Shoji

Good Afternoon Everyone,

Back Story

Referencing a previous post of mine, my 2003 350z had power loss that I just could NOT figure out what was wrong.

To sum up the previous post, back in 2013 I noticed while troubleshooting a botched valve cover replacement job that I stripped out some of the bolt holes in the heads. I ended up paying the dealership to make the repair and piece everything back together. Most of the symptoms went away, but every so often I would have issues starting up, or loss of power while driving. Over the course of 2 years the symptoms have worsened and become more frequent. I've taken it to the dealership numerous times and replaced countless parts.

Problem Identified?

After numerous searches on symptoms, I ran across a post about how bolts on the plenums came loose over time on somebody's plenum spacer install. So after I disassembled the plenum down to the lower plenum, my goal was to retorque everything to spec starting with lower plenum to intake manifold bolts. Boom, problem identified: none of them were torqued anywhere near 100 in-lbs (all super loose) and one of them was stripped, not even able to tighten.

Funny thing is, I had installed the plenum spacer/iso thermal intake manifold gasket at the same time as the first valve cover gasket install, when I over-torqued the bolts on the valve covers. The dealership had to remove the upper/lower plenum in order to access/repair the stripped valve cover bolt holes.

Specific Question:

After over two years, would I be wrong in assuming the dealership is to blame? Do you think in their eyes, I have a leg to stand on in blaming them?
- I haven't torn down the engine, nor had a reason to tear it down this far since
- A reasonable person would assume that since the dealership identified more bolts I stripped and I payed them to repair all (8) that they would have identified this one
- I can't verify the bolts connecting plenum to intake manifold were torqued to spec at all prevoiusly (as they were all loose now). all bolts holding upper plenum to lower plenum were at proper torque when I disassembled them.

Symptoms:

Symptoms:
- Delayed startup in 3/10 attempts (ie, engine turns over 3-5 seconds before start up)
- Engine runs fine for about 10-15 seconds before throttle dies out (car dies usually, then has delayed startup issue 100% of the time then)
- After starting up with delay, SES/VDC/slip lights all on, significant loss in power/acceleration
- jerking acceleration through all gears, usually around 2.5k rpms. Punching the accelerator pedal will cause some spinning tires and rpms going to 3k+ and the symptoms are gone unless I go back down to @2.5k rpms.
- Muffled exhaust sound
- rought idle
- racing the engine (quick acceleration up to 6k rpm) through 1st and 2nd gears would alleviate all rough idle or jerking acceleration issues.

What I've replaced:
- Valve covers (twice each)
- 4 coil packs
- bank 1 camshaft position sensor wiring harness connector (connector only)
- bank 1 and 2 camshaft position sensors
- MAF sensor
- Fuel filter
- (heated) oxygen sensors (behind cat converters)
- Fuel Dampers (both done this week)

My next step was to replace the throttle body.

0jiggy0

iTrader: (13)

How the **** did you strip 8 bolts? So the car was fine, you tryed to fix it and royally screwed up and expected the dealership to know you had no clue what you were doing?

Yes they should have caught what was essentially a horrible vacuum leak. Dealerships are notorious for being horrible diagnostic mechanics. When you have all parts available you dont need to troubleshoot. You will eventually find the problem if you throw enough parts at a problem.

No you dont have a leg to stand on. Stop throwing parts at the car and get it properly diagnosed.

Shoji

Initially I just had the problem of the leaking valve cover gaskets where the spark plugs go. I diagnosed the problem, ordered the parts, and offered one of my Marine friends a case of beer if he wanted to help me out. Really, it was a ploy to use his torque wrench, since I didn't want to spend the cash to buy one.

He had a click-style torque wrench. With him being a mechanic by trade, I opted to let him torque the bolts... but he gave me a weird look after he torqued a few. So I torqued the next few, realizing there was no "click." 100 inch/pounds is NOT a lot of force.

Put everything back together, went to start her up and had more problems than before. I tore everything down thinking maybe I didn't line up the gasket properly and discovered we over-torqued the bolts (bolts spun and spun, didn't want to come out).

