I dropped my car off @ the shop last week to get the valve ajusted because they started get loud again(only after 1500 miles)

The shop said it will ready about 12:30 today so I got a ride over , to pick it up.
Well when he started it, We could still hear the noise.

So he check the valves on that side again to see if he made a mistake.

Top are tight bottom are good. so what is that noise.

WE discover that the valve is moving around in the guide on two of the heads.
One was really bad.

So now we has to break the engine down and send the head to the machine shop.

They said it will be about $3500 for the labor, and $1000 for machine shop and parts. Does this sound right?
Does this issue sound correct ?

Has anyone had this happen to them?

Thanks in advance.

Derek

 

Porsche uses a soft production grade valve guide in the head and it will wear, especially on the exhaust side, and especially on cars where they sit in traffic on a hot summer day...remember, these are only air/oil cooled engines. My guess is that the exhaust valve guides are the ones that he has found to be loose. It happens to all 911s eventually. When I rebuild the heads, I used a race quality valve guide which is harder, but also has better head conductivity than the stock valve guides so last longer and cool the valve better. The price you've been quoted is on the low end of what I normally see with the average being about $4500 to drop the engine, disassemble the heads, machine the surfaces, install new valve guides, perform a valve job, reassemble the heads, checking the springs for wear, setting the proper installed height (I actually set a lower installed height than the spec), reassemble the engine and install it in the car.

You might want to get a breakdown of exactly what is being done. How many miles on the engine?

 

You may be better off getting the top end redone- rings, springs, valves, guides, refacing etc... At least you will have a near new engine, good for 100 k or so.........

 

Geoffrey,
The car just turned 100k And yes it was on the exhaust side, Can you give me a source for the better guides you are talking about?
As for the cost , I am getting charged half price for the labor.

PMB , I will look in to going ahead and doing that as well. since we are doing it already.

What sources would you recommend for the part , and why?

I was also thinking about LWT flywheel and clutch too. But you add all this up and $$$$$$

 

Derek,

Any good machine shop that specializes in Porsche head work should be able to provide the proper aftermarket guides. Check with some of the Rennlist Sponsors.

 

Geoffrey,
Thanks, for the help.

So does everyone agree that I should have the top end redone- rings, springs, valves, guides?

Derek

 

I would not necessarily do the rings. If there are problems with cylinder leakage, it will likely be because the cylinders are out of round and replacing them with new rings will not solve the issue. Further, honing the cylinders requires a special process and tools to ensure the proper RA value.

It is unlikely that you'll need new valves as the margin is quite large on the factory valves and in most cases a simple valve job will clean up the valves. If you have improved the performance of the engine then you may want to replace the retainers and springs, but for a stock engine you can inspect the springs and test them for the proper seat pressure. If they test Ok, I'd reuse them. I'd also shim them up for slightly higher seat pressure. When Porsche says the redline is 6800, they mean it. There is no leway on the valve spring seat pressure.

 

I'm curious, how your mechanic can tell if a valve is loose in the guide without removing the spring retainer and springs??? It must be really worn out, no?

 

I'd say change the valve springs - 100,000 miles is a lot of miles on an engine, and valve springs are really quite cheap in the grand scheme of the process - several dollars each. It would be a shame to have one break because you didn't change them...

 

Garrett, you can use compressed air and a fitting in the spark plug hole to hold the valve and then remove the valve locks, retainer, and spring while the engine is in the car.

 

Garrett,
That is a good question, I watched him ,move the spring and the valve around with a screw driver head. It moved ~ 1/8 inch or so total.
Then him went to the others and they really diidn't move. Can that be a way to tell? He used the ear price thing when the engine was running to pin piont it to there.

Could he be wrong?

 

I don't know but I was curious because the only way I knew of was removing the keepers, retainers, and springs which usually also involves removing the rocker arm and you didn't mention he did any of that...

 

That's a neat trick to keep the valve from sinking down to get off the keepers!