Valve adjustment is right something else is WRONG??
 

Hello Pelicanites.

For starters...
1981 911SC 3.0 - stock all the way around

Activities over the last two days:
AC delete
1st Valve adjustment (very satisfying - but short lived)
New plugs, cap, rotor, Oil & air filter
Oil change (9 quarts + 2 after warm-up)

Engine started on 1st crank. Took the car for an engine warm up spin, re-checked oil & added last two quarts. Engine sounded great a couple of valves aren't perfetc but 1000% better than prior to adjustment.

Here is when the problem began...
Once the oil level was set I went on a 10 mile cruise in drizzling rain. 1/2 way through my Tach went CRAZY! 7K to 1K to 7K back etc. etc.etc. and finally dropped to 0, nada, the big goose egg. The car also began to display significant throttle hesitation. I hit the dreaded hazard button and limped 2 miles home. Pulled into the garage.. erratic and weak 500RPM idle. Shut the car off and it wouldn't start again (i.e., heard the CD box wine(?) from the engine compartment but no crank). 15 minutes later the damn thing started up!?! Galloping idle @ 675RPM OX sensor and battery light intermittently illuminated.

Voltage potential across the battery 11.6V with engine off and 11.3V when engine is running.

Is this a pure coincidence? Based on a search it looks like I should check the alternator... maybe the rain f'd things up once the AC condenser was pulled from the trunk lid..

Some expert guidance would be appreciated!

On a positive note all head studs were in great shape and were torqued to spec.

Thanks everyone,

Jeff

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Targa4now
1981 911 SC targa

my guess is some water got inside the distributor cap.

Jeff,
You are on to the problem. The alternator isn't putting out a charge.
Since the red battery light is coming on, you know it's good. Time to pull the alternator and find a good shop to check it and fix it.
Had mine done for $125 a few months ago.
Of course, carefully check each connection including all of the ground straps including the alternator to motor.

Thanks guys!

Racer...I'll start by trouble shooting the alternator tomorrow night. I picked up my oil laden 101 projects and found a section dedicated to this activity.

One thing I forgot to mention was that I also added a shim that was missing to the fan assembly. I'm thinking that unnecessary tension in the fan belt could have hastened an alternator issue. With this in mind, I went ahead and replaced the fan belt and adjusted shims accordingly. Idle still significantly less than 1K which was typical prior to all the tune up activities.

If my alternator is going bad, would this explain the significant throttle hesitation I experienced?? I'm worried that I'm seeing a motor issue on top of an electrical issue.

Jeff

Jeff,
Fix the voltage issue first, A big part of the rest wll be solved as well.

If you measured the voltage with the engine at 675 RPM then you can't tell if the alternator is working. That is too slow to get it to work. Rev the engine a bit and see what the voltage is. You should see 14 volts if the alternator is working.

-Andy

Here is the brief update... An overnight battery charge and things appear to be back to normal for now. I'll have to monitor the battery potential to see if it holds a charge for any length of time.

Upon an almost fully charged battery (13.6V on its own), the alternator now pumps out 14.3 - 14.4 volts.

I'll perform more thorough diagnostics on the overall system tonight.

Thanks everyone.

Jeff

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Targa4now
1981 911SC Targa

Sounds like just a loose fanbelt?

Why was the battery low on charge ?

Follow the trail...

Agreed as far as the fan belt is concerned. It's been replaced along with the missing shim courtesy of the PO.

I should remind everyone that I acquired this SC about two months ago (pics soon I promise!). The car was rarely driven y the PO and I think the battery was low on charge from the start.

I'm off Thursday and Friday and will follow this trail where ever it leads.

Thanks for everyones help!

Jeff

How old is the battery ? Is there a warranty sticker that could help with this ?

FYI, I had a new battery that I did not install for 4 years and it was weak of course, but now running fine for 8 months. Batteries do seem to die right about end of warranty*, no joke, must be a design thing. * At least when used regularly.

Going home from work yesterday in my 80SC the tach went wild!! Waving around from 0 to max and everywhere in between. Settled down when sitting at traffic light and then went crazy again when under way again. Short time later the speedo joined its neighbor and went beserk!! Eased on home with horrible thoughts of what was wrong. At home car would barely idle and guages still crazy. Noticed that the radio light went completely out a couple of times. Shut down, came back 1/2 hour later and no ignition. Checked the battery and found the positive terminal laying a couple of inches from the post. Obviously didn't tighten the terminal enough when I had the battery out a couple of days prior. Great sigh of relief. Sometimes we overlook the simple things and the SC's remind us in their own unique way!!!!

Update:

Voltage regulator shot.... upon full battery change, I see 16+ volts at the battery when the car is running at standard idle. I've ordered a new on and will install it next week.

Battery age is unknown and I am prepared to replace it with a sealed one shortly.

Thanks to all.

____________
Targa4now
1981 911SC

moved to another thread