TECHNICAL TIPs by John Grant
NOISY 505 GEARBOX? – at the request of Don Howarth.
*The good news is – that Peugeot gearboxes are VERY reliable and even when noisy will generally keep going – except when it is 5th gear.
*The bad news is – that fixing them is VERY expensive, usually far more than the car is worth. Problems within the warranty period are virtually unknown and they can keep going for hundreds of thousands of miles.
NOISES…. First there may be a generalised kind of noise which may not even be the gearbox at all, so you need to check
1] the rubber boot around the gearlever on the top of the transmission tunnel but underneath the console. This is NOT the leather mounting you can actually see on top so you have to remove the console to look at it. If this has even a small split, it will allow you to hear road noise and mechanical noises normally too quiet to register.
2] Check that there is actually oil in the gearbox by removing the plug halfway up the side of the gearbox. On level ground, it should be full to that point. It can happen that the rear seal will leak and permit gearbox oil to seep down the torque tube and into the diff. It should be engine oil in the gearbox and hypoid oil in the diff and contaminating this will cause a problem as the diff will eventually wear. If the oil level is low, always check the level in the diff. If it pours out when you remove the plug, you know it has more oil than it started with.
A seal probably costs around $10 but it is a major job to change as you have to drop the diff to take it and the torque tube and prop shaft out to get at the oil seal.
Time? About eight hours if all goes well.
Is it worth it? Yes – if you have a good car you plan to keep in good order. Otherwise, while it may keep going for a long time, it will get noisier and you have to keep topping up the gearbox and draining the diff. Putting a hypoid type oil in the gearbox as well will protect the diff but the synchromesh in the gearbox will grow weaker in time.
3] If top [5th] gear only is noisy, it does pay to get professional help – which be VERY expensive because that means the bearing a the back of the gearbox on the 5th gear is breaking up and will eventually seize up and break the spline shaft on the back of the cluster gear. Metal fragments will damage all the other gears, and when 5th gear goes, you lose reverse as well. To change a gearbox takes c 20 hours – and new ones are unobtainable. A secondhand one would need to be pulled apart and checked to see if it is any better.
However, John says that the only case of a 5th gear going that he has personally encountered, was on a high mileage 505 which regularly towed a horsebox long distance on the Desert Rd.