Blown head gasket?
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FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
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From: Cabot, Arkansas
Blown head gasket?
I need some more opinions....
If you've been following my adrenaline thread you know I'm having issues with the truck spitting coolant out the degas bottle when I'm driving it.
The first time it did it (yesterday) I was at 30psi and roughly 1250-1300 degrees EGT.
To date I've pressure test the cooling system cold. It will hold 17lbs static. I've pressure tested it at idle and it only builds to 3-4 psi. I also loaded the system to 16 PSI with the engine running and noticed no fluctuation in the pressure. Also pressure tested the cap to 17 PSI. There is no fuel in the coolant, no coolant in the oil, and no coolant out the exhaust. It also seems to idle and run completely normally.
Those tests are the only way I know of to test for a blown HG without a compression tester, and they all passed. Therefore I think the head gasket should not be blown, and yet it still pressurizes the degas bottle and vents past the cap every time I drive it.
Is it possible for a head gasket to loose it's seal while under boost, but then reseal off boost? And if that is possible, how would one go about isolating which bank has the leaker? Not even sure a compression test could find that since it idles perfectly.
If you've been following my adrenaline thread you know I'm having issues with the truck spitting coolant out the degas bottle when I'm driving it.
The first time it did it (yesterday) I was at 30psi and roughly 1250-1300 degrees EGT.
To date I've pressure test the cooling system cold. It will hold 17lbs static. I've pressure tested it at idle and it only builds to 3-4 psi. I also loaded the system to 16 PSI with the engine running and noticed no fluctuation in the pressure. Also pressure tested the cap to 17 PSI. There is no fuel in the coolant, no coolant in the oil, and no coolant out the exhaust. It also seems to idle and run completely normally.
Those tests are the only way I know of to test for a blown HG without a compression tester, and they all passed. Therefore I think the head gasket should not be blown, and yet it still pressurizes the degas bottle and vents past the cap every time I drive it.
Is it possible for a head gasket to loose it's seal while under boost, but then reseal off boost? And if that is possible, how would one go about isolating which bank has the leaker? Not even sure a compression test could find that since it idles perfectly.
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FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
Likes: 6
From: Cabot, Arkansas
No....it's never been to 40 PSI. Back before the injectors when I was on the water/meth I would occasionally hit 35, but that was more than three years ago, and it hasn't been past 32 psi since then.
Thread Starter
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FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
Likes: 6
From: Cabot, Arkansas
Not tonight. I still don't know how to isolate a head with no symptoms.
Postmaster
Joined: Oct 2004
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Likes: 1
Scott, I'm not saying you have a blown HG, but I think there is some solid (since you said "bolts")info in this....It is a Copy/Paste of a post by Dave of SWAMPS that I read on PSN yesterday. He was posting to a guy who blew a HG the other day.
The factory gaskets aren't "junk"...but NEWLY INSTALLED factory HG's are junk.
The new gaskets had not embedded onto the block & heads like your factory (originally installed) gaskets had...the graphite composition of those style gaskets create a mechanical bond to both head & block.
When someone calls up saying that they had just rebuilt the engine, and they installed factory gaskets and studs...I KNOW that even that combination will NOT hold the boost & cylinder pressure of the OEM (many tens of thousands of miles old) gaskets.
Worse yet, someone buys studs from XYZ Performance and actually PULLS THEIR HEADS to replace the (perfectly good) factory gaskets JUST to install new gaskets with studs...with big plans of holding big boost.
Oooooolllllld (original) gaskets with newly installed studs are terrific...and routinely hold 60+psi boost.
new gaskets and studs routinely hold 45-55psi boost.
new gaskets and new stock bolts routinely fail sub 35psi.
Were your block & heads both checked for flatness prior to you reassembling them during the rebuild?
I'm also going to add one more nugget of experience to this, that you are not going to want to hear.
The cylinder which blew the HG will need the connecting rod replaced.
The gasket blowing allowed a big gulp of coolant to wash into that cylinder at full rpm.
Rods do not much care for trying to compress a liquid, and that rod WILL be highly highly suspect in its ability to hold anything more than bone stock power levels reliably.
If you do NOT replace that rod, I would give you a 50/50 chance of getting your head gasket situation resolved with studs...only to have that rod punch a hole through your block within months.
The factory gaskets aren't "junk"...but NEWLY INSTALLED factory HG's are junk.
The new gaskets had not embedded onto the block & heads like your factory (originally installed) gaskets had...the graphite composition of those style gaskets create a mechanical bond to both head & block.
When someone calls up saying that they had just rebuilt the engine, and they installed factory gaskets and studs...I KNOW that even that combination will NOT hold the boost & cylinder pressure of the OEM (many tens of thousands of miles old) gaskets.
Worse yet, someone buys studs from XYZ Performance and actually PULLS THEIR HEADS to replace the (perfectly good) factory gaskets JUST to install new gaskets with studs...with big plans of holding big boost.
Oooooolllllld (original) gaskets with newly installed studs are terrific...and routinely hold 60+psi boost.
new gaskets and studs routinely hold 45-55psi boost.
new gaskets and new stock bolts routinely fail sub 35psi.
Were your block & heads both checked for flatness prior to you reassembling them during the rebuild?
