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General thoughts on Sills

DC911SC

New member
I am currently wondering whether or not to treat the inside of my turbos sills, they are very much rust free. I just wonder if it would put a buyer off as the car is very original.

I have been looking a lot at the sills, what are people doing to keep rust and moisture at bay?

A lot of people say the rusty sills are from condensation, I wondered if moisture in the sills can come from rain water entering the door via the window scrapper and travelling into the sill as moist air??
 
It is like the Bermuda triangle , a complete mystery ? There is that air vent that flows from the door to the back wing ? Intern taking moister from inside the doors into the sills ? Could you cut a round hole in them , treat them and close up the hole again ? May three holes along the full length of the sills ? Like you say, best stick with the original ones .
 
There are lots of posts on this. Just because they look good from the outside does not mean that they look good from the inside....
The grille at the back sort of ventilates them a bit, and you can get access at the front via a grommet under the carpet.
I (and many others) use Bilt Hamber Dynax S-50. This comes in a big can with a long tube with all-round spray pattern. You can lower the tube down the grille, along the inside of the sill and spray while pulling it slowly out, then repeat from the front.
The grille comes out by lowering the tab inside the top of the grille, but be VERY careful when pulling the tab downwards as it is very fragile (don't ask how I know !!) - pull it down just enough to release the top of the grille then hinge the grille forward from the top just enough to lift it out.
There are drainage slots in a row along the underneath of the sills - a unique Porsche feature that enables damp and wet to get inside the sills and rot them from the inside out. Make sure they are not blocked (a lollipop stick is perfect for this)
Surely treating the sills is a positive preventative measure to mention to any buyer?
 
Front grommet access gets you inside the inner sills I think?
I reckon the best way of getting treatment in there is via the drain holes - the attachment that comes with the Bilt hamber dynax fits through them easily enough.

As for the OP - I'd say before you treat them, take some good pics to show prospective buyers how rust free they are, then treat them & take some more pics.

Rust is hard to explain - one of my sills (drivers side) on the s2 was completely rotten while the other was relatively sound.
 
A lot of people say the rusty sills are from condensation, I wondered if moisture in the sills can come from rain water entering the door via the window scrapper and travelling into the sill as moist air??

Unless the sills were completely sealed, with a vacuum inside, some moisture is inevitable. Look at the design of other cars from the time, and see how good Porsche's sill actually is?

You can't keep moisture out, so why not welcome it? Put massive vents through the car's sections to aid air flow, and plenty of drains at the bottom of sections where water can collect, such as doors, sills, boot wells etc., so the moisture can drain away freely, taking corrosive dirt with it The problem with 944 sills isn't moisture: the air is full of moisture and it's a natural thing that Porsche allowed for.

It's the breakdown of the protective coating on the metal that allows rust. This is partly due to age, but then would you prefer to take a gamble on a 1980s Alfa or Capri for perfect bodywork? The main issue is a build up of dirt, trapping salt as well as the moisture, and leading to the inevitable. Again, Porsche's design makes it easy to clean the dirt out: keep the drain holes clear, drive the thing in all weathers, and it'll wash the dust and muck out. How many 944s have spent a large part of their life being driven over salty roads, then put in a nice warm garage to keep the salt trapped for months? The later sill trim doesn't help here, of course.

One fault in the design is the rear corner of the sill, where it can't drain if the car is parked slightly uphill. I guess you can't design the perfect system, and after all the were meant to be used, not parked up!

The other advantage of the "open" design is easy access to check, and treat, the sills. They even made it simple to get a camera in, never mind a lance to wax the sills! If the worst does happen, they aren't difficult to repair (TVR chassis repairs, anyone? [&o]). Unless the rot has been allowed to spread for many years, or there is other damage such as bodged accident repair, it's a smaller problem on a 944 than any other comparable car from the period IMO, and a testament to the design.

It's lack of maintenance that allows sills to rust, or rust to progress, and as they are now out of warranty that's down to us!
 
My sills were rust free so I took plenty of pictures to make sure I was happy there was no rust to worry about.

SNC13946_zps763bccbe.jpg


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I then applied a full can of Dinitrol into the sills via the method explained by Mike (Veerzigzag) above last Winter and have just repeated the process this weekend with another full can. Make sure you get into the arches as well and if you can remove the inner wheel arches then the other rust collection are at the bottom of the wings can also be treated.

Put plenty of cardboard or sheeting below the sills when you do this as it comes out of lots of different holes.

Prevention is always better than having to cure the problem [:)]
 
I reckon the best way of getting treatment in there is via the drain holes
Can't imagine why I didn't think of that simple and effective method - also ensures you are more likely to get an even coating all along.
Thanks for the tip !!
 
These drain holes, does the sill trim have to be removed first to see them? I think it does and that's why I've been procrastinating over this job. When my car was serviced last month I had a look while it was on the ramps and I couldn't tell which screws were for the trim and which were for something else. Also they looked a bit crusty, and difficult to get to when not on the ramps. I've got 2 cans of dynax, what's an ideal amount to put in, a can each side?
Cheers
 
I forgot about the sill covers - mine doesn't have them. Yes they probably do have to come off.

The tech sheets on Dynax suggest you apply sparingly - I'd certainly think 1 can is more than enough for both sides. I used about two thirds I think.
 
those sills are tidy did you use a borescope to get the pics? I has trying a few weeks ago but almost got my hand stuck with a digital camera inside the sill! [:D]
 

ORIGINAL: strath44

those sills are tidy did you use a borescope to get the pics? I has trying a few weeks ago but almost got my hand stuck with a digital camera inside the sill! [:D]

I used a small digital camera with timer and took multi shots. You can get your hand in (just as I have big hands) and move the angle to get the best shots
 
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Mine look like this. Don't be scared to put too much wax in. You can get in through the vent in the door pillar or the bungs behind the carpet on the inner sill or through the bung in the end of the sill structure beside the rear suspension mount inside the rear wheel arch or through the drain holes along the bottom of the sill.Remember there are two voids in the sill one on each side of the center strengthening panel.Sill structure looks like this

sillprofile.jpg
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From all the research I have done on 944 sills, what seems weird to me is that the drivers side (on RHD cars) seems to fare worse than the passenger side (my car included).

This seems counterintuitive as I always believed that in the UK, the passenger side took the worst of the salt and water from being "kerb side" and therefore "in the gutter".

I would be interested to know if other owners concur with the theory that drivers side is generally worse than passenger and if so, why would that be?

M3
 
It's true, over ten years sill rot has swapped sides. [&:]

I'm guessing that the first cars to show problems were on the NS, where the cars pick up all the crud from the side of the road. Most of those will either have been scrapped, or repaired. That leaves the OS sills now seeming to need repairing more often.

I think it was the same with front wings. Mine had a repair to the NS front in about '08, so the OS was far worse when I had them both done.
 

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