Air hose to alternator

[harborman]

I had to do a little repair on this air hose. It seems it also has the outdoor heat sensor in it. Does the alternator have a fan on it to blow or suck air through this tube? Never saw this kind of thing before.

I also had to tighten up one of the front wheel bearings. I was amazed how the Germans do it, real slick with a nut and allan screw. Unlike American cars with the lock nut and cotter pin deal. You can get a precise bearing adjustment on the Porsche.

[JhwShark]

As you saw...the hose connects to the black plastic housing on the Alt backside. It runs forward to the front so the Alt cooling is done by the car moving -- No fan.

[por917]

The purpose of the hose that is running from the front left wheel well area to the alternator is that the alternator fan draws air thru that hose which the outside temp sensor is in. This gives an ambient temp for the climate control to compare. The other purpose is for alternator cooling of course but there is no forced air in the hose due to the enclosed area where the opening of the hose is located.

[harborman]

Thanks, I thought I was on the right path and you confirmed it for me. Thanks again all.

The purpose of the hose that is running from the front left wheel well area to the alternator is that the alternator fan draws air thru that hose which the outside temp sensor is in. This gives an ambient temp for the climate control to compare. The other purpose is for alternator cooling of course but there is no forced air in the hose due to the enclosed area where the opening of the hose is located.

[JhwShark]

Originally Posted by por917

The purpose of the hose that is running from the front left wheel well area to the alternator is that the alternator fan draws air thru that hose which the outside temp sensor is in. This gives an ambient temp for the climate control to compare. The other purpose is for alternator cooling of course but there is no forced air in the hose due to the enclosed area where the opening of the hose is located.

Correct for the newer cars...early models (through '82 I think someone will clarify) did not have a sensor in the hose, it was only for cooling the Alt.

[por917]

My car is a USA 1981 and has the sensor, I'm pretty sure all 928's have the same system. No 100% sure of the 78-79 models though.

[Mrmerlin]

the alternator fan also sucks air for cooling through the hose, so if this hose is off then rocks will get sucked into the rear of the alternator

[harborman]

A mouse had made a nest in the hose and chewed a hole in the hose. I spliced in a section of PVC pipe with hose clamps and first vacuumed out the hoses. My car had been stored since 1992!

the alternator fan also sucks air for cooling through the hose, so if this hose is off then rocks will get sucked into the rear of the alternator

[por917]

Harbourman you can actually buy a replacement hose at Napa. It cost me around 12 dollars and that was with extra hose left over. I belive it is 2" diameter and the Rubber silicone type with a wire core material.

[Mrmerlin]

the correct hose diameter is 2 1/2 inches

[por917]

MrMerlin is correct, it has been a little while since I replaced it. Thx MrMerlin for the clarification.

[harborman]

Ok, might replace it just to make it look better but do it in winter when the car is not driven.

Harbourman you can actually buy a replacement hose at Napa. It cost me around 12 dollars and that was with extra hose left over. I belive it is 2" diameter and the Rubber silicone type with a wire core material.

[2Quick4u928]

I purchased a small diameter black drier exhaust hose which also has the re-enforcement wire internally, looked good, was an easy fit. Is a little large in comparrision but served its purpose. My old one actually crumbled in my hands when working with it, natural as was over 20 yrs old.

[harborman]

I had no luck at NAPA or any other store. My hose is good except for being cut, still trying to find a replacement.

I purchased a small diameter black drier exhaust hose which also has the re-enforcement wire internally, looked good, was an easy fit. Is a little large in comparrision but served its purpose. My old one actually crumbled in my hands when working with it, natural as was over 20 yrs old.

[Mrmerlin]

the aviation supply store has the best quality hose 2 1/2 inch its red silicone with wire,
you may be able to get away with 4 or 5 feet of the hose

[harborman]

I will try looking up a supplier on the Net.

[JK McDonald]

Hey Harborman, A temporary fix that you might look into as an alternator cooling hose replacement is stocked by Wal-Mart in their automotive/camping trailer dept. It is actually a heavy duty, spiral wire reinforced, 2.5” sewer hose but it has held up well for over 5 years without any noted deterioration on several local cars. As you route this hose from the back of the alternator air shroud just flatten it slightly as it passes though the left hand bumper support and out to the external air temp sensor housing. Once the correct replacement part is available - change it out......

Don't forget to add the little crooked over extension of hose on the upper end of the external air temp sensor housing to keep the water, rocks and potential wheel critters out of the air ducting.

Michael

[harborman]

Thanks. Will check it out. The aviation hose looks good but one might have to buy from a local aviation shop not from a distributor in small quantity.

[neil30076]

Originally Posted by harborman

Thanks. Will check it out. The aviation hose looks good but one might have to buy from a local aviation shop not from a distributor in small quantity.

You can order the aviation hose on line from Pilot Supplies, Avionics, and Homebuilt Aircraft Parts from Aircraft Spruce and Specialty Co. - just search for part number 05-29810 - its $6.50 per foot, and they will ship any length.

[bwmac]

I changed my alternator to this and left the hose off, but left the sensor in place.
don't mater much as my dash is in German and I can't understand any of it.

928 Motorsports - Performance Parts - High Output - 200-amp Alternators for Late-Model Porsche® 928