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2005 CTS-V
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30 Posts
Discussion Starter #1
I actually had two plugs fall out of the heads, one at the rear of each side, within 200 miles of each other. Long story short, I'm now faced with removing the heads to fix what another dealer described as improper installation of the spark plugs. The threads are totally gone on the passenger side, and only a few are left on the driver's side. This took some time, but it is what it is.

My question is, should I do anything with valve springs etc. while the heads are off?

I've owned this car, 2005, for 14 years, and the engine has given me zero issues. Car now has 250K miles on the clock, so that's why I'm asking. Any suggestions of other things to look at would be greatly appreciated as I want to take advantage of having the engine torn down to this point.
 

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Super Moderator
'05 CTS-V
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8,251 Posts
Impressive mileage! I'm 100k miles behind you, and I thought I was one of the higher mileage folks.

What was the dealership doing that they managed to make such a mess?! It's not that frickin' hard to thread in a spark plug. Ruining two spark plug holes is just plain brutal incompetence.

I'm always torn about preventative maintenance; if you had said the engine had 125k on it, I'd probably waffle a bit on my recommendations. But with 250k on the engine, I would say you'd be prudent to do everything - new springs, new valve seals, new lifters, maybe a trunnion bearing upgrade on the rockers. Peek down through the lifter bores and see how the cam lobes look.

One of the guys over on LS1tech is in the process of rebuilding his top end. He found a broken spring, and that cascaded into finding another broken spring and some other valvetrain issues. He sent his heads off to Katech to be CNC'd - only $500, which seems like a good deal, since Katech seriously knows their shit when it comes to LS engines.
 

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Registered
2006 CTS-V
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429 Posts
I recommend looking into cylinder head porting and rebuild of the seals, valves, push rods, lifters, CHE trunions and definitely inspect the cam at that mileage.

Consider an oil pump and timing gear set.

Thompson Motorsports has reasonable prices and has a very nice CNC porting setup.

If you port the heads, then consider a tune as well.

At 150k miles I had a lifter that sent needle bearings into my oil pan, so I went all out with new everything including cam. It's my only vehicle, so I wanted to ensure another happy 100k.

-Byron
 

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2005 CTS-V
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30 Posts
Discussion Starter #4
This particular Cadillac dealership has a history of expensive screwups with me, but ownership has changed hands since this one. Pure incompetence by "mechanics" who are more, computer-guided parts replacers than mechanics has been the issue. Even then, this was "special". I may venture into small claims court with this one and see what happens. Worst case scenario, I'm out a little time and $125.

The one on the driver's side is a certified bitch to get to, but not the one on the passenger side. I honestly thought the one on the driver's side had popped out again after paying a shade tree mechanic/friend to figure out why my car was making that hellacious racket. I was very close to his place when it let go, so I just rolled into there. He was able to get the plug seated, but he said there were only a few threads left in the head. These plugs were changed by the dealer some 6 years ago, but that changes nothing about the incompetency part.

When it happened again, I was very close to a Chevrolet dealership, so I rolled into there. I was very surprised when they came out and told me it was the rear plug on the passenger side. This time, there were no threads left to reinstall the plug. Needless to say, I'll be inspecting all 8 holes when the heads come off.

I've spent quite a bit of money on this car over the years, but it pisses me off to spend money because of someone else's negligence when I've paid them to do something that should have been extremely simple. These are primarily highway miles, and I've always kept the crankcase filled with Mobil 1 and changed it regularly. Never a single issue with it, and while I don't abuse it, it has hit the rev limiter on few occasions. It's been a great car overall, and I have never kept anything long enough to put anywhere near that number of miles on. Maybe it's time to button it up and sell/trade it. Problem is, I still love the car and know what it will cost to get anything that will make me happy. It's still as strong and tight as ever... except for when the plugs fall out. :)
 
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