NOISY GEARBOX

[paul]

Hi everyone, my gearbox is getting steadily noisier. especially in third, and nearly as bad in second. there's no extra noise in fourth, hardly any in first, or any other gear when NOT accelerating (as if accelerating is a thing in a Marina ).
The history is i have done around 10,000 miles since a supposedly total rebuild and had the oil level checked around a 1000 miles ago. which it was low, so filled up. ironically it was checked and filled up because there was a hint of noise appearing, so i can only assume that the filling with oil really hasn't helped in slow increase in noise in the last thousand miles. Other than that, it's not jumping out of gear. It;s always been a little crunchy getting it into second from third, and reverse as been elusive sometimes, until i double the clutch. but largely it's been perfect in the last 40.000 miles i have put on it. (the box got rebuild mistaking it needed doing for a prop shaft bear that had gone!)
Any ideas anyone?

[balmy]

Don’t use third

I’d be firstly checking the oil level again and making sure it’s the right oil. Maybe drain and refill?
Otherwise I’d expect it’s bearings but I’m sure someone who knows more than I about gearboxes will advise.


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[david painter]

I feel if its noisy the damage has already been done. If you have had low oil and the fact its quiet in 4th, suggests to me the first motion shaft bearing is failing. With helical cut gears what oil is in the box is pushed backwards thus starving the First Motion shaft of oil. You may be lucky and get away changing that bearing. Left as it is the swarf from the bearing will go around the box in the oil and do more damage.
Dave

[david painter]

I feel if its noisy the damage has already been done. If you have had low oil and the fact its quiet in 4th, suggests to me the first motion shaft bearing is failing. With helical cut gears what oil is in the box is pushed backwards thus starving the First Motion shaft of oil. You may be lucky and get away changing that bearing. Left as it is the swarf from the bearing will go around the box in the oil and do more damage.
Dave

[MarinaCoupe]

Drain the gearbox oil and check it for bits of metal. Refill with fresh oil and drive it,to see if the noise has gone. Make sure that you use the correct oil, check your manual.

If the old oil is clean with no bits in that’s good. Measure how much oil comes out and compare it to how much you have to put in to get it back to level. The difference is how much you have lost through the oil seals. If it’s more than an egg-cup full, then the seals need replacing.

Let us know what you find.

[paul]

thank you Dave, Dave and Chris,
My thoughts exactly, drain check and refill. There's not a lot else i can do anyways! More than that is dramatic, time consuming and costly.
I will be gitting it up on the ramps in the next week or so, when i have time, and will report back to y'all.
The manual says a pint and a half of SAE 90, is that correct?
cheers

[MarinaCoupe]

Yes SAE 90 GL4 definitely not GL5.

[paul]

Late update!
Dave Dave and Chris, advice followed through, gearbox has clean , and correct oil, up to the level , already in the gearbox, so feel that sadly it a worn box. Will carry on ascit is , until it gets worse or unworkable.
I have two spare boxes, which Dave b. dropped off some years ago, which I can use if necessary. Which begs the question, what checks can be made to make sure the box isn't even worse than the one coming out, before it goes in?

're road speed noise, suspect rear axle, which of her checked I managed to squeeze in 400mls before level was reached, and now things are a little winter from that end, thank you.

[MarinaCoupe]

Paul, you didn’t say how much oil came out, to work out how much had leaked out.

[paul]

Hi Chris.
my mechanic, who did the gearbox oil a few months ago, and is the owner of the hydraulic ramp, and the only way i could get to look at the gearbox! Says he checked the oil for level, and was up to level , with the same clean oil he put in a few months ago. also reconing that it was the sae 90 i requested the first time.
cheer paul