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-   -   DIY Valve Cover Replacement (https://g35driver.com/forums/g35-sedan-v35-2003-06/384690-diy-valve-cover-replacement.html)

getupkid 08-01-2011 06:33 PM

DIY Valve Cover Replacement
 
5 Attachment(s)
I changed my spark pugs and noticed I had a little oil in my #5 spark plug. I read a lot on here how its most likely your valve cover and you have to replace the whole thing. I saw that there are aftermarket gaskets for the spark plugs but it requires you to drill our the old ones and I didn't want to do that. After removing my valve cover, the gasket didn't look bad but I had already bought a new valve cover so I went ahead and replaced it. I took some pictures so I figured I would do a brief walkthrough for removal and replacement of the right (passenger side) valve cover and gasket.

First things first, take the negative off the battery!

Remove the engine cover by unscrewing the two screws and two cap nuts.

Remove your Intake by unclipping the four clips at the air filter, unscrewing the two bolts holding it in, loosen the strap around the throttle body, unplug the MAF Sensor and the vacuum rubber line. Take the intake out and set it aside.

Next, remove the upper plenum. There are 16 bolts and 2 nuts. I have attached a sheet from the service manual which shows the order to remove the bolts. Removal goes 18-1. Make sure when you remove these, you keep track of which is which. They are all different sizes so you need to remember which is which. There is a vacuum line going into the side of the upper plenum, remove this line. Tilt up the Upper plenum and use some bungees to hold it up out of the way. There are two lines coming in the back of the upper plenum. These are coolant lines. I kept the connected because I didn't want to mess with them.

Next, remove the lower plenum. There are 6 bolts and 2 nuts. The same attached sheet from the service manual shows these bolts. Same as above, keep track of which bolt is which. There are two bolts in the back that connect the coolant line to the lower plenum, remove these. There are also two wire harness brackets that are connected to the lower plenum. Remove these as well. Be careful when you lift the lower plenum out of the way, there is a gasket underneath that may be stuck to the bottom. Set this aside on a towel so you don't scratch it up.

Now, take a towel and place it over the intake manifold. I used a 2x to hold the towel down. You don't want to get anything down in the engine!

Now, remove the two bolts that hold the wire harness to the valve cover. There are also two areas where the harness is connected with plastic push connectors, remove these.

Now remove the three Ignition coils. Make sure you mark which goes where and which wire connector goes to which ignition coil. Mine had numbers on the wires but yours may not.

Remove the vacuum line going from the PCV Valve on the valve cover. I removed this line completely, it gets in the way otherwise. There is also a vacuum line going from one valve cover to the other. Remove this one as well.

Now its time to remove the valve cover. There are 10 bolts holding this down. They are all on the perimeter of the cover. Again, keep track of which bolt goes where. These are different as well. The corner bolt closest to the fire wall sucks! It took me roughly 10 mins just to get this one bolt and cut my hands up reaching around the wire harness and coolant lines, good luck with this one.

Once all the bolts are off, lift the cover up. It will be stuck because of the sealant and oils on the gasket. There is very little space to move this out so for me it worked best lifting it up as much as possible and then pushing it towards the firewall and then working it out.

Once this is off, clean up all the sealant off the block. I used a flat edge razor blade. Don't drop any of this in the block. If you do, use some compressed air to blow everything out.

Put a bead of red RTV sealant around the front edge where you cleaned the sealant off. Now put the new gasket on the valve cover and install it. Make sure the gasket stays on and the gaskets around the spark plug tubes are sealed properly.

Now work backwards installing everything back the way you took it apart.

I have attached some pictures of the steps to removal. Make sure when your tightening the bolts back that you don't over tighten. I broke one of the bolts heads off on the valve cover and took me 2 1/2 hours taking the valve cover back off and extracting the bolt. If you can get away without making a stupid mistake like this, it should only take you 1 1/2 hours to complete. It is a very easy repair, just take your time and keep track of which bolt goes where.

