SOT: MPG and differential (the sequel)

Just keep driving it, I doubt whether there will be a bang and the gearbox is suddenly and catastrophically destroyed ? Never owned a manual car, but wasn't one trick to reduce gearbox noise to stick sawdust in it ?

Have you thought of just getting a second hand gearbox? Something like

I think it's a K12, eg:

So really comes down to how much labour is involved in doing a swap, versus labour to pull the old one, refurb (+parts) and refit. You could ask the garage for their opinion.

If keeping costs under control is an issue, it depends how you feel about the lottery of:

a) pay less now, take a slightly elevated risk that it'll break in future, or

b) pay more now, feel more confident it won't break, but quite likely that something else will break sooner or later to make the car not economical to repair in future.

Having done a decent bit of bangerology, I have to say that the 'not economical to repair' point seems to take a lot longer than expected. Usually there's a few hundred quid of MOT repairs every year but nothing catastrophic to take out the vehicle. Eventually they die of rust which is a drawn out process.

Theo

Interestingly, Trents offer a warranty that includes labour to fit a replacement, something I've not seen before:

"(PLATINUM) 12-Month Warranty with Labour Cover (+25%): Available for an additional 25% of the item price. This option provides 12 months of warranty coverage, including labour costs for repairs or replacement. Labour cover only applies to the original purchase. The replacement part is covered by the same 12-month warranty; additional labour costs require separate payment (Minimum warranty price: £60).

To qualify for labour coverage, you must submit invoices for the original fitment and any subsequent repairs or replacements. These invoices should detail labour hours and parts used and must be issued under Charles Trent Limited’s name. Prior approval from Charles Trent Ltd is required before any work is carried out. Labour costs are covered based on the original invoice from the garage at a rate of up to £75 per hour."

For another £60 to get a replacement fitted if it fails within a year seems like a useful option.

Theo

Thanks (and to the other respondents). I'm going to go with this as a plan. I was out for a meal last night and a friend suggested I should that it is possible to use higher viscosity gearbox oil (I assume to achieve the same effect as the sawdust). I'll go back to my regular garage to see if he can do this.

I only went to this other garage because I needed an aircon specialist. Thinking back to yesterday, l think the owner talked a bit too much. He seemed to be trying to discourage me speaking to my regular garage or spending too much time thinking about it, and to give him the job. Curiously, they know each other so why would he do this? I may have hit on some inter-business rivalry. He is now fired anyway because he left the airbag light on *and* the indicator not working (because the bulb was left hanging on its wire). I am not convinced about their attention to detail. Communications were terrible throughout.

TBH if the garage wasn't going to be able to do the work and would hand it over to somebody who did, then you might as well go direct. OTOH 'refurb' companies can be a little different - some expect the parts to arrive and depart on pallets and they don't get involved with fitting or removal. So it's not entirely disingenuous for them to do the removal and then send away the gearbox.

But given that used gearboxes are available for ~£100, the "use it until it blows up and then fit a used one" strategy has certain attractions.

Theo

I tried to see if the gearbox is ok for the OP's model (with limited info) and it looks like your one is fine, but the one I linked to (only as an example, though!) won't fit.

And it's 23k less than the OP's box.

Yep, and your follow-up post offers an interesting option for a guarantee.

A banana skin with a noisy differential.

To be clear, this is exactly the situation. The gearbox guy rebuilds the gearbox only. The garage man would remove the gear, send it to the gearbox guy then fit it again afterwards. The ballpark cost was split £400 for labour, £400 for gearbox. Just to add to the intrigue, the garage man says my regular garage man uses the same specialist.

As Mark says, I cannot see a business case in spending £800 pre-emptively on a vehicle probably worth less than that which will probably keep going for a bit anyway.

I asked about this. He said with used gearboxes you don't know what you are getting and reconditioning by someone you trust is much better. He also does work on racing cars so he may have different expectations to me.

Can do. I once had an overdrive fail suddenly (broken gears) and much later I had an auto box which, on starting one day, would only do backwards.

