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Hello,

I have recently changed the front valve cover gasket on my 3.9 '07 Impala because of oil leaks. It was pretty easy doing the whole replacement process for the front gasket. My only problem was that I wasn't able to remove the rear valve cover because of the last screw that is under the alternator mount. The coolant crossover (which is also used as the alternator mount) is blocking access to the last screw. Does anybody know how to remove the last screw without having to remove the crossover? Any help would be appreciated.
 

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Hello,

I have recently changed the front valve cover gasket on my 3.9 '07 Impala because of oil leaks. It was pretty easy doing the whole replacement process for the front gasket. My only problem was that I wasn't able to remove the rear valve cover because of the last screw that is under the alternator mount. The coolant crossover (which is also used as the alternator mount) is blocking access to the last screw. Does anybody know how to remove the last screw without having to remove the crossover? Any help would be appreciated.
I looked in my factory manual. The first line of the instructions is, "Remove the engine coolant crossover pipe." Someone else may still have a workaround, but that's what the GM service info prescribes.

Sorry I can't be more help.

Doug

.
 

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Thank you very much for your help, Doug. It seems that I will have to practice on a junk Impala at a junkyard so that I don't mess up anything along the way when I perform the repair on mine. Thanks again!
 

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Hello,

I have recently changed the front valve cover gasket on my 3.9 '07 Impala because of oil leaks. It was pretty easy doing the whole replacement process for the front gasket. My only problem was that I wasn't able to remove the rear valve cover because of the last screw that is under the alternator mount. The coolant crossover (which is also used as the alternator mount) is blocking access to the last screw. Does anybody know how to remove the last screw without having to remove the crossover? Any help would be appreciated.
I have a 2008 and the factory service manual doesn't mention the crossover pipe, but it could have been different for the 2007 YM.
This is what I have in my GM Service Manual Information for 2006 and I believe it covers YMs 2007 and 2008.

Removal:

1. Remove the generator. Refer to Generator Replacement (RPOs LZE/LZ4/LZ9) or
Generator Replacement (RPO LS4) .
2. Disconnect the positive crankcase ventilation (peV) fresh air tube from the air cleaner
outlet duct. Refer to Quick Connect Fitting(s) Service (Plastic Collar) .
3. Remove the pev fresh air tube from the right side valve rocker arm cover.
4. Disconnect the right side spark plug wires from the spark plugs.
5. Disconnect the right side spark plug wires from the ignition coil.
6. Remove the right side spark plug harness clip from the ignition coil bracket.
7. Remove the spark plug harness.
8. Disconnect the manifold absolute pressure (MAP) sensor electrical connector (1).
9. Disconnect the ignition coil electrical connector (6).
10. Remove the engine harness clip from the ignition coil bracket.
11. Remove the heated oxygen sensor (H02S) electrical connector clip (1) from the
ignition coil bracket.
12. Remove the ignition coil bracket nuts.
13. Remove the ignition coil bracket bolts.
14. Remove the ignition coil.
15. Loosen the valve rocker arm cover bolts.
IMPORTANT: When removing the valve rocker arm cover, ensure the
gasket stays in place attached to the cylinder head.
16. Remove the valve rocker arm cover. Bump the end of the cover with the palm of your
hand or a soft rubber mallet if the cover adheres to the cylinder head.
17. Cut the room temperature vulcanizing (R TV) sealer in the channel where the intake,
cylinder head and valve rocker arm cover meet with a suitable tool.
18. Remove the valve cover gasket.
19. Clean the sealing surface on the cylinder head with degreaser.
Installation Procedure
IMPORTANT: All gasket mating surfaces need to be free of oil and foreign
material. Use GM PIN 12346139 (Canadian PIN 10953463) or
equivalent, to clean the surfaces.

Installation:

1. Install a NEW valve rocker arm cover gasket into the groove in the valve rocker arm
cover. Ensure that the gasket is properly seated in the groove of the valve rocker arm
cover.
2. Apply sealant GM PIN 12378521 (Canadian PIN 88901148) or equivalent, at the
cylinder head to the surfaces where the cylinder head and intake manifold meet (1).
3. Install a new gasket to the valve rocker arm cover. Ensure that the gasket is properly
seated in the groove of the valve rocker arm cover.
4. Install the right valve rocker arm cover.
NOTE: Refer to Fastener
Notice.
IMPORTANT: Use an alternating criss-cross pattern when tightening the
valve rocker cover bolts. Failure to do so may result in oil
leakage from the valve cover due to improper seating of
the gasket.
5. Tighten the valve rocker arm cover bolts.
Tighten: Tighten the bolts to 10 N.m (89 lb in).
9. Install the H02S electrical connector clip (1) to the ignition coil bracket.
10. Install the engine harness clip to the ignition coil bracket.
11. Connect the ignition coil electrical connector (6).
12. Connect the MAP sensor electrical connector (1).
13. Install the spark plug harness.
14. Connect the right side spark plug wires to the spark plugs.
15. Connect the right side spark plug wires to the ignition coil.
16. Install the right side spark plug harness clip to the ignition coil bracket.
17. Install the PCV fresh air tube to the right side valve rocker arm cover.
18. Connect the PCV fresh air tube to the air cleaner outlet duct. Refer to Quick Connect
Fitting(s) Service (Plastic Collar) .
19. Install the generator. Refer to Generator Replacement (RPOs LZE/LZ4/LZ9) or
Generator Replacement (RPO LS4) .

You can also check with a Chevrolet Service Department. A Buick dealership will also have access to this same information.

Maybe it changed some on the 3.9L from 2006 - 2008. I did call and ask a previous forum member who is a franchised Buick-GMC dealership parts department employee to check for this same issue. He pulled it up in service and said there was no mention of the crossover pipe being removed on the 3.9 to get to the right side valve cover (the one next to the firewall). I hope this helps. If you can't find out anything, PM me and I'll send you his contact info.
 

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From Chilton:


Valve Rocker Arm Cover Replacement - Right SideValve Rocker Arm Cover Replacement - Right SideRemoval Procedure


Remove the engine coolant crossover pipe. Refer to*Engine Coolant Crossover Pipe Replacement (LZE/LZ4/LZ8).

Disconnect the positive crankcase ventilation (PCV) fresh air tube from the air cleaner outlet duct. Refer to*Plastic Collar Quick Connect Fitting Service.

Remove the PCV fresh air tube from the right side valve rocker arm cover.


Disconnect the right side spark plug wires from the spark plugs.

Disconnect the right side spark plug wires from the ignition coil.

Remove the right side spark plug harness clip from the ignition coil bracket.

Remove the spark plug harness.




Disconnect the manifold absolute pressure (MAP) sensor electrical connector.

Disconnect the ignition coil electrical connector.

Remove the engine harness clip from the ignition coil bracket.



Remove the heated oxygen sensor (HO2S) electrical connector clip from the ignition coil bracket.


Remove the ignition coil bracket nuts.

Remove the ignition coil bracket bolts.

Remove the ignition coil.


Loosen the valve rocker arm cover bolts.

NOTE

Important

When removing the valve rocker arm cover, ensure the gasket stays in place attached to the cylinder head.

Remove the valve rocker arm cover.

Bump the end of the cover with the palm of your hand or a soft rubber mallet if the cover adheres to the cylinder head.

Cut the room temperature vulcanizing (RTV) sealer in the channel where the intake, cylinder head and valve rocker arm cover meet with a suitable tool.

Remove the valve cover gasket.

Clean the sealing surface on the cylinder head with degreaser.

Installation Procedure

NOTE

Important

All gasket mating surfaces need to be free of oil and foreign material. Use cleaner to clean the surfaces. Refer to Adhesives, Fluids, Lubricants, and Sealers.


Install a NEW valve rocker arm cover gasket into the groove in the valve rocker arm cover. Ensure that the gasket is properly seated in the groove of the valve rocker arm cover.

Apply sealant at the cylinder head to the surfaces where the cylinder head and intake manifold meet. Refer to*Adhesives, Fluids, Lubricants, and Sealers.


Install a new gasket to the valve rocker arm cover. Ensure that the gasket is properly seated in the groove of the valve rocker arm cover.

Install the right valve rocker arm cover.

NOTE

Important

Use an alternating criss-cross pattern when tightening the valve rocker cover bolts. Failure to do so may result in oil leakage from the valve cover due to improper seating of the gasket.

Install the valve rocker arm cover bolts. Refer toValve Rocker Arm Cover Installation - Right Side.


Install the ignition coil.

Install the ignition coil bracket bolts.

NOTE

Notice

Refer to Fastener Notice.

Install the ignition coil bracket nuts.


Tighten

Tighten the bolts/nuts to 25 N·m (18 lb ft).

*


Install the HO2S electrical connector clip to the ignition coil bracket.


Install the engine harness clip to the ignition coil bracket.