I towed the vehicle to the dealership, payed them to diagnose and repair any and all messed up over-torqued holes. After they put it together, they told me I needed to replace coil packs, cam shaft sensors, wiring connectors, etc. I have taken the vehicle to the dealership numerous times to get this diagnosed.

So really the question in my mind is... did I FUBAR the intake manifold bolt holes, too, and they were never identified? Or could I assume the dealership should have torqued everything to spec and identified there was an issue with the lower plenum to intake manifold bolt holes...

0jiggy0

iTrader: (13)

Sounds like the Tq wrench was ****ed up. 100 inch lbs is nothing, 8 and a quarter ft/lbs. You ****ed up the bolt holes. They needed to be drilled and tapped with heli coils installed. Why did you buy all that other crap when you knew what the problem was?

Shoji

For some reason I feel like you are trolling me.

Series of events:
- valve cover gasket leaking oil around spark plug holes
- replaced valve cover gaskets
- problems worsened, disassembled and discovered holes needed fixed.
- towed to dealership, they fixed the holes with helicoils, reassembled, more problems.
- payed dealership to replace 3 parts, they returned my Z to me after 3 weeks and no real progress.
- I have taken the Z to the dealership numerous times since, numerous repairs since. No specific problem identified except chasing rabbits.
- Searching for more answers, I saw a forum post where somebody said their similar problems were a result of bolts coming loose after plenum spacer install.
- I took it apart to retorque everything... problem found. The dealership mechanics were the last ones who touched the plenum.

So the purpose of my post is to ask this question:
- Am I right in placing blame on the dealership for this problem?
- If so, would I be right going to the dealership and asking them to repair it at their cost?

In other words, I'm asking for a sanity check. Thanks.

Shoji

Friendly Update:

I ended up calling the dealership, asking only for them to repair the stripped bolt hole, I would reassemble from there. The service desk manager offered to repair the stripped hole, reassemble the engine and run a full diagnostics to ensure nothing else was missed.

What helped me I think was the original visit (March 2013) where they kept my vehicle for several weeks and ended up releasing the car to me with no idea what's wrong with it, as well as numerous parts purchases since then.

I feel blessed they are assisting me this much, especially because I wasnt asking for this much. Here's to hoping there hasn't been any long term damage from the vehicle not being sealed properly between plenum and intake manifold.

zakmartin

Yeah, you got some seriously stand-up service from the dealership. They really didn't have to lift a finger at this point. You're so far out from the date of the initial work, that I can't imagine a judge in the country who'd take your side.

When you're torqueing down bolts with such low torque specs, use an inch-pound wrench. Even a super cheap beam style torque wrench that measures in inch pounds could have prevented all of this and they cost less than $20 and can be re-calibrated with two fingers. Not wanting to buy correct tools really isn't an excuse given how cheaply you can buy imported stuff from Harbor Freight (don't get me started on HF though; I f-ing hate that place and everything it stands for.)

At such low torque settings, a drop of Loctite Threadlocker Blue on each bolt will save you a ton of heartache down the road as well.

I hope the dealership's fix works out for you. Just remember that they're doing YOU a favor, so don't be an asshat and hold it against them if it doesn't work out. Good luck

Shoji

Another update.

The dealership I took my Z to held onto it for several days, when I stopped by to check on it, I was told that only the stripped hole was repaired. When I asked about the service manager's conversation with me, I was told the service manager doesn't recall promising to put the car back together or doing any diagnostics for free.

I had two choices: to be upset or grateful. I chose to say thanks and move on. I'm a little upset that the service manager did not uphold his end of the deal, but I'm grateful that they fixed the bolt hole at their expense.

Good news: after reassembling the engine to proper torque, everything works GREAT! I forgot how FUN my Z is to drive. I will not be returning to this store for service any longer, though.

zakmartin

Well, you got a happy ending, which is more than what most people end up with in these situations. I'm glad it worked out and thanks for the update.