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Opinions needed – possible plastic diffuser piece fell into engine

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Old 12-09-19, 08:05 PM
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Opinions needed – possible plastic diffuser piece fell into engine

I am replacing my secondary injectors today and when pulling out the diffusers I noticed I knocked a small piece of plastic off with the pick I was using to remove it. It's a very small piece, <1/4" long and 1/16" thick at most. Miniscule. The picture shows the missing sliver on the edge.

I poked around with double sided tape on a screwdriver and didn't find it, so then I took my household vacuum cleaner and stuck it on the lower intake manifold hole and sucked for a while.

Am I being too paranoid here or should I actually be worried about damaging my engine?




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Old 12-09-19, 09:49 PM
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Tonight I also put my more powerful shop vac on it with a sock over the inlet to catch anything. No luck. I think the odds are good that the piece either flew backwards when the diffuser popped free or the first vacuum got it, but I can't know for sure
Old 12-09-19, 11:01 PM
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If the tiny plastic piece fell in, it ain't coming out the intake ports via shop vac.
It would be ejected before damaging an apex seal at cranking RPMs.
The turbine might take a hit, other than that it cant pass thru the cat.
Old 12-09-19, 11:24 PM
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Thanks for posting in my thread ! ( https://www.rx7club.com/3rd-generati...fusers-1140663 )
Damn... We are cursed with those diffusers...
I think mine has the same size too.
In your case, I don't know. It may be already out after your first vaccum.
In my case, I think I will try to locate the tittle piece with an endoscopic camera first, and if I can locate it in the LIM I will vaccum it with a nylon stocking on the the other end of the vaccum te be sure. If the vaccum isn't powerful enough from the top ports if tje LIM, I will add a smaller hose to go vaccum inside the LIM (and maybe inside the engine) and suck the little **** out of there !
Though, what Nakd in fearless say is also good to know... Hopefully those mini pieces can escape the engine through the exhaust without damaging the internals...
anyway, I let you know if I'm succesful with vaccum session in the next few days.

Last edited by tomatoto; 12-10-19 at 12:02 AM.
Old 12-10-19, 08:20 AM
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Unless you want to remove the engine the only next step after attempting to vacuum is to cross your fingers and try to start the car. I think you have a higher chance of being fine than not.

Either the moving parts will crush it into dust, the heat from combustion will burn it up or it will simply be blown out of the engine. It is just plastic after all and I’m sure those guys that run turbos without filters have sucked up way worse without even realizing it. If you get it to crank and start I’d let it run as long as possible to make sure you cook it out.

There is just a very slim chance that it snags the rotors/apex seals just right to prevent the engine from turning. In that case the internals should still be fine for a rebuild as I doubt there is much the plastic can do to steel and aluminum parts.
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Old 12-10-19, 08:39 AM
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That small of a piece I would not be worried about. It's your call at the end of the day but personally I'd crank up and go.

A larger piece or a good portion of that diffuser would concern me, however.

Dale
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Old 12-10-19, 08:45 AM
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i've seen what these engines will do to a bolt/nut, this little piece of plastic won't hurt it at all
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Old 12-16-19, 02:30 AM
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Hey, were you able to retrieve the little piece?

I used my vac-shop along with a nylon stocking (thanks Dale for the tip) and a smaller hose to reach the bottom of the LIM (and possibly inside the housing) and I've been able to retrieve the 'not so little' piece of my diffuser !
​​​​​
I wish that you'll be as lucky as I am.


Cheers
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Old 12-16-19, 12:45 PM
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Well I never found my tiny piece of plastic but the car is running fine now. I cranked it for a while with the injector fuse pulled just to be safe. No idea if it was even in the engine but all is well that ends well
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Old 12-16-19, 12:50 PM
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This is very good to read !
I hope I will write the same when I'll start mine 😅

Btw, are you still using stock injectors? Did you change all o-rings, grommets, pintle caps etc ?

Old 12-16-19, 09:21 PM
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Originally Posted by tomatoto

Btw, are you still using stock injectors? Did you change all o-rings, grommets, pintle caps etc ?
I had this problem when replacing the stock injectors with an upgraded secondary rail and Bosch injectors which no longer use the diffusers. I would definitely recommend changing all those parts while you’re in there, they get old and brittle from the heat and the last thing you want is leaking fuel on your hot engine
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