3.2 Engine exploded!!

[Allan Kelsey]

Guys, Thank you for your input. I am interested in hearing some engine solution options. It could be helpful to understand the source of the problem, because that would lead to understanding a potential ownership, which would obviously be helpful with financing the repair.
I wont know any answers to that, until we dismantle the engine. I plan to get it to a reputable engine builder to do that by the end of the month, but it could be December before I know what we find.
In the mean time, here is a picture of the bits that fell out of the oil drain when we drained the oil.

[proporsche]

Hi Allan..can you take a close up picture of the brake in the material and bottom of the brake on the longest piece..?Do you see discoloration?
Ivan

[RedCoupe]

A couple of thoughts. Was the piston pin and it's retainers intact? A popped snap ring and a moved pin can cause all sorts of destruction. Also, did the shop who built the bottom end use a stretch gauge on the rod bolts? Perfectly clean parts, ARP's special lube, and tightening with a stretch gauge help to get just the right stretch on the bolts. Another thing: I'm not reading too much into the failed pressure plate other than its a strange coincidence. I've seen two different pressure plate diaphragm springs fail, and both were in grocery getters. One a Toyota and the other a Chevy. Remember, the diaphragm is bending all the time, so a metallurgical fault can easily create a crack. I cant see how high revs would create a crack in the diaphragm. A crack in the flywheel or friction area of the pressure plate is where I would expect to see damage from high revs or excess slippage.

[Allan Kelsey]

Redcoupe,
I agree the clutch pressure plate diaphragm failure is probably unrelated to the engine detonation.
The engine builder is a small shop and dedicated to classic Porsches. Clean environments and meticulous methods are the currency of their reputation, however we will hopefully soon find the evidence we need to verify these failure causes.
I also don't believe the engine was overstressed.

The Eurospec version of this motor came with a 10.2:1 single plug design.
Porsche made & still makes engines that run at 11 or even 12 to 1 compressions.
This engine was built to accommodate a slightly higher than standard compression ratioat 11.2:1, but other than that everything else is an over the counter bolt on modification. By all accounts the engine work is a fairly mild modification and 255HP is not such a volatile stress that the motor should detonate after 11 000miles of sensible/informed use.
Investigation is definitely needed to get closer to cause, which will also ultimately help clarify any potential cost sharing.



My opportunity is to decide if I go back to a standard configuration, or if I use the unfortunate circumstance to build a different bottom end, since the top of the motor is ready for a high flow, twin plug configuration.

• Standard 3.2
• Higher compression 3.2
• Standard compression & increased displacement (3.4 or 3.5)
• Higher compression & increased displacement

[Slanski62]

3.6. It will be more powerful, more reliable, and probably less expensive.

Steve

[rkeele]

I had a 3.6 motor with ARP bolts let go while racing shifting from 4th to 5th motor was new with Wossner 11.5 pistons everything done. So after talking to some engine builders that first thought was piston failure Alan at Asse motors told me about Glyco rod bearings DON"T USE THEM!!! spend the money for clevitte! Glyco is OK for others but not for Rods I also had a clearance grind put on the crank this allow's for more oil film on the rod bearing seems with high compression the oil film is pushed out causing seizure of the rod . Were you using Race fuel if not that's to much compression for single plug you should not have drove it. The stress you put on it probably helped cause this.

[rkeele]

Oh and after buying Glyco bearings for the rebuild I saw where they are made everywhere some in Europe some in South America the rods MEXICO!!!! really? no wonder they are junk

[proporsche]

Hi to Laguna..i have experienced the same problem with Glyco bought in Germany from Porsche dealer.They were made in Romania...from that point here you have to ask Porsche if the bearings are meda in Germany or not....the only little problem was the engine had to be taken a part to replace the main bearings again..no big deal since here was no damage done just extra time spent.

Ivan

[nocarrier]

Originally Posted by Allan Kelsey

Guys, Thank you for your input. I am interested in hearing some engine solution options. It could be helpful to understand the source of the problem, because that would lead to understanding a potential ownership, which would obviously be helpful with financing the repair.
I wont know any answers to that, until we dismantle the engine. I plan to get it to a reputable engine builder to do that by the end of the month, but it could be December before I know what we find.
In the mean time, here is a picture of the bits that fell out of the oil drain when we drained the oil.

