About the same for me
Compression check numbers
Thread Starter
Intermediate
Joined: Oct 2002
Posts: 40
Likes: 0
From: Rock Hill SC
Compression check numbers
I am working on a 02 Z bone stock. Water pump was bad and I think sombody ran it hot. Changed the pump left the thermostate out to see it slowly move north of 220* and the fans did not bring it down. No overflow or bubbles in the tank. I did a compression check and came up with these.
#1-180
#3-170
#5-170
#7-170
#2-180
#4-180
#6-200
#8-200
My question is what are normal LS6 dynamic compression numbers (warm). And is it common for the drivers side to go first? Im probly gonna do both sides anyway.
#1-180
#3-170
#5-170
#7-170
#2-180
#4-180
#6-200
#8-200
My question is what are normal LS6 dynamic compression numbers (warm). And is it common for the drivers side to go first? Im probly gonna do both sides anyway.
Thread Starter
Intermediate
Joined: Oct 2002
Posts: 40
Likes: 0
From: Rock Hill SC
Ok little update I redid the compression test after it cooled down and the drivers side went up 185 on all 4?
Pass side stayed the exact same.
I will do a leak down tomorrow and see if I can blow some air into a water jacket. Its probly #5 or #7.
Pass side stayed the exact same.
I will do a leak down tomorrow and see if I can blow some air into a water jacket. Its probly #5 or #7.
Thread Starter
Intermediate
Joined: Oct 2002
Posts: 40
Likes: 0
From: Rock Hill SC
Ok well now Im kinda stumped. I just did a leakdown check on the driverside. all were 100/90 psi and I let it sit for a long time shoving 100psi in each cylinder for atleast 15 min trying to get some airbubbles or somthing into the water jacket. But nothing. 
I would say it could be the sensor if were as complicated as the oil pressure sensor but its not its just a simple thermocouple.
Could it be a cracked head? where it only opens up when the engine is warm? Im not ruling it out as I have the best luck at getting these odd ball problems.
Im going to go do the pass side leak down and see if I find anything.
I would say it could be the sensor if were as complicated as the oil pressure sensor but its not its just a simple thermocouple.
Could it be a cracked head? where it only opens up when the engine is warm? Im not ruling it out as I have the best luck at getting these odd ball problems.
Im going to go do the pass side leak down and see if I find anything.
Melting Slicks
Joined: Feb 2006
Posts: 2,172
Likes: 104
From: Des Moines Iowa
"Could it be a cracked head? where it only opens up when the engine is warm? Im not ruling it out as I have the best luck at getting these odd ball problems"
My experience has been that a cracked head typically leaks more when cold, and less when hot. Metal expands and seals the crack more, when hot...........maybe it's just a bad head gasket that leaks when the cooling system is under pressure?
My experience has been that a cracked head typically leaks more when cold, and less when hot. Metal expands and seals the crack more, when hot...........maybe it's just a bad head gasket that leaks when the cooling system is under pressure?
Tech Contributor
Joined: Jan 2007
Posts: 19,361
Likes: 1,128
From: Dyer, IN
So I take it you are troubleshooting an overheat issue. Besides change the water pump, and remove the thermostat, what have you done? What have you alleviated as a possibility? I would reinstall the thermostat..before you continue.
I take it you have already done a cooling system pressure test before doing a engine compression/lead down?
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From: Slave to the evil empire
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St. Jude Donor '04
You do realize that if there is no thermostat in the engine then it will always overheat.
The thermostats main purpose is to keep the water in the engine long enough for the coolant in the radiator to properly cool down. If the water is constantly moving from the engine to the radiator it will get warmer and warmer and warmer.
The thermostats main purpose is to keep the water in the engine long enough for the coolant in the radiator to properly cool down. If the water is constantly moving from the engine to the radiator it will get warmer and warmer and warmer.
Thread Starter
Intermediate
Joined: Oct 2002
Posts: 40
Likes: 0
From: Rock Hill SC
Actually, it's not. The ECT is a thermistor, not a thermocouple. A thermistor is just basically a variable resistor that changes resistance with temperature. You can check the sensor with a DMM, and use the temperature v/s resistance chart in the service manual as a guide.
So I take it you are troubleshooting an overheat issue. Besides change the water pump, and remove the thermostat, what have you done? What have you alleviated as a possibility? I would reinstall the thermostat..before you continue.
I take it you have already done a cooling system pressure test before doing a engine compression/lead down?
So I take it you are troubleshooting an overheat issue. Besides change the water pump, and remove the thermostat, what have you done? What have you alleviated as a possibility? I would reinstall the thermostat..before you continue.
I take it you have already done a cooling system pressure test before doing a engine compression/lead down?
Presure check was good and I did a leakdown of the rest of the cylinders. It was all normal.
You do realize that if there is no thermostat in the engine then it will always overheat.
The thermostats main purpose is to keep the water in the engine long enough for the coolant in the radiator to properly cool down. If the water is constantly moving from the engine to the radiator it will get warmer and warmer and warmer.
The thermostats main purpose is to keep the water in the engine long enough for the coolant in the radiator to properly cool down. If the water is constantly moving from the engine to the radiator it will get warmer and warmer and warmer.
Ok so i decided it has to be a gasket or head problem. I pulled the heads off and sure enough the 2 head bolts around the #7 felt a little funny coming loose. Probly only took about 40ftlbs to break those two bolts loose. The pass side head was normal coming off. Looks like it was just a gasket problem. I will drop the heads off to be checked tomorrow.
Tech Contributor
Joined: Jan 2007
Posts: 19,361
Likes: 1,128
From: Dyer, IN
After replacing the leaky pump I filled it with water thermostat installed and burped the system of all air. stone cold it got to 220 in a hurry. Kicked the fans on with HPtuners and it slowed but kept climbing. I drove it down the road same thing it kept going north of 240.
Presure check was good and I did a leakdown of the rest of the cylinders. It was all normal.
Yes but with the fans on full and only at idle and outside air temp of 30*f It should stay at somewhat normal levels.
Ok so i decided it has to be a gasket or head problem. I pulled the heads off and sure enough the 2 head bolts around the #7 felt a little funny coming loose. Probly only took about 40ftlbs to break those two bolts loose. The pass side head was normal coming off. Looks like it was just a gasket problem. I will drop the heads off to be checked tomorrow.
Presure check was good and I did a leakdown of the rest of the cylinders. It was all normal.
Yes but with the fans on full and only at idle and outside air temp of 30*f It should stay at somewhat normal levels.
Ok so i decided it has to be a gasket or head problem. I pulled the heads off and sure enough the 2 head bolts around the #7 felt a little funny coming loose. Probly only took about 40ftlbs to break those two bolts loose. The pass side head was normal coming off. Looks like it was just a gasket problem. I will drop the heads off to be checked tomorrow.
