When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
sorry
Im new to the 997 and might be buying a 2007. SoCal car.
First the IMS and now scored pistons? Good grief
How worried should I be about this? Is this just another blown out of proportion issue like the IMS?
thanks
sorry
Im new to the 997 and might be buying a 2007. SoCal car.
First the IMS and now scored pistons? Good grief
How worried should I be about this? Is this just another blown out of proportion issue like the IMS?
thanks
It's a big enough problem that you should include bore scoping in your PPI. This requires the sump to be dropped - bank 2 (cylinders 4 through 6) are most susceptible.
@JustinCase
Interesting; It does sound to me like a thermal expansion issue; post#167 by @Charles Navarro indicates problems are most likely on one cylinder bank, and at that, I've read that one cylinder is more likely than others. If that's the case, it would mean there is a larger than normal cooling disparity across the engine. I don't know if coolant pump with more capacity would help, but certainly, I'd baby that engine for an additional 5-10 minutes AFTER oil and coolant are at normal operating temperatures. It also occurs to me that low-load and higher RPMs (not exceeding ~3,500 RPM or so) might be much better than trying to maintain lower RPMs, but needing to place a greater load (to accelerate) on the piston/bore considering the greater tangential force on the bore from the piston caused by accelerating at lower RPM. I think over-revving is usually caused by an improper down-shift, not acceleration. After heavily modifying a water-cooled 1.8L VW engine, I used to regularly over-rev by 1000 RPM under load before the torque diminished and required me to shift; so my feeling is that since torque is diminishing during over-revving, momentary or accidental over-revving is not likely to cause bore-scoring due to loading issues, but by excess heat if it's done for extended periods of time.
One thing I would suggest is that you record the sound of your engine at idle and maybe under load if possible, and use any of the free audio editing software available to analyze the sound sound wave. If your recording resolution is set to "best" on a good smart-phone, you should be able to visually see abnormalities in the wave, particular to a cylinder. This way if everything is fine now, but you start to think you have a problem, you will have something to compare it to.
Lastly, EBS Racing, who rebuilt my engine for the previous owner, insists on using DT40 Racing Oil in the engine, and since they see a lot of engines, I'm not going to argue with them.
@JustinCase
Interesting; It does sound to me like a thermal expansion issue; post#167 by @Charles Navarro indicates problems are most likely on one cylinder bank, and at that, I've read that one cylinder is more likely than others. If that's the case, it would mean there is a larger than normal cooling disparity across the engine. I don't know if coolant pump with more capacity would help, but certainly, I'd baby that engine for an additional 5-10 minutes AFTER oil and coolant are at normal operating temperatures. It also occurs to me that low-load and higher RPMs (not exceeding ~3,500 RPM or so) might be much better than trying to maintain lower RPMs, but needing to place a greater load (to accelerate) on the piston/bore considering the greater tangential force on the bore from the piston caused by accelerating at lower RPM. I think over-revving is usually caused by an improper down-shift, not acceleration. After heavily modifying a water-cooled 1.8L VW engine, I used to regularly over-rev by 1000 RPM under load before the torque diminished and required me to shift; so my feeling is that since torque is diminishing during over-revving, momentary or accidental over-revving is not likely to cause bore-scoring due to loading issues, but by excess heat if it's done for extended periods of time.
One thing I would suggest is that you record the sound of your engine at idle and maybe under load if possible, and use any of the free audio editing software available to analyze the sound sound wave. If your recording resolution is set to "best" on a good smart-phone, you should be able to visually see abnormalities in the wave, particular to a cylinder. This way if everything is fine now, but you start to think you have a problem, you will have something to compare it to.
Lastly, EBS Racing, who rebuilt my engine for the previous owner, insists on using DT40 Racing Oil in the engine, and since they see a lot of engines, I'm not going to argue with them.
I am just a user full of personal anecdotes and single data points. @CharlesNavarro is an international expert on this subject who has done more research and white papers on this engine and its problems than almost anyone in the world. He also understands the physics, the metallurgy, the engineering, and the plating chemistry. If you want hard answers, he is the source. I'm not sure where he keeps his stuff, but check out LN Engineering, RND Engines, and a few other of his websites. He is also partners a close collaborator with Jake Raby (@FlatSixInnovations), who may have the most hands-on experience in this country, if not the world rebuilding these engines to last. As far as I'm concerned, they are the very best to answer and questions or discuss hypotheses with. Incidentally, LN Engineering recommends DT40 oils.
