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consequences of not relieving fuel pressure?


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Today I replaced the #2 fuel injector on my 90 legacy wagon, 2.2L, 2wd, auto.

 

I've done this 3-4 times on the same car. This time however, was different. After installing the new injector, I went to start the car, and I heard a loud "clunk" from the engine, and then all went still.

 

I tried to start the car a couple of more times, and it finally started, only now it runs with a very loud knocking sound coming from the engine, and it also runs like crap.

 

I suppose I should mention that I did not (and never do) relieve the pressure from the fuel pump, and some fuel went into the hole (cylinder) that the fuel injector sits in. But that's happened before and I didn't have any problem.

 

Did I do some major damage here? I'm guessing the fuel went into the cylinder, and the piston couldn't compress it and I bent something?

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*UPDATE*

 

On further inspection, and judging from the oil spray and metal shards in and around my engine compartment, I have done some major damage. Oh, there's also the matter of the very large crack/hole in my intake manifold...about 4" behind the EJ22 stamp, behind the alternator, which is brand new by the way.

 

Great.

 

Today I replaced the #2 fuel injector on my 90 legacy wagon, 2.2L, 2wd, auto.

 

I've done this 3-4 times on the same car. This time however, was different. After installing the new injector, I went to start the car, and I heard a loud "clunk" from the engine, and then all went still.

 

I tried to start the car a couple of more times, and it finally started, only now it runs with a very loud knocking sound coming from the engine, and it also runs like crap.

 

I suppose I should mention that I did not (and never do) relieve the pressure from the fuel pump, and some fuel went into the hole (cylinder) that the fuel injector sits in. But that's happened before and I didn't have any problem.

 

Did I do some major damage here? I'm guessing the fuel went into the cylinder, and the piston couldn't compress it and I bent something?

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Holy crap!

 

I have a somewhat hard time believing the amount of fuel there'd be just from the fuel-rail pressure would be enough to hydro-lock the cylinder, but it was either that or something else got down there I guess.

 

I mean, if they hydro-locked so easy, I'd assume ones with leaky head gaskets would be self-destructing all the time, no? Even though most leaky head gaskets seem to leak out, you'd see some doing this.

 

 

Dave

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Why were you replacing the injector in the first place? If you had a miss, perhaps the original problem was a bad valve which dropped or another mechanical issue.

 

My second thought: could the replacement injector be stuck open? If it filled the cylinder with gas, hyrdolock seems possible.

 

Nathan

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Wow i thought i was the only person putting holes in un-modified motors.

 

Sounds like something went very pear-shaped. Do keep us updated as i honestly would love to know what happened! (mainly so i dont do it in future)

 

As a side note - when i removed the intake from any car the first thing i do is wedge some rags into all the intake ports - stops any other crap falling in there.

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Wow i thought i was the only person putting holes in un-modified motors.

 

Sounds like something went very pear-shaped. Do keep us updated as i honestly would love to know what happened! (mainly so i dont do it in future)

 

As a side note - when i removed the intake from any car the first thing i do is wedge some rags into all the intake ports - stops any other crap falling in there.

 

Cranking the engine over with the plug out will help too.

 

 

nipper

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wow :eek:

who'da thought you could hydra-lock an engine with gasoline?!

i guess i always thought that like diesel, gas would just detonate at a certain pressure level . . . obviously i'm wrong (or the pressure level required is much higher than a gasoline engine can handle)

 

thats very not good. i'm sorry man :-\

 

+1 on the "what was the reason for replacing the injector in the first place?"

 

chris

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The engine has had a mysterious misfire for about a year. Two different mechanics have not been able to determine the cause. As a result, I have been slowly removing and replacing some of the more obvious parts. It has new plugs, wires, coil, fuel filter, and now--all new fuel injectors.

 

It definitely hydrolocked. It literally blew a hole right through the top of the engine between the #1 and #2 cylinders. She didn't want to start, and that should've been my clue to stop, but I didn't suspect hydrolock, so I continued to try and start it, and just like the dependable Subaru it has always been, it started right up, with a loud knocking noise, and then promptly exploded.

 

I'm going to take it apart today to see if I can determine the extent of the damage, but from what I've read, there is no middle ground on hydrolock. Either you don't do any damage at all (because you don't try to start it), or you start it and mangle the engine so bad that repair is not economically feasible.

 

Does anyone know how hydrolock in one cylinder could tweak the entire engine though? Why could I not just replace the parts in the one cylinder where the stupid mistake was made? I guess if it was under enough pressure to actually blow a hole through the top of the engine, then it probably tweaked everything around it too. I'll try to take some pictures.

 

wow :eek:

who'da thought you could hydra-lock an engine with gasoline?!

i guess i always thought that like diesel, gas would just detonate at a certain pressure level . . . obviously i'm wrong (or the pressure level required is much higher than a gasoline engine can handle)

 

thats very not good. i'm sorry man :-\

 

+1 on the "what was the reason for replacing the injector in the first place?"