Or turn the radio up...

This is my opinion from experience of a few failed gearboxes.

How bad is the noise? How long has it been making this noise? Is it getting worse over time? How many miles do you do in a year?

Some bearings can be noisy for a long time before catastrophic failure. Others fail very quickly.

My option would be to change the oil for new of the same variety. Bearings at end of life make iron filings of an especially hard abrasive material. Even old gearbox oil in a healthy gearbox is not generally "dirty".

I would then wait until catastrophic failure that could still be a while off and the gearbox could even outlast another key component.

Agreed, changing the oil is something you should do in any case. If you're not going to change the gearbox then at least change the oil. It may make things smoother and make the current gearbox last longer.

Theo

Thanks. I'm going to contact my regular garage man on Monday and ask him in the first instance to drain the gearbox and replace the oil. I won't return to the other guy (even if the aircon fails again).

Thanks everyone for the advice.

The oil seal on the end of my wife's gearbox failed, and it leaked oil onto the clutch which started slipping.

It seems the "reconditioning" they did was not to recondition her gearbox, but to replace it with another reconditioned one. Which occasionally doesn't shift as well.

I should have asked more questions. Ah well, she wants another car anyway!

Andy

Filthy oil will contain particles that will gradually attack the gearwheels and bearings. Regardless of anything else, get this replaced by new oil ASAP. You might even find that it alone quietens the gearbox a bit, because dirty oil provides reduced lubrication properties.

The only way that "wait and see" can do irreparable damage to a gearbox is if something damages the casing. All the internals are replaceable - provided the parts are still available. From your description, the gearbox doesn't sound like disaster is imminent, so an oil change then wait and see is my recommendation.

Apart from this, there are some good condition used parts around, provided you could find them. I read somewhere that a Micra can be written off by a rear end shunt, which would leave the transmission fully reusable. If you could find one of those (is there a breaker's yard anywhere near you?) then a simple substitution could be cheaper than a rebuild/recondition fix.

As an aside, I was once given a lift in a Ford Sierra, and its transmission was pretty noisy. I asked him how long it had been noisy like that and he said he couldn't remember exactly but im must have been at least 3 years ago it started to get really noticeable. I got the impression he wasn't bothered by the noise, it was just like his car usually sounded like. It certainly drove OK during my 70 mile journey.

His lack of attention to detail makes him totally unusable in my book. Has he had the same lack of attention in the aircon overhaul, I wonder? Certainly even if he really does know a man who can, could you really trust him to take the old gearbox out and put the reconditioned one back without creating peripheral damage or having some bits left over? And what if his "man who can" has a similar lack of attention to detail?

As you have a regular garage, I would be inclined to ask someone you trust from there to take a ride with you then give an opinion on how long the gearbox sounds it would last. Don't even mention replacing it and you should get a meaningful reply.

Perhaps give your usual garage the job of replacing the oil, and after that was done then ask for the opinion on your gearbox. Don't forget that the existing oil will drain more quickly and thoroughly if it is warm, so go for a bit of a ride round to take the chill off the oil before delivering the car to the garage for the oil change. I would change the oil for fresh oil of the correct grade. Changing it for a thicker oil could affect the synchromesh function on gear changes.

Thank you very much for all this helpful advice. Update is that I went to my regular garage yesterday afternoon. First thing Robert asked was how much I was charged. When I told him it was £666 (work of the devil) he said that was a bit high. He opened the bonnet and found a large piece of polystyrene packing material inside. He just handed this to me without comment with a clear look of disapproval. I did mention the gearbox and he responded that there is nothing wrong with the gearbox (he knows the vehicle and serviced and MOT'd it in March) but said I should take it in for an oil change next week. The garage is about 20 miles away, which should take care of the warm-up protocol.

As an aside, when I collected my car from the aircon garage the owner/mechanic told me his 11-year old daughter wants to be a mechanic and was coming in for the afternoon for some practice. I mentioned this to another mechanic as I was leaving. He said she was in the day before and was criticising some of the work her father had done.