I decided last night to start taking apart the plenum so I can replace the injectors. It wasn't as bad as I thought, time consuming, but not bad. I followed some of the great tips and advice I've picked up from this Forum and I know that's what helped.

Anyway, here are my questions. While taking out the torx bolts from the plenum, some were loose. I've determined someone else had serviced it before me so they probably didn't torque them down right. I will torque them correctly when I put everything back together, but I was wondering if also using loctite on the bolts was overkill. Anyone recommend this?

Now that I have the plemum off, what's the best way to clean inside of it? There is heavy carbon build up and I'd to get it as clean as possible, I will probably remove the runners and clean them too. Does anyone have any suggestions? I was going to use a nylon bristle brush and some Carb cleaner but I am open to try something else if its more effective.

Also, I have the throttle body off and apart for cleaning. I removed the IAC valve but not the TPS as I don't want to readjust it. Anyone have tips on cleaning the TB?

As always, your help and suggestions are appreciated!

 

I just replaced my injectors a few weeks ago and went through the same process with my 89. I got a couple of cans of throttle body spray cleaner, a couple rolls of paper towels and made sure I was outside. The black stuff just washed off a lot easier than I thought it wood. I didn't need any brushes to get any of the carbon off. A flexible rod to push the towels through the runners will help. The inside of plenum was a bit more challenging but I did get it nice and clean. There you might want to use a nylon bottle brush because the inside surface is rough and the carbon needs a little help. I spent about 2 hours cleaning the plenum and both runners. If you didn't get your injectors yet, check out FIC. The prices are the best and the customer service is top notch. Good luck.

 

anyone try this stuff call "Sea Foam"? I've seen some video of the stuff in action, looks like the car is on fire with all the smoke, but it apparently just eats up all the carbon deposits and burns them up. I wouldn't be opposed to trying it, but am curious about others experience first. I just found out that Tractor Supply carries the stuff.

 

Spray-on aluminum wheel cleaner.....

 

John at FIC hooked me up with the injectors. I was thinking of flexible rod, like a thick pipe cleaner for the runners. And I definitely plan to do this outside.

 

On the runners and plenum just spray the with degreaser then take to the car wash unless you have a power sprayer. Do the TB with the proper cleaner by hand.

 

They offer a product called "Deep Creep" that comes with a really long straw with multiple holes in it, and a plugged end so that it will spray out of said holes. It's the same as the other non-aerosol stuff, and works pretty well too. Just don't let your throttle blades snap shut, and snip the straw off.....

As far as cleaning the runners while still on the car, clean them the way you would a gun barrel-make a swab holder from a wire hanger, cut-up a t-shirt, soak it in Seafoam, and swab down each runner. Let it sit for a while, and do it again until the swab comes clean.

 

I've seafoamed the vette, my buick and the cadillac. You would be surprised how much it works. My buick picked up 2 mpg highway after using that. It cleans the valves and everything.

the vette smokedl like a ****, so much that i actually foamed it twice.

It doesn't clean out the plenum/runners, you suck the seafoam through a vacuum line into the intake manifold. So it pretty much does manifold-down.

 

I've read somewhere that you can damage the IAC with traditional cleaners used on the TB. If so, I'd think removing it might not be a bad idea.

 

 

I also recommend replacing all of the fuel rail and line orings. Ask me why I know... These parts are almost 2 decades old and anything rubber or plastic is usually compromised. Also replace every vacuum line you can get to while you are in there. Helps to lessen hard to track vacuum leaks at a later date. If it can leak, at this age, it probably does or will soon. The distributor is easy to get the cap($20) and rotor($3) off while the plenum is off as well, so take a look and replace accordingly.

I did the whole shebang because on the first start of the year it started leaking Coolant out of the head onto the intake base and leaking fuel out of the top oring on an injector. Lucky for me no coolant was in the oil(still changed after work) and the gasket was only compromised allowing a leak out the top or the leak into the engine was so minute I never noticed.

I know my post is kind of random and not all sentences seem to transition well to the ones next to them, but I wrote them while the stuff popped into my head.

Good Luck!

 

Do not use Loctite on the bolts!! You have steel bolts going into aluminum. If you ever want to get this apart again, don't use it. It is recommended that a anti-seize be used on any steel bolt that goes into aluminum. The bolt can gall in the aluminum and freeze. There have been many threads asking.....broke off the bolt.....

Just torque the bolts and you will be fine.

 

When steel bolts become one with alluminum it does not seperate easily. The bolt breaks. Then you drill and tap.

 

I used a long pair of forceps to clean the runners with regular paper towels. The forceps worked real well when I clamped the paper towels in them to get inside the plenum. The injector set from FIC came with all the "O" rings needed to replace the old ones.

 

Thanks for the tip. I purchased new o-rings when I bought the plenum gaskets. I already did a tune up and replaced the cap & rotor. The injectors from FIC are complete so new o-rings there too. I will replace the o-rings on the lines into the rail, etc.

By the way, any tips on getting the EGR valve off? There's this porcelain thing at the base, WTF.

 

Ratcheting box wrench in 10mm(or was it 12?) and patience was what I used on the EGR Valve.

I saw others clarified, I didn't use Loctite and don't recommend for the same reasons.

 

UPDATE.....throttle body is now completely cleaned and polished. I installed new gaskets and a new IAC valve. I went a little overboard cleaning the outside of it with my dremel so I went all the way and wound up polishing it. I have to say, it didn't come out too bad being my first time. I guess watching my Dad polish jewelry all these years taught me something.

I went to clean the runners and the plenum and it just would not come completely clean. Went thru a whole can of carb cleaner and a can of brake cleaner, it just made a dent. I guess 25 years of carbon build up turned it into coal. I wound up sending it out to get cleaned and bead blasted. With any luck, I will have it back by the weekend.

While I am waiting, I figure I may as well redo the valve covers and get them clean. Or maybe just get a new, shiney set.

 

You were right, 10mm. I was able to get it off with an open end wrench with little problem. The temperature sensor screwed into the base was another story. It didn't look to be in the best of shape so I decided to get a new one. It took the better part of the day calling around local stores until I found one on eBay. The bad news was the guy couldn't ship it for 3 weeks! I finally got a GM part number from Covette Mike and did a search. It should be here tomorrow.

 

I'm waiting for my injectors also. I took the runners and filled them with hot tap water, then poured a shot of super clean in them let soak. after 10 min. dumped out cleaner and rinsed ,that easy they look new. same thing for the plenum. Finished with a couple of quick coats of Mercury Mariner silver marine paint, looks great. now just waiting for injectors.