Miata Whine of doom: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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July 14, 2010 3:23 p.m. Capt Slow HalfDork

So on my drive home from work last night I notice the miata started to develop a whine. 1) The whine varies with engine speed

2) Clutch position does not seem to affect the whine

3) It only whines when the engine is warmed up

4) After popping the hood and looking at it for a bit, it seems that the whining is coming from the timing belt area.

5) I just had the timing belt, tensioners, and Cam angle sensor seals changed 2 weeks ago.

I am thinking there was a fault with the timing belt installation or a faulty part has reared its head. Am I right? Is there anything else I can check before I drag it back to the mechanic and ask him to look at it?

I would do it myself but I need to have it up and running sunday, and I am out of time....
July 14, 2010 3:51 p.m. Powar Dork

Sounds like the same noise a faulty replacement water pump made when we put it on a friends '91 during a timing belt service.
July 14, 2010 4:00 p.m. MrJoshua SuperDork

Keith mentioned one of the covers not being seated in its tab will cause it to rub.
July 14, 2010 4:11 p.m. Strizzo SuperDork

have you ruled out power steering pump or alternator?
July 14, 2010 5:06 p.m. Capt Slow HalfDork

I have not ruled out the alternator, though it didn't really sound like it was the alternator when I was reving the engine with the hood popped.

I don't think it the power steering pump since it tone and volume of the whine does not change when I move the steering wheel.

I did have the water pump replaced when the timing belt was replaced, due to the recent repairs I figure its probably one of the new parts gone bad.

I will take a closer look at the covers when I get home, I expect that there would be a visible gap there if its not seated properly?
July 14, 2010 10:12 p.m. Keith SuperDork

Easy enough to tell if it's the accessories - just pull the belts off for a moment :) You won't be spinning the water pump so don't do it for a LONG time, but it shouldn't take very long to figure out if the noise is gone.

If it's the covers, you'll be able to see they're leaned up against something. The biggest culprit is the upper one right behind the water pump pulley. If it's touching, you'll see it. It may not be the problem, but it's easy to check.

More likely its a problem with a bad pulley or incorrect timing belt tension. I'd be amazed if the alternator or water pump just coincidentally threw in the towel right after the other work was done.
July 14, 2010 10:40 p.m. Capt Slow HalfDork

I will try that... The water pump is brand spanking new, So I would be very surprised if that was it...
July 14, 2010 11:08 p.m. Keith SuperDork

Sorry, I meant PS pump. But when something goes wrong right after you do some work, you always go back to what you just did...
July 15, 2010 12:25 p.m. Capt Slow HalfDork

Took it by the mechanic's on the way into work this morning and had him listen too it. He told me that it was the belt was still breaking in and not to worry too much.

If the car had always whined I would like it is now it wouldn't have bothered me, I just don't like it suddenly getting louder.

I guess I should take solace in the fact that it is a non-interference engine...
July 15, 2010 12:40 p.m. Junkyard_Dog HalfDork

Capt Slow wrote:

Took it by the mechanic's on the way into work this morning and had him listen too it. He told me that it was the belt was still breaking in and not to worry too much.

Time to find another mechanic!
July 15, 2010 1:10 p.m. Capt Slow HalfDork

I am going to keep driving on it, it it gets worse I will tear into myself. Like I should have done in the first place.

The autocross season is so packed during the summer I hate taking a weekend off to work on my DD.
July 15, 2010 1:50 p.m. Powar Dork

Timing belt breaking in? What the berkeley?
July 15, 2010 2:07 p.m. motomoron Reader

Mine did that immediately after a T-belt / idler / tensioner / water pump / VC gasket replacement.

I removed the accy' belts to isolate the T belt and it still did it.

I adjusted the T-belt tension based on the book instructions - and didn't add tension to achieve the 9-11mm deflection @ 10kg pressure between the sprockets - and the noise was lessened.

I left it that way.
July 15, 2010 9:01 p.m. Keith SuperDork

You can adjust the tension without having to disassemble much. Pull of the valve cover and the upper timing belt cover, then slide a 14mm wrench down under the lower cover to loosen the tensioner bolt. Using the timing mark on the accessory pulley to set the engine to TDC (T on the timing scale) and the proper tensioning location (timing mark at 12 o'clock, there's a boss on the timing belt cover to indicate it). Takes just a couple of minutes. I've never had to do anything but use the factory tensioner to get it right.