Stupid Question.....

[tomtom72]

....but important ( I think it's important ) maybe to me. How cold does an LT5 have to be before you can pull the plenum?

Yes, I truly do not know the answer to that question.

The reason I ask is that I rent garage space and may not work on the car there. I have to drive it to my apartment to do any work, and by the time I get to my parking space my car is fully hot, water and oil.

I need to pull my plenum as I have an audible vacuum leak coming from under the plenum.

TIA

Tom

I know I should have left it in my space when I finished my work on the car yesterday. I was a bit spent & not thinking clearly. Maybe I was a bit pi$$ed off when I started her & heard the vacuum leak....oh, and my vacuum pump's switch failed at the same time....guess I'll use my spare.

[Aurora40]

I suspect it's not like pulling plugs out of a hot aluminum head, where you have to worry about stripping things. I suspect it's more a matter of how hot of a plenum can you handle pulling?

You'll have to open the cooling system, so you will at least need to wait until the cooling system pressure drops.

[tomtom72]

Good Morning Bob! Thanks for the thoughts. I have gloves so the heat I guess would be okay on my skin. It's just that my or these motors retain heat for a long time once they are to proper operating temps.

The thing I have in my head dates back to the late 60's & early 70's when aluminum engine parts were sort of rare and most of the old time mechanics used to say "do not unbolt hot aluminum parts!" I've never considered the question from a point of view that something bad, like warping, would happen because I've never worked on my LT5 when it was hot. I guess that is my fear and reason for my stupid question.

Thanks for your time!

Tom

[Kevin]

when i was having injector problems i gently limped mine from the hotel to the ncm and parked it for a bit before gordon and I tackled swapping them out. it wasn't cold by any stretch of the imagination

[tomtom72]

Thanks a bunch Kevin! I am thinking that Gordon is as good a source as I can find. Thanks for passing that info along!


Tom

[Kevin]

Originally Posted by tomtom72

Thanks a bunch Kevin! I am thinking that Gordon is as good a source as I can find. Thanks for passing that info along!


Tom

forgot to mention i thought it was a coil problem so we fired it up and let it run for a bit while we pulled wires to see if that was the problem before we dug into the motor.

[jrd1990zr1]

Hey Tom,

If you want to drive it up by me we can pull the plenum in my garage. I've got a lift so you can change the oil, if needed too! Downside is the travel distance. Let me know.

John

Originally Posted by tomtom72

....but important ( I think it's important ) maybe to me. How cold does an LT5 have to be before you can pull the plenum?

Yes, I truly do not know the answer to that question.

The reason I ask is that I rent garage space and may not work on the car there. I have to drive it to my apartment to do any work, and by the time I get to my parking space my car is fully hot, water and oil.

I need to pull my plenum as I have an audible vacuum leak coming from under the plenum.

TIA

Tom

I know I should have left it in my space when I finished my work on the car yesterday. I was a bit spent & not thinking clearly. Maybe I was a bit pi$$ed off when I started her & heard the vacuum leak....oh, and my vacuum pump's switch failed at the same time....guess I'll use my spare.

[tomtom72]

John, you are the man! Thanks, I'll let you know as I have an al fresco plenum pull scheduled for this Friday afternoon, no rain. I've done some diagnostics with my hand vacuum pump last night. I have vacuum integrity on the line from the vacuum pump. So the check valve & tank are good to go.

I'm figuring either I have a bad control solenoid, or a hole in one of the actuator diaphrams the size of the grand canyon....or a mouse got in there & chewed on a vacuum line. She is hissing like all get out at idle, and when you try to get in the secondaries it sounds like it's drowning.


Tom

[Aurora40]

If it holds vacuum with a hand pump and the engine off, why would it hiss at idle? Everything should be the same, except the engine vacuum supply line also has vacuum. I believe that comes from the driver's side front of the plenum?

[tomtom72]

I do not know Bob. That is the symptom I'm seeing. It has a hiss at idle, and until you call the 2*'s it runs normally. When the 2*'s should come on she starts to gurgle like it's drowning. I'll have to admit that I was not insistent on calling the 2*'s. As soon as I heard the gurgling I got out of the gas. I didn't even think to turn the key "off" and test it that way. I should have, but I just didn't think of it at the moment. I blew that one I know!

I was a bit distracted when I was doing a brief diagnostic in the garage where I park so I had to be quick as it was a bad time to be under the hood in the garage, too many people around.

I went back last evening & repeated the pump line test and it does hold vacuum with the motor off. I was going to start it up, pull the left vacuum line, plug the nipple and apply vacuum to that line....but I had bad timing again & there were too many people around again.

Soooo, my diagnostic plan will be to go bring her back to my building on Friday after work ( hopefully no rain! ) and test her with the key "off" and the key "ON" on the way over hoping that will give me some more info to narrow down my search. The hissing is, to my ear, coming from under the plenum as far as I can tell.


Tom