How to tell if its a blown hg or a blown motor

[1badgvr4]

I have a question guys.I found a 2g that i was told blown a head gasket.The guy said the main belt popped off while he was very close to his house so he tried to drive it to the house, but the car shut off before he got there.I also have a 1g the blew the hg,but also fried the rings, and seized up the motor.How can i tell if that didnt happen to this 2g before i buy it.

 

[b00st_catalyst]

See if it spins freely by hand....

There is really no way to tell without pulling it apart, you can "guess" but it would be a shot in the dark.

If he ran it until it shutdown....its most likely in bad shape.

 

[bling5tatus]

Leak down test.

 

[1badgvr4]

I know how to do a leakdown test,but after i do it i guess if its more than 5% difference between the cyls then the motor is bad?

 

[94tsi]

not relly it depends on where in the gasket it could have blown if he blew out the fire ring on the gasket it would show a huge loss if its still in the car check the coolatnt in the radiator there sholud be little chunks of oil in the coolatntkinda like baby puke....hahaha.....if its a motor like previously posted just try to spin it over i might b ok unless it broke a ring land then u really wont know until u pull the head off

 

[b00st_catalyst]

To the OP, the motor was fine until the guy dropped the belt, right?

If that is the case, i assume what you are asking is, would that have caused a blown head gasket or blown motor?

If he drove it until it shutdown, that is not good. First and easiest thing to do...see if you can spin the motor freely, check for fluid mixtures. I would remove the plugs, you will need to anyway for further testing and it makes it easy to spin the motor.

If it spins freely, do a compression test. You can get an idea of ring condition through this. Low or no compression, add a few drops of oil...if it changes, good chance your rings are wasted

No compression, do a leakdown. This will better tell you if its being lost through the head. (valve/valve seats, cracks, etc.) If you have the manifolds pulled, you can usually hear where its escaping, intake, exhaust or crankcase (bad rings)

At this point, if you haven't figured it out...i would pull for further inspection. It may be cracked/broke rings/ ring lands, warped/cracked head...etc...

All that being said, if i was to guess....being run without a w/p, the head is probably warped. Aluminum doesn't like heat, especially not on a cast block.

 

[GS-T_Newboost]

ok, yea go with the compression test but check the oil and look for either water in the oil or antifreez

 

[1badgvr4]

I the head is bad thats fine i can deal with that i just dont feel like pulling a motor.So check for oil in the coolant and vice versa and do a comp test.

 

[b00st_catalyst]

I the head is bad thats fine i can deal with that i just dont feel like pulling a motor.So check for oil in the coolant and vice versa and do a comp test.

Start here..

To the OP, the motor was fine until the guy dropped the belt, right?

If that is the case, i assume what you are asking is, would that have caused a blown head gasket or blown motor?

If he drove it until it shutdown, that is not good. First and easiest thing to do...see if you can spin the motor freely, check for fluid mixtures. I would remove the plugs, you will need to anyway for further testing and it makes it easy to spin the motor.

If it spins freely, do a compression test. You can get an idea of ring condition through this. Low or no compression, add a few drops of oil...if it changes, good chance your rings are wasted

No compression, do a leakdown. This will better tell you if its being lost through the head. (valve/valve seats, cracks, etc.) If you have the manifolds pulled, you can usually hear where its escaping, intake, exhaust or crankcase (bad rings)

At this point, if you haven't figured it out...i would pull for further inspection. It may be cracked/broke rings/ ring lands, warped/cracked head...etc...

All that being said, if i was to guess....being run without a w/p, the head is probably warped. Aluminum doesn't like heat, especially not on a cast block.

 

[1badgvr4]

Thanks guys.