Shot gearbox bearings - noisier when cold

[Fantuzzi]

Hi all,
In late September I had my MR2's gearbox reconditioned due to the bearings going, the work was done and the noise appeared to have gone, the only issue was a noisy cold start from the exhaust, which I assumed was just due to the re-fitment of it.

Then a similar noise to before the work was done, 'rattily' when accelerating from around 2500-3500 rpm in 1st and 2nd, reappeared. It most likely was there from the start. but as most of driving as been sat a motorway speeds with very little 'normal' driving, and sadly my driving has all ben rather mpg friendly so the revs have been south of 3000 to help my ravaged finances,and I hadn't noticed it. It is rather subtle and only really noticeable to a trained ear.

However over the past few months as the mornings have got colder the noise that is still barely noticeable when the car is hot, is really loud when cold.

As the gearbox is still in warranty it isn't a massive issue although given the exhaust issues I had, rasping on start up from cold and a sort of knocking sound on start up when cold, I wasn't sure if it was an exhaust issue rather than a transmission one mainly because of how distinct it is when cold compared to how faint it is when warm.

I plan on taking it to a Toyota garage to get some hears on it, but thought I'd ask the knowledgeable of pistonheads first!

Many thanks in advance

[HustleRussell]

If the sound is actually a 'rattle' at certain engine speeds, I would not immediately suspect the gearbox. I may be wrong but usually when a gearbox goes the noise is typically a whine.

Although you can only hear it in 1st and 2nd, it doesn't necessarily mean that the problem is confined to 1st and 2nd gear- it may be that you simply aren't hearing the noise in 3rd as the road speed has increased and tyre/wind noise is masking it, or the problem when using 3rd/4th/5th ratios does not happen as the resonance of the vibrations will be different as the power/torque demand changes through the gears.

Get an experienced set of ears on it

[davepoth]

I'd go for exhaust. If you get to the resonant frequency of the rattly bit it can be pretty loud. Probably a daft question, but have you tried revving past the rattle to see if it stops?

[Fantuzzi]

davepoth said:

I'd go for exhaust. If you get to the resonant frequency of the rattly bit it can be pretty loud. Probably a daft question, but have you tried revving past the rattle to see if it stops?

Well in first and second the rattle/raspy sound (it seems to change just to piss me off and confuse) seems to continue to around 3500 but then the engine noise is loud enough to drown anything out.

Revving in neutral, no problem. I'm think exhaust after a month of hard listening, the rasp on start up and funny noise when I had the car back on start up makes me think its where its been taken off/put back on.

HustleRussell said:

If the sound is actually a 'rattle' at certain engine speeds, I would not immediately suspect the gearbox. I may be wrong but usually when a gearbox goes the noise is typically a whine.

Although you can only hear it in 1st and 2nd, it doesn't necessarily mean that the problem is confined to 1st and 2nd gear- it may be that you simply aren't hearing the noise in 3rd as the road speed has increased and tyre/wind noise is masking it, or the problem when using 3rd/4th/5th ratios does not happen as the resonance of the vibrations will be different as the power/torque demand changes through the gears.

Get an experienced set of ears on it

Its hard to articulate a noise in words, perhaps rattle is slightly wrong, when the bearings went it was both a heavy straight cut whine in 4/5th but also a harsh fast rotating sound like a broken fan or something.

I know what you mean about higher road noises, Ive been getting, what I'd describe as a very very faint flat snot noise, the same as the cold start noise, when on motorway journeys, so I'm thinking the exhaust.

Ill take it to Toyota and get them to have a listen, if that fails I have an uncle who's spent the last 2 years taking apart and rebuilding a 240z, he's rather knowledgeable about all these things so perhaps a bottle of whine will persuade him to have a fiddle.

Thanks for all the advice!

[Pumaracing]

Fantuzzi said:

Ill take it to Toyota and get them to have a listen, if that fails I have an uncle who's spent the last 2 years taking apart and rebuilding a 240z, he's rather knowledgeable about all these things so perhaps a bottle of whine will persuade him to have a fiddle.

A bottle of 'whine' sounds like a fair exchange for listening to a car's 'wine'

[Fantuzzi]

Pumaracing said:

Fantuzzi said:

Ill take it to Toyota and get them to have a listen, if that fails I have an uncle who's spent the last 2 years taking apart and rebuilding a 240z, he's rather knowledgeable about all these things so perhaps a bottle of whine will persuade him to have a fiddle.

A bottle of 'whine' sounds like a fair exchange for listening to a car's 'wine'

Don't judge me I'd been writing whine a lot...