C200K auto gbox noisy when towing

[Jim Sharpe]

After prolonged(50miles+) towing of 1250kg caravan the fan starts although the engine temp gauge reads normal. Also there is a more disturbing noise that appears to come from the gearbox and sounds like an hyd relief valve blowing. The gearbox continues to operate perfectly normally. Hardly noticeable at motorway speeds the noise is very irritating slower or manouvering. It continues when idling in neutral but stops after a short rest period. Should I be worried? What can be done? Will it be expensive? When not towing the gearbox behaves perfectly at all times. The transmission oil and filter were changed at the 4yr service six months ago. The problem did not occur prior to the oil change. Help, please!

 

[panason1c]

Could be a low g/box oil level or semi blocked filter and your description of the hydraulic type noise that you hear sounds to me like the pump drawing in air as it scavenges for oil, due to either of the above.

Firstly, check the oil level, it just might need topping up...... if that is ok then remove the g/box sump and check that the filter is not semi blocked by debris.............. as you say you have only experienced the problem since the oil and filter change, check that the filter is correctly fitted, it could be that the filter neck '0' ring is not properly seated thus causing the aforementioned 'scavenge' event.

 

[panason1c]

Update?

 

[Jim Sharpe]

Not yet actioned. Watch this space!