what is wrong?

[madranger84]

I have a 5.0 out of an 84 Lincoln town car that was running real shitty, when i pulled out the plugs to do a compression check one of my cylinders was hosing out gas out of the spark plug hole. we checked the compression and it was at 50 while all the others were at 100. in late fall some water got into that cylinder and froze and when i turned the motor over it stopped at that cylinder. what are some things this could be. im thinking a bent valve any other suggestions?

 

[RonD]

And how could a bent valve stop engine from turning?
Wide open valve can but not a bent valve

Not sure how water could get into even an open spark plug hole unless engine was sitting outside.
And if it was then there is water in more than 1 cylinder, via the intake manifold.

You don't mention what cylinder it is that was open to the elements, but each piston has a "double", another cylinder that will be at Top Dead Center(TDC) at the same time.

If memory serves firing order for 5.0l(302) is
1-5-4-2-6-3-7-8

To find the "matched pairs" of pistons, cut firing order in half and place one above the other, so:
1-5-4-2-
6-3-7-8

1 and 6 will both be at TDC at the same time
5 and 3 ""
4 and 7 ""
2 and 8 ""

take spark plug out of the "other cylinder", it probably still has water in it, or fuel, and it is hydro locking.

 

[madranger84]

i had the hood off and it got rain down the carb into the cylinder and froze last fall and it cranked over until it hit that cylinder and i took that plug out and there was ice on it so i took a heat gun and melted the ice so it turned over again and spit the water out. then i parked it for the winter and took it out not too long ago. i've had it running it just runs like shit so when i took the plugs out to do the compression test the cylinder that had water in it was spraying gas out and the compression was really low. also when i am cranking it over puffs of smoke are coming out of the carburator.

 

[Tedybear]

i had the hood off and it got rain down the carb into the cylinder and froze last fall and it cranked over until it hit that cylinder and i took that plug out and there was ice on it so i took a heat gun and melted the ice so it turned over again and spit the water out. then i parked it for the winter and took it out not too long ago. i've had it running it just runs like shit so when i took the plugs out to do the compression test the cylinder that had water in it was spraying gas out and the compression was really low. also when i am cranking it over puffs of smoke are coming out of the carburator.

Please tell us that you 'fogged' or give each cylinder a few shots of oil prior to being "parked"? Water in a cylinder if it hydrolocks will bend parts if rotating fast enough. But water just left sitting in a cylinder for extended time can cause a lot of rust issues. I'd be interested to drop an endoscope camera down the plug holes and see what the cylinder walls look like.

S-

 

[RonD]

Then it now cranks over?
I was under the assumption that it stopped at that cylinders TDC now, not last year.

Then yes you have bent a valve, that was done from the ice on the top of the piston hitting an open valve.
If the only time it stopped and would not turn again was while using the starter motor then all you did was bend a valve, or two, which is bad enough.
If engine was running and just stopped dead then you could have bent a connecting rod.

Both heads will need to come off, then have a look like tedybear said

If water goes down the carb is goes to all 8 cylinders, it just sits at the bottom of the intake waiting for valve to open.

And with 9.0:1 compression ratio you should be seeing 140+ psi from each cylinder, 160psi is expected

 

[madranger84]

water only got into the one cylinder (got lucky on that one) and i pulled the heads off and yah my exhaust valve was very slightly bent

 

[madranger84]

Please tell us that you 'fogged' or give each cylinder a few shots of oil prior to being "parked"? Water in a cylinder if it hydrolocks will bend parts if rotating fast enough. But water just left sitting in a cylinder for extended time can cause a lot of rust issues. I'd be interested to drop an endoscope camera down the plug holes and see what the cylinder walls look like.

S-

water was only in there for a night so i thawed it out the next morning, none of the walls had any scoring so im good there