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Valve Adjustment - How to

My 'good deed' for the day is to divulge my personal experience in valve adjustments for a 911.  I have a 1987 coupe and had undertaken the task this past February with the help of all of the good folk on this list and the Haynes manual, along with a little self produced inspiration to 'know the job had been done right'.  I would recommend that anyone with an interest and mechanical inclination attempt to do this on their 911, it's not very difficult and very redundant (once you've done one, you basically know how to do the rest).  The cost savings are great, and the most rewarding is the self satisfaction of accomplishing the job.

To adjust the valves, it would be ideal to have the car raised off the ground or on blocks for easier access to the lower exhaust banks.  Drain the oil completely (that is the tank and the crank, this is a good time to change the oil anyway).

Parts to be removed:

A/C compressor, loosen the adjuster bolt/nut remove the belt and remove the 4 bolts holding down the A/C unit to the base.  Use a large blanket or comforter and wrap the compressor in it and gently swing it over onto the right side fender (try not to bend the lines to much).

Air Cleaner Box, this just unbolts from the throttle body unit on the inside of the air box and gives you much more room to work.

Plastic air duct on left side (two bolts here, one visible with a clamp and the other behind the blower motor on the top of the duct.)

Cautions:  Some have said it's necessary to removed the plugs when adjusting the valves to reduce compression when turning the crank -- DO NOT DO THIS.  Information from Pfan members has suggested that carbon deposits from the plugs could fall between the valve seat and head, and when turning the crank could cause an inaccurate (way off) reading of the current valve spec.  The compression will not inhibit turning the crank shaft when the plugs are in.

Process:

Once all of the items have been removed (description is based on a 3.2L coupe) and the oil has been drained, the valve covers can now be removed.

Start from the middle and work your way out to the sides in a diagonal fashion (this is more important when re-installing the covers).  This will be done 4 times (two intake banks and two exhaust).

Using a ring spanner (not sure if it's 17mm or 22mm) turn the crank shaft pulley clockwise to obtain TDC (top dead center) on cylinder #1 (the firing order is 1-6, 2-4, 3-5).  This means that when #1 is at TDC and the plug has ignited the gases, the piston will force the crank to rotate downwards from the expansion of gases in cylinder #1 while the #6 cylinder is rotating upwards from a point some where in its compression stroke to be the next cylinder in the TDC sequence.  The crank shaft has now turned 120 degrees to get to the #6 cylinder in the next firing order sequence from the #1 TDC position.  (120+120+120=360 degrees where the sum of each 120 degree marking on the crank shaft pulley gives a 360 degree rotation or 1 full rotation of the crank shaft since the firing order has 6 cylinders the complete adjustment cycle would take the crank shaft through 2 full rotations (360+360 degrees), where each valve at TDC occurs every 120 degrees in the cycle).

To check and make sure the #1 cylinder is on TDC, I had the valve covers removed before hand (making note of where the #1 cylinder is) and rotated the crank via the ring spanner wrench to the designated markings on the crank shaft pulley (some pulleys may not be labeled properly, so just keep rotating the crank to each marking, there are only three).  I would then 'wiggle' the rocker of both the #1 intake and exhaust valves to see where the most play is (it could also go the other way where the valves are in fact tightened and not loosened) so as a check remove the distributor cap and see if the rotor is facing the #1 plug wire.  With these three checks I was certain that I had the right cylinder in the correct position (TDC) to begin the adjustment process.

Once at TDC (based on crank pulley turns to their markings, manual 'play' check on respective rockers themselves for cylinder #1 and positioning check of the rotor facing the #1 plug wire you are ready to begin the feeler gauge process).

It is highly recommended that the Porsche feeler gauge be used (the ones that are advertised in Automotion and Performance Prods).  Get extra blades in case the original cracks, they do crack!  The clearance spec is designated at 0.004" (4 one thousandths of an inch) for BOTH exhaust and intake valves.  The gauge itself must be placed between the top of the valve stem an the tappet on the rocker arm.

I 'practiced' to get the feel of the adjustment procedure on #1 for a while, just to build confidence.  The gauge might fit right in on the first attempt at which the valve is then loose (greater clearance between stem and tappet).  If the gauge doesn't fit in, the valve may be 'tight' where the clearance is smaller than the gauge.  Using a closed end wrench and slotted screw driver, loosen the nut and then turn the screw until the gauge feeler slides between the stem and tappet.  Tighten the screw until there is a mild resistance (best way to describe the feel) between the stem and tappet.  LEAVE THE FEELER GAUGE BETWEEN THE STEM AND TAPPET and tighten up the adjustment nut.  This will prevent the assembly from tightening up on you and throwing off your adjustment.  Pull out the adjuster gauge once the nut is tightened and recheck the clearance.  Do the same WITH OUT turning the crank shaft to do BOTH exhaust/intake valves of the single cylinder #1 on TDC.

