Carbon build up

[project 92z]

I guess this is the best spot for this post... Today I was taking the plenum to be powder coated and had to take apart the TB and the plastic parts. Well once I removed the flapper, I saw a huge carbon build up "growth" that seems to be coming from the EGR mounting plate. Is there a easy way to clean that? Also if anyone has coated the plenum before, how do I remove the (I guess they're) bearings for the TB flapper?

[project 92z]

UPDATE; I got it cleared with the use of PB Blaster, Berryman B12, picks, wire, brushes and the weird but effective YouTube "Redneck TDI Manifold Cleaning". Still got a question though for anybody who has powder coated these. The throttle has bearings in the plenum. How do I remove them or do I need to?

[1988GTU]

It's and non-serviceable part. You will be chartering your own waters should you take on that task. U really shouldnt 'coat' the innards of the TB. The most I suggest to do from my experiences is to just clean it as you did & leave it be or if you have the dedication, polish the aluminum very very very well. Kinda an all or nothing job.

[project 92z]

U really shouldnt 'coat' the innards of the TB.

I wasn't planing on doing the innards. Just the outside of the plenum but they told me no plastic. The bearings seem to be made of poly and steel and notched in place. I'm thinking maybe heating the aluminum up and removing them quickly and the reverse to install them. I was just hoping that someone knew whether or not if l had to remove them.
And as for trying to just clean and polish, I've seen it done well online but I tried with the front valve cover and didn't come out as good. Local powder shop is charging $125 for plenum and VC to be done ceramic chrome.

[Superdave]

you'll most likely have to remove them, the shops want nothing but the bare metal.

The oven is about 400F and the parts take a while to bake, any oil in those bearings will likely leach out and contaminate the coating.

[project 92z]

Hey folks, I was wondering, is the 96 plenum very different? I just remembered that year's plenum has the throttle separate from the plenum itself. Might be easier to accomplish my goal.

[robertisaar]

yes and no. upon first glance, it just looks like the TB was relocated, look a bit more at it and you start seeing other differences.

i think(99% certain) you'll have to use the 96-97 lower intake with it.

http://i1158.photobucket.com/albums/p606/sob0055/for%20sale/20120903_122629.jpg

https://www.google.com/search?safe=off&biw=1280&bih=671&tbm=isch&sa=1&q=9 6+lq1+intake+manifold&oq=96+lq1+intake+manifold&gs _l=img.3...37264.38939.0.39020.9.8.0.0.0.0.130.470 .3j2.5.0....0...1c.1.53.img..9.0.0.nQpcdjycCJU#fac rc=_&imgdii=_&imgrc=c3IQsP0s2oxFYM%253A%3BuK2n2crX y2kfyM%3Bhttp%253A%252F%252Fimg.photobucket.com%25 2Falbums%252Fv234%252Fgpchris%252FFor%252520Sale%2 52FDSCI0185.jpg%3Bhttp%253A%252F%252F60degreev6.co m%252Fforum%252Fshowthread.php%252F40815-Complete-97DOHC-Intake-(UIM-LIM-TA-TB-FR-etc)%3B1024%3B576

(don't know why, but most pics of the 96-97 manifolds are dead links?)

[1988GTU]

Different EGR, lim, uim, changes to cooling lines, and i am sure there's more. To justify that swap, you would consider the heads/cams to complete it. bve32 & I went thru with that swap and it was IMO worth it for the gains of power and mpg.

[pocket-rocket]

You do not need to swap heads and cams to compliment the 96/7 intake. The heads on the 96/7 heads have large pill shaped exhaust ports and clover shaped combustion chambers vs the d port style on the 91-95, but any LIM will bolt to any head (styles of LIM and UIM don't interchange between styles, though; 91-95 LIM must be used with 91-95 UIM).

I've no idea what order this thing will post those pics but in the ones that have both year model shown, the earlier 91-95 is on top and 96/97 on bottom. Hopefully 4MP from my phone is sufficient enough of resolution to help.

If you go from the earlier style I take to the later, there is a write-up on this site detailing it. Besides the obvious LIM and UIM, you also need the later throttle cable (longer than the earlier style), brake booster hose (booster port is in a different area), either cut your rear plug wire boot covers down or grab a set of later plug wires because although it's not noticeable without any sort of reference, the 96/7 UIM is longer than the 91-95 (i was going to swap over a set of front ones on my Magnecor wires vs spending what, ~$200 on a new set?), you could leave your ICM where it's at or grab the bracket and move it behind the PS pump where it won't be directly under the exhaust mani. I'm sure there are a few other things I'm missing as well, so read through the write-up.

91-95 (top) vs 96/7 exhaust ports


91-95 (top) vs 96/7 combustion chambers


91-95 (top) vs 96/7 LIM


91-95 LIM & UIM


96/7 LIM, UIM & intake arm


Edit: not sure which sets of pics have better resolution because I'm on my phone, so I'm leaving the doubles up :P

[1988GTU]

FTR I never said heads had to be swapped. If you wanted the latest and most potential, head changing would be a plus.

[Schurkey]

Thanks for the comparison photos, pocket-rocket. I've got a '96 core engine with the newer heads/intake. I'll have to look into the possibility of throwing them on my '92 when I finally get around to replacing head gaskets.

[pocket-rocket]

FTR I never said heads had to be swapped. If you wanted the latest and most potential, head changing would be a plus.

I didn't mean to make it look like you had, I was just putting the differences between the years out there.

The only other difference other than what I posted was the 94+ engines had an intake cam sensor on the front bank, and I think the oil cooler was discontinued around 93 or 94. Also if you have a 91-93 engine and it has air injection tubes in the exhaust manifolds, it is an engine from a manual car and has the 210hp engine vs 200hp in the auto. I also believe it was determined the small CR boost in the 96/7 engines was from the pistons, not the clover combustion chambers on the later heads.

Edit: More came to me in the shower (odd place, I know...) 94 I believe was the year to get the colletted cam gears vs the crappy lock rings., 95 I believe was the first year for the round toothed belts (runs cooler) where as the earlier ones were square toothed. If you swap to a round tooth style, be sure to get the intermediate shaft gear as well (the collette style gears will bolt right on the older cams just fine and are much easier to reset come belt change time). Also the 97 engines had 33mm lifters vs 35mm on 91-96, and I'm pretty sure there aftermarket lifters for the 35mm style only.

Thanks for the comparison photos, pocket-rocket. I've got a '96 core engine with the newer heads/intake. I'll have to look into the possibility of throwing them on my '92 when I finally get around to replacing head gaskets.

You bet. With all of the parts I have around here, it's about time someone got some sort of use out of them.

I swear, after all of the DOHC stuff Ben unloaded on me I could start a DOHC museum, but I doubt anyone other than a small hand full on here could care otherwise.