After a few hours of installing a new fuel pump and sorting out wiring to the relay, I was leaving my shop and within 1500 feet of travel there came a huge loud bang followed by a exhaling sizzle - directly behind my right ear. A really significant louder than a backfire explosion at 3000 rpm's as I accelerated.

Startled, I shut the engine off instantly while pushing in the clutch and then rolled to a stop. Out of the car and looking underneath, there was no visible giant pool of oil or shattered aluminum case halves, pistons and parts or even the left and right fenders blown off of the car as such a noise would produce.

As a precaution, i pushed the car to a safe parking spot and went home to contemplate the cause (before risking a start-up that would further damage what ever was left of the engine innards............. I consulted several 911 people and the general consensus was that it had to be a fuel accumulation in the muffler from working and testing the fuel pump while not firing up the engine. That, in turn, ignited in the muffler once hot enough - and that must have been the explosion that i experienced.

Rather than turn over the engine, the next day, I drained the oil for inspection. I removed the strainer and mags-drain plug and filter. All were clean and without any debris or shiny stuff therein. So maybe the chunks of debris are so big that they didn't get to the lower part of the engine............ yet...

Kieth came by the shop and we then removed the lower valve covers to see if one of the valves had exploded or a spring had decided to eject thru the opposite side of the internals of the heads / the noise was that substantial........

Valve covers off top and bottom and still no evidence of the cause of the backfire-times-ten explosion noise.......... so we plucked the fan and pulley hatch cover at the firewall.

AhHa!

Three individual guys were definitely involved. (in addition to me...)

They, your honor, were responsible for the BAM!-zzzz that halted my progress home last evening.

Their names were Many, Moe and Jack.........


Apparently the engine fan sucked a big plastic Pep Boy's bag into the shroud area and onto the upper fan pulley from the parking lot debris. That piece of jetsam in turn, whipped around and around as I accelerated - and the hideous bag then caught on to a piece of wire from inside the engine bay at the inner firewall and the two clusters of debris began a death spiral ever tightening the grip on the bag until the bubble of trapped air exploded like no sound I had ever heard from a backfire or other catastrophic event in an engine bay........

The updisde of the story is the oil and filter are now new, the valves are tuned to a perfection, and I rest assured that the bag was not my fault as I have not been to see Manny, Moe, or Jack in several months..........

Yikes what was that wire from? As I was reading I was thinking the muffler explosion was what you were experiencing because I had a v8 Dodge with a leaky carb explode the muffler on startup once. It was super loud and exploded the oval muffler into a circle from the force. Never would have thought that a plastic bag could be that loud.

Glad this had a good outcome! I was nervous reading this!

Ban plastic bags........They damage 914s....

So your -6 is so low you're starting a side business cleaning parking lots now?


Glad there's no more damage than that!!!

my fan once ingested the heater hose after the zip ties attaching it to the fan housing let go... kinda sounded like stepping on a plastic water bottle...

glad yours was similarly minor.

You've run and driven the car since ?
No rubbing fan ?
No wobbily pulleys ?
A very lucky day.

You had me worried Forrest, damn bag

Kudos to Keith and others that helped.

Our current heatwave didn't help you much.



Oscar

That’s good news, but maybe you should hang a rabbits foot or something from the rear view mirror. You’ve had the weirdest issues with that car.

Good story. I love it

Along with the relief, it was great slapstick comedy - think about it

Hang garlic around your neck each time you drive that thing.

(You spelled Keith's name wrong again)

Pretty inexpensive fix - tune up and a new pair of shorts.

that's a running joke....... as opposed to my car...

Good comments all / and very true to the point of each experience in an old car being a good one / regardless of the outcome. A man can spend years in college, gain higher degrees and professional accolades, but nothing,...I repeat Nothing, can prepare one for the life experiences a 914 will add to the journey.

Susan, my lovely wife, wants me to buy a new 911 to, in part, relieve her of the ongoing 9pm+ phone rings with me on the side of the road with one issue or another.

I may do that someday soon but I ain't giving up the mental and physical challenges that keeping a 47 year old humping behind a man entails........ or the wallet drain vortex it involves.

Sure is fun to drive at its limits (and mine) though...........

Good to hear it wasn’t an engine killing event, before I reinstalled the fan cage/shroud, I sucked in the heater hose that went to the passenger side.

Glad to hear it was only a minor setback.

I installed one of these on my old 2.0L motor before the 2056 build

Click to view attachment

I don't think there's anything commercially available for a /6 motor though

How’d a bag get sucked through the engine bay tins or engine cover? That’s one sneaky bag!

Glad it was something ‘small’ and not a $$$$ David Hobbs kablammo moment

I could have used one of those when my 914 was still a /4. I dropped a small pair of vice grips into the fan with the car off while I was working in the engine compartment. Missed picking them up. Horrible noise when I started the engine. Ended up having to replace the fan due to all the broken blades.



Now I always double check the fan before I close up the engine lid.

I suspect that Forrest bought the new fuel pump at Pep Boys.

Once the alternator pivot bolt on my car worked its way loose. It evidently got caught by the alternator belt, because it launched across the engine bay and wedged itself next to the battery. Made a huge BANG when it hit.

Could have been very bad if it had hit the battery...

--DD

Yeah. That's what I was wondering. Do you have all engine tin and engine lid/grill in place?