Once cylinder #1 is adjusted (both exhaust and intake) you now turn the crank shaft pulley 120 degrees clockwise to get to the next cylinder in the firing order sequence (see above) in this case from the #1 it would the #6 that is the next in order to fire at TDC.

Do the 'triple check' i.e.. pulley markings, free play on cylinder rocker arms, and rotor position if in doubt.  I like to compare the free play of the cylinder I'm adjusting on TDC to the other cylinders that are some where in the combustion cycle, you will notice the difference between the play in the cylinders which adds to the learning experience, but always remember, the valves can tighten up as well as be loose, that is why the 'triple check' is important and reassuring.

It never hurts to check, re-check and check again.  It's good practice and provides the experience for the adjustment process.  Re-assembly is just the reverse of disassembly -- DO NOT FORGET TO PUT THE OIL BACK IN !!! as mentioned previously, be good to your car and change it's oil and filter at this time.

It would also be a good opportunity to clean the valve covers and scrape any gasket or grit off the face where the cover bolts onto the head.  These instructions are based on my experience and I've provided a few tips on how to ensure where TDC is.  Thinking this process over and the logistics of the process will make it easy to understand where you are in the firing order sequence.  I would however strongly recommend that this information be used and checked for complete accuracy (not a certified mechanic by any means, just a fellow who loves my car).

Enjoy the process and best of all learn! ... this kind of activity makes Porsche driving even more rewarding!

Joe Sommer  ninja@globalserve.net

 


Valve Cover - Gaskets

Re the valve cover gaskets, there are a couple of types you can get.  The upper gaskets (intake side) are pretty much oil-free, so not a leak issue.

The lower set do need to make an oil seal.  I've had good luck with the green ones that have a narrow bead of grey rubbery stuff going around the edge.

I've gotten these at Automotion and also at a local foreign auto shop.  After 8 months of service, the grey bead sticks pretty well, and is damaged when the covers are removed.  But after only a few days of service I have been able to remove a set with the bead intact, and reuse them successfully.  I install them dry, and clean off the mating surfaces before installation using a rag with a little carb cleaner.

One important issue with valve covers is to avoid over tightening the nuts. The torque spec for mine is 8 Nm, which is INCREDIBLY LOOSE!!!  Get a torque wrench for at least the first time, and you'll be suprised.  If you over tighten, you can easily bend the valve covers, making them leak prone.

- Brad    <Bradmaker@aol.com>
 

 


Voltage regulator - Replacement (84-89)

I just completed the removal / replacement of the voltage regulator on my 85 Carrera. I'm posting this to the list as an aid to those who may go through this repair, or need to simply remove the alternator or fan assembly alone.
The regulator is mounted to the backside of the alternator on the 84-89 models, and this procedure applies to those cars.

1.) Power down the system by removing the negative ( ground) cable from the battery. If you suspect an overcharging condition from the failed regulator (likely), now might also be the time to remove the battery entirely and inspect that area for acid damage due to a boiling battery. Paint / fix as necessary.

2.) At the engine, remove the A/C belt. Loosen  the 4 vertical bolts that hold the A/C to its mounting plate, and also back-off the jack screw (horizontally - on the right).  Slide compressor to the left, ease belt off of pulley. Note: these are not metric bolts. These are 1/2" head, not 13 mm. Most Porsche A/C hardware is not metric.

3.) Loosen fan belt . Keep track of the shims ( I had 6 shims total), and note the number of shims under the pulley, and how many were on the outside. Use all the shims when you put the belt back on later. You will damage the alternator shaft if you don't use the proper number of "outside" shims to get to the 6 total.

4.) Locate the ignition wires running on top of the fan shroud. There are two, 10mm ( head) bolts that secure the wires into the fan shroud, at about the "11 o'clock" and " 1 o'clock" positions . Remove these bolts.

5.) Remove a similar bolt at the "9 o'clock" postion on the fan shroud, near the distributor. This is a shorter version of the other two. Don't mix them up.

6.) Remove the allen bolt ( 6mm allen wrench) securing the large fan strap that holds the fan housing in place. Push the ignition wires back, and "lift" ( bend ) the strap up, to gain access for the next steps.

