95 Audi S6 steering/belt tensioner issues

brakes
steering
belts

#1

Patient is a 1995 Audi S6

5 cyl. 2.2L turbo

145k miles



The serpentine belt tensioner is making a clicking noise like it did before I replaced it about a year ago. Happens at low rpm with more load on the engine (3 point turn). I replaced the pwr steering pump at the same time and the high pressure hoses (a bit later) connecting it to the steering rack and the brake pressure accumulator.



It seems that I am prematurely wearing down the belt tensioner bearing or just that there is additional tension on the pulley due to one of the ancillary systems. This happens with the AC off so I have ruled that out for now (the AC compressor turns smoothly when disengaged). Only other pulleys are the viscus fan which also turns smoothly and alternator (no problems). Upon removal and inspection of the tensioner pulley the bearing still rotates smoothly without noise so it is possibly just additional duty on the tensioner and that no destruction of the bearing has yet to take place.



Upon removal of the serp belt I noticed that the steering pump has rotational difficulty for about 60 degrees of rotation. This only happens when the system is pressurized with hydraulic fluid. The pwr steering pump has 2 functions on this car; pressure to steering rack and pressure to brake pressure accumulator.



My theory is that the pressure relief valve or the check valve (2 separate valves) in the brake pressure accumulator is not functioning properly and causing undo back pressure on the power steering pump and therefore on the serp belt tensioner.



I do have adequate brake pressure and the brake pressure light does not come on. So, is it possible that the relief valve in the pressure accumulator is not functioning properly? This valve runs back to the reservoir which does seem to maintain a proper fluid level (not too low and does not overflow). Is it possible that the relief valve is just clogged up with debris and is working but not as well as it should?



I did recently replace the high pressure hoses in this system because they had both sprung a leak. I did flush the system with new fluid upon installing the new hoses however it may be possible that some of the hose debris was passed through the system and potentially into one of these valves.



I did swap out a newer pressure accumulator at the time of the power steering pump replacement and since swapping back in the original I have noticed that the newer one does maintain the proper brake pressure while the original does not.



Does the diagnosis of a failed/clogged pressure release valve make any sense? How else can I troubleshoot this without purchasing a pricey new brake pressure accumulator or the appropriate pressure tester? Should I just take it to a shop and have them hook up a pressure tester?



Thanks in advance for your comments.




#2

A dirty serpentine belt (debris in the low sections on the drive side of the belt) will cause noise. As your tensioner is quiet when turned by hand maybe a belt replacement is all you need.Your post did not mention belt replacement. By time and mileage a new belt is called for.Just a thought


#3

Yeah, the belt is new too. I even measured it against the factory specifications as someone else had suggested the belt may have stretched. Not so here though. Thanks for the comment.