Starter or Alternator?

[PAULSPEED]

Hi guys,

I have over 56,000 on a 2006 997 S. I just

bought a new battery but the starting is getting weaker. I

have not looked on the 996 site but what goes first.

the starter or the alternator?

Does anyone have any good recomendations for spraying

some fluid on the alternator brushes?

Paul

[RFM]

Look how much volt the battery received with the engine running, do the same directly on the exit of the alternator ( difficult but possible ). If the difference is more than one volt, replace the cable alternator-starting motor-right side of the gearbox. There is nothing visible but the cable have too much transition resistance in the welding points under some conditions.

[Big_O]

Look how much volt the battery received with the engine running, do the same directly on the exit of the alternator ( difficult but possible ). If the difference is more than one volt, replace the cable alternator-starting motor-right side of the gearbox. There is nothing visible but the cable have too much transition resistance in the welding points under some conditions.

Just yesterday I researched starters due to a slight grinding noise when the car starts cold. Turns out, starters are widely replaced on the 911's. Failing starters are a common problem. Renntech's sponsored "Sunset Imports" sells starters for $167.00 and $500+ refundable core charge. Labor at the dealer or shop is about 3 hours. Have no documentation for a DIY install. Maybe someone else can post the install instructions.

Edited October 1, 2008 by Big_O

[PAULSPEED]

Look how much volt the battery received with the engine running, do the same directly on the exit of the alternator ( difficult but possible ). If the difference is more than one volt, replace the cable alternator-starting motor-right side of the gearbox. There is nothing visible but the cable have too much transition resistance in the welding points under some conditions.

If I get this right, I measure the voltage across the battery while the car is running and

I measure the voltage across the alternator terminals while the car is running.

Sure sounds logical to me.

Paul

[RFM]

Battery: between + and -

Alternator: between exit ( big cable ) and ground

All with engine running at idle.

[neil.c]

I would start by measuring the battery voltage with the engine running and with it awitched off. The battery voltage should be around 12.2 volts without the engine running and it should go up to about 13.6 volts (charging voltage) with the engine running.

[dndodd]

Hi guys,

I have over 56,000 on a 2006 997 S. I just

bought a new battery but the starting is getting weaker. I

have not looked on the 996 site but what goes first.

the starter or the alternator?

Does anyone have any good recomendations for spraying

some fluid on the alternator brushes?

Paul

I have read of some issues with the wiring harness on the engine needing to be changed to solve this problem especially if the problem is slow starting when the engine is hot.

[PAULSPEED]

I checked the voltage across the battery.

I had an initial 12.5 VDC.

After a few minutes it dropped to 12.1 VDC.

I could not get to the alternator wire.

I think I have some rocks on the bellpan of the car. When

I throw the car into a massive turn I can hear the

rocks roll. Could these rocks damge the wire from

the battery to the alternator or the starter?

Paul

[PTEC]

If you only have 12.1 at the battery with the car running you've definitely got a problem. Besides outright alternator failure the most common issue here the cable that connects the alternator - starter and the battery. Theres been a problem with the cables where the cable is crimped where it connects to the starter. It causes a voltage drop that prevents the alternator from charging the battery. It sounds like what you have going on. You need some leads with a sharp tip so you can poke through the insulation of the wire and get a reading from there. If you can successfully do it, I would guess you'll see about 13.5 at the back of the alternator. Its pretty much the only way you can condemn the cable.

[PAULSPEED]

Thanks for the answer. It would be a whole lot easier to replace the wire then

th alternator. I will look thru the parts to see where the wire connects to

the alternator. I think I know where it is but I did not remove the alternator to

verify. Maybe if I drive a small trim nail in I can get a reading.

Paul

[PAULSPEED]

I was under the car last night and I could not find

the starter. I wanted to clean the starter post. I

wonder how much stuff needs to be removed to get to the starter.

Paul

[RFM]

You have to remove the throttle body and the connected intake pipe to have access to the starter.

[RFM]

Paul

Check PM.

[PAULSPEED]

Thanks RFM for your post.

I will replace the wire from the generator to the starter. I

will send myself an e-mail so I can order it tomorrow. Thanks

again and I look forward to some great results. For the

mean time, I have placed a starter battery in the trunk should I run into

problems. I normally use this battery to run the moving

map gps in the plane.

Paul

[useridchallenged]

A few price benchmarks... B+ harness replace = $120 part, 4 hours labor ($165/hour at my dealer). Alternator replace = $1050 (parts and labor). Rumor has it that the B+ harness requires removal of a manifold.

[PAULSPEED]

The instructions I have do not involve removing the manifold. There

is alot of work removing the alternator. There is even a special tool for tighting

the alternator belt. I also bet that Suset has the price of the cable less then $120.

Paul

[PAULSPEED]

I got measurements on the alternator tonight.

The generator/alternator read 13 volts and the battery

said 11.5 volts.

Paul

[PAULSPEED]

The part just arrived. It is a bigger wire

then the stock one. It is longer then I expected. I

hope I can reach the starter once the throttle

body is removed.

Paul