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Gearbox oil level and over-filling

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DerekJ

DerekJ

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My gearbox is leaking like a sieve but for reasons I wont go into the earliest I can pull it is the end of July. However I want to keep driving the car so a couple of questions.

1. How accurate is that dipstick - I also find it quite tricky to get an accurate picture of where the oil actually is on the stick.

2. If the LOW level is reached, how much oil is still in the box? How low is low - a quarter full? a half full? or virtually empty

3. To err on the safe side I want to keep topping up the box. Is there any danger from overfilling? bearing in mind the gearbox is going to be pulled anyway.

4. I saw on the Healey list that someone with a similar problem was going to add some 'leak sealing' type product normally used on automatics. Any comments on that? Can it do any harm?

thanks
 
Hi Derek,
On my car, the distance between the two marks appears to be around one pint. Since it holds at least three quarts, a pint low doesn't appear to be significant. Mine leaks also but I have determined that it leaks more slowly when only filled to the low mark. Operating at the low mark doesn't affect transmission operation or OD shifting. It leaks about a pint every 4,000 miles. Not a lot, but enough to make a reall mess on the floor. Amazing how far a pint of oil can spread over time.

The leak on my car appears to be the rear output shaft seal. The seal can be replaced by removing the driveshaft flange from the rear of the transmission. Big very tight nut. No need to remove the transmission. Another source of leaks is along the splines on this same flange. It is well to use a good sealer on the splines when the flange is reinstalled. Since the seal runs on the outer surface of the output drive flange, make sure that this surface is in perfect condition. I think a "RediSleeve" could be used here to restore a grooved seal surface.

I have a new seal but have not become annoyed enough to bother replacing it. Your's may be leaking in another place but this is a likely spot.
D
 
Hi Dave,

I've got my gearbox torn apart right now for new seals and gaskets. I didn't find the rear flange nut to be overly tight when I removed it (and there is a cotter pin to secure it). Do you know what it should be torqued to? What sealant would you recommend for the the splines? Hylomar?

Derek, I would be concerned about adding something to stop the leaks if you have an OD fitted. Since the gearbox and OD share the same oil you might affect the OD function.

Cheers,
John
 
Hi John,
I found that the working clearances were too tight to easily get the nut off with the transmission in place. Next try will be removing the drive shaft to get room & using an impact wrench. I was able to get an axle pinion gear flange off this way.

I have had similar spline leakage problems with motorcycle output to sprocket shafts. I would suggest a hardening sealer for this application. Silicone & Hylomar don't seem to get the job done on this type of application.

It seems to be typical of many designs to provide good seals in the obvious places & ignore the splined connection sealing. One MC had an O ring at the end of the splines but it didn't seal very well either.

I would torque to 80 or more. Similar to the rear axle pinion flange.
D
 
Dave

Thats interesting that LOW may only mean you've lost a pint or so.

I also agree with you about how much mess that can make. I have a large drip tray under the car and have been tring to collect oil from this and transfer it to an oil can to try to judge how much I've lost so I'll know how much to refill. Up to now it always seems less than I am expecting. However the car was just in an auto shop overnight for another matter and the owner made quite a deal about the oil drips on his floor inferring it was a big problem! I've not been able to get under the car myself but the garage guy said its leaking in several places. Don't know if thats right or not.

Any comments about overfilling? Is there any risk?

John- good point about the overdrive - think I'll pass on that one!
 
I don't know about overfilling. Probably no real harm, but not much point in doing so. I'm sure that it increases the leakage rate.
D
 
[ QUOTE ]
I thought it was 140'lbs

[/ QUOTE ]
Probably could be. I said 80 or more. The max. is often limited by the available equipment. I certainly have no problem with 140 if you can get it.
D
 
I just looked in one of my manuals. Coupling flange nut 100’lbs to 130’lbs. I made a bar that bolts to the flanges to keep things from spinning. /ubbthreads/images/graemlins/crazy.gif
217087-CIMG0259.jpg
 
Derek, I attached an old side view mirror to a broom handle and use a drop light on the ground to check under the car from a standing postition. It lets me check all kinds of things I cannot get to easily under the car with out raising it (like the suspension and breaks).Why I have an old side mirror is another embarassing story.
 
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