I have a big problem with my trans am. Its a 1987 305 4bbl carb. I had bought it about 6 months ago from a private seller. The only damage i found was damage in the carpet on passenger side. Everyone said it was my heater core so i bought a new one with a new carpet. I installed them but i noticed the puddle of water that smelled really bad like old water in the spot before i installed and cleaned it up. Today after driving it for about a week after that i noticed that the bad smell came back. So i checked to feel the carpet and under the floor mat it was soaked. I have no clue what it is. I installed the heater core fine with out leaks. It has been raining hear recently. Could there be a spot where the rain is getting in to there from somewhere? Please help I spent alot of money o trying to make my inside look beautiful. Thanks , Nik

 

Does your car have T-top's ?? If so that is the first thing I would suspect. If not then you can still check the seal around the windshield and at the top of the firewall near the base of the windshield.
HTH MY Z ROCS

 

Nik,

Welcome aboard!

I'm thinking you might want to look under the car at the body plugs and drains around the firewall and in the floor pan. There are several places where road splash can get into the floor. Once there, the water will wick through the acoustic padding and into the carpets, making a nice, musty odor for you and your passengers to enjoy. Worse yet, it is a potential spot for corrosion to start.

Later,
Vader

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"Some Body...Someone"

 

I have an 87 FB with the same problem. Generally after a carwash or rain. Seems the vents don't seal good.

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86 FB stock 305 Qjet South California emissions

 

On my 83 I pulled the carpet back and found a rust hole on the upper right part of the firewall. (if you look by the hood hinges where the fender/firewall meet from under the hood) This little pocket had filled with leaves and rusted the firewall.

A little acid/rust remover stuff, a LOT of fiberglass with a mesh, and a little undercoating and presto...no more leak.

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ASE Mechanic/Machinist/Smog Tech

RTKTGTR 1999 NBM T/A, flowmaster,FRA,Pro Kit,BMR STB, polished calipers.
1986 Chevy 3/4 ton pick up,flowmasters,4.10s,
1981 corvette FOR SALE
1995 ZX6R,Yosh,D207s

GO #3

 

I see alot of windshield leaks at work. They get real bad [the carpets] because it usually leaks at a corner, runs down the "A" pillar behind the trim, and gets soaked up by the "jute" or carpet insulation. Then when it is soaked and rotten smelling, you get to sit inside with all the window up while somebody sprays water over it. Whooopeeee.

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"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave

ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE
About Me

 

My car ahs the same problem GMtech is describing i just have been to lazy to do anything about it

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Dave
93 CAMARO- 3.4 v6,5spd,borla cat back,hurst short throw shifter,moroso cold air induction kit,kyb adjustable shocks,17" wheels,275/40zr17 comp t/a's
84 FIREBIRD-2.8 V6,5spd super economy model
no options except t-tops( not even locking),no tilt,no cruise,no delay wipers,no rear defroter,no a/c,no rear spoiler(i put one on)no pw,pdl,pm,pseat,no gauges(just a 85 mph speedo with no trip odometer and a big f***in' gas gauge)
90 FORMULA 350-
Edelbrock t.e.s,gutted cat,Borla cat-back,LT4 hot cam ,24# injectors,holley h.p. fuel pump,K&N Throttle Body mounted air filter,52mm throttle body,accel 8.8mm wires,plugs cap and rotor,ADS superchip,GTA tailights,T-tops
No E.T's yet.

Previous 3rd gen's
83 Trans-Am 305 CFI auto T-TOP
84 Firebird 305 H.O. auto HARDTOP
87 Firebird 2.8 V-6 auto HARDTOP