911SC Engine Rebuild

Groovy911SC · 10-07-2003, 07:38 AM

This is my first post to this forum! I have read Waynes new book, not by choice mind you, and have learned an enormous amount regarding the 911 engine.
My 1980 Groovy911SC has a problem with the engine, which I am assuming will require at least a top end rebuild. I have elected to completely rebuild the engine. I intend to ultimately use this car for competition in PCA races in the G classification. I must say that I am actually excited about rebuilding the engine! I have updated many systems on the car and was hoping that the engine would last quite a bit longer. Alas, something has gone wrong (bad clacking noise eminating from the left side of the engine) and I don't have the money just to send it off and be rebuilt. Besides, why should someone else have all the fun. I do have plenty of space and am willing to take the time to see this through at a high level.
I will post occasionally and keep the status of my project up to date hoping I will lend information to this forum while learning a great deal as well.
If anyone has their rebuilding stories to share, I would like to hear them, good and bad.

HarryD · 10-07-2003, 07:42 AM

Why are you rebuilding. The noise may be a failed tensioner that can be replaced without a rebuild.

What are your leakdown and compression figures? What is your oil consumption? Do you emit smoke on decelleration? Do you have broken headstuds?

Before you spend a bunch of money, be sure you are truly fixing what is wrong.

Groovy911SC · 10-07-2003, 07:51 AM

Hi Harry,

You are right about the possibility of it just being the tensioner. I bought the car last year with out the carrerra chain tensioner upgrade. One of the suggestions that was given to me at that track that day the issue occured, was a tensioner failure. This lead me to believe I could have serious damage to the enigine (valves, pistons etc.). I restarted the engine after it cooled down a bit and made the awful noise that I refered to in my initial description. I shut the engine down quickly and have not restarted it since.
If the tensioner failed, would that not warrant at least a top end rebuild? Comments - Suggestions?
Thanks,

HarryD · 10-07-2003, 08:03 AM

Hard to say if you avoided any damage without compression and leakdown data. If you had a failed tensioner, and the chain jumped the chain wheel, you could have had valve/piston contact that could result in a bent valve or damaged piston. Do a search here and you can read numerous threads.

Some others here can comment with much more authority than I can about the wisdom of doing these tests before teardown. Hopefully one of them can chime in.

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by Groovy911SC
This is my first post to this forum! I have read Waynes new book, not by choice mind you,

Ahh, I see you have encountered one of my cronies who often car-jack people, hold a gun to their head, and force them to read the Engine Rebuild Book!

-Wayne

dd74 · 10-07-2003, 02:10 PM

Yeah, I didn't get your statement either, Groovy.

Not that Wayne needs defending, but aside from this forum, Dave, Jeremy and Tyson at TRE and Wayne's book, I have learned substantially more than I would on my own. These cars aren't red wagons or bicycles - believe me - one needs all the help they can get.

For me, after I spent $147 getting my pop-off valve reseated with epoxy, I knew I had to get an education on these cars. Hence, those I have listed have been invaluable. Excuse me for being just a wee bit protective.

Wayne 962 · Wayne 962's Garage

Make sure you have the Engine Rebuild book and 101 Projects.

Remove the chain tensioner cover and take a look at what you see - you can't do much damage simply by removing the cover...

-Wayne

Groovy911SC · 10-15-2003, 06:16 PM

Update on determining if I should rebuild my engine. I removed the chain covers and I did not find a chain that jumper the sprocket. I noticed that the tensioners have collars installed in the spring loaded units.
I guess my question is should there be any play in the chain at any point? Right now, I can place two fingers under the chain and on top of the chain ramp on the lower left side. There is no play at any other point in the chain.
Cylinder leak down test will be this weekend.

