BMW M5 Forum and M6 Forums banner
1 - 11 of 11 Posts

·
Registered
Joined
·
54 Posts
Discussion Starter · #1 · (Edited)
I've been hearing tapping sound from the car for a while now. Sound is rather "soft" and doesn't sound particularly harmful, but I would like to get rid of it. Sound is dependent of the RPM, but it does not change character even if the RPM raised considerably - it is just more frequent.

Sound is noticeable when engine is warm and when engine oil is already slightly used (e.g. cannot hear it after an oil change for the first 1000km or so). Sound is also always there as long as previously mentioned conditions are met. I have listened to it with stethoscope. Sound is clearly coming from the 1-4 cylinder bank and around the rear of the block.

I already did the rod bearing job because of this sound, but the sound didn't go away, nor change in anyway. Timing chain tensioner is also new. I am also fairly certain that the sound has not changed or gotten worse since I first noticed it maybe 10 000 km's ago.

Ideas what might it be or ways to narrow options down?

 

·
Registered
Joined
·
54 Posts
Discussion Starter · #2 ·
I counted the knocks and the sound is clearly coming on every other rotation. That would indicate one of the valves, right? But what exactly could be causing the sound, in other words what should I plan to replace?
 

·
Registered
Joined
·
11,426 Posts
But what exactly could be causing the sound, in other words what should I plan to replace?
At this stage you have it narrowed down to a location. Now is the time to look. You measure the free space under the cam to lifter, that requires rotating the engine, just for a hint. You still will not know if it is a bad lifter or broken spring if you find one out. It could be something else. The point is that when you have things that far apart to replace something in the valve train waiting for the right part is not going to be a killer.
Before you take the valve covers off make sure it is not a leak in the exhaust gasket, but you usually don't hear those with a scope get louder or quieter as you move around. But you have to be the judge of that.
 

·
Registered
Joined
·
54 Posts
Discussion Starter · #4 ·
Thank you for the input. Based on the sound I think it is very unlikely that it is leaking exhaust gasket, since it can be heard so clearly coming from inside the engine with the stethoscope.

I discussed this with couple friends of mine and also read the discussion on the other related topic here where you also commented. Since everyone seems to think that broken hydraulic lifter or valve spring is very uncommon in S62, it seems that the best bet is there's just crap in the hydraulic lifter's oil channels that prevents it from working properly. I found that Liqui Moly has "Hydraulic Lifter Addative" to get rid of this crap in the oil channels. Given how big operation it is to change valve lifters/springs, I will test if the Addative will help first. I think there is a decent change it might :unsure:
 

·
Registered
Joined
·
11,426 Posts
Since everyone seems to think that broken hydraulic lifter or valve spring is very uncommon in S62, it seems that the best bet is there's just crap in the hydraulic lifter's oil channels that prevents it from working properly.
That sounds reasonable and so does the idea of a cleaner as a first step. It would not surprise me though that a piece of crud may not clean or dissolve with a cleaner, but sounds like the best first step. Lots of other cars use the same lifter.
Many of those have common lifter problems like the E34 inline 6, lesser problems on the E46 6 cyls but still not uncommon. On those the cure seems to be set replacement and as a result the aftermarket has jumped in with "sets" for reasonable money.
Amazon.com : 11321748881
 

·
Registered
Joined
·
54 Posts
Discussion Starter · #6 ·
Good to know that there are decent aftermarket lifters also, though I'm mostly worried about the amount of work in order to replace lifters rather than the cost :rolleyes:

I'll report back if the addative helps!
 

·
Registered
Joined
·
54 Posts
Discussion Starter · #8 ·
Not yet, I've been using my M3 since I stated the thread so I haven't yet had time to do this for M5. Plan is to do this soon though.

Instead of Liqui Moly's addative I decided that I will do motor flush with Forte's products and then add their "Top End Treatment" addative with the new oil as both of them should help with hydraulic valve noises. Forte's products should be pretty high quality at least on paper as they are used by official dealer services (by Mercedes at least in Finland) also.

I will report once I have it done.
 

·
Registered
Joined
·
431 Posts
Please let me know what the result is with the cleaner. I have the same issue now, caused by long term storage. Let the engine run for almost 15 minutes, no change at all. But have heard that it can take almost 3/4 of an hour before the sound disappears.
 

·
Registered
Joined
·
11,426 Posts
Let the engine run for almost 15 minutes, no change at all. But have heard that it can take almost 3/4 of an hour before the sound disappears.
It more often than not requires driving, higher pressures, and higher fluctuations. The lifter only tighten things, you can drive the car safely even if all the lifters were collapsed.
 

·
Registered
Joined
·
54 Posts
Discussion Starter · #11 ·
Not yet, I've been using my M3 since I stated the thread so I haven't yet had time to do this for M5. Plan is to do this soon though.

Instead of Liqui Moly's addative I decided that I will do motor flush with Forte's products and then add their "Top End Treatment" addative with the new oil as both of them should help with hydraulic valve noises. Forte's products should be pretty high quality at least on paper as they are used by official dealer services (by Mercedes at least in Finland) also.

I will report once I have it done.
I did the process now. It didn't take the sound a way completely. It's quite a bit quiter now though, but that's likely because of the new oil. In general hard to say if I there were any gains with the cleaning. The old oil wasn't that dirty/heavy after the cleaning and I haven't notice any change with the car. Probably didn't hurt either.
 
1 - 11 of 11 Posts
Top