G37 Sedan

Dreaded Driver Side Grommet Leak

Old Apr 6, 2023 | 06:44 PM
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Question Dreaded Driver Side Leak

Been chasing a leak, thought it was just contained to passenger but it is not, found water under carpet on driver side. It is not the sunroof drains this time, they were previously addressed when I dropped the headliner, all 8 ends. I know I am getting water on the passenger side likely through a loose harness grommet and loose cowl possibly dripping water into the air intake duct as well, ****ing dumb design. Those are soon to be addressed, likely in this post at some point. I have scoured the interwebs on any info regarding this driver side grommet and can't find much. It appears to be an absolute bear to reach. I am thinking the easiest, is just to clean and wipe everything real good then find a clear silicone with a tip that I can reach down into the brake compartment and spread silicone between grommet and firewall. How has everyone else attack this fix? Anyone pulling the booster to make room? Need some ideas here...

Driver Side Carpet pull up, water under styrofoam

Under driver dash, arrow showing firewall entry, rust on bracket

Brake box with cowl removed, arrow showing firewall entry

Dirty grommet

Best angle of failing grommet

Last edited by kickin_it; May 11, 2023 at 12:12 PM. Reason: Clarity
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Old Apr 7, 2023 | 10:10 AM
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Though not that common, these can simulate the same leak as sunroof.

You dont have to pull the booster but moving the ABS pump lets you get in there. You dont have to disconnect the pump however the 3 12mm nuts need to be removed and the pump can be lifted a bit while connected.

Pull on the harness and pop that grommet out of place ( about 6 inches worth of room) Proceed to clean that area really well, lastly some acetone around the lip and grommet to remove the last bits of glue and cake some Heavy duty RTV (avoid clear) around the lip and pop it back in place. Just like a caulking process, run your finger around the whole grommet to create the Perfect seal transition (tile/bathroom caulk finish style). Your leak will stop. Good luck
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Old Apr 7, 2023 | 01:46 PM
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Fantastic answer, will report back with pics when the rain stops. I think this all started when the windshield was replaced. When I removed the cowl, noticed I don't have the plastic "cords" people reference and I guess because it was AFM windshield, I do not have the plastic "catch" on the back side of the windshield. I did pick up a few different types of weather-stripping foam to replace all the foam on the underside of the cowl. Seems odd the rubber seal doesn't run the length of the car either.

Cowl Parts
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Old Apr 7, 2023 | 03:08 PM
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Correct, that small piece of weather strip is what keeps that cowl from receiving water. They all deteriorate from harsh environment + acidic washer fluid. Toast the rubber and cracks and breaks.
Windshield replacement will finish the job as it wont go back together properly. I believe a few members found an amazon universal replacement for this cowl.

This + sealed grommet will solve your issue.
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Old Apr 7, 2023 | 03:42 PM
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Originally Posted by BULL
I believe a few members found an amazon universal replacement for this cowl.
I'll keep searching! It seems like the seal is good unless the cords not being present means it wasn't "sealed" properly. All of the foam was pretty nasty and deteriorating. Dare say the foam is what helps keep some water out where the windshield seal doesn't run all the way to the ends of the fenders. Got a 6pack on ice.

Edit* Post #239 I think this is it.

Edit** Or the TRIM LOK INC X2199HT - P shaped w/ adhesive

Last edited by kickin_it; Apr 7, 2023 at 06:50 PM. Reason: Clarity
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Old Apr 8, 2023 | 11:29 AM
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Sunny and 70 tomorrow, knocking out this entire cowl project with pictures, trying to get my ducks in a row. All of these projects reference the weather stripping to eliminate the popping noise, which I though typically effected coupes over sedans. I still have all of my pieces as outlined in the FSM below and all appear to be in decent shape. I am replacing all of the foam (#12) as marked below. When people are performing this mod, are they replacing the seal (#2) with the new stripping or adding it in addition to? I though the idea was to run the P shaped strip with adhesive back on to the base of the windshield and the P facing up, then putting all of the cowl pieces back including the (#2) seal? Or does adding the P seal eliminate the need for the (#2) seal? Has anyone added the P seal to the glass and then added D shaped stuck to the cowl? AustinHardware Dot Com sells the trim-lock P seal by the foot at $0.90 and then slaps $15 shipping on it. I will be replacing all of the black plastic push snaps, have bags of new ones. Has anyone 3d printed a plastic shield that can cover the air intake a bit more?

