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OK.....What's Your Opinion On What Happened to This Engine

At the SVRA Indy race.......my 2.0 914 had an engine failure during Thursday's morning practice
Looking for opinions on what caused this and here are the facts:

Coming out of Turn 3........heard a loud bang.......looked in the mirror and saw piece of aluminum (Tangerine Crankshaft Pulley) bouncing down the track......and a nice plume of white smoke. In the paddock......found that the three bolts holding the Tangerine pulley to the crankshaft flange backed out and when the pulley went under the car......it destroyed the deep sump......weekend over

Got home.........purchased another pulley from Tangerine. Took the 914 to my mechanic to have it installed. The crankshaft flange needed to be replaced before installing the new pulley and in doing so.......found that the woodruff key that holds it to the crankshaft was sheared in two. Installed the parts needed to get the Tangerine Fan unit working again and a new deep sump. Filled the engine with oil and attempted to start.......flywheel turned but not the crankshaft.......OK trim to remove tranny.

Removed the tranny and found that ALL 5 of the bolts that hold the flywheel to the end of the crankshaft ......FAILED

So........open on opinions on what happened to this engine???????

In the process of rebuild to get this 914 ready for the Waterford Historic's

Anyone in Michigan have a lightened 2.0 Type IV flywheel?
Old 06-23-2014, 05:03 PM
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The last time the engine was overhauled were new bolts used through out? I had my 2.8L four rebuild many years ago and the flywheel bolts were reused and they sheared in the second race of the weekend at Willow Springs. There were dowel pins (4 I think) and they sheared so that told the shop owner all the parts had been reused! The Porsche manuals say to use new bolts.

The shock of the pulley coming loose in the front of the engine could have caused enough shock to shear the ones on the rear especially if the deep sump was shattered and a piece of metal hit the crank then it would momentarily want to stop and that is a huge shock!

Anyways in my case, the shop covered a full rebuild, covered my Willow Springs entry fee and the mechanic was fired and moved to the LA area!
Old 06-23-2014, 05:19 PM
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I don't think it matters a whole lot what exactly the sequence of events was--I think you need to tear the motor down and inspect it carefully. If the Woodruff key sheared, the snout of the crank is probably trashed. And if the flywheel bolts backed, out, there's a good chance that end of the crank is hurting as well.

There's a good chance you'll need a new motor, quite frankly.

I hope I'm wrong!

--DD
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Old 06-23-2014, 07:09 PM
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914

Thanks for the input
Engine is being torn down for a rebuild.......
Being a retired engineer want to know why it failed......a lot of interesting occurrences
Old 06-24-2014, 03:56 AM
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If the bolts backed out that held on this tangerine pulley, I would assume the cause was they were not tightened correctly, missing lock washers, missing safety wire, or the threads in the hole or bolts where defective.

what is a tangerine pulley? Is it supposed to be better than a stock one? Does it replicate the stock one or is it used to drive something else besides the alternator and fan???

big bummer, let us know what you find, any photos????

So Sad
Old 06-26-2014, 07:09 AM
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Presumably this was a pulley to run either an upright fan conversion, or a horizontal fan conversion. Made by Tangerine Racing in CT.

--DD
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Old 06-26-2014, 01:17 PM
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914

Yep.......my 914 has the Corvair style cooling system from Tangerine Racing
Old 06-26-2014, 01:24 PM
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Engine with Tangerine Racing Fan Set Up


Crankshaft pulley after failure


Deep sump after running over pullet


Crankshaft pulley flange after pulley failure


Flywheel flange/mount after failure


Flywheel after failure
Old 06-26-2014, 03:37 PM
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When my last type four did a "ka-blamo" we used the parts and pieces to make trophys for racing events as that was all they were good for! A couple things to note, looks like only one dowel pin for the flywheel? We always used one between each pair of bolts and they were an interference fir in the crank and the flywheel. The bolts held the flywheel to the crank and not to prevent axial motion. We also made sure the bolts were a tight fit in the flywheel holes so there was no possibility of vibration. I noted the thread holes in the crank where the pulley was attached looked really clean, did you use and Locktight or other thread locker and was the tightness of these bolts checked before each race? Were they lock wired as we did that with my 911 fan conversion pulleys just to be safe. Last of all I am surprised there is no shield to protect the deep sump from objects that can (and did) damage it? Most of the 356 and 914 racers I saw used a 1/4 inch aluminum deflector that would fasten to the engine mount bar. Good luck with the rebuild and post the status of how you do with the new engine! Sux when one blows at the beginning of the season.......
Old 06-26-2014, 04:05 PM
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Looks like the flywheel bolts sheared. Probably after the single pin sheared. The bolts aren't really designed to deal with side forces; that's what the dowel pin is for. If you are making a whole lot more torque than stock, you probably should have more pins added like John did.