7.) Pull alternator "out" toward you. It will move only a small amount, until the fan housing contacts the back side of the crank-mounted fan pulley. Wiggle / tilt the unit until it comes out further- restrained only now by the attached wires. The housing will "just" clear the fiberglass shroud. You now face a small "wedge" opening at the top (between the housing and the shroud) that you will need to do your work. Patience and small hands are a plus.

8.) A funnel-shaped"air duct" with vanes,  is attached to the back of the alternator. It is attached by three , 8mm ( head) nuts on the backside of the alternator. These 3 nuts are in a  "staggered" arrangement with 3 other nuts on the alternator backside (6 total). We won't worry about the other 3 for now- can't access them anyway. We're only interested in the 3 that remove the air duct. Do this carefully, there isn't much space, and there's a good chance of losing the nuts/washers. Take your time , and take breaks, if necessary. Separate the air duct from alternator ( push air duct back).

9.) The regulator , and mounting wires should now be in view. Remove wires, noting their positions. From your  viewing vantage point (from fan end of alternator), with the regulator on "top", the red wire was at the bottom, blue to left, brown ( 2 wires)  to right. Note that the red wire uses a 10mm head bolt, brown uses 8mm, and blue uses 7mm. I guess this is supposed to help us, if we don't remember the wire locations (!).

10.) Now the entire cast fan housing , with attached alternator, can be removed from car. If you're only going to replace the regulator, your'e there. The regulator is held on by two, 8mm bolt heads. Note yellow and blue spade connectors and their locations, and replace. If you want the alternator removed for refurbishment (advised), continue to next step.

11.)You will now note the "other" three, 8mm head nuts ( that you couldn't get to earlier when removing the air-duct). These 3 hold the alternator to the cast fan housing . Remove these 3 nuts, noting their location [ that is, whether or not they were included in holding the air-duct funnel. I used this approach: the nut that straddled the regulator centerline DID NOT hold the air-duct funnel. Every "other" nut ( in a staggered, 120 degree pattern) also DID NOT hold the duct. The remaining three DID hold the air duct. Alternator will likely be "frozen" to the housing. With caution, use a hardwood ( or such) to tap on the 6 bolts to get it out. I even used heat from a hair drier to "expand" the housing, which helped.  Patience ! Go in a circular pattern. I used a metal hammer, which worked, but I "flattened" the end of the bolts slightly causing grief when re-installing the nuts.Don't do this !

12.) Next is fan removal. Likewise, it will appear frozen to the shaft. Support the backside of the fan in the corner of a wooden box ("blocking the fan"), and allow clearance for the alternator to fall out ( not too far!) Allow maybe 2 inches of drop height and place cushioning material underneath). Tap fan shaft end with hardwood block , and unit should drop out. Don't loose the shaft key.  Alternator is now out for repair, which a local shop did for me for $75 ( new bearing , slip rings, and bench testing).

Re-installation is the reverse of the procedure.

Some observations:

1.) I used anti sieze on the fan shaft , and the mating surface of the cast fan housing "bore" that accepts the alternator. This should help keep the units from "freezing" together again.

2.) I bought new 8mm head ( 5 mm thread) nylock nuts for the 6 nuts on the backside of the alternator. Just added insurance.

3.) When re-attaching the wires, don't just note the proper mounting locations. Also try to locate the wires radially inward as much as possible. This helps later air-duct- attachment.

3.) When re-attaching the air duct, you can "rotate" the fan / housing / alternator ,so your "work" ( in re-attaching nuts)  will always be "on top". I believe there was a lot of rotational "give" in a CCW rotation , and not that much CW. Experiment. Rotate back to original postion to continue the installation.

4.) Re-installing the cast housing into the fiberglass shroud will again be difficult. Lifting and tilting before re-entry is advisable.

5.) Push housing back as far as it wil go. There is a "peg" on the engine part of the fan support , that locates the 6 o'clock postion of the housing. Make sure it is engaged properly. Done right, it will allow only minor movement laterally ( rotationally). Fasten strap to tighten completely.

6.) Often overlooked. If your battery had boiled due to a failed regulator, I wouldn't just add water and re-install. The car's electrical system is meant to keep the battery "at charge", it wasn't meant to get it there from a low condition. This puts undue strain on your electrical system. Better, to trickle charge your battery while it's out of the car ( while you're doing the repair), and put it back-in fully charged and ready to go.

Hope all this might help someone!
Regards,
Wil Ferch- 85 Carrera
WFerch6687@aol.com

Addendum: With all the thought I gave to writing this, I noticed that I forgot to mention the usefulness of  a small, "ignition wrench" set sold by Sears/Craftsman.  These physically small wrenches really helped in the tight nether regions of the area.

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