1981 sc 3.0 project / Seized engine investigation

[gs_subsea]

Dear Pelicans

I recently acquired a 1981 911 SC targa project with a seized engine (among other things), I bought it knowing that I could have some serious issues once I started digging into it, but the price was right for me to have some room to play. My goal for this project is to do the majority of work as a father and son team and for both of us to learn a lot in the process.

Today I had some time to spend in the car planning and prepping for dropping the engine and I took the spark plugs off and took a peek with my boroscope. I found out that I have a full rebuild in my hands if not more. Cylinder # 5 seems to be the culprit and all I saw once I pulled the plug was a smashed tip and the view of the rod and pin, no sign of the piston and lots of scaring down there. All other cylinders look normal.

I am looking for some insight from the members on what I could be dealing with, at this stage I am worried about whether the crank and case could be salvaged. See pics below ( include a pic of the undamaged cylinder #6 and the top of #1)

Some background on the engine, webers 40 are on it, carrera tensioners and turbo valve covers, no significant receipts and it appears the damage occured in 2009.

Appreciate all your input / feedback / advice on next steps

[Flat6pac]

Not good to look at.
Take it apart and see what is left.
Cleaning is going to be a challenge to spend all the money to rebuild and not knowing if everything is clean enough
Better sides the piston wiped, not the rod broken on the crank
You have a private message
Bruce

[gs_subsea]

Thank you Bruce, yes cleaning will be fun to say the least, I assume I will have to throw away oil pump and oil coolers, is that a good assumption?

In addition to #5, #1 cylinder and piston looks a tad crusty, not sure what happened there, here are some pics.

Any theories as to failure mode would be welcome

[boyt911sc]

Originally Posted by gs_subsea

Thank you Bruce, yes cleaning will be fun to say the least,[ I assume I will have to throw away oil pump and oil coolers, is that a good assumption?

In addition to #5, #1 cylinder and piston looks a tad crusty, not sure what happened there, here are some pics.

Any theories as to failure mode would be welcome

At this point, do the disassembly and careful inspection of the engine parts. Assess the damage and focus at the engine parts that could be salvaged and used for the rebuild. The damage parts are easy to identify. Do no dispose the oil pump until you have done the inspection of the internal parts. It could be bench tested after cleaning it.

A complete engine tear down is necessary to assess the extend of the damage to the motor. Until then, enjoy the engine tear down and learn more about the project. You and your son will be able to get this motor to run again. Keep us posted.

Tony

[Walt Fricke]

Impressive not to see any of the #5 piston. The OEM pistons don't seem to have a habit of breaking in half, but it looks like this one did.

A dropped valve, either from the head breaking off or some other failure, often leads to blowing out a side or sides of the cylinder. That allows busted pieces to escape. But while terminally damaged, is that cylinder still basically intact?

Oil pumps can be inspected, disassembled if needed, and in some cases repaired. You won't know until it is out.

Odds are that rod is bent. A crank shaft shop can tell you if the crank is bent, and measure it to see how the journals are. And can grind journals as might be needed. Cranks often can be straightened, too, if not too off kilter. With a bearing on each side of every throw, our 911 cranks are pretty stout.

Hard to say what's going on with that one groddy cylinder. I'd start pricing a new set of Ps and Cs. Or looking for a "good used" set - lots of guys here and there have removed perfectly good SC Ps and Cs so they could use something bigger, more compression, lighter, whatnot as go fasters.

The bearing webs on each side of #5 look awful, of course, but there is a very good chance all that is cosmetic. They are very strong and well supported. A machine shop ought to be able to take the case, bolt it together somewhat, and check to see if the crank bore is true.

The search function on this site will lead you to lots of information on this or that. As with anything, expect to see a variety of opinions. Race shops especially throw away all coolers and disassemble (or toss) oil lines so they can be cleaned and there are no joints at fittings (this is mostly an issue with aftermarket AN fittings)which have trapped shrapnel and won't give it up. Others have followed a cleaning routine and have not had subsequent problems. You end up having to decide. I've kept my oiling stuff on a couple of cars and engines after an engine blow up, and haven't had any problems. Shops tend toward the conservative - problems after they have rebuilt an engine are very bad for business. If you end up having to redo something, well you are your own customer - and for a second time will get things done a lot faster and with less head scratching and worry.

By the time you have disassembled that engine you will have learned a lot about how it is put together, as well as been able to inspect everything. You should also cut open the oil filter. I'd expect it to have a fair amount of metal in its pleats, because the strainer on the scavenge pickup isn't super fine, but you don't know. You may find the bearings, other than perhaps the #5 rod, look pretty decent, which suggests not a whole load of debris got into the engine oiling passages.

More of a project than you anticipated, I suppose - but sounds like a great thing to do with a son interested in mechanical stuff.

[gs_subsea]

Thank you Walt, very much appreciate the advice.

The cylinder seems intact, the #5 piston though.... came out of the sump screen in a couple hundred pieces.... it was a more gruesome sight than the picture above

We are hoping to drop the engine this weekend, taking our time documenting and slowly disconnecting stuff.

