Ticking noise from OD pump?

[Micha_H]

Hello all,

over the last winter I placed a XJ6 OD manual box into my S1 2+2 automatic. The conversion went well straight forward, the only missing is the cover on the tunnel. Doing so I did a test ride without this cover. The gearbox and OD worked really well, but there is a ticking noise. I´m quite sure it is originated from the OD pump, it went up and down by speed, independent from the engine RPM, and is accelerate when I disengage OD, so it in line with the RPM of the gear box shaft between main gearbox and OD. I´m wondering if it is normal or if something went wrong by reassembling the OD that getting a complete overhaul including a new pump. On the other hand, function wise it operates perfect.

Has anyone experience how loud it is usually without a cover on the tunnel, on my MK2 I never heard this, but I never drove it without cover on the tunnel.

If you like to hear it: https://drive.google.com/open?id=1_4QRv ... b7Jw6RCYhK

I'm a bit nervous, everything works nice, but if I now damage something I can redo almost the complete job.

Regards
Michael

[angelw]

Michael Wrote:

it went up and down by speed, independent from the engine RPM, and is accelerate when I disengage OD, so it in line with the RPM of the gear box shaft between main gearbox and OD. I´m wondering if it is normal or if something went wrong by reassembling the OD that getting a complete overhaul including a new pump. On the other hand, function wise it operates perfect.

Hello Michael,
Your description doesn't necessarily point to the OD being the problem.

Unless disengaged via the clutch, or the gearbox being in neutral, the final drive and therefore rear wheels, are inexorably connected to the engine. Accordingly, whether by overrun, or drive from the engine the noise won't necessarily be independent of engine RPM.

The shaft you describe as being being between the "main gearbox and OD" is in fact the Main Shaft of the gearbox. Normally the OD is applied to 4th gear. Therefore, the Main Shaft RPM will be the same as the Engine RPM. When shifting to a lower gear, the engine and gearbox Main Shaft RPM will increase until engine braking has slowed the vehicle to a point where the engine is not being overrun by the car. The same applies when switching the OD off, therefore, there will be an increase of engine and gearbox Main Shaft RPM when the OD is switched off. If the noise is coming from the gearbox, then it would follow that the frequency of the noise would increase when the OD is turned off.

I would do more tests to determine more exactly where the noise is coming from. A common source is the Reverse Idler Gear. Start with the car stationary, the engine running and the gearbox in neutral. If your noise is heard, the noise is emanating from the gearbox. Another test would be to have the car coast with neutral selected and clutch disengaged (clutch pedal depressed). In this case the gearbox Main Shaft will be rotating with not much movement of the other components. If your noise exists in this scenario, then its a bit more likely the noise emanates from the OD.

Regards,

Bill

[PeterCrespin]

I'm a bit nervous, everything works nice, but if I now damage something I can redo almost the complete job

Was going to suggest speedo cable stick-slip. It’s not normally heard unless cover is off, or at the top by the dash top being missing. Havibg listened to the noise I now doubt it has anything to do with the cable. Exhaust leak?

[Micha_H]

Hi all,

I did some testing today, first I removed the base valve of the pump. Ok, no noise on the short test loop around the house.

Then I put a small copper washer between valve body and pump. I did so because I saw on another pump I had in my stock that the pump lift is limited first by the valve body.

The result was initially surprising good, but after the gear oil warmed up completely it came back. Maybe a bit less but still ticking. I'm still with the idea that it is from the pump. It depends on oil temperature and gets less when OD is engaged. I'll check again without the valve and warm up the oil again.

Once it is the pump I will check whether the pump can be placed slightly less deep into the mail block.

Regards
Michael