Passenger side Engine Bay Ceiling

Passenger side Engine Bay Ceiling - Printable Version

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Passenger side Engine Bay Ceiling - Wanderman - 08-27-2025

I just went to do some basic check and maintenance and found the Passenger side engine access door compartment ceiling had fallen down at the rearmost section. Looks like the wood is all rotted there. Will be removing tomorrow, but what would cause that? Some water ingress from the outside? We've had a ton of rain lately. Or something above? Any idea what's up there. It is near the rear bath, could be the rear microphor or the shower? Neither of which is being used.

RE: Passenger side Engine Bay Ceiling - Keith Jordan - 08-27-2025

Take the drawers out of the night stand if you have a north south bed. You may find more water damage there. I discovered a leak in the same area as you. Turned out to be trim piece under window.

RE: Passenger side Engine Bay Ceiling - Wanderman - 08-27-2025

Interesting I have a East/West bed.. but may be that as well... but the bath is much closer to that area.... I will look tomorrow!

Thanks,

RE: Passenger side Engine Bay Ceiling - Tony Van Helden - 08-28-2025

Check your storage bay floor as well. The one directly under the bath window. Window was my culprit. I took it out and resealed it only to discover it was the seals around the glass that had been leaking.

RE: Passenger side Engine Bay Ceiling - Wanderman - 08-29-2025

OK.. so.. What a mess. I managed to pull down (after a lot of rusty VERY long screws being removed, the ceiling of the engine bay on the passenger side.

Looks like above it is a blue insulation board, then some kind of plywood/OSB mess that is mostly rotted (back 2/3rds) then some kind of vinyl heavy fabric then some mylar silver bubble insulation and then the diamond pattern engine bay insulation fabric. All this is in an aluminum frame. It looks like there are slots for pinching various layers and then the screws go through the aluminum frame and then up into the frame above. I think!

Looks lik,e the leak is coming from the front right (outboard) corner of the ceiling, That measure out to between the toiler and shower tub in the back. However, sure looks like this water was coming from both the top of the engine horizontal door weatherstripping which never fit right and maybe also the rear cap seam... but that may just be my imagination. I checked the toilet and it's holding water, flushes with no leaks and no visible water anywhere in the rear bath. I'll pull the access panels for the shower valves and tub tomorrow and see if there is any other damage.. Who knows.

Any help getting this redone would be gratefully accepted!

Pictures below.

Thanks!!!!!

RE: Passenger side Engine Bay Ceiling - cwl1979 - 08-29-2025

Sounds like you've got a rear bath with shower in the back left corner like I do in 435. Just curious when was the last time you were up on the roof and checked the sealant for the end cap or bath fan? Could have water penetration coming in through there and running down the back of the shower walls and sitting on the floors under it. Does the shower pan feel soft?
Other possible causes could be the sealant from the shower walls and corners has failed and needs to be fixed.
Either way with the structure under that shower area being that bad it might be a full bath remodel to repair the floor underneath.

RE: Passenger side Engine Bay Ceiling - Wanderman - 08-29-2025

The water damage is limited to the engine bay ceiling.

The bathroom under the granite tile and tub is dry and in good shape. Really looks like the rear seam is traveling into the door and eating the wood. I will check by the shower valves as well, just in case.

What I really need to know is what the rotten wood layer was above the engine bay in the pictures. It's not the thick 5/8 marine ply I have seen before. And how it's all supposed to go together and be attached.

RE: Passenger side Engine Bay Ceiling - cwl1979 - 08-29-2025

Good to hear the bathroom is dry.
From my understanding the floors of the coach ar made of a sandwich of plywood then foam then plywood.
Could what your looking at be the underside of the floor structure? With the silver heat and sound material being screwed up to it?

RE: Passenger side Engine Bay Ceiling - Wanderman - 08-30-2025

Looks like the OSB wood that has disintegrated is below a piece of foam insulation board, the blue stuff.

I'd like to know what thickness it was and how all the layers attached together and then screwed into the steel frame edges above it. Looks like the frame squeezes the layers together and then the frame itself screws to the steel above and then there are through screws with big washers holding up the center and a few other places. These likely just went into the wood... I am NOT completely sure and do not want to have it fall while driving! Smile

RE: Passenger side Engine Bay Ceiling - Wanderman - 09-01-2025

Anyone have any info on what the layers are and the thickness of the wood layer?