 

chris

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Does anyone know how hydrolock in one cylinder could tweak the entire engine though? Why could I not just replace the parts in the one cylinder where the stupid mistake was made? I guess if it was under enough pressure to actually blow a hole through the top of the engine, then it probably tweaked everything around it too. I'll try to take some pictures.

 

I'm not sure what your asking, but the folowing parts take the beating:

Piston

Rings

Connecting rod

Engine block or Cylinder head depending upon where the hole is.

 

The engine is scrap, once you put a hole in it.

 

nipper

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Interesting, because I'm having a running arguement with a couple of posters on another thread on how easily I think an engine can be hydrolcked. The combustion chamber volume (CCV) of 2.5L Subaru engine is only 50cc. That's only 1.69 fluid ounces. So, put even 1.8 fliud ounces of gasoline in a cylinder and it will hydrolock. I doubt that anyone has actually measured it, but many posters feel that about half a cup of gasoline will spirt out of a pressurized fuel line. Obviously, eight ounces of gasoline is more than enough to ruin your day.

I am sorry for the loss of your engine. And I thank you for your post, because I learned something very important fron it. I very easily could have made the same mistake. Thanks.

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Just curious. When you say you tried to start and it did'nt at first, do you mean it turned over and did'n catch or the engine refused to turn over?

 

The reason I asked is that if the engine turned over but did not catch, what happened when it finally started cannot have been caused by hydrolock. If there was enough fuel in the cylinder to cause hydrolocking, it would have been impossilble for the engine to turn over.

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Glad no one was injured. Got any junkyards in the area with a nice 2.2?

 

I found one 2.2 in a junkyard in Houston. We have A LOT of salvage yards here, but Subarus, especially older ones, are nearly non-existent. We don't have much use for AWD cars here, but Subarus are popular with some of the eco-hippy types, myself included.

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The reason I asked is that if the engine turned over but did not catch, what happened when it finally started cannot have been caused by hydrolock. If there was enough fuel in the cylinder to cause hydrolocking, it would have been impossilble for the engine to turn over.

 

It did not want to start. The first attempt at starting it delivered a loud single "CLUNK!" Then I tried it a couple of more times, and it hesistated. A fourth attempt started the engine, and it idled roughly with a seriously loud banging noise. I gave it just a smidgen of gas, and the damn thing just blew up and will not crank at all now. There is a hole, with lots of shrapnel. It must have been the fuel causing it to hyrolock, or at least put it in a serious bind. It was not running too bad before that, with the exception of an intermittent misfire. Excellent mechanical condition overall, very clean, tight transmission. Or was.

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Interesting, because I'm having a running arguement with a couple of posters on another thread . . .

 

argument, it's spelled a r g u m e n t :slobber:

:banghead:

"Dude"- you've officially established yourself as the biggest moron on the usmb. don't take your stupidity that was left to be ignored in one thread, and drag it over to another . . . you being an a$$cap doesn't help the OP's situation . . . :mad:

 

90Legacywagon, sorry again about your car- good luck with the new engine

 

:headbang:

chris

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argument, it's spelled a r g u m e n t :slobber:

:banghead:

"Dude"- you've officially established yourself as the biggest moron on the usmb. don't take your stupidity that was left to be ignored in one thread, and drag it over to another . . . you being an a$$cap doesn't help the OP's situation . . . :mad:

 

90Legacywagon, sorry again about your car- good luck with the new engine

 

:headbang:

chris

 

 

Chris, it can't be easy to be 29 and still need to live with your mom. Lots of other guys your age have good jobs, maybe a wife and some kids. You? Chris, you've got your adolescent hostility, an old car, and judging by your personality, maybe a facefull of zits. But I will be kind, because the world needs losers just like it needs winners.

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this doesn't belong here douche- i mean, dude.

good job, check

nice apt, check

wife and kid, check

did you miss the infiniti G35 cpe part? costs more than you make in a year

 

eat me

 

chris

 

You're right Chris, this doesn't belong here. This board is too valuable a resource to be used for pointless flaming. I'm glad that you see that. So, why did you post a message full of name-calling and flames?

I have every right to refer to another thread on this board that covers the same subject. In my reference to the other posters I purposely did not use any screen names. Nor did I insult or name-call the posters on the other thread. Flaming is puerile and a waste of bandwidth. Don't start none, won't be none. Word.

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  • 10 months later...

to take out the spark plugs and suck out the fuel when you let fuel go into your cylinder while changing fuel injectors...see the hole in the block? This is an update to a thread I posted last year, although last year I thought it was the intake manifold and was less concerned. I have a question related to this problem...I cannot get the engine out.

 

It is seized up, and I cannot turn the crankshaft to get to the bolts in the torque converter service hole. I have taken the spark plugs out, filled the cylinders will PB blaster. It will not turn. I thought it was starting to turn the other day, so I gave it a pull and broke the bolt head off of the crankshaft. I then tried using a giant pipe wrench to turn the crankshaft sprocket gear and it broke off. I can still get a grip on the slick bare crankshaft but do y'all think it is possible that whatever happened to cause the block to explode like that jammed something up inside so much that I will never be able to turn the crankshaft? Any suggestions?

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