Figure 1: Top View of Hole in Engine Case
Figure 2: Top View of Engine Case Damage
Figure 3: Rod #3 on Top, Rod #1 on Bottom
Figure 4: Inside the Engine Case, Rods #1 & #3
Figure 5: Carnage from the Destruction
Figure 6: Remains of Piston #3
Figure 7: Looking Inside Combustion Chamber of Piston #3
Figure 8: #3 Exhaust Valve Missing From Cylinder Head
Here are some photos of a
recent 914 engine disaster. Since a complete teardown has not been performed, there
is no definitive method of determining the exact cause of the failure. I am
currently soliciting ideas on what happened here. If you have any input or questions
that may help figure out what went on here, please
email me, and I will include it in this article. Ok, here's the story.
This engine was recently rebuilt, about 20K miles ago. It frequently went on long
trips back and forth from Lompoc to Los Angeles every weekend (about 150 miles). It
is a 1.7 engine with stock components, and stock fuel injection. The owner of the
car was driving north on a somewhat cool day a few weeks ago. The car had been in
the shop just that morning, for an oil leak problem. The oil leak turned out to be a
loose valve cover gasket that hadn't been replaced when the owner adjusted the valves one
week prior. The car was confirmed to have ample oil in it when it took off on it's
After driving about half the distance (75 miles), the car began
to make a rattling noise, but continued to hold oil pressure. Shortly after that,
the oil pressure dropped to zero, at which point the owner pulled the car over to the side
of the road, lifted the engine lid, and saw many chunks of metal all over the engine
compartment. The car was towed the rest of the way home, where the owner and myself
dropped the engine, and looked at what was there.
Ok, here are the pictures and their gruesome
Figure 1: Here
you can see the size of the hole smashed into the top of the case. With quite a
large hole in the case, you would image that only the rod could have done that amount of
damage. Strangely enough, the rods are intact.
Figure 2: You
can see the two rods (#3 and #1) intact within the case. They didn't break off and
go through the top of the case.
Figure 3: The crank is
pretty banged up, but intact. The Type IV motors have cranks that are pretty much
bullet-proof. You really have to mess up big to crack or break a crank.
Figure 4: Here
you can see the inside wall of the case, and another angle of the crank. There's not
even a serial number left.
Figure 5: Fall out
from the carnage. Check out the top of the case on the left, complete with ground
post for the fuel injection. The small piece of metal located to the upper right is
a piece of what used to be #3 piston. You can see the rings embedded in the melted
Looking at the remains of combustion chamber #3. A small mound of metal still
attached to the wrist pin is what remains of the piston. Other remains can be seen
along the cylinder walls.
Looking down into the combustion chamber (isn't this camera great!). It looks like
something bounced around in there for a while before destroying the piston.
Figure 8: Number 3
exhaust valve has been broken off, and is presumably some place within the engine.
Looks like a dropped valve seat, maybe? I can't really tell from the photo.
My guess on what happened is that the #3 exhaust valve
seat let go, and jammed the valve open which impacted the piston, broke it, and sent it
flying around the case in the near vicinity. A chunk of piston got caught between
the crank and the rod on the upswing and blew a hole in the case. Dropped seats
usually only happen on 2.0L heads, not 1.7L though. Also, dropped seats usually
don't cause this much catastrophic damage. Any
thoughts? We'd like to know...
||Frazer McGuinness adds:
Just seen the pictures of carnage on your website - the 914 that dropped
Well you wanted to know if it had happened to anyone else and hey, it
happened to me last year! I spent a fair bit of money on a blueprinted 2.0L CJ (type 4)
short block for my 73 camper and bought a set of 1.7L heads to go with it (ported
and bored out to 2.0L). 3 weeks later, late at night on the M25 (London - England)
Im 50 miles from home when I hear a rattling sound and oil smoke starts billowing
out behind me. So I pull over and come off the motorway, no drop in oil pressure yet but
when I pull over it drops to zero.
After getting towed home and dropping the engine out what do I find?
Number 3 exhaust valve has sheared, chewed up the combustion chamber, gone straight
through the piston (very little left), bashed around inside the crankcase, mashed up the
underside of the opposite piston then smashed straight through the top of the
Anyways, the pictures looked exactly the same as the damage to my
engine. I stripped the valves out from the head and guess what? - The seat was still
there!!!! However, I reckon that the broken valve was due to excessive play of the valve
shaft in its guide (the remaining inlet / outlet valves in the head were in a similar
condition). So I guess the moral to this sad tale is if you re-build, recondition, or
blueprint an engine, spend the extra bucks and get those heads set up with new springs,
seats, guides and valves!!!!! I thought that my heads had had the full treatment but alas,
didnt check out the valves.....
Hope this helps...