We will be using one of the HF hydraulic tables and expecting the P201 to arrive next week so that we can hang the engine on the stand start the engine disassembly party

I will send new pictures once we progress a bit.

At this stage I am assuming new P&C set, at least one new head, one new rod, and hoping I can perhaps save the case and crank. I suspect the engine is original to car as the serial number fits the range for 1981. Not sure how to verify if it matches. In any case our goal is to learn so we will try to save everything we can.

If anyone knows of a good machine shop local to Houston to send the case and crank for measurement and crank, I would be grateful for the recommendation

[Walt Fricke]

You might luck out with the head. When my J&E piston tore apart at the wrist pin, both valves got bent, but the head itself wasn't really damaged. The machinist put in new guides, as I recall, and took a couple of thousandths off of the sealing surface, but that just calls for a thicker cylinder base gasket for compensation.

I had to use a hand sledge to get the cracked cylinder busted loose from its socket in the case. But because it didn't break, the rod and wrist pin weren't able to saw slots in the case.

If a valve head dropped in there, it might have battered the head beyond economical repair. I think in my case the rocker arms involved just broke - a somewhat useful feature of being cast iron instead of forged.

[gs_subsea]

The project has progressed and we are having fun taking the car apart. Engine is out and we are now on the short block.

We just ran into an issue that I can use the board's advice.

The case spigot on #5 that had the piston disintegrated has a good amount of damage to it by the rod and loose piston pin. I noticed a crack at the 12 ' o clock position and it seems like it goes all the way up to the top rib of the case.

can this case be saved / repaired by someone like Ollie's?

Appreciate the feedback

[Flat6pac]

I would look another case rather than attempt repair with so much damage. I’m sure the repair of the crack is going to exceed the cost of finding a replacement.
Also, you haven’t opened the bottom yet to see the rest of the story.
Bruce

[gs_subsea]

Thank you Bruce, I am on the "case" as we speak, following up on your suggestion

I should have the case opened in a few days and will report back with findings

here is another shot of the "carnage" on #5

Note the perfect black paint on the head studs, I think this poor engine died a very short time after it was rebuilt.... remaining 5 pistons / cylinders / heads look in great shape

[Flat6pac]

It’s kinda standard fare for the total damage. Going to open and check the oil pump for damage.
Bruce

[gsxrken]

Still a fun father and son tear down. I once had a 15 year old snowblower completely lose compression on me and I assumed the worst. Wasn’t going to even bother. My son begged me to take it apart so we/he could fix it... turned out a set screw had disappeared and allowed the cam to crank gear to walk out and get out of mesh. Long story short, I retimed/realigned the cam to the crank, bought a .40 cent Allen set screw, and still have the snowblower. 22 years now.
Enjoy the ride!

[faapgar]

Rod is bent.Case looks to be toast.I have a single large port SC head if you need one.Most likely it was a cast piston that failed and the death was quick.Fred

[gs_subsea]

as per what I understand to be tradition here is the "team" on our first 911 engine drop

[gs_subsea]

Thank you Fred! appreciate the offer, mine is a 1981 with the small port heads. The # 5 head is pretty banged up but the valves are in place with no chunks missing... will need a new head for sure.

Here is the #6 cylinder and piston, I suspect they are alusil , I count 10 fins and the bore does not seem to be sticking to a magnet at all.

Appreciate any help in identifying these

[Mixed76]

Hi subsea,

Any pics of the beat up head and cylinder?

Dan

Sent from my Nokia 7.1 using Tapatalk

[Flat6pac]

Yes, they are alucil.
The head has a casting number you want to refer to. It’s the K# looking at the head, combustion side, Bottom right corner is a K that describes the head, you want to match that number when you buy one.
Bruce

[gs_subsea]

Here are pictures of the #5 head and cylinder before we pulled it out in pieces...

Outside of the #5 damage all the other pistons/cylinders/ heads and valves look great with no signs of piston to valve contact.

We did find that both cams had 2 teeth broken on the spacer gear that indexes the camshaft.

I initially thought it was a "money shift" that doomed the motor, considering the piston was in pieces I can see that piston failure could have caused this mess

[Mixed76]

Thanks for the pictures!

Best,
Dan

Sent from my Nokia 7.1 using Tapatalk

[gs_subsea]

We split the case and pulled out the oil pump and intermediate shaft, cranks bearings on the left side bank look spotless.

the crankshaft initially raised up pretty easy but then I had the bent rod on #5 stop me from pulling out of the case. I am trying to remove the bent rod from the crank, I have one nut off but the second one seems like it won’t take any of my sockets, like the clearance between the rod body and nut has been taken out. I am trying a 14mm wrench but it’s feels loose and I am afraid of rounding it off.

I thought I could jiggle the crank loose of the case and maneuver the rod out but now the crank seems solidly stuck to the right hand case

Any suggestions on how to proceed?