I'm trying to figure out what the smaller bits are. From the pictures they don't appear to have the same finish as the rod bolts. Do they have what appears to be a ground finish to them?

Can you post pictures of the smaller bits from different angles. They appear to be cylindrical pieces. The three pieces look broken on one side and flat on the other.
I'd like to the the "tops and Bottoms" of the cylinders. if possible.

[onevoice]

Originally Posted by Allan Kelsey

That's some real odd breakage.

The angled breaks are characteristic of brittle materials twisted off, that is exactly what a piece of chalk will look like if you twist the ends until it breaks in the middle. However, rod bolts aren't near that brittle, note the larger piece that is bent but not fractured. And the other end that is squared off is also puzzling, why would single bolts break in two places?

Are you sure those are ARP? There have been fake arp bolts found in the marketplace made of substandard material. It is hard to tell from the picture, but when I have used arp, they are almost jewel like in finish, not rough at all.

Will be very interesting when you open it up.

[965flachbau]

Sorry to hear of this, we saw the exact same thing happen on a 3.2 freshly rebuilt from a very reputable rebuilder here. After disassembly he concluded that a moment of distraction made him forget to use Lock Tight on the nut and caused the exact same breakage as yours.

FYI; He also replaced the block to honour his reputation !

[manbridge 74]

To use or not use Loctite is likely to open up a giant can of forum worms!

[Allan Kelsey]

Thank you for the great input and Im sorry about the delay in responses.
I spent the last week in wedding mode, marrying off my oldest daughter and hosting family from all over the place.
I leave for a work trip for a week and when I return will work on getting the car to a reliable place to break the engine down to see that happened.

When more details appear, I will be back to keep you all updated!

[RedCoupe]

Congrats on your daughter's wedding! Events like that kinda put everything in perspective! (As well as drain your bank account of funds available to fix your Porsche!)

[Allan Kelsey]

After the busyness of the year end, we were finally able to get into the motor. Through careful disassembly, we were looking for any signs that might give indication or cause for the detonation. In the end there was nothing that was obvious to see, that could have obviously provoked the #6 rod to come through the case.

If there was an over-revved cause, I suspected we might see some impact marks from the valves on the crowns of the pistons - but there were no marks, the valves and the springs are still good. The bearings were all still good, as is to be expected from a motor with 11 500 miles on it.

What is noteworthy is that both ARP conrod bolts broke, and both still have the nuts attached to the bolt ends. One fell out the bottom of the case through the oil drain plug and the other conrod bolt end (with the nut still attached) got impaled into the inside of the case, and produdes a little through the outside.
The other item to note is that; at installation the ARP - 2000 conrod bolts were all a polished silver in color with black ARP nuts. When we disassembled the motor, 8 of the bolts were still silver, but 4 were now black. Not an oil tarnish that could wipe off. You can see the color changes in the photo's below.

All the ARP conrod bolts have been shipped to ARP for analysis. Im hoping to get conclusive remarks from ARP that can lead to a better understanding of the cause for bolt failure.

[john walker's workshop]

Stock bolts are black. Hmmmm.

[QueWhy]

Thanks Allan for updating this thread.

Originally Posted by john walker's workshop

Stock bolts are black. Hmmmm.

Things could get interesting from a responsibility/liability standpoint.

[ClickClickBoom]

2 sets of 3.2 cases in classified section today.

[donlan]

Hello,Will be interesting to hear what the "bolt maker"says. The part that is embedded in the case looks like the nut is partly unscrewed. The broken bits look like they have been cracked for a while? (Bright/dull surfaces). Sorry to read/see such carnage.regards,Michael.

Gosh, Allen, just found this thread. My sympathies. It seems really strange to me that both rod bolts broke. That must have happened more or less simultaneously, or the car would have made a big enough racket after the first one broke that it would likely have been shut off.

I'm curious if our cast of renowned engine builders (and I mean that sincerely--some top guns here) have seen two snap more or less at once. Anyone?