924Board.org

bseghat · Joined: 30 Apr 2009 Posts: 30 Location: Connecticut

I have a 1977 924 and i am having a few problems. One the car is hard to start and i basically can only get it started if i jump it with another car. But once I get the car started it shakes like mad but once the rpms go over about 1600 the engine runs smooth and doesn’t shake at all. I have been wrenching on this car for two months. I bought it in a non running condition and i wanted to take it to college with me but i have no clue how to solve these problems. Any help will be greatly appreciated
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owner of 2 '77 924, one is in parts

pocketscience · Posted: Mon Aug 03, 2009 8:37 am Post subject:

Need a jump to get it going sounds like a simple battery problem? Did you replace the battery?

Have you checked/replaced all the vacuum hoses?
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Whoever said you can't buy happiness forgot about Porsche!
81 924 N/A, GTS lights, Saratoga, interior, headers, Integral cam, EFI (sold)
95 993
69 911

bseghat · Joined: 30 Apr 2009 Posts: 30 Location: Connecticut

i have put in a new battery and put new rubber hosing on the white vacuum lines at the connections
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owner of 2 '77 924, one is in parts

rkn · Joined: 01 Apr 2007 Posts: 176 Location: Copenhagen

sounds like it may need some new plugs. it's always good to renew those before you start troubleshooting
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1980 924NA ROW

bseghat · Joined: 30 Apr 2009 Posts: 30 Location: Connecticut

i have new spark plugs that have been gapped properly, spark plug wires ( wireset ) new dizzy and distributer cap
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owner of 2 '77 924, one is in parts

Smoothie · Posted: Mon Aug 03, 2009 10:58 am Post subject:

Do you see the battery/alternator light in the dash with ignition on, but before starting? -And does it go out after starting?
If so, good. If not, no good - and get the charging system fixed or you'll be the owner of a junk battery.
-But the problem could be as simple as a poor electrical connection at the battery, alternator, starter, or alternator ground (this one's a common problem with the 924NA).
Recharge the battery with a seperate (from the car) charger. If it takes and holds a charge (12.6V), good, you're lucky. Lead-acid starting batteries have to be kept near full charge or they quickly and permanently deteriorate into uselessness.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

bseghat · Joined: 30 Apr 2009 Posts: 30 Location: Connecticut

thanks alot for the help everyone
smoothie the battery light in the dash does stay on and I do have over 12 volts for the battery but i have to charge it up with another car but after turning the key and the starter turns the engine over for about 20 seconds the battery charge goes down and is unable to turn the starter. I will try to clean and check all the connections. once again thanks for the help
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owner of 2 '77 924, one is in parts

wombat · Posted: Mon Aug 03, 2009 7:54 pm Post subject:

check main earth wires (I ran new shielded ones) I have a 77 in a very similar condition in that I have been working on it for 6-12 months and it has been driving for about 4-6 months but I purchased a new battery only to have it stuffed after the first 4 months for exactly the reason smoothie said. Oh and these things had a quite large CCA battery mine when I got it was smaller than stock and the first one I replaced it with was too (as I just got what was in it) and that did exactly as you are describing, if you cranked it for 20 secs and it didnt start then it was flat. (I think that is what you said I cant remember now), SO check you have a bigger enough battery in it.
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1977 924 2.0 Auto

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Now would be a good time to remove the alternator and take it to your FLAPS to have it tested. Sounds to me like it's not functioning properly. Check the grounds first as others have stated...and also, verify that the alt belt is properly tensioned, just to make sure it's not something simple...but I'm betting your alternator is stuffed.
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erstwhile owner of just about every 924 variant ever made

Smoothie · Posted: Tue Aug 04, 2009 12:27 am Post subject:

Corroded wires to the starter are another common problem with the 924NA. They can corrode internally, leaving the outer insulation appearing relatively intact.
It's a good project to have finished early so it's not needed during the school year.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

masterdave · Joined: 10 Dec 2008 Posts: 183 Location: Harrison NY

i agree with ideola sounds like your generator is not recharging the bat, could also be corroded wires, remember a car that old any thing coated in rubber would not have lasted, i just had to replace all my fuel lines due to corrosion and wear.

bseghat · Joined: 30 Apr 2009 Posts: 30 Location: Connecticut

thanks for all the advice. today i will clean all the terminals on the alt and starter as well as to try and tackel rewireing the wires to them. I will post back later today to tell you if it works
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owner of 2 '77 924, one is in parts

bseghat · Joined: 30 Apr 2009 Posts: 30 Location: Connecticut

I am having trouble finding the gauges of wire running to the alt and starter. is there a way to tell by just looking at it
also i have searched napa auto zone and advance auto parts for the larger diameter vacuum lines such as the ones that run into the master cylinder but no one seems to have the correct size. they do though have heater hoseing that is the correct size. does anyone know if it would ok to use heater hoseing instead of vacuum hoseing
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owner of 2 '77 924, one is in parts

Smoothie · Posted: Tue Aug 04, 2009 7:23 am Post subject:

I'm in the habit of using 4-gauge for the large battery-alternator-starter connections on all of my cars. It's more than adequate without getting ridiculous. The OE sizes are given in the wiring diagrams, which are printed in the Haynes manual, and are given in metric (mm²), so would need to be converted - http://www.rbeelectronics.com/wtable.htm .
The diagrams show a 16.0mm² wire from battery to starter - that converts to about 5-gauge, so 4-gauge is good there (smaller gauge number = larger wire). Also shown are two 2.5mm² wires from starter to alternator...if my math is correct that should equate to a single 5.0mm² which converts to 10-gauge AWG. -So 10ga should do fine there, or go 8ga. if you want to add to the safety margin. The medium-sized (black/red 4.0mm²) wire at the starter would be replaced with 10ga., and the small black one (1.5mm²) converts to 14ga. with a comfortable little safety margin.

Also, most include some type of added heat insulation over the wiring where it passes hot areas of the engine. The enemies to the wiring there are both heat and battery acid.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox