Air filter plumbing question.

[bajacalal]

Today I removed that rubber tube which goes from the bottom of the air filter box to somewhere up in the passenger side fender. I did this because mice had attempted to make a nest inside this tube. That would explain the recent drop in power and corresponding increase in smoke. I also put a hole in the front side of the bottom of the air box to allow more air to enter.

Now I'm wondering if I did a bad, bad thing. Is there anything really wrong with deleting that tiny rubber tube that has at least two 90 degree bends in it? What's it for? American cars generally don't have these contrivances and do fine sucking in engine compartment air. From looking at the front end of the car, I can't imagine the air entering the engine will be that much hotter, it looks like plenty of fresh air comes in.

Is there any reason not to do what I just did? I drive this car on SoCal highways mostly so I'm not too concerned about sucking in snow or rainwater.

This is on my 1985 Golf "GTD" project/daily driver. It has a turbo diesel engine from a Jetta (same year) and the stock turbo airbox parts from that car.

[SolarSteve]

I don't have any tubing to my airbox at all.  Its just the round opening that the tubing normally would side over and hold in place with a screw.  It seems to be running fine and its been like that for a year/ 14k miles now.

I'm sure ducting cold outside air into the box would be better, but how much, I don't know.

[Rabbit TD]

I think the hose being routed like that is for was for intake noise reduction.  I have some large shop vac hose connected to mine to a small scoop in the grill. My clips for the top of the filter box came loose just a little and it made way more noise if it wasn't down snug on the rubber part of the filter.  To me the intake noise on these engines doesn't sound very good but the exhaust does

[jtanguay]

its probably for a combination of noise, and to get cold air in.  theres nothing wrong to run without it... lots of people run the cone filters without too much issues.  the real problem without having a cold air intake, is sitting at the stop light the engine will start to suck its own heat on a hot day, and the engine will chug a bit until cooler air rushes into the engine bay.

[bajacalal]

Thanks for the help.

I'll see how it does. It has to be better than it was with a filthy air filter and a mouse nest. I do have an intercooler on it (my homebrew GTD) so I already get some intake noise (and turbo lag). It should help with the air temperature. As far as noise, intake or otherwise, this is my first little car. My diesel VW is still quieter and more comfortable than all the Jeeps and old pickups I've owned before it.

Another question, the NAPA filter I bought has much less surface area than the German brand that I took out. The NAPA filter is the same length and width but has less filter paper used to construct it so less surface area. Should I toss the NAPA one after 3000 miles and find a Mahle brand filter for it or will the difference not really matter on an engine this size?