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Just curious if the chain tensioners on the 997S use oil pressure, or if they are just spring loaded. My chains rattle for a second when the car sits for a couple of days - sometimes on random mornings.
Loud rattle (top down) but goes away almost instantly - like if the oil pressure takes a second or 2 to build up.
I have read through numerous threads in this forum and it seems like the OEM says it is normal and Jack Raby says its trouble.
Looking for comfort here. My 997 is 53K miles now. Maybe chain tensioner replacement would help?
Fair warning: I am essentially ignorant on this subject -- except for this one tidbit. My engine (M97) was rebuilt at 47,000 miles as a result of badly scored cylinders. After the engine was completely dismantled and inspected, the tensioners were, in fact, badly warn. My builder substituted a new-and-improved tensioner from LN Engineering for this reason. I have only driven the car about 13,000 miles since then, but the chains do not rattle at all. FWIW.
Since 1984, all Porsche 911s have had oil fed tensioners. That does not mean they don't fail occasionally leading to chain rattles. They normally have a check valve that holds pressure to eliminate start up rattling, but a little rattling at start up is OK. if it lasts more than a few seconds, I would investigate further'
Change your tensioners. Start up rattle will damage the plastic guides over the metal paddles, sometimes even breaking off chunks of them. When the guide is gone or broken, you're done as the chain then starts riding on the metal paddle itself and you have to take the engine apart to replace them. For anyone with this start up rattle, have you ever pulled your sump plate to see if there are pieces of black or brown plastic in it or in the filter media. That's the plastic guide material being worn or broken away. They shouldn't rattle on cold start.
The search function on my phone is still a mystery. Is there a DIY for changing the tensioners for those who may be interested in doing so? I imagine this is different on the different motors.
Tools: -Tensioner torque 59 ft-lb -32 mm socket or 1.25 inch -fairly large 8 mm(?) hex key (for bank 2)
Parts: -primary/ims chain tensioner - one ring marking; 996-105-180-58-M100; installs on crankcase near oil filter area; rear of engine -cylinder bank 1-3 - two rings marking; 996-105-186-02-M100; left lower area on cylinder head; points straight down -cylinder bank 4-6 - no marking; 996-105-188-02-M100; right upper area on cylinder head -crush washers usually come with the tensioners -camshaft plugs - 4x - 996-104-215-54
Steps: -index the engine to TDC -remove the bottom bank 1 camshaft plug (looking into engine bay; to the left and look down) -inspect the camshaft slots to ensure they are straight up and down, if not rotate the engine 360 deg; inspect the camshaft slots to ensure they are straight up and down -lock the crank/pulley with a 5/16 inch or 8 mm pin -lock the camshaft for bank 1, rear of engine, left side; use the modified cut-in-half lock tool -unloosen all the coolant hard tubes to gain access to the head of the IMS chain tensioner -replace the IMS tensioner (has one ring) (flywheel end of engine; right side of engine; a few inches up from bottom of engine) -replace the bank 1 (cylinder 1-3) tensioner (two marking rings) (left side/bottom of engine) -remove the camshaft lock -install the new camshaft plug
[here's the "harder" one because one has to move the AC compressor] -remove the TDC pin -rotate the engine 360 deg -lock it with a 5/16 inch or 8 mm pin -lock the camshaft for bank 2, front of engine, right side -move the AC compressor out of the way -replace the bank 2 (cylinder 4-6) tensioner -install the AC compressor -remove the camshaft lock -install the new camshaft plugs -remove the TDC pin
I have some noise on cold startup too, though mine lasts closer to 15-30 seconds before going completely silent. Could be tensioner, not sure. Aside from tensioner or a sticky lifter, what else could cause sound like this? An interesting thing I notice is that the ECU holds the engine idle RPM high for a bit on cold start (as all cars do) but I notice as SOON as the ECU drops the idle down to normal speed (after 15-30 seconds), the sound goes away completely, as if the two things are linked, leading me to wonder if that noise could be something else like a secondary air pump or something?
