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Can you give me an idea of how many labour hours it should reasonably take a mechanic to do this? I know that it involves removing the gearbox etc and is quite labour intensive, but I'd like to have an idea of what reasonable hours he could charge me for. Thanks.

It’s a very difficult question to answer and I will need to make some assumptions on the type of transmission fitted to your Micra. I will work on the theory the transmission is a basic 4-speed unit as opposed to a Constant Variable Transmission (CVT).

Oil leaks from the torque convertor seal are very rare to be honest and can be the result of another problem or not from the seal at all, so the very first step would be to confirm the leak is transmission fluid and not engine oil.

There is a oil seal at the rear of the engine which can allow engine oil to exit via the transmission housing hence the potential for confusion.

So once again let’s assume the leak is in fact transmission fluid and coming from the torque convertor (TC) seal.

The nose of the torque convertor is what passes through the seal and ends up connecting with the transmission oil pump which is located just behind the seal. If the nose cone support bush in the oil pump was to wear excessively, move or break-up oil will exit the transmission via the seal. In other words replacing the TC seal will not fix the problem and the leak will continue.

In summary a very careful examination is required to clearly locate and identify the cause of the leak.

In terms of labour costs, I would estimate around 8 hours in total if it were a straightforward seal replacement.

If the oil pump bush or the nose cone of the TC was the problem, the complete transmission would need to be stripped, cleaned and overhauled as required. The TC itself would also need to be flushed. Total labour time could escalate to around 20 hours in a worst case scenario.

Sorry if it’s a long winded answer, but as I stated earlier leaks from TC seals are very rare (especially with Japanese vehicles) and can be the result of other problems. Hopefully your mechanic is up with the play and carries out all the necessary checks.

Thanks so much for your answer, really appreciate it.

I’ve just the seal replaced and have a couple of questions I hope you can help with.

The car is a 2005 Nissan Micra. At 55,000kms an AA inspection picked up seepage in the transmission assembly area. I took it to the dealer’s service dept who said it was nothing of concern. Recently (at 74,500kms) the torque converter seal needed to be replaced.

Your answer to my previous question prompted me to ask the manufacturer about possible causes and they replied that seals have a limited life and dirts and contaminants may have also resulted in the seal failure. The vehicle has always been serviced regularly, according to the manual, by either the dealer’s service dept or more recently, the AA for the actual repair and subsequent service, so I’m confused about the dirts and contaminants theory? How could that have happened? Am I being unreasonable to expect things to have lasted longer than they did? I’ve never come across this in any cars I’ve owned previously so am a little clueless about the whole thing. Thanks

I wouldn’t have thought a leaking torque convertor seal was caused by contaminated oil to be honest. Contaminated oil is often the result of wear and tear in the transmission so I would expect some warning signs in terms of a drop in transmission performance before the TC seal started to leak.

As I said in my earlier email, it is the nose cone of the TC passes through this particular seal. This means the seal is working constantly whenever the engine is running. Over time, the seal itself can simply lose its tension which can create an oil leak. Very unusual these days but not impossible for this to happen.

The manufacturer is correct – seals like other mechanical parts do have a limited life and you could be unlucky that the TC seal in your vehicle has started to leak at this age and mileage.

Apart from keeping an eye out for oil leaks there is not a lot you can do about it to be honest.

Often oil seepage is best monitored only, its only when oil drops start appearing on the garage floor or concrete driveway do you need to take action.