Transmision Problem

[memini55]

Hello all!
We have a 72+2 with the original gearbox which now has about 37K miles on it and we have put it up for the winter months. I am going to pull the motor and gearbox in the next month to repair oil leaks and try to repair the gearbox. For the last 5K miles or so it pops back out of third gear unless you hold forward presure on the shift lever. Since third is used a fair amount in in town travel we would like to repair. Any good ideas as to what to look for?
Also looking at several oil leaks to fix, the PO had rebuilt the motor at about 20K. It looks to be leaking in two main areas, front timing cover near the the head and also from the rear main seal, best I can tell. I have power washed everythig and going run for a bit to see if I can narrow down. If anyone on the board has any advice to share it would be very helpful. Thanks in advance!
Mark and Patrick Doubet

[Frank Howard]

Mark and Patrick,

Greetings from up the river. The odds of the car having one or two leaks are quite small. Chances are, it has several leaks. I would order a complete gasket and seal kit for the head and block plus a water pump rebuild kit. Then tear it apart and replace all the gaskets and seals. When you put it back together again, chances will be much better that you will now have only one or two leaks.

[memini55]

Hi Frank
I was trying to be kind and go easy on my discribtion, I would agree it has several. My plan is to pull it down and all new gaskets and the pump rebuild as well. Mainly would like to hear what is the best sealers of date to us on what areas and any other advice this great list can give.
We mainly want to slow the leaks to a bearable amount. I have heard of twink not leaking at all but not sure that can be done.
We are either going to repair the tranny or look to convert to a five speed for better highway speeds.
Mark and Patrick(away at school)

[1964 S1]

First I would make sure your oil leaks are not due to excessive blow by. What happens if you lift the oil cap a half inch or so while running at idle? Don't pull it away as oil will be slung out, if a lot of air is forcing it's way out replacing just the rubber seals may be a waste of time. What was done on the previous "rebuild?" It shouldn't be leaking but a few drops (from anywhere and somewhere) after such a short amount of miles. Was it driven hard/raced since rebuild? The "zero leak" engine is chronicled in the archives by a non active member. I'll bet it's leaking now, these cars weren't designed and built yesterday.

[rgh0]

Mark

Best listing of sealants to start from is the following

http://www.elanfactory.com.au/pdf/techn ... alants.pdf

Apart from your list of possible leak sources I would bet it is also leaking from the front pulley seal as almost all twinks leak here due to flex in the crank shaft nose and difficulty in precisely centering the seal with respect the crank when assembling the front cover unless you make a special tool.

As for your gear box problem it is due most likely to wear on the syncro ring engagement teeth, wear in the selection rod detent hole, detent ball and spring assembly or general bearing wear leading to misalignment of gear and syncro components. A few other less likely problems like misadjustment of the selector mechanism or build up of crud in the detent system in the selector also possible.

Like most problems what ever it is it will be fixed by pulling the box down, checking everything very very carefully and rebuilding it properly. No magic bullets unfortunately.

regards
Rohan

[memini55]

The engine rebuild was at 18K and was a tipical rebuild as from the reciept which we have. The motro had sat for several years before our purchase and putting the car back together, about 8 years. Parts included in the rebuild , main rod and thrust bearings, aux shaft bearings,gaskets, valve guides and seats, water pump rebuild, ring set, timing chain, valve springs, breather tube and tune up parts. Also had done gearbox work, replaced a bearing and syncro ring.

Rohan, thanks for the link and list. That should be very helpful.

I will check the blow by, but don't think that is an issue. It has good even compression and I have reset the values. It has just been used as a driver and not raced. Well maybe driven hard by an 18 year old son

I'm not much of a gearbox man but I will certainly give it a go.
Thanks everyone

Mark

[sk178ta]

At the risk of tempting fate (and being unbearably smug) my engine doesn`t leak any oil. It was rebuilt by Dave at High Peak Classic Autos in Buxton at the beginning of last year. 10,000 miles of, mainly, Continental rallys, including the Scottish Malts and the Rallye des Alpes and plenty of different track days has given it a good spanking !!
So it can be done but I reckon the best sealant can`t compete with an experienced engine man.
Incidentally, I can always recognise Rohan`s replies as they are so succinct, to the point, full of top advice, yet modestly written. Top man.
Jim

[simonriley11]

I had the same gearbox problem on my Sprint some years which turned out to be a worn spring for the selector detent. From memory I changed it by simply removing the top cover, of course the engine and box were out at the time.
Regarding the mythical non-leaking twin cam engine, my plus 2 has a very very minor 'mist' leak from the cambox gasket at the front, so that the front of the head above the water pump pulley is very slightly 'damp' after a 150 mile run, but other than that, that's it. I take no credit for this, the PO had the head rebuilt. Also my oil consumption seems pretty low, a recent 600 mile touring holiday resulted in only 1/2 pint of oil usage.

[GrUmPyBoDgEr]

Popping out of 3rd gear!
The same happened to my S4. The engine+g/box were refitted into the car a bit too far forward. This caused the lower part of the gearchange lever (the bit with the rubber bush in) to be a bit too close to the transmission tunnel covering trim. This prevented the gear to fully engage. Try removing or loosening & lifting the trim temporarily to see if your problem goes away.
Sometimes the solutions can be easy, not very often though.
Good luck
John