How to determine a bent connecting rod with motor in car?

[driven87]

Hi new guy here and had a quick question. I had an injector go bad and stay stuck open at idle and flood the motor out. Lots of smoke was pouring out of exhaust and was misfiring bad. Once the spark plug was taken out alot of fuel came out. I don't think i hurt anything for the 45 seconds or so it was running but once i get the problem fixed solved i want to prepare myself just in case i hydrolocked something and bent something with the injector staying open. So my questions is how can i tell with the motor in the car? Thanks for any help

 

[turbofabricator]

Pull the heads (which it sounds like you'll NEED to do) and use a dial indicator on the piston. If the rod is bent, it'll be down in the hole farther than the rest. Rotate the engine and measure deck heighth on a couple of cylinders.
Pull oil pan and look from below. You might be able to see it.

 

[wbrophy]

Do the easy thing first!

Take a compression test first, if you find one that is lower than the rest that might be the first one to look at. Then again you may have more than one. I had number 5 & 6 rods that were bent on a 3.8 one time. Also due to different chamber size from hole to hole the compression "may" not mean a thing but a good way to start.

PS: If they are all close in compression you "may" be OK. "I" would leave it alone if the compression checks out (within approx. 10% of each other from the highest to lowest cylinders, this is just a general rule of thumb).

Note: just in case you don't know. Disconnect the computer wire by the battery first and block open the throttle blade before doing the test so the car won't start and you get air into the engine, when done the compression test close the THROTTLE!!!!! and reconnect the computer wire before starting.

 

[driven87]

Yeah once i get it back together im gonna do a compression test on the motor i have a feeling i'll be ok but i want to make sure. The car ran with the injector like this it was just smoking badly and misfiring alot. Hopefully sometime next week i can get around to putting it back together and checking it out. If the test passes ill just let it run and see how shes does.

 

[Boost231]

i think your motor is fine. i had the smae thing happen to mine. car ran really bad and was smoking out the exhaust. the smoke was fuel mist. good thing there wasnt a spark or the whole house would have exploded. car ran fine for several more years, then i blew a head gasket and did a motor build

 

[driven87]

my main concern is that when i first tried to start it the motor would turn over then stop then try again and it would stop and then finally started and smoked real real bad. At first i had thought the motor seized for no reason then it just fired up, lol. I just hope that initial start did not hurt anything. With just the key on the injector was filling the cylinder right up.

 

[87granny]

my main concern is that when i first tried to start it the motor would turn over then stop then try again and it would stop and then finally started and smoked real real bad. At first i had thought the motor seized for no reason then it just fired up, lol. I just hope that initial start did not hurt anything. With just the key on the injector was filling the cylinder right up.

Sounds like you hydro locked it by the fuel pouring in the cylinder do what Boost231 suggested and check for spark

 

[coach]

Usually when you hydrolic a cylinder, it stalls the engine, because that cylinder wont spin over as fast as the others. This was a major problem 20 years ago with BDS's fuel injected tunnel ram set-up. I watched a guy with a Pro Street Z-24 bend a few aluminum rods just starting and revving it up and moving about 20 feet. I would say, if it never stalled, you didnt build near enough pressure to bend a rod. The compression test will tell you.

Thanks
Coach

 

[driven87]

it wanted to stall for sure but i kept my foot on the gas just enough to get it pulled back into my garage and shut it off. Its def not spark related i know that much. guess once i get it back together i will cross my fingers and see what hte compression test says.

 

[wbrophy]

Rods can be replaced, an emergency is another story.

I did not read your full post before replying, that is why I talked about maybe 2 rods being bent but I hydraulicked/bent a rod in a small block chevy once and I knew I was going to do it before I even started the car (gas had run down the manifold but I had a "real" emergency). The car stopped cranking when that cylinder tried to compress, let it set for a short while; than from some gas escaping past the rings and the rod bending it started and I went where I needed to go. When I got around to taking the engine apart the rod was bent so bad that you could see it with a half blind naked eye, a real classic.

 

[83ttypecooled]

Hi,
I wouldn't worry about it; our motors have pretty tough rods. I have hydrolocked a few of these,and unless it happens at speed, the crank/rod/piston assembly will handle it.

 

[Turbo6Smackdown]

If you ran that engine for 45 seconds, with an injector on constantly, you'd wash all the oil down on that cylinder wall, ruining at least the rings. Now how dilluted the rest of the oil got from that treatment, I don't know.

 

[Boost231]

i agree with turbo6smackdown, when mine was stuck Wide Open and i ran the car for longer then 5 min i drained the oil and it was super runny. it smelt of fuel really bad. but like i said i didnt have any problems with that cylinder. good compression leakdown etc.