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Old Apr 17, 2023 | 08:32 AM
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Originally Posted by kickin_it
Sunny and 70 tomorrow, knocking out this entire cowl project with pictures, trying to get my ducks in a row. All of these projects reference the weather stripping to eliminate the popping noise, which I though typically effected coupes over sedans. I still have all of my pieces as outlined in the FSM below and all appear to be in decent shape. I am replacing all of the foam (#12) as marked below. When people are performing this mod, are they replacing the seal (#2) with the new stripping or adding it in addition to? I though the idea was to run the P shaped strip with adhesive back on to the base of the windshield and the P facing up, then putting all of the cowl pieces back including the (#2) seal? Or does adding the P seal eliminate the need for the (#2) seal? Has anyone added the P seal to the glass and then added D shaped stuck to the cowl? AustinHardware Dot Com sells the trim-lock P seal by the foot at $0.90 and then slaps $15 shipping on it. I will be replacing all of the black plastic push snaps, have bags of new ones. Has anyone 3d printed a plastic shield that can cover the air intake a bit more?

cowl parts
Originally Posted by VQPTK
I have an ‘09 G37x coupe with 161k miles. After I park it in my driveway there seems to be a leak under the passenger side. Should I be worried?
I recommend buying new cowls from Amayama. Waaaaaaaaaaaaaaaaaaaay cheaper than the dealer. I did it on mine as some preventive maintenance because overtime the white rope seals on these will fail. If you found a seal that is equivalent to replace it, that should fix the leaking issue.


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Old May 2, 2023 | 12:52 PM
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Brake booster compartment filled with water

Originally Posted by kickin_it
Sunny and 70 tomorrow, knocking out this entire cowl project with pictures, trying to get my ducks in a row. All of these projects reference the weather stripping to eliminate the popping noise, which I though typically effected coupes over sedans. I still have all of my pieces as outlined in the FSM below and all appear to be in decent shape. I am replacing all of the foam (#12) as marked below. When people are performing this mod, are they replacing the seal (#2) with the new stripping or adding it in addition to? I though the idea was to run the P shaped strip with adhesive back on to the base of the windshield and the P facing up, then putting all of the cowl pieces back including the (#2) seal? Or does adding the P seal eliminate the need for the (#2) seal? Has anyone added the P seal to the glass and then added D shaped stuck to the cowl? AustinHardware Dot Com sells the trim-lock P seal by the foot at $0.90 and then slaps $15 shipping on it. I will be replacing all of the black plastic push snaps, have bags of new ones. Has anyone 3d printed a plastic shield that can cover the air intake a bit more?

cowl parts
So how did the repair go? This same thing happened to me, I fixed sunroof drains a couple of years ago, found last night my drivers side floormat soaked. Pulled everything up, vacuumed up about 1/2 gallon of water from footwell. Looking at the grommet on the firewall, I saw about a quart of water sloshing in the compartment that holds abs pump and booter. Does this thing not have a drain there? Everytime I would hit the gas water was evidently sloshing againt the grommet and into the cabin. It's like the rain is draining from the cowl into a fishbowl.
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Old May 2, 2023 | 02:35 PM
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Originally Posted by ChefMatt
It's like the rain is draining from the cowl into a fishbowl.
@ChefMatt Wouldn't hurt to check your cabin air filter as well. As these cowls age and the seals literally disintegrate, water is known to leak into the fresh air intake as well. I just had to deal with that a few months ago...
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Old May 2, 2023 | 05:13 PM
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Yeah will do thanks!
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Old May 4, 2023 | 12:25 PM
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I'm still working on this damn thing. I replaced all the foam on the cowl pieces last night and finally sealed all the firewall grommets. I will get pictures and products updated today/tonight. Hoping to attack it hard this afternoon before the rain this weekend.
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Old May 4, 2023 | 12:26 PM
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Never knew about Amayama, thanks for that tip! The cowl pieces are in decent shape, just all the foam around them has gone to ****.
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Old May 4, 2023 | 12:31 PM
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Originally Posted by kickin_it
Never knew about Amayama, thanks for that tip! The cowl pieces are in decent shape, just all the foam around them has gone to ****.
I don't think the black EPT foam does any sealing I believe. It is the white "rope" gasket that seals against the windshield. They are tucked into a channel on the Cowls.

Yes Amayama and Partsouq are the best for buying OEM parts. The prices are mostly 50% cheaper or more sometimes, even with international shipping it's almost always cheaper than the dealer. Very large and heavy items though will cost more to get from overseas.
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Old May 5, 2023 | 10:54 AM
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I replaced all of it, the EPT foam on the cowl pieces as well as the battery and brake lids and covers. I also purchased a black foam rope to fill in the cowl channel gap. I also "deleted" the air check valve and just added a generic valve and blue silicone hose. I finally got it wrapped up last night. I know, it's dirty, kick rocks kid. I'll get some more photos up but I'm happy with the repair so far.


Black Foam Rope Install (6mm)



Finished Cowl Update

Last edited by kickin_it; May 5, 2023 at 02:03 PM.
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Old May 5, 2023 | 02:09 PM
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Looking back through my pics, I did not take pictures of the new foam on the cowls before install. IF I need to pull them for any reason, I'll snap a pic. Here are some other shots.


Generic Check Valve Install and Pipe Delete


Cover, new foam


cover, new foam

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