40 cabin water leak

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L

lester5

10 Year 15 Year
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Apr 19, 2009
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This is my first time here so bear with me please.. I recently got a 1974 titled fj40 (some or most of it appears to be later model). It's great, but water leaks into the cabin down through the dash onto the floor board while it is sitting in the driveway. I've sat in it during the rain and it isn't coming in at the windshield. It drips down from under the dash. It is a significant amount - last rain about 1/4 - 1/2 inch of water in the floor on both sides. Does anyone out there have an idea where it is getting in and how to fix it? Thanks,
lester5
 
Check the seam between the cowl and firewall. This is one of the major reasons that I do not Chem dip Tubs any more. You will need to scrape the old body caulk away, clean, and re-apply caulk to the seam. This should solve your problem. You may also want to check the cowl vent for holes. Good Luck!
 
It's most likely your cowl vent drain tubes #4 & #5
112E.gif
 
OK, there is no cowl vent. It is titled as a 74, but most everything looks 78-79 so there is no cowl vent. I have no idea what or why the former owner did it this way and he's not available to ask. The windshield gasket looks good. There is a seam at the bottom of the vertical winshield support where the cowl meets, but it looks to me like a welded seam - it doesn't look like a regular joint, but then I don't know... It's very small and I don't see any way to get into it without messing up the paint. Looking at it, it looks like the only possible entry would be there or the winshield hinges. It appears to be too much coming in for it to be the hinges.
If I do get something very thin and dig down in the seam, what kind of sealant should I put back in? Thanks for all your help,
 
Dusty 66 said:
It's most likely your cowl vent drain tubes #4 & #5
112E.gif
Click to expand...
I love those vent drain tubes. So easy to replace. And cheap too :crybaby:

Not.
 
The hood hinge bolts (on the cowl side) are another possibility. They need sealant on the threads because they screw right through the body and can allow water into the glovebox and behind the dash.

(I would have suspected the cowl seam too - but if it is leaking you should be able to see where rust has opened up the seam to allow water to enter.)

(And windshield frame leaks would tend to leak water inside ABOVE the dash where you can easily trace it.)

Could be the lower sections of windshield hinges - The bodywork has a habit of rusting out completely behind them!

:cheers:
 
glad to know about that seam..

Ihave that leakage too.and at first i looked at the seambut couldn't believe something like that was the problem.

I now think on removing the old caulking and reseal with urethane (commonly usee here in El Salvador to seal glass,weatherstrips and windshields) and the good thing is that it is somesort of flexible...won' t crack
It willbe an obvious seam since mi Bj40 is green and the urethane is black but i guess it should solve my problem.

What do you think? any advice or comments?


Thanks y'all
 
Hugh Heifer said:
I love those vent drain tubes. So easy to replace. And cheap too :crybaby:

Not.
Click to expand...

I am having the same problems with mine. My cowl vent tubes were not replaced by the PO and I get major water leaks when it is raining. I have no problems replacing the tubes, but for the life of me, I can not figure out where the tubes exit the cabin to the outside. :doh:

Can anyone help me???:confused:
 
D'Animal said:
They exit through holes in the floorboard.
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Bear with me; I am very new to 40's. I checked for holes in the floorboard, but didn't see any. The only holes are near the front of the driver's side seats. Could you tell me the exact locations of the holes you are talking about? Perhaps the PO filled/patched over them. :confused:

Would they be on the tranny hump? Perhaps behind my heater? I have a 1968 if that helps.
 
MScruiser said:
Bear with me; I am very new to 40's. I checked for holes in the floorboard, but didn't see any. The only holes are near the front of the driver's side seats. Could you tell me the exact locations of the holes you are talking about? Perhaps the PO filled/patched over them. :confused:

Would they be on the tranny hump? Perhaps behind my heater? I have a 1968 if that helps.
Click to expand...

74 they go out through either side of the fire wall, by memory, on either side of the engine about 10" down and 12" apart. In 75 they go through the tranny hump on either side of the heater.

68, likely has a functional cowl vent... Seal could leak, and drain tubes likely also take a couple of quick bends and exit through the fire wall.:cheers:
 
bikersmurf said:
74 they go out through either side of the fire wall, by memory, on either side of the engine about 10" down and 12" apart. In 75 they go through the tranny hump on either side of the heater.

68, likely has a functional cowl vent... Seal could leak, and drain tubes likely also take a couple of quick bends and exit through the fire wall.:cheers:
Click to expand...

Yup, after further inspection, it appears that the PO did in fact patch over the holes. :doh:

I am going to buy some 1" silicon hose and a 1" hole cut saw from Harbor Freight and put some new holes in the firewall.

Thanks!
 
Check where the rain gutter pieces (just ahead of the front doors) end - by the kick vent. I had that seam leak on my '78 and it was very frustrating to find. You may find several sources of water leaks on an FJ40, not just one source ;-)
 
x2 on mudnyreye's comment on the seam across the cowl. it has been known to be the culprit before, I have read a couple of threads that tracked the leak to that seam. If you wanted to test it, cover the seam with duct tape and hose her down. that seam can leak more than you would think. I originally thought it was a weld, too, so don't feel bad.

here is the seam (no windshield, but you can see the vents) you can see, my cowl vent is also covered, welded close.
100_4988-1-1.jpg


up close you can see the rust setting in where I scraped out the old seam sealer. Once the sealer starts to break up, water can just wick right through. I you are careful, you could use a pick to get the old seam out without damaging the paint(I went a little happy with a wire brush).
100_4987-1-1.jpg


not that the cowl vent couldn't be a problem. it sounds like OP vent was sealed over. if the cover job wasn't complete, it could certainly be leaking. lester, if you look under the dash, there should be a box in the center, this is the compartment that was part of the cowl vent. if you have someone hose the area down while you watch the drain holes on the box, you will know if it is leaking.
 
I keep coming up on this thread when searching about cabin water leaks so I figured I would ask here. I tried the hypothesis of the hood hinge bolts, but water is not coming in through those. Any tips on how to reseal this properly, water is coming in through this seam. It seems the previous seal has obviously failed:
image.jpg
 
I just wanted to put this in here for future generations if someone comes across this as I did, during the monsoons. I don't have a garage and so can't take my truck out of rainy service for 24hrs or more to re-seal this seam. Captain Tolley's is fantastic stuff. Not going to claim this is a permanent fix, but it does work at least for the season until you can get dry time to properly re-seal things. While it was starting to rain I ran a small bead all the way around the cowl, have done this on my FJ60 with a rain gutter leak as well.

Clark
 
I parted out a 40 in the mid 90s that must have been owned by a really crusty guy bc he solved his rain gutter leak by completely filling in the gutter with Henry’s roof cement until there was NO gutter.

And as if that wasn’t enough, he got tired of trying to remember how to adjust the 8 wheel cylinders on his drum brake truck, so he…





etched the instructions for all 8 cylinders onto the inside of his driver’s door!😱
 
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