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Automania/Repair & Maintenance
AUTO QUESTIONS AND ANSWERS FOR WEEK 13 YEAR 2000
by Bob Hagin
Q. I recently purchased a used 1992 Mazda MPV van from a local Mazda dealer. It had 100,000 miles on it and I have added about 1000 miles since I bought it. The dealership gave it a three-month, 3000 mile powertrain warranty, the same one they put on all their used vehicles. Whenever I start it cold, the engine ticks with a sound like a sticky valve lifter. It goes away after the engine warms up. I have checked the oil all along and it doesn't use any at all. I talked to the dealer and was told that it was normal for Mazdas and that there was nothing to worry about. It is not a really loud sound but definitely noticeable. Is this sound normal?
A. You don't mention what engine is in your Mazda but two were available on the MPV in '92. One was a 2.2 liter four-cylinder but with this engine the van was very underpowered. Most buyers opted for the 3.0-liter V6 which I assume is in your van. We tested a new MPV recently and noticed no "ticking" coming from the engine either cold or hot. The V6 engine in your van had lots of problems, although I think they mostly had to do with the cylinder head gaskets. If your cold-run noise sounds like a single sticking valve rather than all of them, I suspect that you're right in your assumption, although it could also be piston slap which would also go away as the engine warms up. It would be a good idea to take your van to an independent shop for analysis. A technician should be able to pinpoint your problem using a stethoscope but he'll need to check it cold so you'll probably have to leave it overnight.
Q. My 1989 Mitsubishi pickup loses power on hills. On even slight inclines on the highway it will drop down to a lower gear as I try to maintain 55 MPH. On steeper hills at 35 MPH and on highway arterials, it refuses to go to a lower gear and instead it will gradually slow down. If I jiggle the accelerator, I do get a limited response and eventually it will drop down to a lower gear but I'm still unable to get the performance I had in the past. Does this sound like a carburetor problem? My auto mechanic thinks that it is. I would like another opinion before I spend $1200 for a rebuilt carb. The fuel pump has been replaced with no improvement. The 2.6-liter engine has 76,000 miles.
A. The carburetor on your truck is a two-barrel, two-stage unit which means that the secondary barrel doesn't come into action until the engine needs the extra fuel for additional power. In some cases, the second stage throttle is activated mechanically by nailing the accelerator pedal. In others, it's vacuum-operated by venturi vacuum when the engine load increases. Your mechanic can get a pretty good idea of its action on the shop floor by working the throttle by hand with the air cleaner off and the engine shut down. If it's vacuum operated, he can use a hand-operated vacuum pump to activate it and then check the vacuum source. If the secondary side is working, its possible that the exhaust system is plugged and the more fuel you dump into it on a grade, the harder is for the exhaust gas to get out and the engine slows down.
Q. I'm just beginning to rebuild the 330 V8 engine on my '67 Olds Cutlass Supreme. It's going to be my hobby car rather than my go-to-work car. Among other things, I want to replace the camshaft with a hotter one. I took out the valve lifters and they looked OK but I wonder if I should replace them too.
A. Cam followers "bed" themselves into the camshaft lobe they ride on. A new cam requires new lifters or they both may quickly wear out. This can also happen if old lifters are removed and reinstalled on the same cam but on different lobes. Buy as much new stuff as you can afford.
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