Plenum Pull Q's

[jrd1990zr1]

Originally Posted by Norsky4360

I'd wait until it has cooled down enough for the coolant pressure to be almost gone. Then crack the expansion tank cap to relieve the rest of the pressure.

When I was doing my 'very last first' plenum pull someone shared a tip to drain the coolant from the expansion tank rather than drain everything via the radiator. Naturally I saw that after I'd already drained the radiator. I'll have to dig a little to find it.

When I went to Gordon's school last year he pulled the expansion tank loose drained some coolant and left it lower than the plenum. Seemed to be the quickest way too get the coolant below the plenum.

Quickest way is to get a sucker. One of the better tools to have as it helps in changing rear diff fluid and sucking fluid out of hard to reach pockets.

[GOLDCYLON]

Originally Posted by gene

On this note, what is the concensus on coolant by-pass on plenum & throttle body??

I have it, Live in Arizona, no issues and keeps the ZF.Doc (My tuner) happy

[tomtom72]

Okay since this is my thread I would like to mention a few things for the first time plenum puller to observe:

1. Remember that the motor should be cooled off before dis-assembly. It will be warm to the hand, so check the coolant. If you can detect any heat enough to do harm to skin, stop & wait.

2. Draining the radiator thru the pet-**** is okay but if you are removing the I/H's be aware that the coolant level will be still in the heads. It's okay but be careful, or just open the T-stat housing & get it all.

3. On the 90's the fuel block at the rear right of the plenum has the inner fuel line in the way of that plenum bolt. There three screws, torx T45(?), you need to loosen two of them to swivel the line next to the boly out of the way to get on that plenum bolt squarely. I expect that this might apply to all of our set-ups. You can remove the lines entirely as new O-rings come in the top end set & if you're doing injectors you must do that. Oh, bleed the schrader first!

4. If it's really your first time use the blue painter's tape to label all the electrical connections and hoses. If ya got a digital camera use it! Or you could just label all the connectors with a sharpie. Point is the first coupla times there is a lot of stuff & a little cheat sheet will pay back big time.

5. The bag & tag thing will help alot if you're going down to the valley floor to do housekeeping. There is a lotta stuff under there so go slow the first few times because it all goes back....no parts left over!

6. Don't yank the plenum till ya got all the vac lines & DIS connections off!
For the 90's there are three vac lines on the T/B: the double left side one, one under @ the right side ya can't see till you lift the front of the plenum about four inches. The two center high vac lines, L & R, the MAP, Regulator, P/Booster, PCV top connector. The two T/cables, IAC, IAT, TPS, Two front DIS connectors, one rear DIS main harness connector has a 7 or 8 mm bolt holding it on & ya get that after ya r&r the MAP bracket + MAP and the lower PCV hose w/PCV's or ya can't see the bolt let alone get on it from the trans tunnel. You get all that stuff & now ya can lift the plenum off of the I/H's.

At this point ya can pretty much do everything like starter, coils & wires, injectors, 2* throttle system parts, clean the oil in the valley & evict the mouse & spyders (dead ones for those of us that DD the car ), about the only thing ya can't do is the gasket for the CCVbox cover. That requires more r&r of stuff. Oh, also consider that the A/C system's vac check valve is the big check valve under there along with the two temp senders in the left I/H. The box cover hoses can be dunn also if they are bad. I can't remember if the A/C & Alt are in the way of just doing all the stuff save the CCVB gasket....I did r&r them when I did my box cover gasket along with the shield & 2* t-linkages...of that I'm sure. You'll see when ya get there as it is obvious once ya get all the stuff on top of the CCVB out of the way.

Anyway, I hope this might help anyone who has to do this the first time. Go slow & take notes. It is more intimidating than it is difficult. You do it once & ya got this pretty much beat...ya do it twice and you will wonder why ya thought it was so hard. Familiarity makes it straight forward.


Tom

[Aurora40]

Originally Posted by tomtom72

5. The bag & tag thing will help alot if you're going down to the valley floor to do housekeeping. There is a lotta stuff under there so go slow the first few times because it all goes back....no parts left over!

FWIW, what I do is just take a piece of printer paper, and draw on it a quick sketch of the piece. Then I stick the screws through the paper where they line up on the piece. It's quick and easy and works great.

Originally Posted by tomtom72

5. The bag & tag thing will help alot if you're going down to the valley floor to do housekeeping. There is a lotta stuff under there so go slow the first few times because it all goes back....no parts left over!

Bag and tag, what is that. I throw everything into a single box!

Originally Posted by tomtom72

Two front DIS connectors, one rear DIS main harness connector has a 7 or 8 mm bolt holding it on

It's a 1/4" bolt that holds the main DIS connector on. The other smaller 2 wire one is the connector for the crank sensor signal.

Originally Posted by tomtom72

you get that after you r&r the MAP bracket + MAP and the lower PCV hose w/PCV's or ya can't see the bolt let alone get on it from the trans tunnel. You get all that stuff & now ya can lift the plenum off of the I/H's.

You can actually access the MAP sensor wire and vacuum tube before you get this far. You can squeeze your hand behind the plenum on the drivers side and undo all of these.

Originally Posted by tomtom72

about the only thing ya can't do is the gasket for the CCVbox cover. That requires more r&r of stuff.

You can get the breather box off with out removing the injector housings. It is very tight, but can be done. You must have the starter and the coil packs out of the way though.


Good write up Tom.

[tomtom72]

Thanks Jeff!

Now class pay attention, that includes me also , to what corrections Jeff made. I get a D- on the written part of my exam.....however, since the end result on the practical part of my exam is that I now have a ZR-1 again and not some car that just looks like a ZR-1, I get a passing grade of "good".

I would also urge any first time plenum pullers to check out the Pacific Northwest home page for the skinny. Also the Texas chapter's(Big Country Corvettes) home page and Corvette Action Center's ZR-1 section for a complete and accurate step by step on this task.


Tom

[A26B]

Originally Posted by Jeffvette

You can get the breather box off with out removing the injector housings. It is very tight, but can be done. You must have the starter and the coil packs out of the way though.

Coil pack base yes, starter no.