John K

Has anyone had to replace their valve guides? I had my car in the shop for a climate control issue and asked about adjusting the valves. The guy told me that the valves may just need to be adjusted or the guides may need to be replaced to the tune of $6K+. I've never heard of any year 964 having guide issues. He told me it is common for the guides to wear out between 60-90K miles (mine has 70K). Is this guy trying to make a boat payment of does this sound legit?
Thanks for any help.

MelissaM

John,

Is your car using a lot of oil?

I asked my mechanic about the valve guide issue a few years ago -- do the 3.6 liter engines have the same tendency that the '87-89 3.2 liter engines have with premature valve guide wear? His answer was that it was still too early to tell, but the symptom of premature valve guide wear was using a lot of oil.

-- Melissa

PS My car doesn't use much oil, so my valve guides are probably a-ok.

John K

Melissa,
My car uses about half a quart for every 1K miles. There are no leaks in the engine. I don't think this is excessive but I'm still learning all the quirks of the car.
Thanks

MelissaM

John,

[quote] My car uses about half a quart for every 1K miles. <hr></blockquote>

This sounds normal to me. There's a tip somewhere that says normal oil usage is around 1 quart for every 1000-1500 miles. (If I'm remembering correctly.)

How is your car running in general? Any reason that the guy might have suspected worn valve guides (other than he thinks it's a typical 964 problem?)



-- Melissa

John K

Melissa,
The only reason he mentioned the valves was because I asked him to listen to them and check for excessive noise. When I'm idling next to another car or some sort of barrier that reflects my engine sound, I can hear the valves clacking somewhat. The car is running great. I bought it with 60K miles and a major service done as part of the purchase agreement. I visited the shop that did the service and they confirmed that everything looked/ran great. I haven't had any problems for the last 10K miles. I was really surprised when he mentioned the possibility of the guides being worn because I've never heard them going so quickly.
Thanks again.

Kevin

John;

There are known issues regarding accelerated valve guide wear. The engine under tray is in suspect to keeping to much heat in the cylinder head area. There has been wear even in the 993's.. There is a very easy procedure to see if your valve guides are wearing, roll you engine to top dead center on the cylinder that is in question. Take a screw driver and see if you have any movement of the valve (side to side) if there is any type of play you have wear. The brass guides that Porsche used, don't compare to the silicone bronze or the new manganese bronze guides that are used today.

John K

Kevin,
Thanks for the tip. At the risk of sounding lame, how do I get either of the two front cylinders to TDC? Is this something that takes a few minutes or quite some time? It sounds basic but it seems like nothing is easy on these cars.
Thanks again.

Kevin

John;

Nothings lame. The front two cylinders are going to be #1(left side) & #4(pass side), the firing order for our engines is 1-6-2-4-3-5. Turn your crankshaft pulley clockwise to the mark z1 (your pulley has 3 marks in it, grab a mirror to see which is z1)it needs to be pointing straight up to your fan housing (there is another mark in the fan housing, the pulley and housing mark should align). Unfortunately, you have to pull your distributor caps off. When at number 1, your left rotor should be at 12 o' clock pointing straight forward, and lining up with a mark. The right rotor will be at 2'o clock, there is also a mark. Rotate you crankshaft 120 degrees, ( all clockwise, or to the righthand rotation)this will be #6, then again to #2, then the next will be your #4 ( also a complete 360 rotation.) Hey, while your at it you could be doing your valve adjust. Thats a topic for another day. Hope that works. Your exhaust valve will be the most likely to wear the most, they are also the easiest to check.

George Stevens

John

Easy tip for checking the health of valve guides is to ask a friend to follow you in another car.

Warm your car up, drive it hard and ask your friend to check for blue smoke on hard accelleration and on over run when you slow down using the gearbox.

1 quart per 1000 miles isn't excessive but is quite high, mine uses about 1 litre per 2500 miles the engine has done 70,000 miles

You should also get a second opinion and have a pressure test carried out.

MelissaM

George,

Good tip about checking for valve guide wear!

[quote] 1 quart per 1000 miles isn't excessive but is quite high <hr></blockquote>

Right, I really need to find the actual quote for the oil consumption. I think it was a tech tip in one of the old Automotion catalogs (yes, before they were bought by Performance).

John said that he consumes 1/2 quart / 1000 miles, making it 1 quart / 2000 miles. Is that still on the high side?

I checked my owner's manual, and it wouldn't give a ballpark figure for oil consumption. It said that oil consumption depends on driving conditions, yada yada yada. However, it did say that oil consumption was perfectly normal.

As far as noisy valves go, it seems that I remember reading in a Porsche FAQ that some valve tappet noise was normal. (I know, I need to quit with the "fuzzy quotes." Sorry 'bout that.)

-- Melissa

John K

To all,
Thanks for the help. I'll try to determine if the guides are worn. Does anyone else have any valve noise when the car is warmed up? I know "any" can be vague but I'm trying to determine what's normal.
Thanks again.

George Stevens

Melissa

Porsche were usually over the top about oil consumption propably to cover themselves against warranty claims

My previous Carrera 3.0 used a lot of oil, but Porsche stated that the oil consumption margin was between 1.5 and 5 litres per 1000 kms

That equates to about a quart per 650 miles!!!!!

I agree that consumption does vary on driving styles, town driving will increase consumption as will short trips where the engine does not reach optimum temperature.

horst

John. The lower valves (exhaust) are the ones to be the most likely to be out of adjustment, of any. Yoy need to drop the mufflers to get easy access to them- very easy. I would check them first. For the intake side, it is almost easier to drop the engine, so try the exhaust side first. Drain the oil first (I forgot, and my garage made the EXXON vValdeze spill look puny by comparison) Actually a bit of valve noise is better than none. Too tight valves can burn, but will be nice and quiet as they become toast. When you have the covers off, you can also judge the side play of the valves and get an idea of wear. You might even find a broken spring! BTW, I have about 50K miles on my 90C4, and do not notice any oil usage. (all engines use some, but with 12 qts there is quite a safety margin.)

Riccardo

John K,

I can hear a similar noise to you when I drive with the windows open and there is some noise reflection. I hear a clacketing type of noise, not very sexy really.

Still, my specialist says the car is in good health. If I were you I wouldn't worry. I've also heard another 964 with similar noise.

How about the rest of you, do you hear this noise?

Randall G.

I believe all 911s are going to clack a little bit at least. A 911 in dire need of a valve adjustment will clack a lot. Somewhat subjective impressions, I suppose.

All three 911s I've owned have always clacked a little bit, even after a fresh valve adjustment.

I think Horst put it well, "Actually a bit of valve noise is better than none."