[snova]

Hello,

 

I'd like to know if it is normal for the power deliver when accelerating hard from idle to  4000  rpm to feel like its has surging points.  

In other words, Its not linear but feels like it surges forward in about 3 or 4 places between idle and 4000 rpm.  After 4000 I can feel it surges a great deal after that in ONE swift final charge from 4000 ---> 6300.  I'm not sure if this is the way  variocam is supposed to work or if this is abnormal. I can believe the 4000->6000 switch over if its anything like Honda V-TEC.  However, I'm not sure about what is happening below 4000 rpm?  

 

misc info about the health of the charging and ignition system below: 

 

I've had some rough idling happening and a lot of vibration after 4000 rpm. I replaced  all the plug wires including the one feeding the distributor and changed out voltage regulator. It fixed the idling and most of the vibration above 4000k RPM. Plug where supposedly replaced last year by a mechanic but I have not doubled checked. Took them at their word. When changing the voltage regulator, I noticed that the harness going out of alternator to the starter is missing about a 2-3 inch sectiion of insulation. looks straight cut off or maybe pulled away from the end at the alternator. The rubber boot is toast, all split and cracked.  further back I do see cracking about 1/2 way to the starter.  Alternator is working when checked at the battery terminals.  headlights and dash lights much brighter now after the voltage regulator was changed.  So yes, the alternator to starter harness needs repair, but I'm not sure its causing the surging below 4000 rpm.

 

thoughts? 

 

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[pdxmike]

Can you clarify about the surging? Is it hesitating or bucking below 4000? 

 

I'd suggest cleaning the MAF if you haven't done it. Cheap and very easy. 

 

The starter harness - the missing insulation is from the brittle old material falling away and your harness definitely needs to be changed ASAP. I noticed significant improvement in my charging system after swapping mine out - car is at least 0.5V higher on the voltmeter in all conditions. 

 

Did you have A&P do your belts? 

 

I'm local however my car is still in winter storage. Happy to meet up this Spring to compare/contrast! 

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[snova]

OK, pulled the plugs. Found teaspoon of oil in the spark plug tubes 2 and 3.   Pulling them shows both covered in fresh oil. Just changed in a couple days ago.

Could not find anything about how to fix this on the 968. The 944's have a cam tower gasket.  Is it the same procedure on the 968?

any videos or pointers to the procedure would be appreciated. TIA

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[snova]

stuck in some cheap new spark plugs as a test.  Surging issue gone.  However, its a temp fix obviously.  The root cause is the oil leak.

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[J.Elenbaas]

Probably have to replace the valve stem seals # 928 104 601 07 

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[Waylander]

It will be the 4 plug tube seals that need replacing to stop the plug wells filling with oil,


The only downfall to that is you will also need a cam cover seal, the 13 bolt seals, the O ring and gasket for the variocam actuator

 

Parts List

928 104 443 08 x4

928 104 115 02 x13

999 701 693 40 x1

944 104 463 02 x1

928 104 447 09 x1

 

I would give the cam cover bolts a little lossening tap on the heads before attempting to undo them, i have seen a few snap, and they are only 7ft/lbs when you do them back up

 

 

use a little black RTV in the corners of the cam cover seal and the plug seal rings, stops them falling off as you attempt to line up the cover

 

 


If it was the valve stem seals the car would blue smoke on throttle after a long slowdown in gear, as the massive vacuum sucks the oil down the valve guides then burns it, blue / white smoke


Other than that its a simple job

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[J.Elenbaas]

Yep Waylander your right on that one.

 

I missed out the part of the "spark plug tubes", and for that thinking about oil in cilinders (and on the sparks as wel).

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[snova]

thank you Waylander and J. Elenbaas.  Does sound too bad.

 

However, I have no records of prior Variocam service on the car. Its at 113k miles. Sounds like that's a common area of concern for 

both age and milage.

I suspect I'll also need to look at that.  Have either of you had to replace components related related to Variocam?

sounds like Timing belt will need to be removed in order to do that. Which I just had replaced 1000 mi ago. errr.

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[J.Elenbaas]

It's just the ageing process that's making the rubber hard and brittle.

 

I have replaced the camshaft chain and slidingpieces from the chain adjuster a long time ago, together with a new headgasket etc.

 

Yes you/they need to remove the timingbelt for this, because you have to take out the camshafts to get the new chain around the sprockets and the old one away.

Make sure that also replace the slidingpieces (944 105 509 00) from the chain adjuster are done when they renew the chain.

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[snova]

I guess I'll venture into resealing the plugs and cam cover and have a look at the condition of the chain, teeth, and chain guides.  If cam needs work, I'll decide what to do at that point. i.e. they or I.   Its not a daily so I'm ok working on it as long as I have all the necessary tools and not screw anything up.  Got to learn someplace, right?

 

Thanks again

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[Waylander]

I would just take the cover off and inspect the cam gears for wear, my car has done 160k miles and still has the original chain cams and pads, I have inspected them twice in 7 years and nothing has changed


i think the main reason for chain failures is using the wrong lubricants, 

 

replace all the seals and gaskets and your good to go

 

cams are now $3000 a pair and the vario cam unit is nearly $2000 exchange

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[ds968]

You really can’t see the bottom pad all that well , even with a telescopic mirror, and that pad usually wears out much faster than the top one ( seems competently illogical to me, but it’s true ), but unless you see badly worn teeth or very deep tracks and cracks on the top pad, it’s probably not an impending doom scenario ..

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[J.Elenbaas]

No it's  not, unless like me you have to replace the headgasket.

Then i like to change out all wear and tear parts that you get your hands on removing and installing anyway.

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[Waylander]

second option, only if you need to get the HG done, then the parts list will be considerably longer, and more expensive,

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[snova]

for future reference to anyone replacing the main cam cover gasket, stick to the Porsche branded part. I had to do the gasket job twice because the 3rd party gasket was a bit too short and out of spec.   Sigh.  Porsche branded gasket is your best bet. It may take a bit longer to order but its not worth the risk using something that is not quite right.

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[Waylander]

Victor Rienz should be fine, as they make all the gaskets for Porsche anyway

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[snova]

Victor Rienz should be fine, as they make all the gaskets for Porsche anyway

That's what I order the first time.  

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