replacing valve cover gaskets

[kingfish]

I have badly leaking valve cover gaskets. Bought left and right. I had to remove the throttle body to get the right one out. Had to remove about everything on the left to get that one appart. While taking off the throttle body I noticed much crud on the inside of the plenum. How can I clean this without taking the plenum off? And is there anything I need to know other than remembering everything to put back regarding the gaskets?

[Q451990]

to NICO kingfish!

You're probably due for a full plenum cleaning. There's really not a good way to clean it yourself without removing it. Some shops have a way to inject a cleaning agent into the airstream through the EGR port to fog clean it, and that's your only option without removal.

If you remove it, you will probably need to replace the brittle hoses under it as well as the large gasket o-rings that fit between the runners. There are also coolant hoses that run between the left and right heads that are good replacement candidates. If you find cracked knock sensor housings (you probably will) you'll want to replace them and their electrical subharness.

The point here is that it's difficult to know where to stop. You can easily drop a $1000 or so in parts in hoses, knock sensors, and a subharness if you get into that job. That said, the car will perform much better when you're done.

In terms of the rocker cover gaskets - get new OEM ones from the dealer or someplace like http://www.everythinginfiniti.com or http://www.orderinfinitiparts.com and use RTV on the "half moon" portions that fit into the grooves in the heads. I noticed that Permatex gray is now available at Walmart, which is the recommended RTV for Nissan applications. You'll also want to order a new throttle body gasket. Some members will also recommend replacing the rubber washers under the acorn nuts that hold the covers down to get the correct torque - but there's some debate on the necessity of that.

There's a good diagram with torque specs. in the factory service manual available at http://www.nicoclub.com/FSM/

Good luck!

Heath

[kingfish]

to NICO kingfish! I'M GOING TO RESPOND IN CAPS.

You're probably due for a full plenum cleaning. There's really not a good way to clean it yourself without removing it. Some shops have a way to inject a cleaning agent into the airstream through the EGR port to fog clean it, and that's your only option without removal. I DON'T HAVE THE COURAGE TO REMOVE THE PLENUM. I THINK I'M ALREADY OVER MY HEAD. I GOT THE VALVE COVERS OFF. THE RIGHT BANK WAS PRETTY EASY. THE LEFT BANK WAS VERY DIFFICULT ESPECIALLY GETTING TO THE THROTTLE BODY HEX SCREWS. FINALLY GOT IT OUT. THE THROTTLE BODY GASKET APPEARS TO BE FINE. SHOULD I REPLACE IT ANYWAY? I DECIDED TO TAKE OUT THE PLUGS. THE RIGHT BANK WAS PRETTY CLEAN, BUT THE LEFT WAS NASTY. #1 WAS FULL OF OIL (LEAKING HEAD GASKET) #3 WAS CLEAN LITTLE OIL, #5 HAD OIL DEPOSITS NOT AS BAD AS #1. #7 WAS WORSE THAN #1 BROKE THE PLUG GETTING IT OUT, IT WAS FULL OF OIL FROM THE LEAKING HEAD GASKET. THE OLD GASKETS WERE VERY BRITTLE, BROKE UP WHILE REMOVING THEM FROM THEIR GROVES.

If you remove it, you will probably need to replace the brittle hoses under it as well as the large gasket o-rings that fit between the runners. There are also coolant hoses that run between the left and right heads that are good replacement candidates. If you find cracked knock sensor housings (you probably will) you'll want to replace them and their electrical subharness.

The point here is that it's difficult to know where to stop. YOU CAN SAY THAT AGAIN. THIS ALL STARTED WITH A BAD STARTER, WHILE REMOVING THE STARTER I FOUND OIL EVERY WHERE ESPECIALLY THE ALTERNATOR, SO WHILE REMOVING THE STARTER (4 HOURS) I TACKLED THE ALTERNATOR... 8 HOURS LATER WITH CUT UP HANDS THE ALTERNATOR WAS ON THE WAY WITH THE STARTER TO THE REBUILD SHOP. TOTAL COST TO REBUILD ($230 BUCKS FOR BOTH. You can easily drop a $1000 or so in parts in hoses, knock sensors, and a subharness if you get into that job. That said, the car will perform much better when you're done. I'LL BE DOING GOOD JUST TO GET IT BACK TOGETHER FROM THIS POINT. HERE IS WHERE I AM AT. BOTH COVERS ARE OFF, ALTERNATOR IS OFF, STARTER IS OFF. I PURCHASED NEW OEM GASKETS $45 BUCKS. I PICKED UP PERMATEX ULTRA BLACK RTV. IS THAT GOING TO WORK OR SHOULD I TAKE YOUR SUGGESTION AND GO GET THE GREY RTV AT WALMART? THE FSM SUGGESTS PUTTING RTV IN THE ENTIRE GROVE OF THE VALVE COVER PLUS THE HALF MOONS. DOES THAT SOUND PLAUSABLE OR SHOULD I JUST RTV THE HALF MOONS?

