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Good question...unfortunately I'm not sure of the answer. The solenoids/actuators seemed to be working when I tested them with the durametric. I'd really rather not change the actuators @ 1k apiece - only to find out that I'm still in the same boat. I wonder if it could be the chains (stretch?) They certainly looked ok, with no visible signs of damage. I did order new ones which I should have in another day or so. I'll probably pop the cams back out and change the chain - the first time was good practice.
Good question...unfortunately I'm not sure of the answer. The solenoids/actuators seemed to be working when I tested them with the durametric. I'd really rather not change the actuators @ 1k apiece - only to find out that I'm still in the same boat. I wonder if it could be the chains (stretch?) They certainly looked ok, with no visible signs of damage. I did order new ones which I should have in another day or so. I'll probably pop the cams back out and change the chain - the first time was good practice.
Is chain stretch something you can measure?
Forgive me as I don't know too much about this topic, but, wouldn't chain stretch take quite a large number of miles to occur?
I think the deviations we're talking about are in the thousandths of inches, so measure? yes. Large # of miles? It all depends - mechanical things fail at different rates for all different reasons. FYI, I'm pretty sure my engine has at least 100k miles on it (I'm pretty sure it's not the original engine). The vario-cam pads have clearly been replaced, but I don't know when - and I don't know if the chains were done at the same time.
I think the deviations we're talking about are in the thousandths of inches, so measure? yes. Large # of miles? It all depends - mechanical things fail at different rates for all different reasons. FYI, I'm pretty sure my engine has at least 100k miles on it (I'm pretty sure it's not the original engine). The vario-cam pads have clearly been replaced, but I don't know when - and I don't know if the chains were done at the same time.
I'd be curious what other components you'd be able to measure to root cause this. Maybe the sprocket teeth are out of spec?
Just thinking out loud.
I appriciate the thoughts...I suppose it's a possibility, but there are other more probable causes I would think. Especially, seeing as there are 5 chains...There are a lot of moving parts to a chain so they would be my first guess. Unfortunately, most of them are buried in the crankcase...
Yes those pads have definitely less than 50k on them, your code could have came from the timing being set on the verge of being out of spec and with a little more chain wear it set the lite off. I'm guessing you didn't log the deviations when you first got it?
The chains CAN be measured for "stretch". It's really not a stretch but a wear of the pins and links in an oblong pattern stacked up over many links ends up lengthening the chain. ALL the chains in the early 5 chain motors weather it's the short cam to cam single row chains, or the long IMS to cam double row chains are .375 pitch.(meaning .375 from center of pin to next center of pin), So for 14 links it should measure 5.250 inches, 28 links 10.500 inches ect. The general rule for industry is 2% wear, but on critical chains such as this I suggest 1%. It's a bit hard to measure and with a tape measure it is not real accurate, so I use a dial or digital caliper and with the INSIDE tips measure INSIDE of 14 links. With measuring the INSIDE of 14 links you have to subtract the diameter of the roller which is .250, so the "new" length should measure 5.000 instead of 5.250. Then you can just do a little math and determine that .25% =5.012 .50%=5.025 1%=5.050 2%=5.100. I suggest replacing at 1%!!
I didn't do a data log in Durametric (I don't think), but I did take photos of my screen, so I do remember the deviations. Bank1 was -6.13 and Bank 2 was -7.25
So, I installed a new vario-cam chain yesterday (Iwis). It's even easier the second time around...One discrepancy I ran into was the torque values on the exhaust cam sprocket. Knowledge Gruppe - has them being torqued to 14nm and the Bentley Manual has them at 10nm... I used Jake's #'s as 10 nm (7.5 ft lbs) seems a little light for those bolts? Any feedback?
I agree, the 10nm (7.5 ft/lb) is the Porsche spec also, and seems to be to light. Makes me a bit nervous to leave them at that. I always go a little higher just to make myself more comfortable.
I agree, the 10nm (7.5 ft/lb) is the Porsche spec also, and seems to be to light. Makes me a bit nervous to leave them at that. I always go a little higher just to make myself more comfortable.
It seems that the current revision is 14 nm. I hope I don't have to drop my engine in 2018 (next revision) just to tighten up my cam chain sprockets !
I did bank 2 yesterday afternoon - all very similar. Vario-Cam pads barely worn. Changed out the vario-cam chain and pads anyway. Did the cam timing on bank 1, and stopped there. I should get to timing bank 2 later on this afternoon. I won't post any photo's, as they're pretty much identical to bank 1. The cam cover sealant while pretty heavy on bank 1 was just ridiculous on bank 2. I'll post a photo of that later on as I saved all the stuff I scraped from the edges (inner and outer)... I should start reassembling the engine after I get the second bank timed and will hopefully have it done by the end of the week. Maybe even get it installed next week...
Ha! Oh well, never mind... it looks like it is a different part, but it was listed in the parts drawings as the same part # - I must have just gone with the first one on the list (it was also a few $ less, but that wouldn't have made a difference had I realized it was different)... Anyway, I'll just put the original one back in 'til I get the new one.
Great thread Dporto...following along with interest and the hope I don't have to do it! I am getting geared up to do the IMSS on my car as well. Is it a good idea to replace all three tensioners? I was under the impression there was a design change or??? My 2004 has 40K miles...
06-06-2017, 09:25 PM
