T25 Diesel Conversion Gearbox Problems

[aahridey]

Hi,

Last September we bought a 1984 T25 high top Autohomes camper off Ebay. It's been chopped about a fair bit inside but we love him and have had some great times over the last year.

Anyway, the van started life with a 1.9 petrol engine but at some point was fitted (badly) with what I was told is a 1988 Passat turbo diesel engine. We had a few initial woes as the guy we bought it from had overfilled it with oil as the engine being mounted at an angle meant the dipstick read incorrectly. Despite having a new clutch before we bought it, it soon started slipping as oil was being forced past the oil seal onto the clutch plates. With the oil drained and refilled we continued to use Kippin daily but have had to go easy on the right foot in 3rd and 4th gear to stop his clutch slipping.

With the MOT approaching in July I started to notice a noise from the gearbox which has got progressively worse. The noise is at its worst when the engine in ticking over in neutral. It sounds like a dry bearing noise. It disappears when you put the clutch down but becomes evident again when driving in any gear. When pulling away in first gear it sometimes makes a bit of a squealing noise. The gears engage fine and it drives fine other than the gearbox noise. When engaging reverse and slowly moving backwards it occasionally feels like there's a brick under the rear wheel and doesn't want to move, or if moving back wards will stop sharply as if it's hit something.

Can anyone advise me what this could be? I'm hoping it's not a gearbox problem, but fear it is. Maybe the idle shaft bearing or output shaft bearing? Could it just be the clutch release bearing? If it's a gearbox problem, does the engine need to come out as well? Is it worth trying to fix a gearbox problem or is a replacement a better option?

Any help or advice would be much appreciated.

Cheers, Mark

[cadillacvw]

Hiya, it is most defo your axle carrier bearings. if you look at your driveshafts as they enter the transmission. you will see the circular covers that contain the bearings. when at rest the axle is not supported because the bearings have collapsed, and when you reverse the bevel gears clash and try to lock up. there is a special tool to undo and set the bearing pre-load. as you accelerate the movement slightly raises the final drive and the noise level drops. probably a result of excessive speeds. replacement is your easiest option or see a sympathetic gearbox rebuilder

[Aidan]

if in any doubt about the gearbox drop the oil and see what the darinplug magnet has to say
the noise in idle neutral suggests either mainshaft bearing, input bearing or clutch issue
the lock up in reverse suggests worn pinion bearing with the pinion shaft moving backwards underload in reverse causing the crown and pinion to misengage
eitherway I'd expect the drain plug to have a fairly large build up of fines on it, and rather than just a head on the magnet there would be a sludgy stem, ie the whole magnet covered
if the 1.9TD installation wasn't done correctly then there's no spigot bearing fitted and the oil thrower and input seal will be damaged and leaking, often it's missed out first time and 350 miless later it's leaking badly into the bellhousing, mistake is realised and a spigot bearing is fitted along with a new oil seal but the damage to the oil thrower behind the seal isn't rectified and then it carries on leaking
box out doesn't require engine out