I'm also going to add one more nugget of experience to this, that you are not going to want to hear.
The cylinder which blew the HG will need the connecting rod replaced.
The gasket blowing allowed a big gulp of coolant to wash into that cylinder at full rpm.
Rods do not much care for trying to compress a liquid, and that rod WILL be highly highly suspect in its ability to hold anything more than bone stock power levels reliably.
If you do NOT replace that rod, I would give you a 50/50 chance of getting your head gasket situation resolved with studs...only to have that rod punch a hole through your block within months.
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Postmaster
Joined: Feb 2004
Posts: 3,266
Likes: 0
From: Levittown
Chit!
Scott
The 15/17 psi coolant test might be to low of a pressure
to see/find the leak. Your going to have to test from the
cylinder side. Its a much higher pressure.
They do have test strips for the coolant. It test for combustion
gas in the coolant.
Bill
Scott
The 15/17 psi coolant test might be to low of a pressure
to see/find the leak. Your going to have to test from the
cylinder side. Its a much higher pressure.
They do have test strips for the coolant. It test for combustion
gas in the coolant.
Bill
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Thread Starter
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FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
Likes: 6
From: Cabot, Arkansas
Scott, I'm not saying you have a blown HG, but I think there is some solid (since you said "bolts")info in this....It is a Copy/Paste of a post by Dave of SWAMPS that I read on PSN yesterday. He was posting to a guy who blew a HG the other day.
The factory gaskets aren't "junk"...but NEWLY INSTALLED factory HG's are junk.
The new gaskets had not embedded onto the block & heads like your factory (originally installed) gaskets had...the graphite composition of those style gaskets create a mechanical bond to both head & block.
When someone calls up saying that they had just rebuilt the engine, and they installed factory gaskets and studs...I KNOW that even that combination will NOT hold the boost & cylinder pressure of the OEM (many tens of thousands of miles old) gaskets.
Worse yet, someone buys studs from XYZ Performance and actually PULLS THEIR HEADS to replace the (perfectly good) factory gaskets JUST to install new gaskets with studs...with big plans of holding big boost.
Oooooolllllld (original) gaskets with newly installed studs are terrific...and routinely hold 60+psi boost.
new gaskets and studs routinely hold 45-55psi boost.
new gaskets and new stock bolts routinely fail sub 35psi.
Were your block & heads both checked for flatness prior to you reassembling them during the rebuild?
I'm also going to add one more nugget of experience to this, that you are not going to want to hear.
The cylinder which blew the HG will need the connecting rod replaced.
The gasket blowing allowed a big gulp of coolant to wash into that cylinder at full rpm.
Rods do not much care for trying to compress a liquid, and that rod WILL be highly highly suspect in its ability to hold anything more than bone stock power levels reliably.
If you do NOT replace that rod, I would give you a 50/50 chance of getting your head gasket situation resolved with studs...only to have that rod punch a hole through your block within months.
The factory gaskets aren't "junk"...but NEWLY INSTALLED factory HG's are junk.
The new gaskets had not embedded onto the block & heads like your factory (originally installed) gaskets had...the graphite composition of those style gaskets create a mechanical bond to both head & block.
When someone calls up saying that they had just rebuilt the engine, and they installed factory gaskets and studs...I KNOW that even that combination will NOT hold the boost & cylinder pressure of the OEM (many tens of thousands of miles old) gaskets.
Worse yet, someone buys studs from XYZ Performance and actually PULLS THEIR HEADS to replace the (perfectly good) factory gaskets JUST to install new gaskets with studs...with big plans of holding big boost.
Oooooolllllld (original) gaskets with newly installed studs are terrific...and routinely hold 60+psi boost.
new gaskets and studs routinely hold 45-55psi boost.
new gaskets and new stock bolts routinely fail sub 35psi.
Were your block & heads both checked for flatness prior to you reassembling them during the rebuild?
I'm also going to add one more nugget of experience to this, that you are not going to want to hear.
The cylinder which blew the HG will need the connecting rod replaced.
The gasket blowing allowed a big gulp of coolant to wash into that cylinder at full rpm.
Rods do not much care for trying to compress a liquid, and that rod WILL be highly highly suspect in its ability to hold anything more than bone stock power levels reliably.
If you do NOT replace that rod, I would give you a 50/50 chance of getting your head gasket situation resolved with studs...only to have that rod punch a hole through your block within months.
Thread Starter
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FTE Leadership Emeritus
Joined: May 2001
Posts: 13,653
Likes: 6
From: Cabot, Arkansas
You mean a compression test? What else is there from the cylinder side?
Elder User
Joined: May 2008
Posts: 860
Likes: 2
From: Liberty Lake, WA
Seems like it would be smoking like a banshee if you have a blown HG. Anti-freeze would be entering exhaust and thru your turbo and out the tail pipe. It would also be likely you'd see some seeping out the head.
Thread Starter
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FTE Leadership Emeritus
Joined: May 2001
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From: Cabot, Arkansas
Originally Posted by Tenn01PSD350
At what point does it start puking coolant?
Thread Starter
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FTE Leadership Emeritus
Joined: May 2001
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From: Cabot, Arkansas
Exactly what I'm thinking....neither of those things are happening.