Connect the ignition coil electrical connector.

Connect the MAP sensor electrical connector.


Install the spark plug harness.

Connect the right side spark plug wires to the spark plugs.

Connect the right side spark plug wires to the ignition coil.

Install the right side spark plug harness clip to the ignition coil bracket.



Install the PCV fresh air tube to the right side valve rocker arm cover.

Connect the PCV fresh air tube to the air cleaner outlet duct. Refer to*Plastic Collar Quick Connect Fitting Service.

Install the engine coolant crossover pipe. Refer to*Engine Coolant Crossover Pipe Replacement (LZE/LZ4/LZ8).



HTH
 

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I have a Haynes Manual 24047 Impala 2006 thur 2008. For rear valve cover it states "15. On 3.5L engines, remove the water crossover tube."
I also have a GM Service Database on CD and it also states remove the coolant crossover pipe on the 3.5L but not for the 3.9L.
 

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I have a Haynes Manual 24047 Impala 2006 thur 2008. For rear valve cover it states "15. On 3.5L engines, remove the water crossover tube."
I also have a GM Service Database on CD and it also states remove the coolant crossover pipe on the 3.5L but not for the 3.9L.
Bill, that's what mine has as well. I have the GM Service Database and it doesn't have anything about removing the crossover pipe on the 3.9L.
 

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Hello,

I have recently changed the front valve cover gasket on my 3.9 '07 Impala because of oil leaks. It was pretty easy doing the whole replacement process for the front gasket. My only problem was that I wasn't able to remove the rear valve cover because of the last screw that is under the alternator mount. The coolant crossover (which is also used as the alternator mount) is blocking access to the last screw. Does anybody know how to remove the last screw without having to remove the crossover? Any help would be appreciated.
I need to correct my last post. I need to do the same thing to my 2008 9C3 and unfortunately, you'll need to remove the coolant crossover pipe. The GM Service Data doesn't include this where it describes the steps for R&R of the rear (right side) valve cover gasket that I can find. It probably refers that in some of the other instructions, which is usually the case when one step has to be done before the other. However, these are not always printed together in the same location. According to AutoZone, it does have to be removed. I believe AutoZone gets their info from Alldata. I apologize for the misinformation.
 

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Engine Coolant Crossover Pipe
Replacement (LZE/LZ4/LZ8)
Removal Procedure

1. Remove the intake manifold cover.
2. Remove the generator. Refer to
Generator Replacement (RPO LS4) |
Generator Replacement (RPOs
LZE/LZ4/LZ8).
3. Remove the drive belt idler pulleys.
Refer to Drive Belt Idler Pulley
Replacement or Drive Belt Idler
Pulley Replacement.
4. Remove the power steering pump.
Refer to Power Steering Pump
Replacement (LS4) | Power Steering
Pump Replacement (LZ4/LZE/LZ9).
5. Reposition the coolant recovery
reservoir hose clamp at the fill tube
fitting.
6. Remove the coolant recovery
reservoir hose from the fill tube
fitting. Position the hose out of the
way.
7. Reposition the radiator inlet hose
clamp at the crossover pipe (3.5L
shown, 3.9L similar).
8. Remove the radiator inlet hose from
the crossover pipe.
9. Reposition the thermal bypass hose
clamp at the crossover pipe.
10. Remove the thermal bypass hose
from the crossover pipe.
11. Remove the coolant crossover pipe
bolts (2, 3, 4).
12. Remove the coolant crossover pipe.

Installation Procedure
1. Position the coolant crossover pipe
to the cylinder heads.
2. Install the coolant crossover pipe
bolts (2, 3, 4).
Tighten the bolts to 50 N·m (37 lb
ft).
3. Install the thermal bypass hose to
the crossover pipe.
4. Position the thermal bypass hose
clamp at the crossover pipe.
5. Install the radiator inlet hose to the
crossover pipe (3.5L shown, 3.9L
similar).
6. Position the radiator inlet hose
clamp at the crossover pipe.
7. Install the coolant recovery reservoir
hose to the fill tube fitting.
8. Position the coolant recovery
reservoir hose clamp at the fill tube
fitting.
9. Install the power steering pump.
Refer to Power Steering Pump
Replacement (LS4) | Power Steering
Pump Replacement (LZ4/LZE/LZ9).
10. Install the drive belt idler pulleys.
Refer to Drive Belt Idler Pulley
Replacement or Drive Belt Idler
Pulley Replacement.
11. Install the generator. Refer to
Generator Replacement (RPO LS4) |
Generator Replacement (RPOs
LZE/LZ4/LZ8).
12. Install the intake manifold cover.
Refer to Intake Manifold Cover
Replacement or Intake Manifold
Cover Replacement.
 

