High Pressure in Coolant Lines
09-11-2012, 11:49 PM
#1
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Thread Starter
High Pressure in Coolant Lines
Hey guys,
I've got a problem that rubs me the wrong way and I want to make sure I'm not missing something important.
So I recently have been seeing some leaking of anti-freeze on the ground within 5 minutes of shutting down and then it stops. Then it would happen again the next time I ran it, but only after the engine got hot.
I figured I had a bad seal around my lower radiator hose mount (that's about where the leak was), so I tightened it and it stopped.
Then the heater control valve BLEW UP on my way to work!!
It really just split in half and very quickly emptied 80% of the system contents.
So then I used a bunch of high-heat plastic epoxy and fiberglass to hold it together (just curious
) and it worked somewhat but then I noticed that all the hoses looked bloated after I had it running for awhile. So I opened the bleed valve and it hissed out a bunch of air and hoses were normal again. Could it be that I wasn't bleeding the system while running/hot and the high air pressure is what has been causing all this? Or is it possible I have a blockage somewhere (and could that cause the air pressure)? I have a new heater control valve ready to go in, but if the pressure is coming from somewhere else then I don't know what I should do. Any ideas or should I be good with an effective bleeding and new valve?
I've got a problem that rubs me the wrong way and I want to make sure I'm not missing something important.
So I recently have been seeing some leaking of anti-freeze on the ground within 5 minutes of shutting down and then it stops. Then it would happen again the next time I ran it, but only after the engine got hot.
I figured I had a bad seal around my lower radiator hose mount (that's about where the leak was), so I tightened it and it stopped.
Then the heater control valve BLEW UP on my way to work!!
It really just split in half and very quickly emptied 80% of the system contents. So then I used a bunch of high-heat plastic epoxy and fiberglass to hold it together (just curious
) and it worked somewhat but then I noticed that all the hoses looked bloated after I had it running for awhile. So I opened the bleed valve and it hissed out a bunch of air and hoses were normal again. Could it be that I wasn't bleeding the system while running/hot and the high air pressure is what has been causing all this? Or is it possible I have a blockage somewhere (and could that cause the air pressure)? I have a new heater control valve ready to go in, but if the pressure is coming from somewhere else then I don't know what I should do. Any ideas or should I be good with an effective bleeding and new valve?
09-12-2012, 09:30 AM
#3
Proprietoristicly Refined
Rennlist Member
Rennlist Member
Do a proper "leak down test".
You may have a bad HG head gasket and it is pressurizing the coolant system.
You can listen for air leaks/bubbles out of the coolant reservoir tank/cap, the exhaust pipe, oil filler cap...
http://www.dietersmotorsports.com/Co...akdowntest.htm
A warm engine is preferred for the test- both leak down and compression if done.
More info:
https://rennlist.com/forums/924-931-...dc-or-tdc.html
GL
John
You may have a bad HG head gasket and it is pressurizing the coolant system.
You can listen for air leaks/bubbles out of the coolant reservoir tank/cap, the exhaust pipe, oil filler cap...
http://www.dietersmotorsports.com/Co...akdowntest.htm
A warm engine is preferred for the test- both leak down and compression if done.
More info:
https://rennlist.com/forums/924-931-...dc-or-tdc.html
GL
John
09-12-2012, 01:06 PM
#4
You should always bleed it after draining coolant. Was it running hot afterwards? Too much air in the system will case a hot condition, and perhaps your bulging hoses.
09-12-2012, 01:45 PM
#5
Nordschleife Master
The small leak you had at the front, is it still there? Could be a loose hose clamp but could also be the first sign of a pump failure. They leak a little coolant before they fail.
The heater valve bursting was probably because it was old. They do just give-up without warning.
Bulging hoses will happen with air in the system, a blockage or a defective cap.
The bleed valve will collect air as its (just about) the highest point of the system. When I bleed I like to jack the front of the car to get that bleed valve even higher.
You do need to bleed the system with a Motive and with the heater on to get all the air out.
GL
The heater valve bursting was probably because it was old. They do just give-up without warning.
Bulging hoses will happen with air in the system, a blockage or a defective cap.
The bleed valve will collect air as its (just about) the highest point of the system. When I bleed I like to jack the front of the car to get that bleed valve even higher.
You do need to bleed the system with a Motive and with the heater on to get all the air out.
GL
09-12-2012, 07:11 PM
#7
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Sounds similar to what I went through this summer. My cap was OK, but it probably wasn't properly vented. I replaced pretty much every coolant hose including my HCV (yes that blowout is spectacular, eh? props on the MacGuyver save with yours, luckily it's a cheap part).
Once I had the last hose replaced and did a proper 'burping' after refilling the coolant a month ago now, I haven't had any issues and the car doesn't overheat. Even idling in traffic. In Dallas. In August. Loving it!
