I recently bought a 1990 244 and am currently trying to work out several of the problems it has. I have found most of the answers to my questions on brickboard.com. I bought it for some cheap transportation but I am really beginning to love it and with all the information on this site I'm finding it pretty easy to work on.
When I was cleaning out the inside of vehicle, i pulled out the carpet and seats to give them a good steam cleaning. Behind the center console, near the firewall, there was a ton of leaves and debris that had gotten inside the car. I noticed that there was also a ton of debris in the cowl vents but there does not appear to be any way to remove the cowl to clean it all out. Is this where the leaves inside are coming from? and any suggestions on how to clean out the stuff already in there? I plan to get a set of vent covers but want to clean out what's already in there first. any help would be appreciated.
My sunroof is also leaking. any suggestions on fixing that would be welcome also. thanks.

Art's post says it all, or nearly. But to get the leaves etc out from under the vents on the scuttle you need an even thinner pipe extension, that will go between the slats of the vent. It takes an age because some leaves will be too big to go up the pipe, but if you sort of jiggle it about you can manoeuvre them up, or they break and you suck up the bits.

You've happened upon the achilles heel of the 240 at a very good moment - no vent screen. Good moment, because you have the carpets and chairs out. The leaves eventually settle in the rocker panels as part of the "flow thru ventilation" scheme. They decompose and clog the drains. The rust kills the car, which otherwise might have gone half a million miles.

Here are some shots describing how I try to clean these passages. The corrugated tubing is flexible electrical conduit from a home center store.

I couldn't tell exactly where to insert the vacuum. When you have the chairs out, where do you insert the vacuum hose to clean out the passages in your pictures???

Pull out the 70mm plastic plugs, as seen on the floor in those pictures.

You can also pull out the seatbelts.

Also remove the kick panels. On the right, remove the ECU and the blank plate where a vent ought to be. On the left, remove the kick panel and the vent.
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'73 142, '75 242, '75 245, '80 245, '86 244, '87 745T