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Engine Coolant Crossover Pipe
Replacement (LZE/LZ4/LZ8)
Removal Procedure...
Refer to Intake Manifold Cover
Replacement or Intake Manifold
Cover Replacement.
Got this done today. R&R the right side valve cover gasket and of course, had to R&R the coolant crossover gaskets since it had to be removed to get to the right side valve cover. I wonder what idiot designed this cluster?
 

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I wasn't terribly thrilled about that either, however...
The biggest thing was having to order the front and rear crossover gaskets, that had to be ordered in addition to the valve cover gaskets.

I will say as well, I disconnected most of the spark plug wires, for which I found this diagram to be extremely helpful (please note I used this on my 2007 Impala so it covers 2006-2011 3.5L's)
:
 

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I wasn't terribly thrilled about that either, however...
The biggest thing was having to order the front and rear crossover gaskets, that had to be ordered in addition to the valve cover gaskets.

I will say as well, I disconnected most of the spark plug wires, for which I found this diagram to be extremely helpful (please note I used this on my 2007 Impala so it covers 2006-2011 3.5L's)
:
Sweet diagram! On the 3.9L, the coil pack has each spark plug numbered, so all I had to do was to number the plug wire with a piece of masking tape and a black Sharpie.
 

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Sweet diagram! On the 3.9L, the coil pack has each spark plug numbered, so all I had to do was to number the plug wire with a piece of masking tape and a black Sharpie.
Yeah on mine it's labeled as well, technically once you can remember that the back set is 135 and the front is 246 you really don't need a diagram but it still helped me know that.
 

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Yeah on mine it's labeled as well, technically once you can remember that the back set is 135 and the front is 246 you really don't need a diagram but it still helped me know that.
Yep, I use a lot of diagrams quite often. I had actually forgot about that initially...then after about the second label, it dawned on me of the sequence.
 

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I wanted to add pictures of the rear valve cover I just did on mine (a 2007 3.5L), they are in sequential order but mostly I focused on pointing out certain things... Like where the bolts and nuts are, and some of the tricks I used.

Hopefully it helps someone.
The red stuff is RTV gasket sealant.

Also I'm going to list out my tools:
10mm short socket with 1/4 drive ratchet
10,13 and 15mm regular and deep socket, 3/8 Drive with ratchet
10,13 and 15mm open and closed end wrench
needle nose and regular pliers (for annoying clip-hose clamps)
3/8" drive torque wrench
tie-down strap

and in my case I also had:
1/2 and 3/8" drive air ratchet and impact wrench
rubber mats

Other notes:
I manually "pushed" the new gasket in the groove by going round and round with my fingers, it's not really difficult but I took a little time to make sure it was seated in the groove.

I held the new crossover gaskets in place with two top bolts (shown in pictures) as I pushed it back onto the engine.

The alternator does not need to come out completely, I just moved it to the side and back a little, especially since I couldn't get the signal wires unhooked.

I only got the top radiator hose off...

Some pictures contain clues besides the obvious and the circled stuff.
(yes I decided to take the entire motor mounts out and not just loosen the 1 bolt)

Getting the motor mounts out and hooking up that strap allowed me to (manually) "rotate" the engine towards the front, doing so gave me a few more inches of space to work in. Once the motor mounts are out the engine doesn't require much to be pulled forward, it really can be done by hand but I highly recommend a strap to hold it in place.
On that note I probably should have disconnected that rubber air intake hose going from the MAF to the Throttle Body but I got lucky it just stretched it a bit.

There is a second post on the next page with the rest of the pictures and a few more clues.
 

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decided to make it two posts

the pictures are 90+% in chronological order, none were switched around but I did take a few later in the process as I remembered something but most are where they should be.

I was unable to disconnect the Oxygen sensor wire so I let the ignition module hang down there in back sitting upside down on top of the exhaust basically.

The valve cover bolts have a "stop" so if you tighten them down gradually and you keep going sooner or later you won't be able to go further, don't want to put a ton of torque on them but you won't "squish" the gasket either (at least that was my experience), you should be able to go after them with a 3/8 drive and twist them down until they "stop."

