**MOST Common 928 Issues AND Fixes**

[MPDano]

Issue: Need Wheel Offset HELP?

Fix: Download this 928 Wheel Fitment Spreadsheet. FYI, I didn't create this Excel Spreadsheet, but it works great in figuring out what offset will fit. Spreadsheet Authored by Andrew Olson.

Pics: No need.

Wheel Size-Offset Fitment Spreadsheet

[mproseusa]

Thanks Leo for incorporating an INDEX in "MOST Common 928 Issues AND Fixes"! It really helps to find issues, especially for old codgers like me. Great Tread. I must have been sleeping when you put it in.

[Mrmerlin]

Air intake tubes.
They only make one it has come in a few different sizes,
but again they only make one the driver side will fit on the passenger side.

Simply turn the rubber collar 180 degrees,
and there is another hole so the tube can be flipped to the opposite side.

[Big Load]

hi everyone i'm newbie so when i started reading this i couldn't stop it's brilliant..a wealth of information. i hope when i get my 928 on tuesday i can help and add to this thread. keep up the good work

[bigkid]

wow=wow---great post==thx for all the hard work

[JK McDonald]

My ignition switch had begun acting up in Miss Purdy and would also intermittently not return to the run position after the engine had started. 1st I removed the lower sheet metal cover (two screws) just under the instrument pod and decided to see if I could replace the ignition switch without a major tear down.

After disconnecting the battery ground terminal, I then removed the electrical connector plug from the back of the ignition switch assembly. Then (for some room to work) I pulled the lower right rectangular connector from the bottom of the instrument cluster. This is seen when looking straight up just beside the ignition switch. Finally I pulled the two pin connecter from the intensive washer button by the drivers right knee. With all these connectors tucked out of the way - it was time to get serious.


There are only two flat tip machine screws that attach the electrical half of the ignition switch to the mechanical key/tumbler half and you can clearly see one of these screws with the lower metal pod cover removed. (Note: I'd replace these two flat tip screws with Phillips head screws for much easier ignition switch replacement next time) I used a small flat box end ratchet wrench (1/4" - 3/8") and a flat tip bit to remove the lower ignition switch screw. The flat tip bit was held securely in the 1/4" end of the ratchet box end wrench with a thin piece of old rubber glove. Once the screw was turning freely, I used a second flat tip bit like a short screw driver for the final few turns by hand.


The top screw was a little more difficult but was loosened using a regular 1/4" drive ratchet and a 1/4" socket with a flat tip bit (again) held in place using a thin piece of rubber. Once the top screw was loose, I used the 1/4" socket with the flat tip bit like a short screw driver for the final screw removal. Make sure to use a flat tip bit that is small enough to easily fit down into the screw slot. I had started off with a bit that was slightly too thick for the screw.....

With the old switch pulled out, I applied a dab of the yellow 3M non-hardening upholstery sealant to the screw/mounting holes of the new switch. This sealant stays soft and sticky enough to keep the two attaching screws in position but sufficiently pliable to let you easily turn the screws during the final installation. A small alignment pin (electrical switch half) and hole (mechanical half of the assembly) makes sure everything goes together correctly oriented. The center cross piece (with the key in the off position) will now also be aligned right.


Once the lower screw has been started to hold the new switch half in place - use the 1/4" socket with the flat tip bit as a small screwdriver to start the upper screw. If you cup the fingers of your left hand over the top of the switch assembly you will feel a slight groove or trough in the switch housing that leads to the upper screw. The final step is a little slow going and is pretty much by feel, but use a light touch of your finger tips to determine when the bit engages the screw slot. Note: Here is where the Phillips head screws would have made this step easier....

At this point check to make sure both screws are tight and there is no movement seen between the electrical switch half and the mechanical half of the assembly. Reconnect the ignition switch electrical plug, reinstall the rectangular instrument cluster connector (make sure the plastic electrical film straddles it's card edge before the connector is pushed back into place), the two pin intensive switch, lower metal pod panel - and the battery ground terminal. Start up your new car and take her for a spin.

Good Luck, Michael

[MPDano]

Issue: Air Intake Hoses bad?

Fix: Here is an alternative to OEM. They are Mecedes Benz hoses. You'll need 4 and a coupler.

Part Number=1170940382

Genuine Mercedes
Air Intake Boot/Hoses; Intake Scoop to Air Filter Housing
1 per car.

$12.96

Pics:

[Danglerb]

Was kind of weird buying 4 of those at the MB dealer. I wonder what I have done with them?

Note to self, don't put parts you plan to use "soon" in other than clear storage bins.

[MPDano]

Issue: Got Blown Subwoofer? Yes this is pertinent since our Blaupunkt Speakers also use Foam Surrounds. Same concept, different scale.

Fix: My Ford Expedition custom sub box I build 14 years ago finally blew the foam surrounding. I decided to repair it with a new foam surround that I bought off eBay for around $26 for the kit with two surrounds. My woofer is a dual voice coil rockford fosgate punch, which is a saver if I could.

First step is to remove the old foam. Then put the included (kit) adhesive to both the speaker coil and foam, let it try till tacky, then apply. Do the inner first. Let it dry for about an hour, then proceed to do the same on the outer. Let it dry for another hour.

Pics:

[MPDano]

...she lives to BOOM again!

[rastapapa]

Originally Posted by MPDano

Issue: Air Intake Hoses bad?

Fix: Here is an alternative to OEM. They are Mecedes Benz hoses. You'll need 4 and a coupler.

Part Number=1170940382

Genuine Mercedes
Air Intake Boot/Hoses; Intake Scoop to Air Filter Housing
1 per car.

$12.96

Pics:

Who makes those intake hose couplers? How do I find them? Thanks!

