Almost blew my head off, literelly

[callmethewander]

I'm a '44 guy but...(i posted this on the 968 forum, but i would like your thoughts here also) I went to look at an '86 928 today that hasn't run in a couple of years, the owner said it was running fine but he had not been using it so only started it occasionally until once when it did not start. He bought a 968 and was living out of town so the car was just sitting for close to a couple years now. Well, of course it wouldn't start so we opened the airbox and i sprayed in starter fluid as the owner cranked the engine, it seemed to almost start several times until, as i was spraying in the starter fluid... BOOOM!!! I am not kidding the sound deafened me and sent me backwards. When i moved back to look under the hood, both of the air inlet boxes on the sides of the intake manifolds had blown completely off at the place where they clamp onto the the intake pipes, the insulation from the hood was blown off and all over the place, a small pipe at the back of one of the side airboxes was broken off, and i was completely disoriented. What the heck could have happened? anybody know?

[callmethewander]

I meant "i posted it on the 928 forum", my ears are still ringing by the way.

[944 boy]

nice, sounds like the starting fluid pooled in the intake and caught when it backfired.

[Dtchy]

Yup...sounds like a starting fluid OD.

Are you still considering buying it?

[callmethewander]

actually, i am, the car seems ok, if i can figure out why it's not running and get it going so i can see how it is i would still like to buy it.

[legoland951]

Backfiring normally happens if the firing order (spark timing) or the physical cam timing is off detonating combustible gases when the intake valve is still open. I would question whether that car was running well before unless the timing belt is broken/skipped. The 86 is a 32 vave engine and I believe its an interference engine so the valves may be bent if the cam timing is off.

[plyhammer]

I had that happen once and it shot the dipstick up into the ceiling.

[Razorback1980]

Never seen the dipstick trick, but I've had it backfire with a perfectly configured engine...I just used too much! Starting fluid is designed to have a very low flash point to help engines with weak compression or poor ignition to start. When the exhaust valve opens, not all the exhaust fumes leave the cylinder and what is left there can be quite warm when igniting starting fluid. So when the intake valve opens on the next stroke....if there is an abundance of starting fluid already there...because it has such a low flash point, it will ignite from the heat of the exhaust gases and come back up through the intake and then the other cylinders which also have extra starting fluid in there also ignite and then you lose your eye lashes. Very combustible stuff so be careful! Carburetor engines in the old days did this a lot when they would flood and the excess gas would ignite in the same manner.

Pictures? LOL I think I might pay to see that! Insulation shredded off the hood and gently floating through the air, the black stuff covering your face with that look of "what just happened here?" ..or the owner's look which had to be one of disbelief. Definitely a "You might be a redneck if" joke in there somewhere. Still have eyebrows? Sucks trying to explain why you don't have eyebrows at work the next day..or even worse when you have one eyebrow but not the other...not that it's ever happened to me or anything.

Glad you are ok....please be careful how much you use.

[Damian in NJ]

Say what? I can't hear you??

[Scuba Steve]

I'd be slightly annoyed if someone did that on a car I was selling, then went 'oops!' and ran off! I guess it's a little different that the car doesn't run though.

[callmethewander]

I didn't run off, and we were trying to get it running together! Funny stuff Razorback, it really was a powerful blast but noone got hurt, and it sounds like it's not a totally uncommon happening that those things blow off, they attach with rubber hoses w/ hose clamps so nothing broke thank God, I'd prolly be dead if that was a solid piece that shattered! the only damage was a small pipe that's attached to the rear of the side airbox, I think it broke off form the movement of the airbox, we didn't know what it is tho.

[fastfredracing]

When I used to have employees, one of them disintegrated the airbox on a Chevy box van trying to start it with start fluid, I heard the noise, and thought that he was dead. I have this happen to me more than once.