I never found specific information on this so I tightened the water crossover bolts to 18 ft.lbs.
There are SIX of these and the FRONT ones are a different length from the rears, probably best to remember each one's specific location

I also removed two of the idler pulleys, not sure if this was needed and none of the documentation and videos I saw mentioned it so I didn't include it in the process.

Last but not least after it was all said and done I let the car sit for 24 hours to allow the RTV sealant to cure proper (and this may not be required but I did not want to do this job twice LOL).

Other notes:
It is a REALLY good idea to replace your spark plugs and wires while you do the valve cover gaskets, more so if it hasn't been done in over 50k miles.

As tough as this job seemed I didn't find it too much harder than the front one, keep in mind I had done the spark plugs and wires and the front one first.
Also I did watch several videos and read quite a bit and studied the whole thing...
Both valve cover gaskets took me about 4-5 hours each.
Don't forget to disconnect one of the battery cables before you start working on this.
 

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decided to make it two posts

the pictures are 90+% in chronological order, none were switched around but I did take a few later in the process as I remembered something but most are where they should be.

I was unable to disconnect the Oxygen sensor wire so I let the ignition module hang down there in back sitting upside down on top of the exhaust basically.

The valve cover bolts have a "stop" so if you tighten them down gradually and you keep going sooner or later you won't be able to go further, don't want to put a ton of torque on them but you won't "squish" the gasket either (at least that was my experience), you should be able to go after them with a 3/8 drive and twist them down until they "stop."

I never found specific information on this so I tightened the water crossover bolts to 18 ft.lbs.
There are SIX of these and the FRONT ones are a different length from the rears, probably best to remember each one's specific location

I also removed two of the idler pulleys, not sure if this was needed and none of the documentation and videos I saw mentioned it so I didn't include it in the process.

Last but not least after it was all said and done I let the car sit for 24 hours to allow the RTV sealant to cure proper (and this may not be required but I did not want to do this job twice LOL).

Other notes:
It is a REALLY good idea to replace your spark plugs and wires while you do the valve cover gaskets, more so if it hasn't been done in over 50k miles.

As tough as this job seemed I didn't find it too much harder than the front one, keep in mind I had done the spark plugs and wires and the front one first.
Also I did watch several videos and read quite a bit and studied the whole thing...
Both valve cover gaskets took me about 4-5 hours each.
Don't forget to disconnect one of the battery cables before you start working on this.
Nice work! I took the power steering pump and moved it out of the way and put my coolant overflow tank in the same location as you did. Like you, I'm unsure if it makes any difference by removing the idler pulleys. The GM manual said they have to come off, but after taking mine off, it didn't appear that was needed.
 

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There are SIX of these and the FRONT ones are a different length from the rears, probably best to remember each one's specific location


Thank you very much for this write up!

I'm elbows deep replacing upper intake, lower intake, valve cover & coolant crossover gaskets on a 2002 3.9L Impala. I failed to mark the bolts I took out of the coolant crossover and now I can't find the right combination that works when reassembling. Does anyone have a diagram that shows the bolt length and correct position on the crossover?

Also, for anyone else doing this job... I'm waiting on a dorman pipe plug 090-108 Pipe Plug C.S. Hex M12-1.5, Head Size 6mm to plug off the unused coolant port on the rear crossover gasket. When I removed the original gasket the rubber covering that threaded hole was pretty well deteriorated.
 

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sorry, didn't post correctly the first time.
Thank you very much for this write up!

I'm elbows deep replacing upper intake, lower intake, valve cover & coolant crossover gaskets on a 2002 3.9L Impala. I failed to mark the bolts I took out of the coolant crossover and now I can't find the right combination that works when reassembling. Does anyone have a diagram that shows the bolt length and correct position on the crossover?

Also, for anyone else doing this job... I'm waiting on a dorman pipe plug 090-108 Pipe Plug C.S. Hex M12-1.5, Head Size 6mm to plug off the unused coolant port on the rear crossover gasket. When I removed the original gasket the rubber covering that threaded hole was pretty well deteriorated.
 

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Hello,

I have recently changed the front valve cover gasket on my 3.9 '07 Impala because of oil leaks. It was pretty easy doing the whole replacement process for the front gasket. My only problem was that I wasn't able to remove the rear valve cover because of the last screw that is under the alternator mount. The coolant crossover (which is also used as the alternator mount) is blocking access to the last screw. Does anybody know how to remove the last screw without having to remove the crossover? Any help would be appreciated.
That coolant crossover pipe MUST come off. There's no way around it! I had to do the same on my 2008 9C3. It's not so difficult to do, but it's a lot of labor time!
 
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