gearbox query

Post by **youngun** » Sat Apr 05, 2008 4:38 pm

Seeing as im rebuilding the engine, ill obviously be putting the gearbox back on as well soon. So, having had a quick look at my gearbox (which is a goldseal with 6,000 miles on it) ive noticed a nice 1/4 inch thick coating of black oily sludge all over the inside of the bellhousing. Now im guessing that this shouldn't be there! So where's it come from and how do I rectify it?

Post by **MoggyTech** » Sat Apr 05, 2008 6:05 pm

Common, could be coming from the crank scroll seal, caused by poor crankcase breathing or worn shells. Could be from the scroll seal on the first motion shaft in the gearbox, if it is PM me for a front gearbox cover plate with proper oil seal at a great price

Post by **les** » Sat Apr 05, 2008 6:13 pm

Mt a question, the front cover oil seal mod, is the original casting used, in other words can one be modified to accept a seal? Looking at the one I have it seems unlikely.

Post by **bmcecosse** » Sat Apr 05, 2008 6:30 pm

Not very usual for the gearbox to leak - but very common for the engine rear seal to leak. Give away is if the back of the flywheel is coated with oil/muck ? Gearbox leak would usually just make a path down the bellhousing from the input shaft.

Post by **youngun** » Sat Apr 05, 2008 11:03 pm

Hmm, its the bottom of the bellhousing mainly.....thick black gunk. Ill have a look at the flywheel tommorrow.

Post by **MoggyTech** » Sun Apr 06, 2008 12:12 am

les wrote:Mt a question, the front cover oil seal mod, is the original casting used, in other words can one be modified to accept a seal? Looking at the one I have it seems unlikely.

AFAIK the modified covers are simply machined where the 1st motion shaft comes through, and an oil seal driven into the new machined section. Could be a special casting though, I don't have a standard one to compare it to.

Post by **MoggyTech** » Sun Apr 06, 2008 12:20 am

youngun wrote:Hmm, its the bottom of the bellhousing mainly.....thick black gunk. Ill have a look at the flywheel tommorrow.

The dust from the clutch linings is what makes it so black and sludge like. The source is often from the 1st motion shaft scroll seal when you park facing downhill. As the shaft isn't turning the oil can seep along the scroll. Another possible leak is oil seeping through the front cover plate studs, a bit of thread seal can stop that. Just be greatfull BMC fitted that split pin drain hole

Post by **bigginger** » Sun Apr 06, 2008 12:39 am

... and resentful that they fitted a daft scroll, not an oil seal

Post by **Alec** » Sun Apr 06, 2008 8:19 am

Hello B,

I suppose it is due to the age when the engine was designed?
Jaguars of that era used an inserted strip of seal that required sizing to the crank, and it often leaked anyway.

Alec

Post by **youngun** » Sun Apr 06, 2008 6:58 pm

Well ive had a quick look at the flywheel, and the engine side face is covered in the same (albeit less oily) sortve gunk.
The gearbox seal doesnt look like its been leaking, so im guessing its the rear crank seal?

Post by **bmcecosse** » Sun Apr 06, 2008 7:04 pm

Guess so!

Post by **MoggyTech** » Sun Apr 06, 2008 7:15 pm

youngun wrote:Well ive had a quick look at the flywheel, and the engine side face is covered in the same (albeit less oily) sortve gunk.
The gearbox seal doesnt look like its been leaking, so im guessing its the rear crank seal?

Yes it does sound as though the crank scroll seal has been leaking, or blow by gasses into crankcase causing it. If the bearings are OK proper crankcase breathing should fix the problem.

Post by **youngun** » Sun Apr 06, 2008 8:11 pm

Brilliant, it is most likely a breathing issue, considering the sludge and crap and cacked on crud inside the engine. I spent 2 hours today cleaning the ring grooves on the pistons, full of some black limescale like stuff!

Post by **bmcecosse** » Sun Apr 06, 2008 9:49 pm

'Carb cleaner' from Poundland works well on pistons!

Post by **youngun** » Mon Apr 07, 2008 4:40 pm

too late, theyr'e all clean now!