Belt cover to air box hose, important?

[DMRK]

Does anyone know how important the hose that goes from the air box to the belt cover is. I noticed I left mine off and was wondering how high of a priority it is. I will put it back for sure, just don't know if I want to tonight. Thanks, Dave

[#391]

Not a big deal. A lot of people leave them off. In fact, I have heard (but I don't know how true it is) that there was a service bulletin issued about removing/capping that line to eliminate vacuum sucking water into the airbox/intake in the event of driving through standing water. Regardless, it's not an issue.

[Techno Duck]

Not a high priority. Take it off if you wish, otherwise leave it on. Cap the holes if you do decide to take it off.

[DMRK]

Ok maybe they'll stay off then. Thanks guys.
Any thoughts why they are there? Belt cooling?
Any Ideas on what to use as a good cap?

[ERAU944]

there was a large discussion about this awhile ago. IIRC, someone (razorback i believe) said there was a service bulletin back in the day saying it should be removed, but my shop (porsche factory techs) haven't said anything for 7 years i've been visiting them with my car. leave it on, take it off, it makes little difference to me. FWIW i still have mine on, it makes a big black part on the filter where the belt dust collects.

[SoCal Driver]

Leave the vent hose on but stay clear of any water deeper than 12".

[Techno Duck]

The PET book i have for the 924/944/928 (i think 2000 edition) has all the service bulletins in the back of the book. The deletion of the hose is in there. I forget the complete details, but it says to delete the hose and cap the two nozzles off with caps (part #'s are given). It says something about later belt covers still having the nozzle but the hole not being bored out...and not to make an attempt to bore it out.

[RIchard944]

There are 2 rubber end caps that fit where the hose was. I think I paid $5 each.

[Aerkuld]

I leave the hose connected but I have blocked off the inlet to the air box inside the hose. If I ever want to go back I can just take the hose off the airbox, take out the blanking plug, then reconnect the hose. This way the hose is right there and not lost in a box in the garage.

[Razorback1980]

I'm going with the Porsche engineers as they are pretty smart guys and recommend things based on their experiences. The tech bulletin says to take it off, so I took mine off and have had no issues with it off. I have had one of these cars since 1986 and put a lot of miles on them, so running without it doesn't hurt anything. If I feel the need to vent my belts, I'll find another way without any access to water or antifreeze to put in the intake....not good for a motor.

[Techno Duck]

Take the top portion of the belt cover off if you want max venting...thats what i did . Actually i did it because i was going to be retensioning the belts. I retensioned the belts and never put it back on, it makes inspection alot easier.

One thing i think would be a nice aftermarket option would be to make lexan or polycarbonate clear belt covers. Probably would be expensive to produce however.

[ERAU944]

for those of us who don't have PET, theres no way to verify that the bulletin exists, except by word of mouth. i'm sure the super porsche geniuses are right about the hose... maybe i'll remove it one day. as far as i'm concerned, it's much more dangerous to have the airbox routed through to inside the front fender (at least in early cars where it's very open) than it is to have a small hose to the belts, where one day you *might* get a little antifreeze on the air filter. if your water pump fails that catastrophically, you've got bigger problems than some water in your airbox. i believe it's much more likely to run through a puddle than it is to have a catastrophic water pump failure that might get you some water in the intake.

now that i think about it my boss just had the water pump go (fairly catastrophically) on his '89. IIRC, his issue wasn't water/coolant going into the intake, it was going up into the distributor cap and rotor. i still say the fender hole is more dangerous - but i guess performance is considered over the slight chance (which IMO is more likely than a catastrophic water pump failure) that someone will be a moron and drive through a large puddle at the right speed to get water in the intake.

my $.02

[Eldorado]

Mike, I think the concern is having the belts pick up the water, pass it up the hose into the air box so it can be sucked into the engine... not the vent for the airbox being in the fender.

I think...

[ERAU944]

i know, i was iterating my point that a much larger and more likely opening for water was 'overlooked' by the porsche geniuses. i've limped home with a head gasket leaking water into a couple cylinders and after changing the head gasket, belts, and spark plugs, she ran just fine. a small bit of water wouldn't concern me. hydrolocking the motor due to picking up massive amounts of water when driving through a puddle kind of gives me the willies though...

[SoCal Driver]

There are actually two bulletins on the air box; one calls for removal of the vent from the belt covers the other calls for cutting the intake duct half way between the fender and filter box.

Only takes a few ounces of water to hydro lock a cylinder and bend the piston rod.

Think about the prior comment about always finding belt shavings on the top of the paper filter. Now think about water instead of belt shavings.

[Techno Duck]

[conkeytonk]

Looks like “That Guy” just eliminated the mystery so many of us have sometimes venomously debated. I’m plugging mine.

[conkeytonk]

BTW Jon, The GHL test pipe is on its way to me. I'll let you know how it fits.

[Tidybuoy]

Great info.....Techno Duck! Thanks

[Techno Duck]

Funny thing is ive had that picture saved on my webspace for a while now, i just forgot i had it.

Let me know how things go with the test pipe. Take some video also. Interested in doing it to my car also, just dont want the resonance of a regular gutted cat.