90VetteZR-1

I'm not sure what it is called, but I need the part that the hose connects to, which goes into the plenum. This is on the driver side, that sits on top of the PCV pipe leading to the PCV Valve. I learned the hard way that this piece doesn't accept too much torque and have learned my lesson. This temporary fix works just fine, but is losing a small bit a coolant and looks bad, to me. It irritates me and I want it fixed. So..... anyone can lead me in the right direction??? I already tried Jerry's Gaskets and they weren't there.

Dominic Sorresso

It does look like crap. Why not just block off the coolant passages?

Goldcylon

It a 90 degree coolant passage port. As those are pressfit into the plenum you will prob need to pull the plenum to knock it out from the back side as im fairly certain the pressed portion is still in the plenum. Dom is right you could plug both sides

90VetteZR-1

I thought about plugging both sides, but it seemed like that flow wouldn't be complete and it wouldn't cool properly. Also, knocking it out doesn't seem like it would work because the coolant runs through the plenum, not just passing through it, right?

Paul Workman

The coolant passes through the throttle body only.

As others suggested, I plugged my injector housings to reduce heat in the plenum (cooler intake air), but the biggest advantage is being able to pull the plenum w/o draining some coolant, and then having to refill it again.

I don't drive much in winter (cuz of the salt, doanchaknow), but in cold, damp climes, the coolant through the TB prevents freeze-up. I've never had the problem, even in sub zero temps, fwiw.

P.

Paul Workman

I'm thinking one could drill it out w/o having to pull the plenum, if replacing the elbow was the choice.

To the OP: Its been a while, but I bought a pipe flange tool that was used for either flaring pipes, or creating the little shoulder (ring) stop in tubing, such as that found on that elbow. It wasn't expensive, and I wonder if Summit Racing (or Harbor Freight?) might have one.

P.

Dominic Sorresso

Same here.

Dynomite

Eliminated TB coolant on both a 1990 and 1991 ZR1 with NO issues. I used a Unique Coolant Refilling Technique that works 100% of the time which Coolant Refilling Technique you want to use with TB Coolant Eliminated or NOT Eliminated. see Item #3 below

Once TB Coolant is ELIMINATED.......The Coolant System is not re-opened during the pulling of the Plenum and NO Coolant Refilling Technique is required.

1. Eliminating TB Coolant and Air Induction, Added Oil Catch Can and Painting
2. TB Coolant Discussion
3. Filling With Coolant and the Air Locked Water Pump
4. LT5 Eliminated Systems
5. LT5 Radiator and Exhaust Install Tricks
6. See this link for TB Coolant Blocking drilling and threading details Injector Housing TB Coolant Blocking

1990 LT5


1991 LT5


I am sure I have a couple and can send you one but if you broke it off or about to break it off...then time to drill it out and since press fit....the one I would be sending you may not fit. The Trick is to get hold of what is left with vice grips and wiggle back and forth (rotating) gently and it will loosen up so you can extract it (If you have a torch you can apply a little heat to the plenum surface around the fitting). A new fitting can be inserted with red loctite or even a tad of JB weld to assure it does not leak cleaning up any excess red loctite or JB weld showing before it hardens.

No Back Side there Daryll

The coolant passes through the rim of the Plenum only and does not cool the Plenum in any way. Technical Details provided above. Or.....in Signature which covers almost everything technical related to both the 1990 and 1991 LT5/ZR1 (LT5s shown above)

5abivt

If the ports are plugged on the plenum are the hoses blocked off or joined across via hose?

Dynomite

No hoses at all...they are eliminated as you can see in the photo.

There is one hose that is blocked off just up from the radiator cap (Brass Pipe Plug) which is the return to the Coolant Overflow Tank for TB Coolant.

There are six 1/8 inch NPT Allen Head Aluminum pipe plugs involved.
1/8 inch Allen Aluminum Head Pipe Plugs

Paul Workman

Some bypass the TB for performance reasons (cooler intake air), by routing a hose across underneath the plenum, thus linking the two sides of the plenum while bypassing the TB.

I've not had any issues as result of plugging the IH ports leading to those right angle pipes. I did, however, leave the pipes and hoses intact, thus looking stock to the casual observer.

Dynomite

The Casual observer does not know the difference between an LT5 and an L98

If I were closer to ya Paul I would be over at your place with wrenches helping you get that 90' back on the road

90VetteZR-1.....PM me your address, I have the fitting in envelope ready to send

90VetteZR-1

Thanks again, Dynomite. You've been much help. I will post a pic when the new part is in place.

