Well gang, here's a topic that's been beat to death...but let's give it another swing shall we?

I saw an old forum thread where a guy put a Halloween fog machine in his car and with all the windows up, turned it on which showed all the air leaks in the cabin.  Specifically, he did it to find where exhaust was sneaking into the cabin when driving with the windows were down.

I gave that a shot this evening and found that it is my taillight gaskets, but the strange thing is they are brand new from Motorsport.  We even removed the black trim surrounds and bolted them back to the body and you can see the smoke sneaking around the gasket edges regardless of how tight we make the bolts holding the gasket to the body.

The gaskets are reasonably squishy (I have no idea how gummy these are supposed to be but they are very pliable).  I did notice that the plastic housing has raised bumps where the mounting bolts come through which would mean the gasket wouldn't be laying flush in the areas between these bolt bumps, right?  Was I supposed to install these with gasket maker between the rubber gasket and housing?

Edited May 3, 20231 yr by chaseincats
added image

15 minutes ago, chaseincats said:

Yeah, I finally had enough too.  Even though I used my friend's fog machine, it is definitely worth the price of admission to buy one for this project.  All your local Z friends will be happy to come over and do their cars too I bet haha.

So, in the end, what all did you replace and where were most of the leaks?  I'm sure mine leaks at all the usual spots.  The hatch gasket, tail lights, hatch trim panel, and all the pass-thoughs for fuel and vent hoses.  Right now, mine doesn't even have the hatch trim panel installed.  That might be the biggest offender.

What would be the difference or downside to using a smoke machine in the car and force air into car and see where the smoke leaks out?  That is what I did.  I put the smoke machine in the back of my Z, cut a piece of cardboard with a hole for the vacuum (on blower mode) and turned the vacuum/blower on to see where the smoke came out. 

2 minutes ago, Duffman said:

What would be the difference or downside to using a smoke machine in the car and force air into car and see where the smoke leaks out?  That is what I did.  I put the smoke machine in the back of my Z, cut a piece of cardboard with a hole for the vacuum (on blower mode) and turned the vacuum/blower on to see where the smoke came out. 

The only downside is that it might be harder to see the smoke from the outside.  Some of the leaks could be above the tank, behind tail light trim, and the smoke might travel before appearing.  The gaskets are also working the correct direction when a vacuum is drawn inside with the smoke outside.

Excellent. And in theory, that peel-n-seal stuff is removable enough that if you ever do have to pull the tail lights out again for anything, it will let go easy (as designed) and you won't have to put a lot of stress on the plastic light housings.

Glad you got the fume issue under control!

11 hours ago, Jeff G 78 said:

So, in the end, what all did you replace and where were most of the leaks?  I'm sure mine leaks at all the usual spots.  The hatch gasket, tail lights, hatch trim panel, and all the pass-thoughs for fuel and vent hoses.  Right now, mine doesn't even have the hatch trim panel installed.  That might be the biggest offender.

All of the above.  I will say, though regarding the trim panel, I sealed the back of it with a bunch of tape then poked holes in the tape where the screws would go.  That trim panel tends to sag since its so old and no longer seals that hole.

EDIT: I forgot to add that I found the reproduction hatch gaskets were a bit too small and ended up ungluing itself in the top area by the dome light since it was too tight.  I ended up buying the OEM one but it wasn't cheap (I think around $250) but worth it at the end of the day.

Edited October 16, 20231 yr by chaseincats

10 hours ago, Duffman said:

What would be the difference or downside to using a smoke machine in the car and force air into car and see where the smoke leaks out?  That is what I did.  I put the smoke machine in the back of my Z, cut a piece of cardboard with a hole for the vacuum (on blower mode) and turned the vacuum/blower on to see where the smoke came out. 

We found that after the car fully pressurizes, the larger leaks show themselves but the smallest ones stop which didn't make sense but that's what happened.  The rivet leak for example only showed itself after we held the smoke machine behind the car and turned on the vacuum

1 hour ago, Captain Obvious said:

Excellent. And in theory, that peel-n-seal stuff is removable enough that if you ever do have to pull the tail lights out again for anything, it will let go easy (as designed) and you won't have to put a lot of stress on the plastic light housings.

