Manual Gearbox Query

Technical questions and answers about the Mazda Bongo

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Ian
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Manual Gearbox Query

Post by Ian » Sun Nov 08, 2020 9:55 am

I am posting this on behalf of a new member who lives in North Carolina (!)

He has recently purchases a low mileage 1995 4WD diesel with manual transmission and reports the following problem. Can anybody help?

There is a problem with the clutch. (it has only 13k total kms.) When cold the clutch or something slips a little under high torque situations like full throttle in 3rd or 4th gear. You can see the tach rev up in RPMs while it slips. And then it settles back down and drives normal for just steady driving. After running for 30 minutes or so, it doesn't slip any more. I've tried replacing master and slave clutch cylinders to no avail. And weirdly I had to add over a quart of gear oil to the tranny to fill it up. But it is not leaking that I can tell. The situation is the same right now after those attempted fixes. Just this week I went ahead took the plunge on a 250km + trip. Some slippage when I first started out and then no problem for rest of trip.
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rita
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Re: Manual Gearbox Query

Post by rita » Sun Nov 08, 2020 5:21 pm

Owing to the fact that the GB is losing oil there is a strong possibility that the GB spigot seal is leaking and oil going on the clutch and driven plate.

Check the drain hole on the bottom of the bell housing for signs of an oil leak .
DaveH76
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Re: Manual Gearbox Query

Post by DaveH76 » Sun Nov 08, 2020 5:45 pm

And of the gearbox oil loss was a one-off due to perhaps not being filled to the maximum level after the gearbox was last removed then I would be looking at an inferior clutch pressure plate.

I have had a similar issue with a Ford Connect and the only way to rectify was to get a genuine Ford part.
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Northern Bongolow
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Re: Manual Gearbox Query

Post by Northern Bongolow » Sun Nov 08, 2020 7:16 pm

When I first got my manual boxed bongo the clutch was terrible, they do seem to be not up to the job, new master and slave kits helped, new clutch fitted later, the best quality one I could afford helped further, it did seem to work better slightly loose on the adjustment rather than where it says in the manual.
Recommend that all things are also looked at like wheels and tyres sizes and pressures, props and transfer box etc, any wind up in the transmission can really load up the resistance to travel and load the clutch.
As said above inspect the seals to the bell housing through the drain and you can view with a camera through the side of the bell housing if you remove the bearing fork seal at the slave cylinder.
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BongoNC
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Re: Manual Gearbox Query

Post by BongoNC » Wed Nov 11, 2020 5:24 pm

Thanks all for your responses. So excited to be a new Bongo owner. The Bongo name alone causes instant smiles to anyone who sees it.... ... OK, so last week I had completely swapped out the tranny oil to new Mobile 1 synthetic gear oil. It of course made no difference. There is still some mild slipping under high torque demand in higher gears for about the first 20 minutes of driving. The seal issue mentioned by @Rita sounds like a real possibility. I will get back under the Bongo later this week to try to find that drain hole in bell housing. I'm a novice at things mechanical but will check it out. And also thanks @DaveH76, might also look into your suggestion on trying to see inside. @northern bongolow - agree on all things to check - tires are proper size and inflated, transfer case is slap full of oil as well. Total kms on the odo now at 14km. The journey continues!
1995 Mazda Bongo Friendee 5MT 2.5TD WLT engine SGLR chassis 4WD
DaveH76
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Re: Manual Gearbox Query

Post by DaveH76 » Thu Nov 12, 2020 11:18 pm

You will not see anything faulty if you look inside the bell housing if the clutch pressure plate is weak. I am afraid it will be a case of fitting a new clutch and trying it, so this may be the last thing to try because of the cost.
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BongoNC
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Re: Manual Gearbox Query

Post by BongoNC » Mon Nov 16, 2020 12:24 am

Hello again. I crawled under my Bongolow today and had a look at the bottom of the bell housing. Every surface around the hole at the bottom are bone dry. I can't find evidence of any trans oil coming out of bell housing nor the transmission itself. Attaching a photo of the rear side of bell housing. Sigh. Maybe this is leaning toward just a bad clutch? At only 14km total miles.
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Manual trans back of bell housing
Manual trans back of bell housing
1995 Mazda Bongo Friendee 5MT 2.5TD WLT engine SGLR chassis 4WD
rita
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Re: Manual Gearbox Query

Post by rita » Mon Nov 16, 2020 11:30 am

It would be worth checking that the withdrawal lever has clearance and not sticking.

Another way to check the strength of the clutch assay is to drive the vehicle at a fair speed keeping your foot on the accelerator , quickly dip the clutch and release. If the clutch is faulty you will know.
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BongoNC
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Re: Manual Gearbox Query

Post by BongoNC » Tue Nov 17, 2020 5:28 am

Thanks Rita. Is the withdrawal lever you mention behind this square rubber gasket that the clutch slave cylinder attached to?
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PXL_20201115_192556507.jpg
1995 Mazda Bongo Friendee 5MT 2.5TD WLT engine SGLR chassis 4WD
rita
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Re: Manual Gearbox Query

Post by rita » Tue Nov 17, 2020 10:38 am

BongoNC wrote: Tue Nov 17, 2020 5:28 am Thanks Rita. Is the withdrawal lever you mention behind this square rubber gasket that the clutch slave cylinder attached to?

Yes thats thats the lever.
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BongoNC
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Re: Manual Gearbox Query

Post by BongoNC » Wed Nov 25, 2020 3:39 am

@rita I got under my Bongolow tonight and removed the clutch slave cylinder and the rubber boot covering the clutch lever in the bell housing case. I couldn't tell is anything is out of sorts but i made a quick video showing the action of the lever with nothing attached to it.

https://photos.app.goo.gl/hHgrTvS6YzUNH19y7

Hope that link works.
The picture below here just shows the lever with the boot off.
Slave cylinder and rubber boot removed
Slave cylinder and rubber boot removed
1995 Mazda Bongo Friendee 5MT 2.5TD WLT engine SGLR chassis 4WD
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