90VetteZR-1

Thanks, Dynomite. I got the part in the mail today. I will be working a way to get the piece in the manifold out. There is no bit of plastic sticking out of the manifold that I remember, I will take off the epoxy tonight. Will bolt removers be able to grab onto the remaining pipe and pull it out?

Matthew

P.S. - Like I said Dynomite, I don't have much to offer at all, but if there ever is anything I can do, let me know.

Dynomite

Matthew:.......The only way I am able to get such out including the coolant manifold bolts sometimes is to use a torch with a little heat. A reason not to use heat in your case...it disturbes the original coating.

But you cannot do that if you do not have much left to grab with vice grips. You could drill but you have to be VEEERRY careful so as not to upset the base hole that is Aluminum....

1. First try vice grips and after you destroyed anything you can grab on to (if that is the case)....
2. use an Easy Out. Then after that does not work (if that is the case)....
3. Use an Easy Out inserted in the pipe with vice grips tight on outside and slowly wiggle (rotation) clockwise/counterclockwise many times untill the fitting loosens. If that does not work.....
4. use a drill as follows.......

a. I would start out with drill bit that just fits inside the original tube.
b. Drill the length of that pressed in insert (the fitting I sent you should be clear on length of inserted part).
c. Go one size drill bit up and drill again....1/64 inch increments
d. Keep doing that untill the last pieces of the pressed in fitting come out which last drill bit should be less than hole diameter in the Aluminum.
e. Again....only go as deep as that new fitting indicates. This after you have exhausted all techniques of pulling with vice grips and easy out.
f. If you can get the drill bits in 1/64 inch increments the better. You have to keep the drill bit straight somehow.

5. Practice with the drill as having a very light trigger finger able to stop the drill and KEEP the drill bit just barely turning is key. Secondly...keeping that drill bit straight with the fitting without a drill press is also key.

Others may have some suggestions but I am at a loss.........of easier methods.
Say....after you get the crapola off the fitting, can you take a picture of what is left before you do anything? Is your plenum original coating? I assume you want to do this WITHOUT removing the Plenum?

JB Weld around the pressed in part of the fitting I sent you will correct for any screw ups drilling I would think. If you get the fitting out without any damage to the hole in Aluminum, just use some Red Loctite around the fitting before inserting.

90VetteZR-1

Ok, I actually did what you said before I read your post. I started with a bit that just barely hit the walls of the broken piece, then went up one size at a time. After a few minutes, the bit grabbed the piece and it came right out. VERY slight damage to the outside of the plenum that surrounds the new piece. Will keep an eye on it, but I'm sure it's cosmetic damage. When I save up the funds, I will get the whole plenum restored, and yes, it is the original coating. Now, what are the ideas to press the new piece in? I thought about using a rubber mallet to tap it in, but wanted ideas before making a mistake I can't fix.

As always, thanks.

Matthew

WVZR-1

You should be able to use the appropriate sized end wrench slipped over the tube and tap the tube into place, you can rotate the end wrench @ 90* to get 360* coverage on the raised portion of the fitting. A flare nut wrench might offer better coverage, don't know.

Dynomite

Perfect

Clean out the fitting hole in the Plenum of any debree and old sealant. Use a vacuum if you have to and some cue tips.

Do exactly what WVZR-1 suggests .......tap lightly rotating the wrench so as to not mar that raised ring on the fitting. If it is tight...make sure you have some red locitite on it to start with which should make it go in easier also and act as a sealant.

90VetteZR-1

I did exactly as WVZR-1 suggested and got it on in less than a minute. I am letting it cure right now. I'm not sure how long it needs, so I figured it will sit all day today and I will test it tomorrow. I will upload a pic later today. Thanks to everyone who helped, and much thanks to Dynomite for the speedy delivery of the part.

Matthew

combatdoc

It's funny you should mention the casual observer doesn't know the difference, I was at Patriot Motors, a dealership in Killeen, Texas the other day, my buddy is helping them install a blower on a new camaro, anyhow I pulled into the bay and here is this red vette on a lift, I knew it wasn't a ZR-1 but wouldn't you know one of the mechanics got into a pissing contest with me saying, " this is a ZR-1, the owner said it was, and just look at it, 6 speed and it's got the ZR-1 badge on the back". I laughed at him and told him he was in the wrong line of work, and told him good luck fixing that L98 with LT5 parts!
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