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Rear of sill drain holes

N

Neil Haughey

New member
I don't know if we have discussed this before guys but have any of you drilled a small downward facing drain hole in the section right at the bottom of the rear quarter after the sill? I believe I mentioned it as an idea a couple or three years back as the large rear facing vent/drain hole down there seems to be ineffectual leading to that area of bodywork rusting through in practically every late 944 and increasingly 968s as well although its not obvious on the 968 due to the plastic rear quarter panel.

 
I think it general moisture in the sills that's the issue, not water collecting in quantity. External corrosion is worse when there's physical damage to the underseal, or salt on the car, but internally it's condensation as much as anything.

You can't keep the sill moisture-free: it's designed to ventilate itself, but there's moisture in the air. I guess that you might have some water collecting if the car is un-used for long periods in cold weather, and parked facing uphill?

Better to just spray protection in there regularly, and make sure the exsisting drains are clear, than drill holes that might just let more (and dirtier) water in, I'd say.
 
I don't agree Paul, there is a very clear pattern to where the rust occurs and its right in front of a large vent hole which is raised up from the area and facing backwards. The inside of the rear quarter is of course a large space in which condensation can form but when it condenses on the inside of the panel and runs down where does it go? The problem is it can't go anywhere unless the car is moving such that air is drawn along the sill box section to dry it up and out that rear facing vent hole which isn't btw a drain as you say, its raised slightly from the floor of that entire area such that it can't function as a drain for any of the sill or rear quarter. My old S2 shell was a case in point, that area had rusted out but once through the dip at Surface Processing Ltd there wasn't an inch of rust anywhere else on the entire body.
 
A couple of years ago I had both of my rear sections cut away and new box sections made and fitted.Within a week of them being fitted I waxoiled them and the moisture that came out and dripped on the floor was startling,especially as the car did not move in between.I drilled rear drainage into the rear section bottoms as a precaution...cant hurt I guess.
 
That's exactly it, I think its an unintended design flaw because if any condensation can form anywhere forward of the wheel arch it will either have to evaporate again or run down into that tiny little section. Its a huge area we are talking about as well from the rear quarter glass to the B post and back to the middle of the wheel arch and at the bottom its only about 2 to 3 inches long by maybe an inch wide. I think I will be drilling a 3mm hole into mine on each side before cleaning out and given her another course of the dynax s50.
 
Pics please gents. This is sounding like a subject well worth considering.
Thanks
Mick
 
Should already be a drain hole. But it not like the rest. It's more off pressed stamp shape like a runout/ slope. Trouble is the opening its facing the wheel so over time it could get clogged up going Un noticed.
 
Mick, the best sill images I have seen were posted recently - they were of a Silver Rose I think, it showed all the subtle shapes in the main member and outer sill pressing. Cant recall the thread but some-one on here will

All my experience of 944's has been that the sills don't drain particularly well

George

944t
 
Exactly because it isn't a drain hole its a vent which looks like its intention was to draw air through the sill and out into the rear wheel well as that area will likely be under vacuum when the car is moving. This is great when the car is moving all the time not so great when its sat motionless through damp blightly winters.
 
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