I have some noise on cold startup too, though mine lasts closer to 15-30 seconds before going completely silent. Could be tensioner, not sure. Aside from tensioner or a sticky lifter, what else could cause sound like this? An interesting thing I notice is that the ECU holds the engine idle RPM high for a bit on cold start (as all cars do) but I notice as SOON as the ECU drops the idle down to normal speed (after 15-30 seconds), the sound goes away completely, as if the two things are linked, leading me to wonder if that noise could be something else like a secondary air pump or something?
I think you're going to need to visit someone who's experienced with the flat 6 engine sounds.
15-30 seconds is seemingly too short for true warm-up to affect clearances.
It's too long for normal tensioner behavior. Meaning they should pump-up in 1-2 seconds.
Get a buddy and have them start the car while you're using a mechanics stethoscope to safely listen to things.
Prior to one engine start, remove the serpentine belt to take it temporarily out of the equation.
Does the amount of "garage time" seem to influence the behavior? Meaning, the more it sits between starts the longer there's noise? This could mean a tensioner is bad and leaking down. Not sure if lifters display the same correlation.
I think you're going to need to visit someone who's experienced with the flat 6 engine sounds.
15-30 seconds is seemingly too short for true warm-up to affect clearances.
It's too long for normal tensioner behavior. Meaning they should pump-up in 1-2 seconds.
Get a buddy and have them start the car while you're using a mechanics stethoscope to safely listen to things.
Prior to one engine start, remove the serpentine belt to take it temporarily out of the equation.
Does the amount of "garage time" seem to influence the behavior? Meaning, the more it sits between starts the longer there's noise? This could mean a tensioner is bad and leaking down. Not sure if lifters display the same correlation.
Thanks for the reply. Yes I'm quite new to the flat 6! So. Many. Sounds! Have only had the car a couple weeks.
Happens on any cold start when it's been sitting overnight. Doesn't seem to be any worse after 5 days vs 1 day. Serpentine belt is new.
I've been wrenching on cars for years but this thing is so unique to me at this point that that I think I should just heed your advice and take it to the awesome local Porsche indy shop and see what they say. Could be something normal. And I haven't heard many people complain of timing chain issues on a 997.2.
If it is a timing chain rattle at start up get it checked out ASAP, visit BMW and Merc forums major topic, this was posted days ago on this forum, 2014 Boxster 3.4s engine for sale $2, 500, car has done 47,000 miles. This car had auto stop/start which I believe makes this problem worse.
Since 1984, all Porsche 911s have had oil fed tensioners. That does not mean they don't fail occasionally leading to chain rattles. They normally have a check valve that holds pressure to eliminate start up rattling, but a little rattling at start up is OK. if it lasts more than a few seconds, I would investigate further'
So a loose timing chain at startup is OK
Chain links riding up the teeth of the timing gears causing gear teeth to wear is not OK, there is the possibility a loose timing chain at startup with worn cam gear teeth could jump a gear tooth and loose timing. this may cause engine damage possibly like pics in my last post.
If the car has stop/start tech starting car dozens of times each day is even worse, these engines are very expensive get it checked out.
I think Jake's official position on this was "REPLACE YOUR TENSIONERS! Any death rattle at startup is not NORMAL. Its your chains guides 'beating your chains into submission' from a failed tensioner." Check your oil filter for brown debris. Thats from your chain guides.
Get them replaced. I think they are inexpensive and pretty easy to install on a 997.1.
Change your tensioners. Start up rattle will damage the plastic guides over the metal paddles, sometimes even breaking off chunks of them. When the guide is gone or broken, you're done as the chain then starts riding on the metal paddle itself and you have to take the engine apart to replace them. For anyone with this start up rattle, have you ever pulled your sump plate to see if there are pieces of black or brown plastic in it or in the filter media. That's the plastic guide material being worn or broken away. They shouldn't rattle on cold start.
I inspected my oil filter during my oil change this weekend and found these black bits in there. They look like hard / black plastic bits and I saved the larger ones I found. Possibly from the chain guides. What do you think?
I do have occasional chain rattle episodes on cold starts after the car sits a couple of days (loud but for just a second). I am looking into replacing the IMS chain tensioner soon just in case.
I also send an oil sample to Blackstone to see what it says since the bore scoring scare is getting to me.
10-09-2019, 03:28 PM
Chain Tensioners
