Can this little engine still do it?

September 30, 2009 11:48 AM

My 1998 Mazda Protege is making a new noise, and I'm wondering what it might be and if it's a bad idea if I keep driving her.

I have a 1998 Mazda Protege (called Frances) with about 98K miles, automatic, and kept outside for the past ten years in various climates. She's been almost free of major mechanical issues and was inspected in February 2008.

I put less than 7,500 miles a year on the car, and during the last couple of times I've driven her, I've noticed a high-pitched noise when I'm pressing on the accelerator, specifically when the RPMs are around 2.5-2.75 regardless of the speed of my car at the time. When I take my foot off the accelerator, the noise stops. I haven't noticed any other problems with the performance of the car or changes in gas mileage.

The noise isn't a squeal, more like a high-pitched drone, an "extra effort" noise, but it's new. I normally drive alone, and I'm worried about it being something that might cause major damage if I keep driving Frances until I can get her checked out. I do have a mechanic I trust, but he's quite far from where I am, and I wouldn't be able to get the car in for a couple of weeks. Of course, I'd love to know if you have an idea about what this noise could be, but I'd also like to know if I'm taking an unacceptable risk in the meantime still driving her around on trips of 50 miles and less?

posted by gladly to travel & transportation (10 comments total)

When was the last time you changed the belts?
posted by torquemaniac at 11:54 AM on September 30

Could be bearings on any of the belt driven accessories, too.
posted by torquemaniac at 11:55 AM on September 30

high-pitched drone, an "extra effort" noise

Seconding torquemaniacs accesory/belt suggestion.

Could also be an exhaust leak.

Just making sure, but your check engine light isn't on, is it?
posted by Jon-o at 12:14 PM on September 30

I can't remember the last time I changed belts. I know one's been changed, probably in either February 2006 or February 2007 (all my maintenance happens at inspection time). Unfortunately, I can't remember which one was changed, and I'm not near my maintenance records. My check engine light is not on.
posted by gladly at 12:22 PM on September 30

Belts, tensioner, wheel bearings, etc. It could be a lot of things, many of which will leave you stranded. I vote getting it checked out sooner than later.
posted by damn dirty ape at 12:35 PM on September 30

I'd also say check the alternator and battery (not urgent); I can see this noise being an electrical one, from a voltage regulator (built into the alternator on your car, and most cars these days) getting near end-of-life.
posted by davejay at 12:35 PM on September 30

Could also be a vacuum leak.
posted by luckypozzo at 1:02 PM on September 30

Check your transmission seals.
posted by C17H19NO3 at 2:26 PM on September 30

Scratch what I said above.

This sounds like an issue I had before. Is is a howling sound? When you say it stops when you let off the accelerator, I'm thinking the issue is with your transmission.

From here:

Automatic transmissions make specific noises when a malfunction occurs. An automatic transmission is a hydraulic pressure driven system and it can make different noises than a manual transmission. If the transmission filter becomes plugged due to debris, it can make a howling noise. If the fluid level is low, you might hear a gurgling sound, caused by the pump scavenging fluid inside the transmission pan. Most internal failures are due to bearing, clutch or hard part failure. When such a failure occurs the transmission can make grinding, howling sounds or no noise at all. When a transmission has a major failure you might hear a loud pop which could mean a drive component inside the transmission has failed and the car will stop moving.

Anytime you here an automatic transmission noise inspect the fluid level by starting the car on level ground and allow the engine it idle. Next remove the fluid level dipstick and using a shop or paper towel to whip the stick clean. Reinsert the stick completely and remove it it inspect the fluid level. Add fluid as needed, also inspect the fluid condition, it should be a clear pink or red color with a normal hydraulic oil odor. If the fluid condition is dark and has a pungent smell it probably means the transmission is having a problem and needs to be rebuilt or replaced. If the transmission filter is plugged it can also cause a howling noise as the pump is fighting to pull fluid through it. To check for this condition remove the transmission oil pan and inspect the filter condition and replace if needed. Some transmissions have no fluid level dip stick, these vehicles require replacement whenever a transmission malfunction occurs.


posted by C17H19NO3 at 2:35 PM on September 30

Next remove the fluid level dipstick

Make sure you are doing this with the transmission fluid dipstick, not the crankcase oil dipstick, which is usually the more obvious one to find.
posted by intermod at 7:10 PM on September 30