IF YOU WANT TO EMAIL DIRECTLY, I CAN SEND PICS. [email protected].

In terms of the rocker cover gaskets - get new OEM ones from the dealer or someplace like http://www.everythinginfiniti.com or http://www.orderinfinitiparts.com and use RTV on the "half moon" portions that fit into the grooves in the heads. I noticed that Permatex gray is now available at Walmart, which is the recommended RTV for Nissan applications. You'll also want to order a new throttle body gasket. Some members will also recommend replacing the rubber washers under the acorn nuts that hold the covers down to get the correct torque - but there's some debate on the necessity of that. FUNNY YOU SHOULD MENTION THE RUBBER WASHERS UNDER THE ACORN NUTS. AFTER GETTING THE VALVE COVERS OUT, I NOTICED THE RUBBER WASHERS. THERE SHOULD BE TOTAL BETWEEN BOTH COVERS 36 RUBBER WASHERS. I ONLY COUNTED 33, BUT I DO HAVE 36 ACORNS. WHERE CAN I GET 3 RUBBER WASHERS AND THEIR METAL DISK COVERS?

There's a good diagram with torque specs. in the factory service manual available at http://www.nicoclub.com/FSM/ I KNOW THE TIGHTENING SEQUENCE BUT IS TORQUE REALLY NECESSARY? I DO NOT WANT TO GO OUT AND BUY A TORQUE WRENCH.

Good luck!

Heath

[youtube][/youtube]

[Q451990]

The oil in your spark plug tubes is part of the leaking rocker cover gasket issue. The factory gasket should come with those seals that will take care of that too.

If you look on page EM-20 of the FSM, it'll give you a good breakdown of how to apply the RTV. I have always read that as just applying RTV in the half moon portions of the groove. I think that was the whole point of this design of the gasket vs. the one we have on the 90-93 that was all RTV. I'd get the grey RTV since that's what's recommended. It's sold at parts stores too - I just found it to be a little cheaper at wallyworld. Less than $6.

Get an extension and a hex bit and you'll have no problem getting that throttle body back on. I yank them in about 10 minutes at the junk yard I would replace that gasket and clean the throttle body with brake parts cleaner. The back side should have a nice black layer of carbon. If you have a Harbor Freight nearby, I would look to them for a cheap torque wrench and hex socket set... Their tools aren't the best, but for occasional use, they get the job done and with their coupons and sales you can get their stuff dirt cheap.

http://www.harborfreight.com/6-piece-38 ... 67891.html

http://www.harborfreight.com/3-8-eighth ... h-807.html

I'm guessing those rubber washers and metal disks are factory only parts. If you have a pull-a-part type yard nearby, you might just scavenge some if they're special order and will take time to order.

Alternator installation is a lot easier if you pull the four bolts out of the a/c compressor so that it can drop a little and remove the top alternator bracket. I just did this job, and unfortunately I'm getting ready to do it again... my Q is eating them for some reason.

Heath

[kingfish]

Heath I went over to Harbor Freight and picked up a 3/8 drive torque wrench. Maybe I should have gotten the 1/4 drive inch/pound wrench? Since I'm in this deep, I'm thinking I ought to do the plenum, it's pretty crudded up especally inside where the port for the egr valve vents into the plenum. I"ve got about everything off anyway, why not? I cracked the throttle body gasket so picking up a new one monday before I begin the install. If I brave it... can I use the old Plenum ring gaskets? Dealer wants $8 per ring. They say I should take mine off first and then decide how many to replace if any. What do you think? Another thing I need to do is lower my compressor to get my alternator back in. There are 2 bolts from underneath easy to get at and one in the front. Is there any other bolts that I'm not aware of holding the compressor, I'm not discharging just moving it to make room to get the alternator back in. They should have designed the alternator to be on the bottom and the ac on top instead of the way they did it. I read that there are 4 bolts holding that compressor, but I can't find the 4th one, is it behind the compressor???... how would you ever get to if if it is????? So far all that you've posted has made it pretty easy. I really appreciate your posts. Thanks Kingfish

[Q451990]

Yeah... there are four bolts on the compressor... that fourth one is fun. I used my torque wrench to get to it since it has a longer handle. I could get about a 1/8th of a turn on it at a time. It's definitely tough.

Those plenum o-rings will all be brittle. So will the hoses and all of the fun parts under there that I mentioned. There's not a lot of cross-over between the plenum and valve covers - so if you can get it back together, it might be worth taking a break and regrouping if finances or back pain is an issue!

Heath

[OwnerCS]

If you're tackling (or thinking about) tackling the plenum, there are some pictures in the following slide show..

http://s286.photobucket.com/albums/ll11 ... =slideshow

[elwesso]

You definitely don't want to reuse those plenum gaskets, even if they look decent I've traced some nasty vacuum leaks from used ones.