Sadly, the original design of the 964 was quite poor in that department. Porsche didn't figure that out for some time. I can't tell you the number of Carreras I recall seeing with moisture buildup inside those areas in 1989-1992. I believe many were fixed under warranty but probably most never were taken in.

 

Brael, I would like to see a picture of the large tube under the rear cabin blower fan (left of your current pic) to see what vents you have. If that taped up elbow was connected to distributer you would be sucking ozone into the passenger compartment. I am pretty sure that is not a good idea. I would pull that elbow and grommet out and find a rubber plug at a hardware store. measure the hole so you can drill the appropriate one if indeed there is a clear hose exiting your distributer housing.

 

I don't have one handy of that area, but I'll try and get one asap. Thanks for the follow-up.

 

Surely that area would have a positive pressure and be blowing air into the distributor.

 

Here's a photo looking down into the area left of my originally posted picture. I think it shows what you'd like to see. If I 'read' the tubes correctly, it looks like my tail light venting is tee'd with my distributor vent. The taped up elbow (in my previous picture) may be evidence of a previously incorrectly installed distributor vent mod.

Would appreciate your opinions. Thanks in advance.

 

Looks exactly as you have deduced to me.

 

The taped up elbow is fitted to the intake side of the rear cabin blower fan. What you now have with that tee works but may allow condensation/moisture from tail light assembly to enter distributor. It looks like most of your work is done so buy a plug and more hose to make two specific hoses for vents. There is probably a reason porsche mounted the distributor hose a bit higher than the tail light vent.

 

Thanks, I'll start with removing the unused elbow and properly plugging the hole.

Just so I'm sure I fully understand, the hoses connect to the rear heater blower outlet tube, so air flows from there towards the tail lights and distributor. For tail light condensation to make it's way to the distributor, I can only imagine this happening if the blower stops, or if the car is parked (engine off).

Is there a Porsche TSB that describes how to do the distributor vent mod (including exactly where to drill holes etc)? I did a scan of pcarworkshop but nil found.

 

Hi, yes the condensation would occur when engine is not running. The two vents on the the down wind side of the bower create positive pressure. That big picture that wachuko posted should be printed out and kept in your file. I have some blower gremlins I need to sort out as my rear blower runs randomly and i get too much hot air from center dash vents even with temp set on blue dot? Hopefully I will get to see my mechanic this week and do the distributor belt so I can sleep at night!

 

Why not do it properly? The hose routes direct between distributor and the blower. Teeing into the lamps vent is the shortcut method. The TSB can be found here: http://www.pcarworkshop.com/images/7...0394geolab.pdf

Kits available at Pelican.

Regards

H

 

Thanks for the link, didn't see it when I checked.

 

Any idea why I cannot print the PDF from Harry App?? I tried two different computers?

 

In other words you can download and view, but not print? Print worked ok for me first time. Not sure why it wouldn't for others.

Did you notice that Porsche says to drill 40 mm to the right of the tail light tube hole?

 

Yes, i did? I thought maybe it was removed laying on a bench? I saved the file and still could not print? Paper just glides through printer without ink? I can print other docs?
That is a terrific website BTW! if only I could print! I am going to do this DIY after lunch and find my metric measuring device for proper drill bit size................I will take pics. I wonder if Wachuko pic is factory or upgrade?

 

True, it would be interesting to know what the mod looked like from the factory (you'd assume that it would look exactly like the TSB, but then again....). The TSB says that the factory production cut-in was Aug 13, 1993. Anybody out there that can provide a photo of their post Aug 13 '93 tubing?

So far, three versions: The Wachuko picture, my Tee version, the TSB.

Also, is it ok to somehow add to the thread title since the discussion now covers rear light venting and distributor vent mod?