Most common rebuild mistakes

[markwemple]

Reading all the posts here gave me an idea. With the horror stories and the fact that we all make mistakes, what do you think is either the most common or worst to make during a rebuild (on our 911s of course). Don't forget to name the size/year of the engine.

[350HP930]

With any type of split case motor I would say case sealing.

I have seen enough posts here to indicate its also a big bugaboo with 911 motors.

[mtelliott]

Case sealing, guilty as charged.

Worst part is, you have to go all the way back to the beginning and start over. It's like rebuilding the engine twice. Great experience, but your off the road while you are doing it.

[Alan Cottrill]

I forgot to put the seals on top of my oil pump.

didn't realize until I got the case all put together.

[ChrisBennet]

Yep, case sealing.
-Chris

[88911coupe]

Probably not having Wayne's book or failing to use this board as a resource. Both of those would eliminate a LOT of headaches.

[jgparker]

Re-using Dilivar head studs is my biggest mistake. I’ve found some real doozies on engines I've pulled apart too. Like hand installed time-serts on head studs, and radically wrong spring height settings for the cam used.

JP

[TimT]

Or realizing you forgot to install the pilot bearing in the flywheel..
after you have the engine tranny back in the car

[Jim Sims]

Thinking you can do it for less than $3000. Jim

[Wayne 962]

- Oil pump seals forgotten
- Not cleaning the cam towers well enough
- Not installing the starter ring gear
- Installing the cam sprockets backwards
- Wrong distributor drive gear
- Reusing rod bolts
- Not keeping the chaing tight when working with the timing/chain tensioners
- Forgetting to install the sheet metal between the cylinders
- Mixing up the left and right camshafts

There are lots of mistakes to be made...

-Wayne

[oneblueyedog]

Installing the metal air guides between the cylinders backwards.

[jgparker]

I have to agree that Jim Sims answer is the probably the most common mistake. Everyone seems to think they can do a rebuild for $3000 until they get deep into it.

JP

[rcwaldo]

How about not removing the cam housing spray bars for detailed cleaning..

I did remove mine due to paranoia, and found a good amount of junk in there.. I guess its more piece of mind really...

[adomakin]

Rebuilding my 75 2.7s and only repairing the two pulled stud threads, then pulling two more on the other side of the engine less then a thousand miles down the road. NICE.
If id have just known about this place it would have never happened.

Andy - on his second rebuild (400hp 930) armed with the book and $hit loads of money.

[Wayne 962]

Originally posted by jgparker
I have to agree that Jim Sims answer is the probably the most common mistake. Everyone seems to think they can do a rebuild for $3000 until they get deep into it.

JP

As I mention in the book, you can indeed sometimes get away with a $3K rebuild if the following is true:

- Aluminum case
- Reusable pistons & cylinders (Nikasil)
- No broken head studs or broken parts (bearings, etc just wore out)
- You do all the work yourself

-Wayne

[markwemple]

Right now, my top-end will be in the neighborhood of 2k with the clutch work.

[Jim Sims]

Unfortunately, many of the engines are run until something breaks and prompts the rebuild. Then it is more than just worn bearings; expensive new parts and machining are required. It would interesting to determine how many rebuilds were done for $3000 or less and how many were above $6000. Jim

[Doug Steinel]

Mark,

did you get the rest of those dilavar studs out?

[markwemple]

Not yet Doug. Still trying to find someone with an O/A torch they are willing to rent or loan. GRRRRR!

[ischmitz]

cylinders upside down
pistons upside down
Loctite on rod bolts
RTV silicon to block oil passages

Ingo