It looks like the flywheel lock plate was not used, and the bolt heads were directly seating on the flywheel center. It is possible this contributed--the bolts may have bottomed out before full clamping force was achieved, for instance.

I don't really know enough about the TR fan conversion to give you any feedback. The pulley mount photo makes it look as if you used the stock fan hub. In which case the nose of the crank might be OK? Hard to tell anything about the Woodruff key with the hub still on the crank, though.

You might ping Chris at Tangerine Racing and see if he has any insights. He does have more experience with his cooling setup than anyone else, after all.

Depending on how the deep sump is mounted to the case, you may need a new case anyway.

--DD
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Old 06-27-2014, 06:27 AM
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Originally Posted by Dave at Pelican Parts View Post
Looks like the flywheel bolts sheared. Probably after the single pin sheared. The bolts aren't really designed to deal with side forces; that's what the dowel pin is for. If you are making a whole lot more torque than stock, you probably should have more pins added like John did.

It looks like the flywheel lock plate was not used, and the bolt heads were directly seating on the flywheel center. It is possible this contributed--the bolts may have bottomed out before full clamping force was achieved, for instance.

I don't really know enough about the TR fan conversion to give you any feedback. The pulley mount photo makes it look as if you used the stock fan hub. In which case the nose of the crank might be OK? Hard to tell anything about the Woodruff key with the hub still on the crank, though.

You might ping Chris at Tangerine Racing and see if he has any insights. He does have more experience with his cooling setup than anyone else, after all.

Depending on how the deep sump is mounted to the case, you may need a new case anyway.

--DD
Have been in contact with Chris at Tangerine........he's wondering about all this too
Looking into a source here in Michigan that can gun drill the crank and flywheel for extra pins
Put a new clutch in a year ago and am thinking the shop did not face the surface correctly and got it out of balance
Locking plate was used on flywheel
Old 06-27-2014, 07:44 AM
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A couple of thoughts after reading the replies and seeing the pix. What caused the marks on that steel contraption affixed to the end of the case? They lok as if something ground on it, and they're not positioned in a way that the pulley could have done the damage. The "dent" in the deep sump doesn't look like it could have been made by the pulley, unless the ground clearance was REALLY low. The flywheel bolts: Looks like the end of a 912 crank that suffered a bad downshift. An abrupt and significant change in the relationship between transmission speed and engine speed can do this. I'm NOT saying you missed a shift, just that something like that can result in something that looks like this. For example, if the engine seized while the car was moving at pretty high speed, both the flywheel and the pulley (which is attached to a fan assembly with some flywheel-like characteristics) could shear the pins and bolts (especially if the bolts were at all under-torqued) and there you have it.....

One more thought, relating to DD's post. There are 2 different length flywheel bolts. It's remotely possible that the wrong bolts were used. I could see the long ones bottoming out if the center of the flywheel had been cut and the locking plate weren't used. I've always thought the bolts "locking" when tightened directly against the flywheel wasn't as good as when they had the soft lock plate to grip.

The Cap'n
Old 06-27-2014, 07:45 AM
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A couple of thoughts after reading the replies and seeing the pix. What caused the marks on that steel contraption affixed to the end of the case? They lok as if something ground on it, and they're not positioned in a way that the pulley could have done the damage. The "dent" in the deep sump doesn't look like it could have been made by the pulley, unless the ground clearance was REALLY low. The flywheel bolts: Looks like the end of a 912 crank that suffered a bad downshift. An abrupt and significant change in the relationship between transmission speed and engine speed can do this. I'm NOT saying you missed a shift, just that something like that can result in something that looks like this. For example, if the engine seized while the car was moving at pretty high speed, both the flywheel and the pulley (which is attached to a fan assembly with some flywheel-like characteristics) could shear the pins and bolts (especially if the bolts were at all under-torqued) and there you have it.....

