NEED HELP Fuel lines and removing intake manifold

[deagle12]

Found oil in spark plug well #3 on my 2005 4.2L and research tells me it is likely the valve cover gasket.

I am researching how to do this job - even got the Haynes. I know it is a "big" job, involving the removal of the intake manifold and alternator.

Some threads state to relieve the fuel pressure, and disconnect some fuel lines in order to remove the intake manifold.

Ex:

http://forums.trailvoy.com/showthread.php?t=17334

http://gmtnation.com/forums/threads/how-to-remove-i6-intake-manifold-and-valve-cover.12225/

However, my Haynes does not mention the need to relieve fuel pressure or remove any fuel lines.

Both these posters seemed to be doing more work though after removing the intake manifold... (not just replacing the valve cover gasket)

TL;DR Is it necessary to remove fuel lines, or can the intake manifold be removed without doing so?

 

[Mounce]

Fuel rail is connected to intake manifold. You might be able to remove it from the manifold and maybe it would sit out of the way but then you've gotta worry about the o-rings on it and might need to replace them. And then again I'm not sure that you'd have enough slack in the line to be able to take the rail off of the manifold without disconnecting the fuel lines anyways. I'd leave the fuel rail on the manifold and disconnect the fuel lines from the rail which would require relieving the fuel pressure.

4.2L btw.

 

[Sparky]

1st question is, how much oil? Having some is not unusual with this valve cover design (Seen it a lot on other makes also with DOHC and those donut gaskets). Could try snugging down the valve cover bolts first.

Or, depending on how much oil it is, just leave it. Sop it up, check it in a little while and see how much is in there. I always had some oil down my one plug well (I think it was #2 or #3) but it wasn't a whole lot so I never bothered with it. Never got worse even after the engine had 215k miles.

 

[Mooseman]

1. Don't need to pull the alternator
2. Don't need to pull the fuel rail. It's in the head itself.
3. It's not a bad idea to disconnect the fuel lines from the fuel rail because you have to remove the bracket that holds them and will give you more room to get at the manifold bolts.
4. To relieve fuel pressure, start the engine and pull the fuel pump relay until it stalls.

But, for such a minor leak, I would try this first. Pull all the ignition coils, unscrew the bolt from the coil and add a washer under each bolt head and re-install the coils. This will add a little extra pressure on the gasket around the plug wells. Also re-torque the valve cover bolts. Even if this doesn't work and oil still seeps into the plug wells, I'd just let it go.

 

[deagle12]

Thanks guys, I will definitely try this first then. I'll go ahead and re-torque the valve cover bolts and tighten the coils. Then after a couple weeks maybe reassess.

Good to know the alternator doesn't need to be pulled, though.

Here is an image of how much oil was in the well (attached).

Plug #3 was the only one with oil built up in the well. Plug 3, 5, and 6 had oil on the threads too.

I should also note the trailblazer has a bit of a rough idle. I was wondering if cyclinder #3 could be misfiring at all from the oil and if this could fix that. Right now there is no check engine light. Although my girlfriend reports it has come on and off in the past few months.

Also I'll add that I have already cleaned the throttle body.

 

[Mooseman]

Just clean out all the oil and replace the plugs. Then, move coil 3 to cylinder 2 and vice versa. If the misfire moves to 2, then the coil is at fault.

Oil is not conductive so technically, it shouldn't cause a misfire unless there is moisture mixed in it.

 

[Redbeard]

For the little bit of oil you have there do as Mooseman suggests: clean it out, replace the plugs and call it a day. If there is a misfire, it isn't due to the bit of oil there anyways. Several Nissan's I've had in the past at times showed worse than yours without any firing problems. I still didn't like it, but it just wasn't worth all the trouble trying to stop such a slow leak.

 

[deagle12]

Thanks guys, I will take your advice and not worry too much about any leak.

I think the vibration issue with the truck may actually be the motor mounts. There is a vibration on the passenger's side during acceleration that sounds like it is coming from under the dash. In addition to vibration at idle, there is also a "diesel shake" when shutting the engine off. My girlfriend says sometimes the vibration gets worse when it's hotter, and even makes the windshield wipers vibrate at idle. So I may explore this then update you guys with the progress.

 

[Sparky]

Very good chance. Last I knew, the only motor mounts worth anything were AC Delco mounts. All the others just didn't have the right "stuff" in them and wouldn't dampen vibrations properly.

 

[deagle12]

Thanks, Sparky. Here's an update:

Inspected spark plug well #3. Dry after replacing spark plugs two weeks ago, and running for a few hundred miles. Looks like leak is real slow as you guys say, so I won't worry about that any more.

Ordered GM motor mounts and will install those this weekend. Are those just as good as AC Delco, or are AC Delco better than OEM? (The GM mounts were cheaper).

This weekend a check engine light came on. P0128. Replaced the thermostat with a new part from the store, seems to be working OK.

Still having some vibrations at idle and with revving the engine, so hoping the motor mounts will solve this.

 

[Mooseman]

ACDelco is the supplier for GM so for all intents and purposes, they are the same. Surprised they were cheaper at the Stealership.

 

[deagle12]

Replaced the mounts with GM mounts. Running very well! Very little vibration at idle and no more weird passenger-side vibrations with acceleration. Girlfriend says the trailblazer feels new!

Thanks again for your guys help.