Just took my car in for a verified cylinder #6 score. Its a Porsche Cherry Hill in NJ. I have a fidelity power train warranty, the inspector was just there today and stated they wanted to do a tear down. I am going to talk with them tomorrow. We will see where this goes.....Wondering about anyone else's experience in this situation.
NE Car its whole life, 80K miles, 1 quart per 300 miles, sooty left tail pipe, loud tick at idle from right bank....... oh and the picture of the cylinder.
Ask them what they attribute bore scoring ro, why it's usually cylinder #6 and what is going to be done differently to prevent you from having to do this again? Please keep us posted on your service experience as well.
Ask them what they attribute bore scoring ro, why it's usually cylinder #6 and what is going to be done differently to prevent you from having to do this again? Please keep us posted on your service experience as well.
The replacement factory shortblocks do nothing to address this deficiency which would require a change in cylinder process, increased clearance, and/or bank specific pistons with correct offsets.
What have you guys paid to get the cylinders bore scoped? I'm looking at a 2006 with only 11K miles and wondering if it's worth the expense to have this checked at this low mileage. The car looks showroom condition and has full documented maintenance history.
Option 1 - from each side:
1. Jack up rear of car
2. Remove rear tire
3. Remove muffler (3 mounting bolts, plus 1 muffler clamp with 2 nuts)
4. Remove heat shield
5. Remove ignition coil
6. Remove spark plug
7. Insert endoscope and check cylinder
This will take you about 1 hour to do, hardest part will be muffler removal first time you've done it.
Option 2 - from oil pan:
1. Jack up car, put on jack stands
2. Drain oil.
3. Remove the oil pan. (see re-assembly note below)
4. Look into piston cylinders from underneath
Re-assembly:
1. Clean all gasket residue from engine and oil cover using acetone and a brass brush.
2. Use Drei-bond and put a 1.5mm bead of sealant on the oil cover (Loctite 5900 or 3-Bond 1209)
3. Torque all bolts to 7.5 ft lbs.
This will take you more than a few hours due to oil drain and oil pan re-assembly.
No idea what a shop would charge do this, but at least you know what is involved.
If you are handy yourself this is pretty easy to do with a $39 endoscope (or cheaper) from Amazon here:
There are two options for doing this:
Option 1 - from each side:
1. Jack up rear of car
2. Remove rear tire
3. Remove muffler (3 mounting bolts, plus 1 muffler clamp with 2 nuts)
4. Remove heat shield
5. Remove ignition coil
6. Remove spark plug
7. Insert endoscope and check cylinder
This will take you about 1 hour to do, hardest part will be muffler removal first time you've done it.
Option 2 - from oil pan:
1. Jack up car, put on jack stands
2. Drain oil.
3. Remove the oil pan. (see re-assembly note below)
4. Look into piston cylinders from underneath
Re-assembly:
1. Clean all gasket residue from engine and oil cover using acetone and a brass brush.
2. Use Drei-bond and put a 1.5mm bead of sealant on the oil cover (Loctite 5900 or 3-Bond 1209)
3. Torque all bolts to 7.5 ft lbs.
This will take you more than a few hours due to oil drain and oil pan re-assembly.
No idea what a shop would charge do this, but at least you know what is involved.
Thanks for the info and if this was my car already I would definitely do it myself. But I doubt the seller is going to let me wrench on his car for a few hours so this is something I would have to get done by a shop during the PPI. I know this is not part of the normal PPI inspection that my indy does so I'm assuming the additional cost would be something similar to spark plug change.
Regarding the method of checking via the oil pan, wouldn't the top of each cylinder be blocked by the piston? I would think this would only show the bottom half of each cylinder liner.
If you take a look at this scored piston (that came out of my engine), you can see that the scoring goes the full length of the skirt. So you would see it on the bottom part of the cylinder as long as the piston is near the top.
To get it to the top you can use a 24mm socket on the front drive pulley and rotate the engine clockwise.
If you take a look at this scored piston (that came out of my engine), you can see that the scoring goes the full length of the skirt. So you would see it on the bottom part of the cylinder as long as the piston is near the top.
To get it to the top you can use a 24mm socket on the front drive pulley and rotate the engine clockwise.
Thanks for the explanation. Much appreciated.
If anyone else can share what they paid to have a shop perform this inspection that would be great.
08-09-2018, 03:15 PM
