Cleaning the intake collector (plenum) and a couple other things

[s14=pimpin']

hey all,

so, the plenum is removed, and it is a mess. How do we clean this thing ourselves? Is there some sort of product we can use?

Also, cylinder #2,4,6,8 valve cover gasket is shot, we discovered the plugs were covered in oil. Any suggestions on how to properly replace the gasket, and other things that we should check while we are down there??

last thing, how do we release the fuel pressure out of the motor, without the motor being in tact? We want to check the injectors, but aren't too sure how to release pressure without cranking her over.

thanks guys

[RobHakari]

This reminds me of something I planned to post but got side tracked by college life. In the end of augut i went to Crest Infiniti(in dallas close to plano) and asked how much it would cost of the to clean out the plenum. first they had no clue what i was talking about. then once the realized what the plenum was they said 39.99. and i was happy. then i realized they meant to just chemical clean the outside of the engine...

so then one of the sales reps who had been there since 93 came over and eventually realized what i meant. and then he gave me a "how stupid are you" look and said "why would anyone want to clean the plenum out?". so i responded with something about better performance and something, because i had no real clue i just remembered seeing it on here. he was like, "no... it wont do anything for you, is pointless to clean it out."

i just walked out.

so... was he right about there being no purpose to it, or was he just pulling stuff out of his arse and actually knew nothing about it. because i swear that ive read on here thing saying its benificial to clean it out.

btw... sorry to steal your post. it jut reminded me of my story.

[elwesso]

I really dont think it will improve that much performance.... I could be wrong, but I cant see how it would make much of a difference.......

What you do it for is to clean the dirt out, because the dirt getting into the cylinders makes it wear faster.......

Anyway, to clean the plenum, best thing to do is get a 6pk of carb/TB cleaner, a rag, and go nuts...... Look into getting those disposable shop rags, or use ones you dont want back, because you wont want them back after your done!!! I consider myself spoiled, since I have access to an industrial parts cleaner......!

Valve covers are a GREAT job to do..... You should do both while your in there..... If you are even close to needing new plugs, now is the time.......

Also, Id recommend taking pictures of the heads with the covers off, so we can see what they look like (like how much wear has occured)......

Releasing fuel pressure is easy..... Just take out the fuel pump fuse in the passenger cmpt block, crank the engine a few times........

[Highway Q45]

I can't vouch for performance improvements on a 240 but on my Q the improvement was amazing...no bull. My plenum was so dirty. I used TB cleaner, STP Grease Eater, and Easy Off oven cleaner on the interior surfaces. The TB cleaner just made the grime run and then it dried again. The Grease Eater was OK, but the Easy Off made it look like new. I used a 12" long round bristle brush to get into the tubes. Worked like a champ. The cleaner plenum and runner bodies made my Q idle about 400 rpm high which needed to be brought down using the IAC idle adjustment. Good Luck and hope it works as well for you.

Steve

[s14=pimpin']

thanks steve, I'll try that. elwesso, the motor is in pieces, i guess I should have been a little more clear, but is there anyway we can release the pressure without having to put the motor back together (i'm not sure if we can crank her with the covers off).

we were pretty much cleaning the plenum for maintenance issues more than performance. the thing is filthy, there must be some gains after cleaing it out. and we are working on getting a digital camera some time soon.

thanks guys (any idea which gasket/ seal needs to be replaced, causing the oil to spill into the plugs?)

[PalmerWMD]

As long as you have the plenum out definetly clean it <well> if your arm isnt too muscular you can reach deep into it with a cleaner soaked rag. from the intake ( have done that).

Call Joe for teh parts he'll tell you which ones and out of courtesy for the guidance buy them from him ( he gives great prices too)http://www.infinitipartsusa.com/Default2.asphis #1-888-216-5328

Fred..

[elwesso]

Since you got the engine apart, I suppose your only way is going to be to undo a fuel line, and put a bucket in front of it since the floodgates are going to open...... Momentarily anyway.......

Then take out the fuse........ Just to be safe.....