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MG MGF Technical - Rattling Noise In Neutral

Afternoon Chaps

We've noticed a funny rattling noise that has developed when the car is sat in neutral. (The car is a TF 135 Anniversary Edition) It was rather worrying because it makes the car sounds a little diesel-ish I've done a quick search of the archive and seem to have found an explanation posted in 2005 but I just wanted to check that this received wisdom still stands or if there is a reason to be further concerned.

<quote>
Don't rush to replace anything. Here is a "cut and paste" of a post from another forum about this issue:

The PG1 gearbox has a very good reputation and usually doesn't give any problems. The noise you describe is however sometimes an issue (I have it on my TF 160) but the knowledge and understanding about it seem rather limited among MG technicians (at least those I've come across...).

The information below was given by Nick Adams, Chief Engineer at Lotus, on the sorely missed "Lotuslife" bulletin board. It explains it all in a very clear way:

"It's not unknown for the first motion shaft bearing to give trouble on the K series box, but the trouble usually goes no further than a little noise. What happens is the bearing develops a little play and chatters when the box is in neutral and under no load. Dipping the clutch allows the shaft to turn slower or stop and the rattle goes away. When the shaft is transmitting torque (ie you are driving) the side loads generated by the gears take up the tiny amount of side play and the bearing runs happily. Therefore the problem rarely gets any worse. It's not worth fixing the noise unless it really wories you, it's a common feature of just about all gearboxes with an unsupported 1st motion shaft and will not affect the gearbox function or reliability at all. My advice would be to leave it alone, but it's your call...

(...)

The first motion shaft is the input shaft that transmits the power from the engine into the gearbox. The shaft runs on a bearing fitted into the back of the engine crankshaft and a second bearing in the gearbox itself. These bearings are designed to be able to cope with a small degree of misalignment which is inevitable when the engine and gearbox casings are machined seperately as they will be in a mass producion situation. If the misalignment is smaller than average the bearings can generate a little noise as the shaft turns without transmitting power (ie: in neutral). As soon as any load is applied the shaft loads the bearings and the noise disappears. Don't worry about it, it simply shows you have a good engine to gearbox matching!! "
</quote>

Also, has anyone experienced knocking following the fitting of stainless steel coolant pipes. We've had this ever since they were fitted a couple of months ago. I'm not sure that it could be anything else as you can physically feel the knock from under the car and it seems to travel. Any thoughts appreciated as always.

Thanks

Sally
S Crowley

Yep, I have a slight chatter in neutral, it's quite normal.

My stainless coolant pipes also bonk as they warm up/cool down! At least it shows there is still water moving about in them ;)
Tony

Thanks for the reassurance Tony. We've had a few repair bills recently, replacement pipes included, and the thought of another was filling us with dread... Love the car but our bank account doesn't and sadly it's making Mr Sally fall somewhat out of love with it. I think that he needs another trip to Shropshire and some empty roads.

Cheers

Sally

Sally

This thread was discussed between 27/09/2009 and 30/09/2009

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