PorscheTSC · 10-15-2003, 07:31 PM

Im new to the board but I must say both of Waynes books are worth much more than the cover price. The bench in my garage contains three books : Porsche 911 Engines , 101 Projects and Porsche 911 performance handbook. These books are my lifeline. When my 911T needs attention I could send it out and await its return. To do so though is like flying blind . If you did not know the shop people how would you know what they did and did not do. I like to hold the parts in my hands ,install them myself ,I sleep much better this way. I also enjoy the car so much more knowing it from the inside out.Keep reading Waynes books their an education equal to MIT without the student loans and inflated tuition

Groovy911SC · 10-16-2003, 05:33 AM

Thanks PorscheTSC, I feel the same way. Doing the work myself is not all about saving money (it helps however)! It is about the piece of mind I get when I know the job has been done correctly and I didn't get screwed. I did puke when I took my car in to have a service performed this summer. Valve job, oil change, new distributor... $1200.00 later, I felt like looking for the automotive "Rape Crisis Center"
After reading Wayne's books I realized that I can take care of my car at a high level with no anxiety about someone else in the picture. I have a great deal to learn yet, but ain't it fun!!!!!

1fastredsc · 10-16-2003, 05:36 AM

I'm not sure dude, but i don't think there's supposed to be any play in the chain at all. If there's play on one side and not the other it could just be that one side is being pulled under the normal rotation of the engine and is under pressure. But then again i'm not too sure about your post either since i'm confused with the way you worded it.

kstylianos · 10-16-2003, 06:49 AM

If the chains are correctly tensioned, it should be very hard/near impossible to get a finger between the chain and ramp. Take off those collars and try pressing up/down on the idler arm to see if you get any movement of the tensioner shaft. It should be very hard, again, to move the idler arm against the tensioner (spring loaded or hydraulic).

I'm thinking you may have a failed tensioner(s). Those little collars may have saved your top end. A compression/leakdown test will let you know for sure.

red-beard · red-beard's Garage

Quote:

Originally posted by Groovy911SC
Update on determining if I should rebuild my engine. I removed the chain covers and I did not find a chain that jumper the sprocket. I noticed that the tensioners have collars installed in the spring loaded units.

Good News and Bad News:

1st the bad: You failed a tensioner.

Now the good: You had the stop collars installed on the engine which prevent catastrophic damage!

Do a leak down test and make sure the engine is OK. Go out and buy the Pressure fed tensioner kit and install it.

Then drive it like you stole it!

James

PorscheTSC · 10-16-2003, 06:38 PM

Your very welcome Groovy. I feel the same way. Years ago I purchased my first Saab 900 turbo . I took that car in once for service and that was the first and the last time,highway robbery. I stood there one day looking under the hood of that little sweed turbo car. My thoughts were it does'nt look so complex. The downside was books such as Wayne's just did not exist for the Saab turbo. So I did what I had to do,rolled up my sleves and threw caution to the wind. All went well and I found the Saab to be a breeze to work on . I will say though I like the old Porsche's even better though. Enjoy and have fun with the project.

The only Porsche project I have ever seen and did'nt like at all was these people that do the GM conversion. My thoughts on that are why would anyone want to drop a small block chevy motor into a Porsche. I guess to each their own but you can be guranteed thats one project you'll never find in my Garage

Take Care All

Wayne 962 · Wayne 962's Garage

Porsches are no harder to work on than any other car. It's just that they are so unusual in so many aspects that good, available, reliable information was very hard to find (in the past...).

-Wayne

Jay Auskin · 10-17-2003, 06:54 PM

From my experience, Porsches (well..at least my '72) are extremely "serviceable" vehicles. I can't say as much for a '95 Chevy Beretta. Just try changing the belt!! @($@*!)#!

Wayne 962 · Wayne 962's Garage

Or how about removing the starter on a BMW E30 3-series. Wow, not designed to be an easily serviceable part...

-Wayne

Groovy911SC · 10-30-2003, 07:38 AM

Here is my updated status on correcting the issue with my engine.
I tested all cylinders with the Matco cylinder leak down tester. The engine was cold. I have read that it should be warm, but since the engine needs repair I have no way of warming before I tested. The results were all in the 20% area. Meaning to me, that there was compression and I did not do serious damage to the valves, pistons, cylinders. I did notice a slight fizzle sound in the #4 cylinder coming from the exhaust.
My question now is... seeing how there was slack in the left side chain, after I install the carrerra pressue fed tensioners, should I re-time the cams?

aigel · aigel's Garage

Groovy:

You are probably fine. If you are unsure if the chain might have jumped, check cam timing.

G