A Funny Sound Happened on the Way to the Forum

[Jagshund]

LSS: During a spirited drive, my car developed a smoke screen to rival that of Spy Hunter. After finding that the sump had cracked, I filled it with oil, made it two miles back to the house & shut it down without issue.

Two years later, finally having the time to swap out sumps, I put it all back together and (after some cajoling) the car cranked and ran well for ~30s before shutting off following a loud BAM!!

It sounds like the starter is spinning freely or the engine is spinning freely, finally having cast off its cumbersome chains (of timing).

My attempts to post a video here have failed miserably. However, imagine the awesome sound of a 911 starter spinning without the engine firing.

Any suggestions regarding what in the heck I may have screwed up are welcome, as well as recommendations as to whether to pull the chain covers or the entire drivetrain.

[porsche930dude]

Ever thought maybe 911 ownership isnt for you? now is a great time to sell Im joking. There is a chance you didnt put the sump on the right way and starved the engine of oil. The drain goes to the driver side. This would be bad.

[Jagshund]

Destroying the engine through such inattentiveness was obviously my first thought following the horrendous sound but I double-checked everything and all appeared fine. The only issue that came up during the reinstallation process was getting the filter console bolts to thread & they eventually agreed to seat.

[porsche930dude]

so the starter spis without spinning the engine?

[sugarwood]

How did you fail at posting a video?
Did you upload it to Youtube?
Just wondering how you can't paste a link.

[Jagshund]

The 8s clip is roughly 16mb, or 11mb larger than the site is comfortable with. Yeah, there's probably a quick way to circumvent all of the hoops but atm I do not have the time to research options (I put the sump back on 6 months ago, so we're 30 months from last drive to give you an idea of how much free time I have these days).

I am certain that some hero is lurking, waiting for a chance to strike with the right blend of biting sarcasm and wisdom in an effort to explain the error of my video posting process ways.

Hello? Hero? Anyone?

[T77911S]

is it a 68?
carbs, sounds like they could have back fired

how do you crack a sump plate?

pull the plugs and see if you can turn it over by hand and listen for any noises..
then do a compression test and/or leak down
if good, check for spark

you might consider pulling the valve covers and checking the head bolts for a broken stud.
dont know if it would make noise or how loud it would be. just something to consider but my money is on it backfired.

maybe a stuck float and it is dumping fuel since it has been sitting,.

[cabmandone]

Little help on the video, if you have a youtube account post the video to youtube then copy the embedded code and paste it here. Posted the vid below just as an example of the steps.

[gomezoneill]

What do you mean sump? Are you talking about the sump plate or the oil tank? If you mean sump plate how do you crack a sump plate? Was the smoke coming out from the exhaust pipe or off the headers? Knowing the year of your car may help.

[E Sully]

I like to upload videos to youtube and then post a link.

Originally Posted by Jagshund

Destroying the engine through such inattentiveness was obviously my first thought following the horrendous sound but I double-checked everything and all appeared fine. The only issue that came up during the reinstallation process was getting the filter console bolts to thread & they eventually agreed to seat.

The mention of the filter console leads me to believe it was the oil tank in the fender, is this correct? Did you happen to notice if the oil gauge was indicating pressure?
After a long rest, I like to disable the fuel pump and spark, then crank the engine till I show pressure on the gauge to prime some oil to the engine before starting.
Anyway, "It sounds like the starter is spinning freely or the engine is spinning freely, finally having cast off its cumbersome chains (of timing)." A bit vague, need to know if engine is spinning or just the starter. If just the starter, Can you rotate the engine with a wrench? If you feel resistance, it may be internal parts coming in contact. Might want to remove a valve cover and take a look.
Hoping it may just have been a backfire and blown airbox, good luck.

[Jagshund]

Thanks for all of the replies. Yes, I am referring to the oil reservoir not the sump plate. The car did not backfire- it was running well before the moment it wasn't.

The car has parts of 20+ 911s ranging from 1965 to 1997. The majority of it is from 1968, but the engine is a 2.3L 1973S spec unit with about 3500 miles. I am not sure if the noise is the starter spinning freely or the engine rotating without chains- I've never had to endure listening to the latter. To my ears it simply sounds like a high torque starter spinning its wheels. I'm fairly certain there would be some horrendous rattling noises coming from the boxes if something happened like a dropped tensioner?

I'm planning to pull it all out this weekend. Will post updates- pictures are no problem but I only use my iphone for . . . everything . . . so video has been an issue.

No yt account. I don't even tweeter!

[T77911S]

is the engine actually turning over.

pull the plugs and turn it over by hand.

[scarceller]

Does the crank pulley and the engine fan turn? I suspect they are not?

If the main crank pulley is not turning but the starter is spinning your issue is likely the starter.

Also can you turn the motor by hand using the crank pulley? Try doing that slowly to see if you have compression. On most 911 motors you can usually even turn the motor over my rotating the engine fan by hand if the belt is tight enough. If she turns remove the dizzy cap and see if the dizzy rotor turns when the engine turns. Again everything by hand, do not force it to turn.

[DanielDudley]

Starters spin very fast if they are not engaging anything. If it wirrs at high speed, it is spinning, if it chugs a bit, it seems like it would be engaging. The speed will be constant, and the pitch won't rise.

I'm not a doctor or anything, but timing failures tend to sound like protracted train wrecks.

[gomezoneill]

Maybe broken teeth on the ring gear after the backfire.

[Mixed76]

Or the starter solenoid is done, not engaging the flywheel.

Sent from my Nokia 7.1 using Tapatalk

[ed mayo]

When you bolted the oil filter console to the oil tank did you make sure the two feed holes matched up?

[Jagshund]

Originally Posted by ed mayo

When you bolted the oil filter console to the oil tank did you make sure the two feed holes matched up?

Multiple times!

I'm going to break down and figure out the video-posting dance before the inevitable, "Animal, vegetable or mineral?" question. I've only been a member here for a decade. It's time, right?

[Jonny042]

Well for what it's worth you don't seem to have let it affect your sense of humor at all. Kudos to you for that!

If the crank is turning, then maybe pull top valve cover to see if the cam is turning?

[Jagshund]

The engine is turning. I haven't dropped the entire drivetrain yet but am working towards it. So far, in addition to noting that the OFC was correctly installed, I have discovered very fine metal (look like stripped threads) on 2/3 filter console bolts and a strange lack of oil in the new filter. Tomorrow I intend to remove the left timing chain cover & see what rabbit hole that leads down.

As an aside, it's amazing to realize how much work the car could stand even through it was fully rebuilt less than 5 years ago. Hard miles, I suppose.

edit: I will also be removing the lower left valve cover to see what kind of unsupervised nonsense is taking place there.