Gearbox oil leaking fast

[bychance]

I've always been concerned that my 1976 Silver Century uses a bit too much gearbox oil. I did a run last weekend, approx 20km in total I reckon; all went well with no hiccups, on return I decided to check the gearbox oil level to find that there was mostly salt water in the gearbox instead of the EP140 that I topped it up with before the trip. It wasn't coffee coloured either, just clear salt water with some globs of EP140 in it. The gearbox doesn't drip much in the garage; the cap gasket and grit seal are both in good condition and the bushes seem pretty good. There is a little bit of movement fore and aft of the prop shaft, about 2 - 3mm, but no sideways movement (or very little). Can the gearbox oil evacuate any other way?

[charlesp]

The 'fore 'n aft' movement you describe is quite normal, provided the gears mesh properly. The threshing and churning motion of those gears would normally produce the coffee coloured emulsion.

Are you sure you weren't topping up a gearbox that was already full of seawater? If you drain it of all the water, then top up the oil and take it for a run it should emusify.

[Rex NZ]

Bychance

I had a gearbox that did a similar thing

It turned out to be there was a mark on the propshaft across the bearing journal. It acted somehow like a pump & swapped all the oil for water. My forensic analysis concluded the mark was caused by some damn fool having grabbed the shaft with pliers, maybe vice grips, to stop the shaft turning so they could extract the prop over a burr left by the propspring. It was a WSC clutched silver century, so the shaft had alot of fore & aft travel.

Ended up dumping the shaft

Rex NZ

[bychance]

Thank you for the replies. The gearbox was drained and refilled before the trip, I did fill it up more than normal to help, maybe doing this didn't. I'll check the propshaft for any errors; I didnt notice any when I dismantled it yesterday. I have ordered some V12A oil seals from RS. They should arrive today.

[chris]

I had it happen with an old century that had done a lot of work, the bush which the drive pinion goes through was worn and the oil was coming up through the pinion and bush

[bychance]

I pulled the lower gearbox assembly off the motor this afternoon; there is very little play in the pinion part of the drive shaft. There is no staining or smell around the impellor to (maybe?) indicate that some of the Penrite EP140, blue in colour and very smelly, has been in the area. If the pinion bush and oil seal are worn, is that the path that the oil would take and then get pumped up the water pipe? Is there a way to test this?

[electrosys]

Is there a way to test this?

'tis turning into an Agatha Christie mystery, this ....

Well, if this was my motor - I'd put it back together - re-fill with the same 140 oil, and run the engine in a test tank full of clean water. Then stop the engine and inspect (gearbox, water quality, signs of leaking etc) after (say) 5 mins, then if nothing amiss, after 10, then after 20 and so on. At some point something amiss should show itself. If not, then I'd put the previous oil loss down to human error or an early onset of Alzheimer's (I know - really shouldn't joke about such things ...).

Must say that using coloured oil when looking for an oil leak is an inspired idea.

[bychance]

Good idea! Yes, I'll do a test this weekend.