Three weeks then this!
11-11-2012, 06:59 PM
#1
Track Day
Thread Starter
Join Date: May 2011
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
Three weeks then this!
After months of searching I found our 05 blk/blk CS, 81K at a GM dealer (was trade-in). Wife and I drove for three weeks and love it, then it acts up. Wife calls and says it won't start and smells like gas. So I get to vehicle 2 hrs later and get it started. It's running real rough and feels like it's running on 7, so I nurse it home. I'm thinking coils, so I manage to get 8 coils and new plugs next day. I replace both plugs and coils and while doing so notice that #2 looks richer than others. Others are tan and in good shape. #2 is blackish brown. Start it up and it still runs rough and sound awful (pulsing/sucking noise in intake). I just happen to feel the intake runners and notice #2 is warm while others are not. While it's running I am getting blinking CEL then it goes solid. I pull all the coil connectors and plug #1 and do comp check to get a baseline. 175 psi. Replace plug #1, pull #2 and run comp check and get what I didn't want to see, 0 psi. I re-test one and 2 and get same results. Also checked #3 and it was 175 psi. So I'm thinking at this point, bent or burned intake valve(s). I have a 50/50 pay 30 day warranty with the chevy dealer, but I'm sure this is not going to be cheap. I'm just praying that it's top end only. I have to get it towed now because it won't start at all (I assuming the computer has disabled the ignition or something). Does anyone know why all of the sudden a perfect running engine would bend or burn an intake valve? I would think this can only be the result of a spring failure not closing the valve before it gets whacked by the piston. I'm going to ask the dealer to do a scope inside to verify that it is a valve and that the piston is OK. I've read about the wall scoring on here, but I think the warm intake runner, the noise in the intake and the 0 compression are indicative of the valve. I suppose it could also be stuck open. I assume, but don't know, that these are interference valves. Also, can the head be removed w/o pulling the engine? Any and all thoughts are welcome.
11-12-2012, 08:57 AM
#5
Given your symptoms (especially the warm intake runner) it sounds like you have a valve spring that failed and is stuck open or partially open.
As a reference point, a new set of cams and springs for one side of the engine is about $5k w/labor. I doubt you will need cams so you should be able to avoid a few $$$ given the diagnosis is correct.
As a reference point, a new set of cams and springs for one side of the engine is about $5k w/labor. I doubt you will need cams so you should be able to avoid a few $$$ given the diagnosis is correct.
Trending Topics
11-12-2012, 12:10 PM
#8
Intermediate
Join Date: Sep 2012
Posts: 34
Likes: 0
Received 0 Likes
on
0 Posts
Wish you were here in Massachusetts. In California you have, as in all states, an implied warranty of merchantability. I would STOP trying to fix this yourself and go have a business like chat with the General Sales Manager of the dealership. A decent dealer would, after only three weeks, fix the problem or buy back the car. Here in Massachusetts, we would have to by law.
Good luck.
Good luck.
11-23-2012, 09:00 PM
#10
Track Day
Thread Starter
Join Date: May 2011
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
Update: Mechanic pulled engine out and removed head and determined the problem to be a dropped intake seat. It couldn't have dropped much, like completely out of the head or I would think it would have made a lot of noise and damaged the piston and head. I'm getting this info through the chevy service guy, not the actual mechanic. I'm going to try to talk to him on Monday. I would really like to know why the seat dropped. I'm guessing it just shifted in the head somehow causing the valve to possibly bend and not seal, or at least just not seal because the seat is not true. Anyone ever heard of this?? I never have. I've heard of seats dropping and basically destroying that piston, head and usually the cylinder. I'll keep everyone updated as I move forward. One silver lining here, I'm getting a great deal on my coolant pipe upgrade since the engine is out!
12-03-2012, 03:31 PM
#13
Track Day
Thread Starter
Join Date: May 2011
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
Got the car back last Friday. Dropped seat (must have been slight vs full since no damage to piston or head) with no root cause known. This is the only one Newport Beach Porsche had ever heard of (they didn't do the work, just a quick phone conversation).
Two good news items to go with this bad news story: 1) I only had to pay 1/2 of the $3200 bill (labor, parts, machine shop work) and 2) I got the aluminum coolant pipes I ordered installed for $170 since they already had the engine out and head removed saving me the headache and time associated with that work. Hopefully I can use the Cayenne for a while, maybe even a long time, before the next issue arises.
Two good news items to go with this bad news story: 1) I only had to pay 1/2 of the $3200 bill (labor, parts, machine shop work) and 2) I got the aluminum coolant pipes I ordered installed for $170 since they already had the engine out and head removed saving me the headache and time associated with that work. Hopefully I can use the Cayenne for a while, maybe even a long time, before the next issue arises.