[MPDano]

I got them off ebay. search silicone hump coupler and the ID size. I don't know it off hand.

[dtool242]

Here's what I did to get my front brake rotors off that were stuck on there good. Probably had never been removed before. The threads blew out in the jack bolt holes so this is what I did to get the rotor off.


After liberally applying the lubricant of your choice (I used Kroil), put a 7/16-20 bolt through each of the brake caliper mounts then put a washer and nut on each bolt. I started by just using another nut at the very end of the bolt to try to spread the load out and protect the surface of the rotor. Then I added the piece of stainless steel you see in the picture. Turns out I'm going to replace the rotors anyway... So just thread the nut nearest the caliper mount to add pressure to the rotor. Go back and forth between the two. Once you get it moving, release the bolts, turn the rotor 180 degrees and repeat. Mine didn't just pop loose, I had to work them off like this the whole way (they were pretty rusty on the inside).

[MPDano]

Issue: Got dripping Hood Heat Shield?

Fix: Replace it with a new one. Use a Wet/Dry Vac to remove old material. Use PB Blaster to remove the old adhesive and use Weldwood Contact Cement to adhere the new Heat Shield.

Contact Cement goes on real smooth and easy using a paint roller. I used a brush to get in the nooks on the hood.

You can get a Kit (Small Pan, 1/2 size Roller and Brush) at Home Depot where I got the Weldwood Contact Cement.

FYI, I didn't take a pic of when I sprayed the hood a second time to get all the old adhesive off.

Pics: Hood Liner install pics.

[MPDano]

More pics:

[camo]

Originally Posted by steve322s

Aluminum BALL JOINTS!

best to change even if they feel good.

I had my car on the lift the other day to change all the belts and checked my old alum. ball joints before i took her off the lift. seemed solid boots were not cracked all seemed good. drove 60 miles home then went to pick my wife up from work, Well pass side lower ball joint popped, good thing i was in the parking lot traveling slow, no damage.

this along with the fuel lines should be 1 and 2 on this list!

Wait.. So the ball joints are ALUMINUM? Isn't that a little.. Underkill? I think I just made a new word.

[l_turn9]

Howdy - I normally lurk on the 911 list but a lady stopped me & said she needed someone to work on (or buy) her 91 928. The problems I know about are leaking fuel tank and leaking radiator. Your tank repair was very helpful - i didn't realise the 928s have plastic tanks, since I haven't had chance to see the car. I was wondering what you did to eliminate the gas fumes from the tank before you started heatng it? I've heard of people filling tanks with water but since you had no flames or sparks I assume that wasn't needed? Thank for the articles. This ladys 928 hasn't been driven for 2 years so I expect the worst. Don't know if I would want to buy it or just work on it... for now I'm just researching the problems I know about. Is the radiator plastic like the fuel tank? BTW, i have the WSMs so that's my next stop. I appreciate any comments you might have for me...

[MPDano]

Originally Posted by l_turn9

Howdy - I normally lurk on the 911 list but a lady stopped me & said she needed someone to work on (or buy) her 91 928. The problems I know about are leaking fuel tank and leaking radiator. Your tank repair was very helpful - i didn't realise the 928s have plastic tanks, since I haven't had chance to see the car. I was wondering what you did to eliminate the gas fumes from the tank before you started heatng it? I've heard of people filling tanks with water but since you had no flames or sparks I assume that wasn't needed? Thank for the articles. This ladys 928 hasn't been driven for 2 years so I expect the worst. Don't know if I would want to buy it or just work on it... for now I'm just researching the problems I know about. Is the radiator plastic like the fuel tank? BTW, i have the WSMs so that's my next stop. I appreciate any comments you might have for me...

Remove the tank and drain it of gas, then rinse with water. Leave the gas cap off and you'll be fine. It's a heat gun so really no flames used anyways. Good luck.

[Plexus928]

Originally Posted by l_turn9

Howdy - I normally lurk on the 911 list but a lady stopped me & said she needed someone to work on (or buy) her 91 928. The problems I know about are leaking fuel tank and leaking radiator. Your tank repair was very helpful - i didn't realise the 928s have plastic tanks, since I haven't had chance to see the car. I was wondering what you did to eliminate the gas fumes from the tank before you started heatng it? I've heard of people filling tanks with water but since you had no flames or sparks I assume that wasn't needed? Thank for the articles. This ladys 928 hasn't been driven for 2 years so I expect the worst. Don't know if I would want to buy it or just work on it... for now I'm just researching the problems I know about. Is the radiator plastic like the fuel tank? BTW, i have the WSMs so that's my next stop. I appreciate any comments you might have for me...

WARNING!!!
Be VERY careful using a jack to Re-install.
If the tank is not going all the way back to original location DO NOT THINK IT WILL GET THERE WITH JUST A LITTLE PRESSURE WITH THE JACK!!
This cost me a new tank,
Tanks will split if you lean on them too hard. (30 year old plastic, it may be thick,-good news, bad news- this makes it brittle)
I posted this somewhere else on the forum, could save you a heap of dramas.(and money)
More room when re-installing fuel tank

[Plexus928]

Also , if you are "welding" the crack with a soldering iron, shave a little plastic from somewhere on the tank to use to melt in, you should not need much, High up preferably
Plastic from the same tank will guarantee it will melt in, so many types of plastic out there, and 928 tanks do not have an ID anywhere on them to identify the type Porsche used.
I took a sliver from the mounting lug next to the filler,
worked great-until I put the jack under to "push" the tank back in PING!- big crack!
I kept a hunk of the old tank for welding plastic in case I do something stupid and have to do a seal up on a 928 tank sometime in the future