position. If it's simply got "stuff" or gum in it, a commercial auto chemical in the oil can often free it up. Obviously it didn't do that. Another problem can be that the camshaft lobes and/or the bottom of the cam followers wear and make noise. Ford had a lot of problems like your with its venerable 2.3-liter four cylinder engine some years back. If new camshaft followers (lifters) are installed on an old camshaft, the cam and followers sometimes fail prematurely since the original units tend to "lap" themselves together and mismatched new units fail. I'd go for a new cam and followers before I'd buy a new engine since I'm willing to bet a new motor is lots more than $1000.
Q. I read somewhere that motor oil can be filtered through a roll of toilet paper in a filter-holder and never needs to be replaced. Why don't auto makers put these filter into new cars?
A. Toilet paper oil filters work too well. The remove not only the usual impurities but modern oil additives as well. They are trickle-through units and can't hold up to engine oil pressure so they require a low-pressure "feed" and a gravity return to the oil sump.
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