jorgens

Hi all

A friend of mine downshifted instead of upshifting on a trackday last week, with the result of a over rev of the engine. After this the engine idle speed dropped 300 rpm`s and started to have a rough idle.. He was told that he probably have bent some exhaust valves. When checking compression today we stated that he have lower compression on 2 cylinders. He have checked with some workshops here in Norway to take the engine out and overhaul the damaged heads, but with a HUGE difference in prices..
So, to you 911 guru`s out there; do you find the explanation with the bent ex valves to be possible? And, how long time does it take to remove a 3,2 engine from a 86`model car? Should the valve guides also be replaced? What would a job like this be in hours done with someone familiar with this car?

Thanks in advance!

Jørgen
Norway

Amber Gramps

Happens all the time. Very common.

As to cost, it is all over the board.

upier

That happened to me. Fifth to first turn one at Road Atlanta. Car kept running on four cylinders. Compression was 0 in one and 10 in another. Car drove okay just down on power but the damage was done. Bent exhaust valves. Engine takes about 1-1.5 hours to remove. I did I my own. Sent the heads out to have work done. Yes to having guides changed.

theiceman

This is often called " the money shift" and the reasons for this are quite apparent as you are finding out.
valves are bent for sure so engine removal and head removal is a given. The issue becomes how far do you want to go with this slippery slope.
If you and your buddy have any mechanical aptitude i would take the engine out ( quite easy actually ) and even put it in a truck and take it somewhere to have the work done if you are not comfortable , or as mentioned above , do it yourself.
Lots of threads on this site you can learn from.

jorgens

Thanks guys, you gave the info I needed! "The money shift"
I`ll be sure to tell him that!

Cheers
Jørgen

jorgens

The saga goes on- we have found a ex Porsche mechanic who will do the job. But we have to take the engine out and deliver to him. Is there a good instruction of "how to remove a 911 engine" somewhere? We need some basic steps of what is needed and in what order. Are there some special tools needed?

Jørgen

rusnak

Jorgens: Since your friend takes his 911 on a track, I think it make a lot of sense to be able to remove the engine at home. There is a good thread on Pelican called "supporting engine at removal". Just google that term after site:forums.pelicanparts.com. There are many ways to safely remove the engine. Just be sure to use two 6 ton jack stands at the rear.

I also think having a veteran mechanic do the engine work is a good idea. You want an experienced guy to do the inspection because he'll be able to tell a lot about the engine from visual cues. Hopefully, it's just a straightforward valve job.

theiceman

Thought you would go that route and that is the best.

Removing the engine on a 911 is really quite easy . the Pain in the *** piece is just getting the car high enough.

As Rusnak pointed out there are a ton of threads on this . You will find it pretty straight forward once you get into it ..

The connections to the oil Tank i have heard can be a pig but other than that pretty routine..

Ed Hughes

It's not just a matter of rebuilding the heads, the engine should come apart and be rebuilt.

The 3.2's have relatively weak rod bolts, due to their size, and typically stretch during such an over-rev. Another form of damage related, is that the rod ends can get "ovaled" when the over-revs hit and the bolts stretch, requiring the rods to be reconditioned. As part of the rebuild, one can use ARP rod bolts to beef up the bottom, and Ti valve spring retainers and racing valve springs to help keep down any high RPM "valve float" in the future.

Sorry, but your friend is looking at a rebuild.

jorgens

Hi.

Googled it and found it :-) Thanks for the tips, seems useful!

Br
Jørgen

Ed Hughes

Interesting- selective reading of and response to only certain posts?

I think my reply was useful too, and pretty accurate. I actually went through this same experience. I also am of the belief that any knowledgeable builder of these motors would offer similar advice.

dshepp806

Best of luck to you Jorgens.

A good Porsche mechanic (that is, both good and "real" P-wrenches) will guide you through your challenges ahead. Always a good approached to "plan for the worst".

Let's see what shakes.

Best to you,

Doyle

Ed Hughes

Like I said, "real" Porsche engine builders would offer the same counsel.

Steve Weiner-Rennsport Systems

Pretty darned close, yes.

dshepp806

The "counsel" I'm referring to would be to "guide you through what's needed",..not neccesarily "agree".

I would agree that real could be considered synonymous with knowledgeable (sorta'),..

Pretty darned close is a good characterization (Steve's) ,....as it means almost 100 % but not totally.

Again,..best to you, Jorgens!

Doyle