camshaft plug issue
 

Hello dorki folks. I'm curious if any Cayman owners have run into this issue before, and if any others have ideas.

I've got a 987.1 2.7L with 95k miles. Motor has been solid up until this point. My knowledge of the M97 is extremely limited so some of this might sound crazy.

Item #32 in the following link (part # 99610421602), located on the passenger side rear of the motor, popped out and dumped oil everywhere. I replaced the plug and it happened again after a short spirited drive, once the motor was up to operating temperature. Not sure at which point the plug pops out. It's only when I stop that I can identify the failure. Smoke comes billowing out of the right rear wheel well. Motor runs, sounds, and feels normal.

http://www.autoatlanta.com/porsche-p...section=103-00

Some possible causes I've identified are the following.

1. AOS hose from driver's side of motor might have a crack in it. Found one instance of this and an explanation here:
https://scotthuntersmith.com/2017/12...s-popping-out/
-Access to this hose for detailed inspection is extremely difficult and might require taking the intake manifold off?

2. Scavenge pump might be broken and the area with the cam is filling up with oil and forcing the plug out.
-Anyone have experience removing the pump right below the plug?

3. Some have mentioned this occurring after having some engine work done, with excess sealant causing a blockage somewhere. My motor hasn't been opened up, so I don't see this as a possibility.

4. Cracked piston ring causing blow-by. I would expect some smoke from the exhaust but there doesn't appear to be any.

Thanks.

I had the same thing happen on my Audi at VIR last fall due to excessive blow-by on one of the cylinders. And no, I didn't see any visible smoke out of the exhaust. The oil dumped right on the exhaust and caused a fire under the hood. I was able to put it out, but fair warning - motor oil doesn't burn easily but on a red hot exhaust it can catch on fire. Bottom line is, cause is likely pressure build-up in the block which, and a hate to be a bearer of bad news, is most likely due to bottom end issues and usually requires an engine rebuild. I just finished swapping the block on my car, hopefully this will last me a while.

1. Don't think it's AOS as that would more likely cause oil ingestion if it failed at the diaphram or poor running with an embalanced air fuel mixture.

2. Pump comes out easy although a knuckle buster on the firewall head. Four screws hold it on plus loosen (do not remove) the two case screws on either side. Remember to tighten them to 7.5ftlbs after inserting the pump back in.

The area behind the pump is a cavern if spinning chains and goes all the way down to the sump. It's not localized oil. It is excess block pressure from somewhere. Leak down test may be a quick diagnostic

Start there. Low cost/effort and rules out a lot.

10-4. Thanks Martin and VC.

A few years ago I was following a 911 at VIR. He spun out and caught fire. After speaking with him later since I had him on video I was shooting he got back to me the next week that one of his plugs came out which caused oil to spray on his tires. With the now easy to spin car when it happened oil sprayed onto the hot exhaust and caused the fire. The next season I was at NJMP Lightning and spun out on a gentle turn. Got back on the track and got black flagged for excessive smoking. I didn't know it at the time and fortunately had trailered the car up. At the shop the diagnosis was one of my plugs had come out and sprayed oil out, it was all over my left rear tire and wheel assembly. I had all the plugs pulled out and reinstalled with a good sealant to keep them in place. If I recall they are not in place with any sealant from the factory. My engine had less than 10K miles on it from its rebuild at the time and there was no indication of anything having caused it other than the plug itself only being held in place by being compressed in. Upon the teardown when the engine burned up the second time at 18k miles there was no issue with the AOS, pumps, or anything else other than the the results from the oil starvation.

So this sounds like a common issue for the M97 engine. Have your shop pull them all and get them perminently reinstalled with a good sealant so you don't have to worry about it.

Mike - I'm going to respectfully say that this is bad advice. Porsche designed the plugs to be installed and remain without sealant. If they come out, then there is a problem somewhere causing it.

In my case no reason was found, we did look for a cause. That certainly doesn't mean you may or may not have an issue that caused yours to come out. Let us know what it gets traced to.

Leakdown and compression tests came back good (motor was cold). Spark plugs were very clean too (30k miles on them).

Leakdown (tested in firing order: 1, 6, 2, 4, 3, 5)
1 - 98
2 - 99
3 - 98
4 - 97
5 - 99
6 - 99

Compression (tested in order, 1 to 6)
1 - 165
2 - 170
3 - 165
4 - 175
5 - 200
6 - 185

Gonna do a deep dive on the AOS system next. Any advice for the line that comes from the front driver's side of the motor? Looks like I might have to disassemble part of the intake manifold.

Just a thought but perhaps might be a contributing factor to your crankcase pressure is worn valve guides. When I rebuilt my engine around 70K miles on it and no track time the valve guides were completely worn out with the valves wobbling. This could create a blowby issue adding to your crankcase pressure. The guides are brass and very soft. From some earlier research it is common for them to wear out quickly in the M97 engines. This would not be apparent on the leakdown test because the valves are closed.