Head gasket diagnosis help
Thread Starter
Staging Lane
Joined: Sep 2006
Posts: 80
Likes: 3
Head gasket diagnosis help We bought a 2000 Suburban with a 5.3 knowing that it had a blown head gasket. They had just put a water pump on it and the shop had diagnosed it as a bad head gasket after the water pump. The radiator is cracked as well. it was definitely putting air in the cooling system and pushing out water.
It idles with a slight miss but really not that bad. My scanner isn't picking up any misfires. A compression test shows even compression. When it is cold it will warm up without putting any air into the surge tank. If I just fire it up cold and drive it to work which is about 5 miles it will push 2 gallons of water out of the system. If I fire it up and let it warm up then drive the same distance it goes through less than half a gallon. I know that it could be the metal expanding to make it seal somewhat better but it doesn't seem like a gallon and a half difference would be possible with metal expansion. The thermostat is opening and closing properly. I did notice that the steam vent line to the radiator doesn't seem to be as warm as the radiator hoses and lines to the surge tank. The oil is fine, it is not milkshake.
I really feel like I am missing something here even though I was solid in my diagnosis initially when seeing the air in the surge tank.
It idles with a slight miss but really not that bad. My scanner isn't picking up any misfires. A compression test shows even compression. When it is cold it will warm up without putting any air into the surge tank. If I just fire it up cold and drive it to work which is about 5 miles it will push 2 gallons of water out of the system. If I fire it up and let it warm up then drive the same distance it goes through less than half a gallon. I know that it could be the metal expanding to make it seal somewhat better but it doesn't seem like a gallon and a half difference would be possible with metal expansion. The thermostat is opening and closing properly. I did notice that the steam vent line to the radiator doesn't seem to be as warm as the radiator hoses and lines to the surge tank. The oil is fine, it is not milkshake.
I really feel like I am missing something here even though I was solid in my diagnosis initially when seeing the air in the surge tank.
Thread Starter
Staging Lane
Joined: Sep 2006
Posts: 80
Likes: 3
The plugs looked like the normal lightly toasted marshmallow tan. I would've agreed with the shop 100% if the amount of loss was the same or more when doing a cold start and drive vs a warm up and drive. It just feels like im missing something. I'm going to air check the cylinder next weekend and look for bubbles in the surge tank.
You can't expect to drive around with a cracked radiator and not push water out
Do a cooling system pressure test. Rent the tool and the cap adapter from your local auto parts store
The silverado/tahoe/suburban are known to have leaks at the heater hose connectors at the firewall
Do a cooling system pressure test. Rent the tool and the cap adapter from your local auto parts store
The silverado/tahoe/suburban are known to have leaks at the heater hose connectors at the firewall
Coolant System Pressure Hi Skylark, not sure as you state a "broken" radiator as the cause ?
The cooling system MUST hold pressure OR the coolant WILL BOIL.
When the other items are repaired/correct, YES do a "leak down" if it overheats.
I do not trust those "repair shops" for good tech.
Lance
The cooling system MUST hold pressure OR the coolant WILL BOIL.
When the other items are repaired/correct, YES do a "leak down" if it overheats.
I do not trust those "repair shops" for good tech.
Lance
Last edited by pantera_efi; Jul 30, 2017 at 04:15 PM.
Teching In
Joined: Nov 2016
Posts: 47
Likes: 0
From: Va
Ive seen the hole in the radiator for stem line clog up often and cause it to overheat because it cant properly bleed the air from the system. The steam line should have coolant flowing through it back to the tank. If not something is clogged and it will overheat.
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The cracked radiator is sucking the pressure out of what is suppose to go to the thermostat. The radiator being cracked is taking away it's heat transfer abilities, you end up just boiling the coolant in that radiator hose and it blows out of the reservoir
Replace the radiator
Replace the radiator
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Thread Starter
Staging Lane
Joined: Sep 2006
Posts: 80
Likes: 3
Just for grins I had the shop that does my fleet work do the chemical test. The fluid went from outhouse water blue to a slight dark green tint. If combustion is present it should be yellow but the color change threw us off. What do you guys make of that?
I was bored when I got home and I air checked the cylinders with 130-140 psi. No bubbles. Then I did a compression check, 160-170 in all 8. The new radiator won't be here until Friday, possibly Monday. I will update as I have more info.
I was bored when I got home and I air checked the cylinders with 130-140 psi. No bubbles. Then I did a compression check, 160-170 in all 8. The new radiator won't be here until Friday, possibly Monday. I will update as I have more info.
Just for grins I had the shop that does my fleet work do the chemical test. The fluid went from outhouse water blue to a slight dark green tint. If combustion is present it should be yellow but the color change threw us off. What do you guys make of that?
I was bored when I got home and I air checked the cylinders with 130-140 psi. No bubbles. Then I did a compression check, 160-170 in all 8. The new radiator won't be here until Friday, possibly Monday. I will update as I have more info.
I was bored when I got home and I air checked the cylinders with 130-140 psi. No bubbles. Then I did a compression check, 160-170 in all 8. The new radiator won't be here until Friday, possibly Monday. I will update as I have more info.
Also starting to sound like you may not have a blown headgasket if you pressurized the system and saw no bubbles, but things change when it's hot and under combustion pressure so hopefully you get lucky.
Thread Starter
Staging Lane
Joined: Sep 2006
Posts: 80
Likes: 3
Well guys, I'm surprised. A new radiator and no more bubbles. I have straight water in it for the moment but I'm planning on driving it the rest of this week. If all goes well I will flush the system on Saturday and refill with distilled water and antifreeze. Thank you for the help!
Thread Starter
Staging Lane
Joined: Sep 2006
Posts: 80
Likes: 3
It passes the chemical test. Unfortunately I'm not convinced that I'm in the clear. Twice now on a cold start it runs rough for about 30 seconds and then it clears up. I'm not convinced that it isn't putting water into the cylinder. It is odd that it will maintain system pressure all day and then again all night. Hopefully I will get a few to play with it again this weekend and see if i have a wet or clean plug now that it can build and hold pressure.
Lol it's a suburban you picked up dirt cheap that's had zero maintenance done to it. Toss in a set of copper ngk plugs and some new wires, replace the fuel filter and do an oil change.
Thread Starter
Staging Lane
Joined: Sep 2006
Posts: 80
Likes: 3
Short of the oil change that is exactly what I did. It was serviced regularly. I have all of the maintenance records back to 2006. The lady literally cried when signing the title. It is actually pretty darn nice. I was going to do the oil change this weekend but I won't do that if I confirm a head gasket problem. Hopefully I will get enough time tomorrow to check it out.
Hyper Lube Coolant Tech Hi Skylark, I serviced my cooling system, new pump, rad, belts, etc.
I found Hyper Lube Coolant Treatment for $12.00 at Car Quest. (1/2 that of a gallon of Antifreeze Coolant)
This product will ADD the required chemicals to make the Distilled Water stable.
I also used one gallon of normal coolant mixed with "soft" water.
I believe it is normal for a slight "rough run" at start up, not a coolant leak.
Lance, BTW I place a magnet inside the Oil Filter.
I found Hyper Lube Coolant Treatment for $12.00 at Car Quest. (1/2 that of a gallon of Antifreeze Coolant)
This product will ADD the required chemicals to make the Distilled Water stable.
I also used one gallon of normal coolant mixed with "soft" water.
I believe it is normal for a slight "rough run" at start up, not a coolant leak.
Lance, BTW I place a magnet inside the Oil Filter.