One more thought, relating to DD's post. There are 2 different length flywheel bolts. It's remotely possible that the wrong bolts were used. I could see the long ones bottoming out if the center of the flywheel had been cut and the locking plate weren't used. I've always thought the bolts "locking" when tightened directly against the flywheel wasn't as good as when they had the soft lock plate to grip.

The Cap'n
This failure occurred during acceleration Turn 3 at Indy..........was already in gear at the time. Used same gear......Turns 1 thru 3........in 3rd. No missed shifts
Bolts were correct length
The aluminum pulley went under the car and crushed the deep sump.......lifted the car right off the ground for a second or two
Old 06-27-2014, 07:52 AM
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I guess I'm not properly visualizing the size of the pulley. It must be bigger than I thought, and the car must be lower than I thought. Does the engine turn over? Still looks to me like an abrupt drop in RPM could have caused the bolts and pins to shear.

The Cap'n
Old 06-27-2014, 08:05 AM
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I guess I'm not properly visualizing the size of the pulley. It must be bigger than I thought, and the car must be lower than I thought. Does the engine turn over? Still looks to me like an abrupt drop in RPM could have caused the bolts and pins to shear.

The Cap'n
The 914 is quite low.........
Engine turns.......but not the flywheel
Old 06-27-2014, 08:47 AM
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It'll be interesting to see what you find when the engine is opened up ........................

The Cap'n
Old 06-27-2014, 08:55 AM
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It'll be interesting to see what you find when the engine is opened up ........................

The Cap'n
I am too........................hopefully my mechanic will have it out and apart within the week
Old 06-27-2014, 09:15 AM
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This morning I talked to the mechanic that built the type four engines I used for years, before switching to a six and he also did the engines in the same car since 1980, way before I bought it. Anyways, he did not like the cooling setup like you have mainly due to the design of the pulley which acts like a long lever that is constantly trying to work loose. The fan and sheet metal are great but getting the power up there is hard work. He only used the 911 style since the crank pulley was the same as a stock one and also made of steel. Yours looks like aluminum which is really going to flex and move around?

I also asked about drilling the crank for extra pins as they sold their jig years ago but he said a competent race machine shop should be able to do it?
Old 06-27-2014, 10:34 AM
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...
Anyways, he did not like the cooling setup like you have mainly due to the design of the pulley which acts like a long lever that is constantly trying to work loose.
...
The alternator groove in that pulley is no further from the nose bearing than on a stock fan. The pulley was computer designed with proper consideraton for the intended purpose, and CNC fabricated. There is no problem with it flexing or adding side load to the engine bearings.

Another pic of the hub shows the pin and one bolt sheared off, with two bolts missing. I would guess the bolts had started backing out a while ago because the installer didn't use locktite. Since they're a bit hidden when in the car, they were probably ignored as part of the inspection routine.

The plate (steel contraption) on the front of the crankcase is aluminum. The wear marks are from the loose pulley rubbing the edge of the opening. I'm guessing this may have delayed complete failure until the loose bolts departed.
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Old 06-27-2014, 11:20 AM
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The alternator groove in that pulley is no further from the nose bearing than on a stock fan. The pulley was computer designed with proper consideraton for the intended purpose, and CNC fabricated. There is no problem with it flexing or adding side load to the engine bearings.

Another pic of the hub shows the pin and one bolt sheared off, with two bolts missing. I would guess the bolts had started backing out a while ago because the installer didn't use locktite. Since they're a bit hidden when in the car, they were probably ignored as part of the inspection routine.

The plate (steel contraption) on the front of the crankcase is aluminum. The wear marks are from the loose pulley rubbing the edge of the opening. I'm guessing this may have delayed complete failure until the loose bolts departed.
Chris;
As an engineer.........your design is great!!!!!
I highly recommend this set up to anyone race a 4 cylinder 914
Have no intention of ever changing back.
Concur with your assumption on how the pulley failed......just interesting all this happened at the same time and what sheared the woodruff key.
With this rebuild will have the flywheel and crank worked for extra dowel pins
Undecided about buying a new Scat crank or using one of the two used ones that came as spares.........spares are an unknown quantity at this time
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