Wow, sage words from a well-known contributor! Take heed!
Once I had the last hose replaced and did a proper 'burping' after refilling the coolant a month ago now, I haven't had any issues and the car doesn't overheat. Even idling in traffic. In Dallas. In August. Loving it!
Wow, sage words from a well-known contributor! Take heed!
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09-12-2012, 08:48 PM
#8
It sounds like a lot of pressure in your system if the pipes are swelling.
There is a thing in England that the mechanics slang term is sniff test, it basically uses a chemical to test for exhaust gasses in the coolant expansion tank, maybe you could take it to a shop and have them run that test, it takes less than a minute to do.
Air in the system will definitely increase pressure but i'm not sure it would to that extent
Good luck
kim
There is a thing in England that the mechanics slang term is sniff test, it basically uses a chemical to test for exhaust gasses in the coolant expansion tank, maybe you could take it to a shop and have them run that test, it takes less than a minute to do.
Air in the system will definitely increase pressure but i'm not sure it would to that extent
Good luck
kim
10-22-2012, 06:21 PM
#9
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Thread Starter
Followup
Thank you all for the great responses, and I apologize for the time it's taken me to input again.
Thanks, 44cupmaster and John_AZ, I think I DO have a HG problem. When I start the car it sputters for about 4 seconds with slightly more visible exhaust than normal. I think this is coolant burning out of the cylinders. The coolant probably gets into the cylinders after shutdown when the pressure in the hoses that came from the combustion gasses seeps backward through the head gasket leak.
The leak IS coming from a hose connection which I have tightened up, but the pressure is much higher than normal so it nonetheless finds a way out.
I have found a head gasket set with all the associated gaskets and such for about $100, does anyone know if this is the best deal out there before I order it?
Again, thanks a ton everyone!
Thanks, 44cupmaster and John_AZ, I think I DO have a HG problem. When I start the car it sputters for about 4 seconds with slightly more visible exhaust than normal. I think this is coolant burning out of the cylinders. The coolant probably gets into the cylinders after shutdown when the pressure in the hoses that came from the combustion gasses seeps backward through the head gasket leak.
The leak IS coming from a hose connection which I have tightened up, but the pressure is much higher than normal so it nonetheless finds a way out.
I have found a head gasket set with all the associated gaskets and such for about $100, does anyone know if this is the best deal out there before I order it?
Again, thanks a ton everyone!
10-22-2012, 07:49 PM
#10
Proprietoristicly Refined
Rennlist Member
Rennlist Member
You have an '89 944NA with the 2.7 (pls update your signature line)
You should get new head nuts, a couple of exhaust manifold flange gaskets, and everything you can think of that is under the intake manifold. Clamps, hoses, ties, ICV mounts, AOS seals, oil dipstick "O" ring, maybe a new heater control valve.
If your coolant is over 2 years old flush the cooling system before you start and refill when finished.
About $100 is very good for a HG set. I hope it has not sat on a shelf since 2000.
The WYAIT stuff is very important. Allow at leat 3 hours to clean all the gasket material off the block.
Do you plan to have the head machined? If not, are you going to replace the valve stem seals and check the valves for sealing with the water test?
New Injector seals?
On and on...
GL
John
You should get new head nuts, a couple of exhaust manifold flange gaskets, and everything you can think of that is under the intake manifold. Clamps, hoses, ties, ICV mounts, AOS seals, oil dipstick "O" ring, maybe a new heater control valve.
If your coolant is over 2 years old flush the cooling system before you start and refill when finished.
About $100 is very good for a HG set. I hope it has not sat on a shelf since 2000.
The WYAIT stuff is very important. Allow at leat 3 hours to clean all the gasket material off the block.
Do you plan to have the head machined? If not, are you going to replace the valve stem seals and check the valves for sealing with the water test?
New Injector seals?
On and on...
GL
John
10-22-2012, 08:26 PM
#11
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Join Date: Oct 2009
Location: one thousand, five hundred miles north of Ft. Lauderdale for the summer.
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my car is living large thanks to head gasket sealer.
now like, 14 k miles since the cheap fix.
most under-rated product evarr, imo.
now like, 14 k miles since the cheap fix.
most under-rated product evarr, imo.
10-27-2012, 07:23 PM
#12
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Thread Starter
This scares me a bit, not sure I would want to put that kind of product in my engine. Does anyone have anything to support my hesitation or is it worth a shot? I'm not overly opposed to replacing the gasket, but it DOES seem to be a small leak and if I don't have to, well, I'd rather not.
07-13-2015, 11:13 AM
#13
Hi TheCousinDan, did you find a solution to your coolant bloating problem? I have a similar issue with excessive amount of air into the coolant after starting the engine.
Br
-Nik
Br
-Nik