Glad you got the fume issue under control!

Glad to hear it but I'd be really nervous to remove the lights and sever that 'glued' seal

1 hour ago, chaseincats said:

All of the above.  I will say, though regarding the trim panel, I sealed the back of it with a bunch of tape then poked holes in the tape where the screws would go.  That trim panel tends to sag since its so old and no longer seals that hole.

EDIT: I forgot to add that I found the reproduction hatch gaskets were a bit too small and ended up ungluing itself in the top area by the dome light since it was too tight.  I ended up buying the OEM one but it wasn't cheap (I think around $250) but worth it at the end of the day.

Thanks for the detailed answer.  I left the tailgate trim panel off for now since my door locks are worn out, so if I replace them with good used ones, I will swap the hatch lock as well.  I didn't want to seal it up and then peel it right back off.  I assume I'm getting a ton of leakage through that wide open hole.

Just now, Jeff G 78 said:

Thanks for the detailed answer.  I left the tailgate trim panel off for now since my door locks are worn out, so if I replace them with good used ones, I will swap the hatch lock as well.  I didn't want to seal it up and then peel it right back off.  I assume I'm getting a ton of leakage through that wide open hole.

You absolutely are.  Just tape it shut in the interim - you're not losing anything but braincells outside of a bit of ducttape

20 hours ago, chaseincats said:

Final update:

We fogged the car like in that video again last weekend and confirmed sealing the taillight gaskets with Seal 'N Peel (one bead between the gasket and the light housing and a second between the gasket and body) worked perfectly - no smoke escapes there anymore.

That said it didn't 100% fix the issue meaning there were leaks else where which we found due to a shotty weld job done by the PO when replacing the hatch base which must have been rusty.

Fogging:

 - I saw this originally on another thread which I cant find but besides what we did (throwing the fog machine in the car and shutting the door) there's actually a better way to do it.

- Once the car is fully pressurized with the fog machine, the smoke will escape from the paths of least resistance, which isn't the tiny pinholes in the back.  The trick is to have someone hold the smoke machine behind the car and move it around while you turn on a shop vac and let it sit in the hatch area creating a vacuum (just like how the car works while driving).

You will see where the smoke is sneaking in then just wipe some seal 'n peel or whatever sealant you have left and its game over.  You'd be surprised where smoke sneaks in, for example, smoke was sneaking in AROUND one of the rivets I found.

This is definitely worth your time to do at least in my opinion. 

Do you happen to have a video showing you doing the fog testing?

10 minutes ago, texasz said:

Do you happen to have a video showing you doing the fog testing?

There is one on the ZCCA page but all it is, is me opening the door and having smoke pour out.  It really is as simple as throwing the machine in the back of the car with all the windows up/hatch down and waiting.  I didn't dangled the cord out of the window and rolled it all the way up, then sealed the rest of the area (maybe an inch) with painters tape.

Sucking smoke in from inside the car arguably works better.  I had someone hold the fog machine near the hatch, and placed the shop vac hose in the trunk area and squeezed my way back there as well with the vac on.  You do not need to seal the car, just having the vacuum on is good enough (my doors and windows were open for example).

I hope that helps!

39 minutes ago, chaseincats said:

You do not need to seal the car, just having the vacuum on is good enough (my doors and windows were open for example).

This surprises me.  When we do smoke testing at work, we seal it up tight.  We cut cardboard to fit the driver's door window and that gets taped on tight.  The inside guy then climbs into the trunk/hatch area with a flashlight and a 2-way radio so he can direct the smoke machine guy to all the possible leak paths.

In our case, we are dealing with very small leaks, so it takes a bit of time to make sure everything is sealed tight.  Even brand new cars with modern sealing will still leak around tail light gaskets, trim holes, and wiring grommets.  I can only imagine how bad the average 45 - 50 year old car leaks.