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Blown Engine Replacement

S

SteveF

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Last week the engine in my 1984 C4 let go while on the highway at 80 mph. Compression tests show about 50 lbs in each cylinder. Timing chain / gears are okay so I believe the problem is in the block. So here's my question. Does the corvette use a block that's specific to a vette or can an "ordinary" 350 block work? Will the heads, intake, ect work?

I got the car to drive & have fun with & don't enter it in shows, ect so I'm not concerned with the devaluation of the car that the use of a "non - corvette" part could cause. I would like to know if I need to find a corvette block / engine or can use a standard 350 block. I've even asked my local chevy garages & they're not sure.

Appreciate the help & thanks in advance

:confused
 

Edmond

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That would be a standard 350 SBC gen I block.
 

1995 RedVette

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I would buy a short block from GMPP. I think they run $1500-1800 depending on options. Then have a new set of valve seals put in your heads just so everything is sealed up nice again and put it all back together.

Brett
 
S

SteveF

Guest
Thanks for the info. The more my buddy, who's also my mechanic, & I have been checking the car we're leaning towards something happening to either the cam or the crank.

At first check I was hoping the timing chain let go & I only bent a few valves but all the timing marks line up okay & with the distributor cap off & bringing the engine up on #1 cylinder everything lines up the way it should.

I'm now debating selling the car the way it sits or fixing it. Engine had 80,000 original miles when it let go.

If I sell it, I know I'll get another one pretty quickly. I got bitten by the "Corvette Bug" & no other car can replace it now.

Thanks again,
 

G Winter

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If your distributer is in time I don't think the cam is broken. You didn't describe what happened. Big bang, quit running? I am really intrested what would let go to still allow you to get a compresion test and have the engine in time.

Glenn
:w
 

garycr14

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Interesting that the compression is down equally in all cylinders. Would that happen if the timming gear slipped a tooth or two? This would be my best guess.
 

G Winter

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If the timing mark and the dist match it doesn't seem logical that the chain is slipped unless it slipped 180 deg. Remember cam makes one revolution per 2 of the crank. If by chance that happened it would appear to be in time. Put your thumb over the number 1 sparkplug hole and crank till you get compression,see if there is a corrilation with timing mark.


Glenn
:w
 
S

SteveF

Guest
I had driven the car about 70 -80 miles earlier in the day. Had just stopped for gas and while back on the highway for about 5 minutes the engine started to lose power & a loud rattling sound began. Engine then shut down. No loud "booms" , ect. Engine would turn over but not fire, even sounded like there was low or no compression when trying to restart.

Thanks :confused
 

garycr14

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It just seems to me that it has to be the valve timing is not in sync with the crank. If the motor will turn over, and the compression is in the same range on all cylinders, then the timing chain must have slipped. I can't think of anything else it could be. I hope someone else chimes in here with a suggestion. You may want to run this by the Corvette Forum as well to see if you can get another opinion.
 

garycr14

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You'll get nothing for it without the motor, you may as well fix this one.
 

MoeJr

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I love my 84 but people will not pay anything for them with a dead engine. You can buy decent running ones for 5k so you would be lucky to get 2k.

You have gotta tear the front of the engine down and check the timing chain and cam. Take the Intake off and go at it. No senseguessing what may have happened. Tear it down and find out. Good Luck.

:beer
 
S

SteveF

Guest
Sorry it took some time posting an update. My mechanic is working on the car on the side to save me some money so it's rather slow going. Picked up a block for the car & he's in the progress of pulling the motor.

Spoke to him yesterday & he hasn't gotten too far & isn't positive yet what let go. Hope to know some time this week & I'll put up a post.

Thanks everone for your help. :drink
 

MoeJr

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Why would you buy another engine when you have no idea what is wrong? He shouldn't even be pulling the engine until he knows what is wrong. Sounds like alot of work for nothing except to line your mechanics wallet. What you escribed was not a catastrophic failure.
 

garycr14

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Why would you buy another engine when you have no idea what is wrong? He shouldn't even be pulling the engine until he knows what is wrong. Sounds like alot of work for nothing except to line your mechanics wallet. What you escribed was not a catastrophic failure.
I would agree. You should have at least detirmed what the cause of the probem was. Unless we dn't have all the information it seems like it is something less severe that a total engine rebuild. Although it is not my $$$ I thought I would throw in my own $.02
 

John Robinson

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I had driven the car about 70 -80 miles earlier in the day. Had just stopped for gas and while back on the highway for about 5 minutes the engine started to lose power & a loud rattling sound began. Engine then shut down. No loud "booms" , ect. Engine would turn over but not fire, even sounded like there was low or no compression when trying to restart.

Thanks :confused
Check your gas for water. It sounds like you got a bad tank of gas with water in it. That would explain the detonation sound. You may have a claim with the gas station for a new engine. Hopefully you put the gas on a credit card. Document everything that happened. I had a friend who had the same thing happen to him and there was a gallon of water in the gas tank.
Let us know if this is what happened.:ugh
 

garycr14

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Check your gas for water. It sounds like you got a bad tank of gas with water in it. That would explain the detonation sound. You may have a claim with the gas station for a new engine. Hopefully you put the gas on a credit card. Document everything that happened. I had a friend who had the same thing happen to him and there was a gallon of water in the gas tank.
Let us know if this is what happened.:ugh

That may all make sense, but I am not sure that this would cause the compression to go down, but it reinforces the point of having the engine check out before removing for a complete overhaul. If it was something laike bad fuel, then of course you would need to drain the tank before firing up the new motor.
 

John Robinson

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Bad Gas 2

If the engine was at full operating temperature and the gas from the fill up had water in it the following would happen. You would have water turning into steam in the cylinders. That could crack the piston or burn a hole in it. That would explain why the timing looks right etc. It also would explain why the compression is down in all the cylinders. As for not starting the knock sensors reacted to a bad knock condition and shut the engine down which is what they are supposed to do. I still think this may be what you are describing as having happened. If so the gas station owes you a rebuild.
 

garycr14

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If the engine was at full operating temperature and the gas from the fill up had water in it the following would happen. You would have water turning into steam in the cylinders. That could crack the piston or burn a hole in it. That would explain why the timing looks right etc. It also would explain why the compression is down in all the cylinders. As for not starting the knock sensors reacted to a bad knock condition and shut the engine down which is what they are supposed to do. I still think this may be what you are describing as having happened. If so the gas station owes you a rebuild.

I understand that is something that could happen, but in all 8 cylinders?
 

John Robinson

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Engine Damage

I understand that is something that could happen, but in all 8 cylinders?

Absolutely. At the RPM's the engine was running it only takes a couple of seconds for all 8 cylinders to fire. I have seen this happen and it will damage all the cylinders before shut down occurs.
 
S

SteveF

Guest
Hello all,
Thanks for the recent posts. My mechanic has checked the timing chain, etc & all appears to be okay. Can't find any other cause other than something let go in the block.

Luckily for me my mechanic is a good friend & isn't charging me anything until the car is up & running again & we know what the exact problem is. Also picked up an engine "on consignment" from another friend. I'll pay him for it if I need to use it. I'm very lucky knowing both these guys!

John. never thought about the checking the gas. i'll look into that & thanks for the info.

Thanks again,
 

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