Third Gear Howling - Gearbox Questions

[Kauai1800]

Aloha Guys

Out for a ride today in my 1800 and third gear started to make a loud howling screeching sound. The other gears are OK it seems. I have a '64 1800S with Laycock OD...M41.

Couple questions - how on earth do you change the gearbox oil? I have 2 manuals for this car and neither one explicitly tells how to do it. There's one photo (with no supporting explanation) showing the 2 bolts for filling and draining - these are on the gearbox under the car? Is this the only way? I bought 2 liters of plain M30 weight oil for this.

I recall people talking about adding gearbox oil through the shifter - is this only for Amazons? Or something about adding oil through a "top plate"? I've searched the forum threads but haven't found the info I need.

What's the chance that adding oil to the gearbox will fix this 3rd gear screeching issue?

And if not, are parts available for the M41?

Thanks in advance!

[c1800]

Drain from the lower one and fill from the upper one. the oil flows from the tranny into the OD so you'll need to be sure you give it enough time to flow there. I'd suggest if it hasn't been changed in a long time that you do this twice to give it a flush. Also once it's filled and you've run it for a few miles, check the level and top up as required. As to the screech, it may, but typically that sound is something on the way out. Let us know how it works out and good luck!

[Kauai1800]

Thanks c1800.

I topped it off (can't say that was convenient) and drove it around - but no change. I'll get more SAE30 and flush it tomorrow, but don't think it is going to solve the problem.

Only third gear is making the noise. It's more of a "whirrrrr" and mainly happens on upshift. On downshift it doesn't really make the noise at all.

Any more ideas or comments?

Sounds like I'm going to have to have the gearbox taken out and gone through.
I can do a lot of work myself, but not transmissions.

[dingov70]

When only one gear begins to whirr , whine or scream , it is normally due to
A) low oil level which B) leads to wear in any bush that supports the gear on the shaft or C) a needle roller bearing has worn / picked up debris in the rollers .

Due to the wear occuring , you may get enough movement that means the gear teeth no longer mesh accurately & become noisy as a result . The only proper way to find out is to remove & strip the box , BUT only after you have drained the gearbox oil and peered into it's murky depths . Sparkly silver or "gold " particles tell you everything you need to know , as these are metallic particles have been worn off the gearboxes internal surfaces

Drain the oil & post an image of what you find as we can then advise further

Hope this helps you . good luck

[Derek UK]

"loud howling screeching sound" sounds more like clutch release bearing. It's rare for a loud noise to suddenly appear (sic) from the gearbox. Bearings get noisy slowly. Is the noise continuous or only when you change gear? When the engine is running, have a close listen around the bell housing area. If the release bearing is noisy the bell housing tends to amplify the noise.
All this related to the fact that my estate goes in to the garage tomorrow to have the bearing changed. New clutch fitted just before the Amazon meeting and I made the mistake of requesting them to fit an all steel type one that I had instead of the plastic type one that came with the LUK clutch. It works but is very noisy. I think it's being driven all the time, and singing away to itself, by the LUK diaphragm arms which stick out a lot more than the F&S and B&B ones (B&B came out). Expensive mistake and wiser after the event as long as the plastic bearing cures the problem! Must get up to the garage to take the rubber mat etc out, don't want them splitting that!
While you are under the car, check your clutch slave push rod adjustment. With the spring flipped off there should just be a small amount of play in the lever. 2mm 3/32" is fine.

[iwakbogo]

Originally Posted by Kauai1800

Thanks c1800.

I topped it off (can't say that was convenient) and drove it around - but no change. I'll get more SAE30 and flush it tomorrow, but don't think it is going to solve the problem.

Good luck !!!

[mike gilbert]

As you've found it is awkward changing the gearbox oil without a pump as you need to get above it for gravity to do its job. If you take the centre carpet out you will find holes in the transmission tunnel that have rubber bungs in. You're supposed to be able to access the filler hole from above through one of these, and you can but there is not a lot of room to manouvre the pipe into the hole.
You can take the gearstick out and pour it down the remote linkage but the gearstick is 'sprung' in place so putting it back can be awkward unless you have a helper to hold it down while you do up the allen bolts. And you may need to jack up the rear wheels so it flows forwards into the box. Remember to remove the old grease from the 'hole' first and re-grease afterwards.

[rainflye]

I have an ES but gearbox is probably similar. To fill I get a long piece of hose that will fit in the fill hole of the gearbox. Run it up through the engine bay and stick a funnel in the end. You can add small amounts of fluid checking for overflow at the gear box frequently. If you have completely drained the gear box just add the full amount listed in the spec.

Having fun!

Craig

[Volvo_133]

If you do drain the oil to replenish with new, the overdrive has a plate on the same side as the filler level plug. This plate is held in place with 4 small bolts.
When drained, remove plate, you will find a filter gauze basket and magnetic washers. These need thoroughly cleaning in paraffin, white spirit etc.
The contents of the filter will also give an indication as to the condition of the g/box.
Chris.

[Kauai1800]

Thanks guys.

Derek - would it possible for the clutch to only make the noise in 3rd gear?
I would prefer it to be a clutch issue - but I would think that would affect all gears. And I'm confused: am I listening to the running engine to see that the sound IS there?

The sound is a whirrrr that only happens when I shift into 3rd gear, mainly going up the gears. It gets louder and fainter if I drive in 3rd (which I'm trying to avoid) like whirrr WHIRRRRR whirr WHIRRR - so it's not only at first when I change gears. When I downshift into 3rd from 4th there's really no noise at all...but I only was in 3rd for 15 sec or so.

Unfortunately I'm completely deaf in one ear so I can't localize sound very well. I can feel the sound coming through the housing and into the stick shift but I can't distinguish exactly where the source is.

And thanks everyone for suggestions on how to fill the fluid. I took a hose and a funnel and some silicone tape and made something that only leaked 20% of the oil all over the place. Until I kicked over the oil can - that made a real mess. I'm debating whether to pull the lower plug, flush the system and look for "magical gold" or just take it in and have the garage have a look.

I can see that clutch plates are available and so are some of the bearings and bushings for the M41.

ps...I just called the "good" repair shop and they won't work on this - too complicated. I've got a call into the "bad" shop and we'll see what they say. My options here are very limited.