worn valve guides

[Alan Cottrill]

I have what I'd consider a noisey top end.

I don't have a good frame of refrence as mine is the only 911 motor I'v ever heard.

I've adjusted the valves 3 times now. The last time, tripple checking my settings by going through the firing order 3 extra times. If anything the valves are a little tight.

I've posted about this before. valve guide wear was mentioned as a likely source of the noise.

if the guides were worn enough to be noisey, would I notice a lot of oil burning?

the reason I ask is because I was ready to pull the motor and do the top end when I realized it wasn't really burning any oil.

will adjusting the valves too tight cause a loud top end?

I followed the procedure in 101 projects to the letter. the only thing i question is my idea of snug. It takes some effort for me to remove the feeler and the feeler is slightly deformed by the tightening of the screw..

I've listened to the noise with an automotive Stethoscope

the noise is louder on some valves than others

the noise is louder at the valve covers over the rockers than on the heads, or manifolds.

the noise cannot be heard on the cylinders.

just a side note, the bottom end is supprisingly quiet.

I'm not trying to be cheap. I'd just like to drive the car for the summer if i can. I know if I tear it down now it won't go back together unitl the fall, thats just how things work out for me. (too many irons in the fire) I guess I'm just being selfish, it's just so much fun to drive.

any advise would be greatly appreciated.

[Rick Lee]

You may want to move this to the engine rebuilding forum too.

[1fastredsc]

Well, i'm no expert on mag cases but i don't see why not. But in case your not familiar with 911's, the valve trains are always noisey, especially when cold. But if there worn valve guides it should be burning oil, although if a recent top end was down and the heads had new seals put in without checking the guides then your scenario is possible i guess. I wouldn't see anything catastrophic happening soon. Although if i were you i'd check the head studs during your next adjustment just in case. Cause when the break some of the combustion leaks out during the power cycle and would result in a slight popcorn type sound. And btw, your supposed to tighten the valves to the point that the gause is snugg, not getting mildly stuck and indenting the feeler gauge.

[Rot 911]

Actually you may be using oil, but not burning oil, that is not seeing smoke in the exhaust. If you have worn intake guides oil would get sucked into the cylinder, be burned and show up as blue smoke out of the exhaust. If you have a worn exhaust guide the oil can just be sucked out the exhaust without burning and just become sludge or coke in the exhaust system. But back to the point, how much oil are you using every 1000 miles?

[1fastredsc]

Not to question you, but i thought that if the exhaust got hot enough after running for awhile that oil could burn even if seeping out of the exhaust guide.

[Jdub]

What grade of oil are you using?

John

[Alan Cottrill]

20w-50

[stormcrow]

The noise you are experiencing is the valve adjusting screw with the elephant's foot. I recently changed mine and it made a world of difference with regard to the noise. There is still noise there but not of the same magnitude as before.

My engine had 108 thousand on it before I changed them.

Steve

"A Porsche does more then just go fast in a straight line"

[dmac]

Your 77 has the newer style valve guides (same as the SC) that should last a long time. How many miles on your car/engine? If there is no excessive oil consumption you should be okay.

[Alan Cottrill]

150k miles on the odometer. the engines history is questionable.

Each time I've adjusted the valves it felt like there was a lot of play in swivle foot of the adjuster

I suspect the rocker shafts will have to come out to replace the adjuster screws.

Can I get the rocker shafts out without taking the motor out?

[stormcrow]

Yes you can, I just did mine recently. The hard part will be getting the allen wrench into the socket on the #3 & #6 cylinder. The rest is a piece of cake.

Just make sure you are at TDC with the piston before you remove them. Use the short end of the allen wrench to push out the rocker shaft.

Steve

"A Porsche does more then just go fast in a straight line"