308QV Plenum -- Painted on the car

I would have primed the bare spots with a primer for aluminum and used Liquid Sandpaper (carefully) on the original paint to optimize the VHT's bond. Its not the heat that gets the plenum paint; its the expansion-contraction from constant heating and cooling. Aluminum expands twice as much as steel. Thus the common spalling of the paint where there's no contact.

 

i used my heat gun to get the plenum hot prior to spraying. also did the sandpaper on a sanding block to highlight the ridges and script.

 

Use a portable halogen work light to get the crinkle to come up fully. They get a couple hundred degrees. Hold it very close move slowly over it and it will be done in minutes.

 

Even a hair dryer will help-just don't TELL!

 

For those who repainted their plenum in the car, how did you prep? Did you remove all of the old paint? If so, how? My old plenum is cracked and I got alot off with a brass brush but some of the remaining old paint is pretty stubborn. Considering taking a Dremel to the rest but would like to hear what others did.

 

Of course, I mean the PAINT on the old planum is cracked - not the plenum itself!

 

Agreed - this is a great collection of ideas. It gave me enough confidence to work on mine instead of waiting until I need to remove it. Unfortunately mine had a bit more paint missing than yours (big chunks actually) so I'm trying to at least get a majority off or I'm afraid I'll see 'rises' from the old paint underneath. Going to try a Dremel with a brass brush attachment and go slowly. Off to the garage!!

 

You could remove the plenum, clean the years of accumulated oil and dirt from the engine valley, replace numerous leaking vacuum hoses...and replace all those old, rotted coolant hoses and end up with this gem. Looks good, spotless and no more fuel, coolant or vacuum leaks...for at least another 10 years, or so.
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That looks awesome!

 

Here's mine before and after. Just had it done by Linco Plating last Month. They actually polished then outline to chrome like finish.
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+1....what brand are the hose clamps, David?

 

Multiple-brands are used, depending on the size and application. All of the clamps used are lined, meaning that there are no perforations which could penetrate the hoses. We care about this, as over time, these types of clamps will naturally loosen...as the hose outer skin is penetrated. To clarify further, the clamps used are smooth on the inside where they contact the hose.

Coolant hose clamps: Typically Norma brand. The clamps I use on the large diameter coolant hoses are 12mm wide versus the standard 9mm. With more surface area, a better seal can be obtained and minimize the possibility of seepage. (As I was provided with a complete SRI hose kit for this car, the clamps were a very high quality American made equivalent of the Norma clamp I typically use.)

Most other hoses: Norma brand/9mm width

Small diameter hoses: Currently using Norma "band-type" screw clamps, although switching over to the ABA stainless steel hex-driven clamps. Although these are much more costly, as availability in multiple sizes improves, I'll switch over.

 

For some very strange reason the PO of my car painted the plenum black. It is flaking very badly. I took a wire brush and a dremel with one hand and a shop-vac with the other to remove as much of the paint as possible. The paint in the lettering is very stubborn and I figure will need chemical removing. Any recommendations? For now the plenum is aluminum silver. Until my next major I will be painting in-situ as well.

 

Thanks very much for the details, I appreciate it.

 

IMHO, it would be best to remove it, soda blast it, and have it refinished. That will give you a good opportunity for a good throttle body cleaning, etc. My factory red finish is flaked in many places, but to me it's just a sign that it's time to pull it. Intake seals are still soft, but it's time to have a look at it all and replace it. I'm going to leave that paint there until the Fall, then remove the plenum and the manifolds for cleaning, hose work, engine cleaning, new injectors, etc. I will likely pull the belt covers and water pump tensioner bracket as well, for blasting and a nice high-temp clear coat.

Just my ten cents

 

Amazing ideas here.

I too need to repaint the plenum on my 3.2 due to flaking paint over time etc.

How do you remove the plenum with all those hoses and tubes connected etc? Is it a DIY job? If not i may have to paint it while still installed but would be difficult to get a consistent finish in the areas underneath.

Thanks.

 

Its not hard, there are only 8 nuts that secure it, but read up on it & look at the parts diagrams before you try it. There are some metal spacers in there which , if one gets hooked up on a stud as you lift the plenum off, can disappear down an inlet port faster than you can say "oh sh*t" !

The safest thing to do is actually to just loosen the nuts under the plenum & then undo all all the nuts at the base of the manifolds & lift the two manifolds and the plenum off as one unit & then seperate them on the bench.

That of course is also an ideal opportunity to inspect/replace the two coolant link hoses under the plenum, clean out the middle of the engine V, raplace the lines to/from the expansion tank, take the injectors out & get them cleaned (or replace them) etc etc etc

Also, if its a 3.2, the silver/grey wrinkle paint round the sides of the plenum & on the throttle body is not easy to find & is very expensive.....

 

No need to blast...and not the safest way. Chemical strippers work just fine, anyhow. That's how we do it.
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The advantage of removing the plenum and the throttle body off the car is that you can match port the two parts as they are not exactly port match. On top of these, the plenum/T-body gasket is not exactly match neither, you can easily trim the gasket to match both parts. This will improve a lot in the upper/highend range in speed. Just my .02

 

After reading this thread, I decided to give it a go last night and painted the plenum on the car. The finish was not great (too smooth), but after going for a nice 25 mile drive, the paint was perfectly wrinkled when I got back home. I'm pretty happy with the result.
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I have been researching on Fchat and the general internet to try and get the correct color for my plenum. I have seen many red wrinkled finishes that look awesome, even though the VHT red wrinkle is not a exact OEM corsa match. I have also seen silver wrinkle, black wrinkle and flat black. What is the correct color? I bought mine and it had the dull aluminum finish which looks like bare metal to me.