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16H Gearbox issue after gear oil change

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16H Gearbox issue after gear oil change

Posted by stuart_anderson at June 18. 2017

Replaced the Gearbox oil in my 16H yesterday, used Gulf SAE50.  Took it up to a show today (~80 miles round trip) At first it seemed really good, however once it got hot was having a little bother changing down to 3rd, you were having to push the leaver down before it would change down.  When comming up the bypass was sitting about 60 when it seemed to loose power and was sort of costing, pulling the clutch in and letting it go didnt seem to be doing what it was suposed too but it did sound different.  I then changed it down to 3rd and it bump started.  After that it was really good for the ~10 miles back to the hose, changing no problem.  I assumed it was maybe a little low on oil so checked once it cooled, but it was at the level.  Put some oil in the oil bath but not a lot.

It does about 200 miles a week and have had false neutrals and the occasional jump out of 3rd gear but nothing serious.

Any ideas what could be up with it?  It was very warm today and i was hiking on a bit...


Re: 16H Gearbox issue after gear oil change

Posted by David Cooper at June 18. 2017

Sounds more like engine than gearbox to me (although odd changes might be improved by adjusting the pedal link rod). Could you kickstart it when hot? If so, then at least it probably is not the magneto.

Could it simply be fuel starvation (  at that extreme speed)... e.g. the classic case of blocked breather hole in fuel tank top?

Re: 16H Gearbox issue after gear oil change

Posted by Neil Wyatt at June 18. 2017

60 sounds more like blowing up speed for a 16H to me, unless you have some tall gearing.

These engines do run very hot but if your oil levels are OK then as said above, try adjusting the linkages. Third gear is always first to fail as it is passed through most, usually worn dogs.

I use EP 140 in my 16H gearbox without issue (SAE 50 was recommended when new and one oil did for everything) But I have some Shell grease that turns into liquid when hot I will use when I replace my outer dolls head cover.  (Broken at the filler)  No more leaks when stood cold!

Sounds like it was just getting a bit too hot, Stuart, even on SAE 50!.  Richard P might know better. I wonder how they managed in the North African desert?

Re: 16H Gearbox issue after gear oil change

Posted by stuart_anderson at June 19. 2017

Thanks for the replies, took it to work this morning (25 miles) and it was fine, selecting as it did before and no sticking in 4th on changing down to 3rd.

Don't think it was engine as normally you would feel (and smell) it.  It was just all of a sudden when it was running perfectly, was only not running for about 20 seconds, didn't actually come to a stop just coasted a bit and then bumped at about 25 in 3rd.  60 isn't common, but have done it before without issue and it can hit 70, how accurate the speedo is however...  Normal speed is 40 to 50 though.  I think the previous owner said it was either a 19 or 21 tooth sprocket it runs, will need to count them.

Could be breather, but when i got home i tried stopping and restarting it with the kick and it started straight up no bother.  It was blocked when i first got it so I keep and eye on it.

Is it worth trying some Hypoid 80/90 in it?

Engine is running SAE 40.

Re: 16H Gearbox issue after gear oil change

Posted by john_holmes at June 19. 2017

A 90W gear oil is the same viscosity as an engine 50W but with additives to cushion the gear teeth from each other where they mesh under load. A 80/90W gear oil will be slightly thinner when cold (same as engine 40W) and then take on the 90W properties as it warms up. So it should give you a slightly easier gear change when cold and add extra protection to the gear teeth.  Does not sound like you had a gearbox issue but an engine/ignition issue to me, maybe just some dirt on the inlet valve that cleared.

Re: 16H Gearbox issue after gear oil change

Posted by stuart_anderson at June 19. 2017

Thanks for the explination John, I have loads of straight 90 for my Defender so will give that a shot first, save me buying anything.

Your probably right, just seems weird it was sticking going down to 3rd but that stopped at exactly the same time, maybe the jolt from bumping it was enough and unrelated.

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