While I had everything removed, I cleaned the plenums with throttle body cleaner. My car idols much smoother now! Just be careful not to move the throttle body around, this can cause you to idol high and have relearn the throttle body position which is easy but some people have troubles getting the timing down.

getupkid 08-01-2011 06:35 PM

3 Attachment(s)
More pictures

NFSP G35 08-06-2011 02:53 PM

I've never had my passenger side valve cover off... just the driver's side :bowrofl:

It was my #6 leaking oil, all the pass side ones were fine :dunno:

But I do have a pair of covers in the garage waiting to be painted (still deciding on color) so this will definitely come in handy later :biggthumpup:

hL. 08-06-2011 05:44 PM

I'm doing my spark plugs tomorrow and I know I'll probably have a leak like everyone else. Will it be ok if I reuse the valve cover or will the be a leak if I do that?

NFSP G35 08-06-2011 05:53 PM

^You can reuse it, if it continues to leak, it will probably be a slow leak, and it doesn't really seem to affect the plug :dunno:

If one of them is leaking, there's a vendor on here that sells replacement gaskets. You'll be fine waiting a week or two until you can get the gaskets in.

jimNC 08-13-2011 12:55 PM


Originally Posted by getupkid (Post 6034618)
The corner bolt closest to the fire wall sucks! It took me roughly 10 mins just to get this one bolt and cut my hands up reaching around the wire harness and coolant lines, good luck with this one.

Indeed it does suck. I swapped the driver side out awhile back but punted on the passenger side when I saw this (at the time, only one spark plug seal was bad on the driver side but I'm sure by now there are one or more bad on the other side).

Any tips on getting that out? Just perseverance? I've been wondering if something like a bent ratchet or crow's foot might be of some aid. Thanks.

ps To me if it only took you 10 min. to get that bolt out you did pretty good.

re-crue13 08-13-2011 02:20 PM


Originally Posted by NFSP G35 (Post 6044708)
I've never had my passenger side valve cover off... just the driver's side :bowrofl:

It was my #6 leaking oil, all the pass side ones were fine :dunno:

But I do have a pair of covers in the garage waiting to be painted (still deciding on color) so this will definitely come in handy later :biggthumpup:

Still deciding? It looks to me like you're set on the black and white

Beanz 09-22-2012 06:08 AM

I tried doing mine tonight. This is my first big diy on my car. I also broke a bolt head off on the valve cover. How did you get the old one out and where did you get the replacement?

I got down to the passenger firewall bolt you mentioned and can't get at it. I'm thinking of getting a swivel or wobble set tomorrow unless you have any better ideas.

getupkid 09-24-2012 06:27 PM

you need to us a bolt extractor. You drill a small hole in the center of the bolt and us the extractor to turn it out. You can then just take one of the other bolts to home depot and buy another one that is exactly like it. Make sure you get the right thread or you will tear up the aluminum block. Good luck, this was a pain! I did use a few swivel socket to get that bolt out.

MPG35fiend 10-14-2012 05:49 AM

subd. good write up.. will need to do this soon.

vrezhg 01-05-2013 07:56 PM

I just changed my spark plugs today, two of my plugs on the right side had alittle bit of oil in there and one on the passenger side. -__- so that sucks, but looks like imma have to do it soon too. The only thing I'm wondering is how important this is to do since there isnt any oil being burnt, atleast none that i notice. Im wondering how much oil im actually losing between oil changes.

Ps how much do the parts cost for this job?

SuperMike242 01-07-2013 07:11 PM

If you are interested I have a new pair of valve covers and the gaskets for sale. You can private message me for more details.

GODDI507 03-11-2013 02:42 PM

I will be jumpin on this DIY this weekend... wish me luck!

GODDI507 03-11-2013 02:45 PM

quick question though... cause i did notice a little bit of oil in one of my spark plugs also... Is the replacement of the cover gasket going to solve that issue or do i have to replace other gaskets also?

kpowe1 03-11-2013 10:46 PM


Originally Posted by GODDI507 (Post 6711685)
quick question though... cause i did notice a little bit of oil in one of my spark plugs also... Is the replacement of the cover gasket going to solve that issue or do i have to replace other gaskets also?

Changing the gasket will not solve your problem, you will need to replace your cover


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