Whining under acceleration

[BonzoG]

Seems my '5 has developed a new noise in the past week or so. In any gear between 5-7k rpm with foot to the floor, there's a very loud high-pitched whining noise. It doesn't happen on the overrun with foot off the throttle, regardless of revs or road speed. Only between 5-7k, under load, and with foot to the floor. I can't pinpoint exactly where it's coming from. Gearbox oil and diff oils were changed 5k miles ago.

I know the details are a bit vague, but any thoughts? It does sound as if something is being chewed to bits!

[PaulHogan]

Have you thought of leaving the O/H at home?

[Digby]

Does it do it with the air con on and off?
Belts possibly or tensioner maybe?

Also just found this with a bit of googling..

"If it does it only when it's in gear. It is probably the counter-shaft bearing in the tranny. All of the gears except 4th run off of the counter-shaft, so if it does not make the sound in 4th gear, bingo. Mine was doing it like crazy, & I had replaced everything from the diff to the timing pulleys. I just happened to catch a thread talking about this problem. Apparently it's a common problem in Mazda transmissions, even Rx-7's. I just replaced my tranny a couple of weeks ago and guess what, no whine"

Edited by Digby on Sunday 5th September 00:14

[BonzoG]

PaulHogan said:

Have you thought of leaving the O/H at home?

My MX-5 appears to have had thus far a repulsive effect on the fairer sex...

The thought did cross my mind, maybe it's not the car, but that's my excuse and I'm sticking to it!

Digby said:

Does it do it with the air con on and off?
Belts possibly or tensioner maybe?

Not got aircon, but my alternator pulley did look a bit grotty when I last changed alt + PAS belts. Has been fine since though and is still well tensioned.

Google said:

...if it does not make the sound in 4th gear, bingo.

Unfortunately it does make the noise in 4th gear. Havn't tried 5th by virtue of wanting to keep a clean licence.

[y282]

how long ago was the cambelt done? early tensioner failure can lead to the belt being overtensioned on one side of the engine which will result in failure.

i say this as i have one sat on my driveway atm with this exact problem. sound prior to it failing was this and the miata-king yank fellow on the interweb described it as exactly the same.

thank fk for non interference engines.

[BonzoG]

Now that's a good question! One of the perils of buying a car with no history is that I had to take the sellers word that the belt was done at 65k. Given the other maintenance related niggles that have cropped up, I wouldn't be surprised if that was a load of twaddle.

It's coming up to 117k now, so I'd been planning on having the belt changed shortly anyways. I'll change that to "sooner rather than later" and let you know if it cures it...

[y282]

order it all from mx5parts.co.uk, they do a kit with all belts and tensioners. do the water pump at the same time.

it's an easy job, but long winded.

[BonzoG]

Good news - job jobbed, timing belt + pulleys + water pump changed, frankly amazed I didn't cock it up completely.

Bad news - noise still there!

Nothing's fallen off yet and the gearchange feels no different, but as soon as I get the chance (and get paid ) I'll ditch the castrol syntrax & diff stuff for some Redline and see if that makes any difference. Beyond gearbox/driveline, I'm stumped as to what the noise could be.

[anonymous-user]

Sorry to go off topic but did you ever get your sills done Bonzo? I'm sure I read in a previous thread you were getting them done in the Glasgow area, I was reading with interest as I too have a mk.1 in the same colour as yours that needs 1 sill doing, so would be interested in some feedback (and photos!), details of where, costs etc!

[MX-5 Lazza]

Did you change the other belts at the same time?

[BonzoG]

yellowbentines said:

Sorry to go off topic but did you ever get your sills done Bonzo? I'm sure I read in a previous thread you were getting them done in the Glasgow area, I was reading with interest as I too have a mk.1 in the same colour as yours that needs 1 sill doing, so would be interested in some feedback (and photos!), details of where, costs etc!

I had both sills done earlier this year by Classic Coachworks in Wishaw. They welded in repair panels for the outer sections and fabricated their own inner sections, and did a sterling job getting the paint matched as well - even the orange peel stone chip finish on the lower half. Cost was £500, and my sills were pretty disgustingly rotten. Sorry I don't have any pics to hand at the moment, but for a rough idea, each side had holes the width of 50p pieces and about 5cm long!

MX-5 Lazza said:

Did you change the other belts at the same time?

Yup! Both less than a year old, but the PAS belt looked to have been contaminated by a spillage at some point and had loads of cracks on the grooves. Alternator belt was in perfect nick but changed it as well anyways.

[anonymous-user]

BonzoG said:

Cost was £500, and my sills were pretty disgustingly rotten.

Sounds very reasonable, I've only just started to get bubbling on drivers side sill (sill and hood drains all blocked on that side when i bought the car) but I'd like to keep the car long term so I think I'll pay them a visit!

[dylan0451]

after i stuck some poly diff bushes in, i get a huge whine. i was always under the impression that whine under load is normally diff related - bearings dying