last thurs i developed the dreaded timing rattle. i took the front end apart in a panic thinking it was the sc (both ends of the sc had plenty of oil). i changed both idler pulleys with no improvement. the car, apparently, went pretty low on oil (1.5 qts) in a short period of time (drips were found where the pan meets the gearbox). once i realized it was coming from the timing area, i changed the chain tensioner with no luck (still rattled). now i've got a big oil leak & 'death rattle' symptons, so i took the car to my mechanic (a crew i trust). they say the rattle is indeed from the timing end, but they also did a compression test. it had 90-95psi across 3 cylinders & 135psi on the 4th. they said it's not worth doing the repair to the timing end just to find out what's causing the low compression problem. they're concerned the engine is dunski. i still owe $7000 on this car. some thoughts & opinions would be appreciated.

 

+1 on your mechanics advise. But, question, did you pull the tensioner back out after you changed it to make sure that it even expanded? Sure it doesn't have an impact on compression but could still be your rattle.

 

yeah, i sure did. it dawned on me that the old 1 came out fully extended. the 1st step i took, with no change in the rattle, was to take out the new 1. it was fully extended.

 

How well does the engine run? Also, how many miles showing on the odometer? I would do the compression test again just to make sure.
Did you change both tensioners and the chain guide or just the external plug type tensioner?

 

If you're chain rails have broken apart from driving on the worn tensioner then you can drop the pan and check for plastic bits at the bottom of the oil pan. Loose timing chain/ improper timing from broken guide rails can cause low compression. Seen a couple Audi's in the shop before that were improperly timed that came in with low compression.

The mechanics have given you their best guess but that's all it is until further $$ is shelled out for more in depth diagnosis. Have them drain the oil through a mesh screen to catch any plastic bits. Drop the pan and check for more. Remove valve cover and cam or cam gear or whatever is necessary to remove the chain guide rails.

The rails are only $50 or so. It is DEFINITELY worth it to get a positive diagnosis when you're talking this big of coin on repair.

 

i didn't press the engine after the rattling started. i was short shifting, so i'm not sure i have a good feeling for how it was running. i do know this, i could downshift & let the car decel from 5000rpm & it sounded/felt normal with no rattle. car has 135,000 miles. wasn't aware that there was any other tensioner except the external one. that's the one i changed. did not go into the timing cover.

 

did the audi(s) have low compression across the board or only in certain cylinders? they were concerned because the compression numbers were not even. well, draining the oil is easy enough. the rest of those checks could end up costing quite a bit, however. i'm probably gonna pick the car up & start going thru all that myself a weekend at a time. apparently, i'll need to get used to riding the triumph in the rain for a while.

 

If this were my Cooper S I would plan on buying a new timing chain, guide and the internal tensioner and the related oil pump seals. You should remove the timing chain cover and oil pan too as previously suggested to inspect for damage, debris and the source of the rattle/noise. At 135,000 miles of service the nylon portions of the timing chain guide and internal tensioner could have severe wear. Just removing the cylinder head cover will only give a partial view of the timing chain system so the front cover needs to be removed.
Also, how often do you change the engine oil and oil filter?

 

yeah, i think i'm with that plan. the only thing that throws a wrench (pun intended) into that plan is the fairly large oil leak. if that turns out to be the rear main, i'm not sure i could do that myself (i've heard it's a tuff job).

and, i'm good for changing the oil twice a year (falls every 7500 miles, or so). purolator filters & rotella t6.

 

If this were my Cooper S I would reduce the oil change interval to only 5000 miles and use only OEM oil filters. Search for the thread on the oil filter with the broken plastic oil drain back valve to see why. If you live and drive in a cold climate I would use 0-40 Mobil 1 for cold operating conditions and for good lubrication flow on cold starts.

 

well, we could start 'another' conversation about filters & oil. the start of this whole mess was not due to change intervals or type. it was due to severe loss of oil in a short period (2 weeks) with no signs (i.e. drips, puddles, oil 'pinstripes', etc). peanut butter would be better in the crankcase, than nothing at all.