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How to remove air from cooling system

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erictr6 Avatar
erictr6 eric l
Denver, NC, USA   USA
In a 1981 TR8, a little background, the header tank had a leak around the top seal. Removed it and had a rad shop, tin it and resolder, being careful not to go near the low coolant sensor since I wasn't able to find a replacement at the time. He pressure tested to 15psi and held nicely. Installed the tank added coolant, went for a ride last night under the full moon for about 40 minutes.When I returned and pulled into the garage the overflow tube blasted coolant all over the floor. Cleaned up and called it a night This morning added coolant, let the car idle with rad cap off until the coolant level in the header tank went down, shut down, added more coolant, ran again till hot and then the header tank overflowed. Repeated the process and same results. The correct thermostat and water pump were installed within the past 18 months along with new hoses, Wedge Shops aluminum radiator and electric fan. There is no sign of coolant in the oil. I'm thinking its air in the cooling system. The red book does not have a detailed process to bleed air. Can someone advise the procedure?
Could it be something else?

Thank you in advance for your reply.



Edited 1 time(s). Last edit at 2017-11-04 10:28 AM by erictr6.

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darrellwalker Darrell Walker
Vancouver, Washington, USA   USA
1966 Triumph TR4A "Christy"
1981 Triumph TR8 "Kate"
First of all, how much are you filling the overflow tank? If I fill it more than half way, it will vent fluid.

I've found jacking the front end of the car up as high as possible helps get the air purged.



Darrell Walker
66 TR4A IRS-SC CTC67956L
81 TR8 SATPZ458XBA406206
Vancouver, WA, USA

TeeR8 Avatar
TeeR8 Gold Member Henri Lefebvre
Calgary, Alberta, Canada   CAN
Does your thermostat have a vent hole to help purge the air through the thermostat? You can drill a small hole, about 1/8", on the edge of the thermostat and position the hole at the top position when you install the thermostat.
As mentioned, raising the front as high as possible helps purge the air in the top hose.
Massaging the top hose also helps move the air towards the rad and pump coolant in the hose.
Repeating the cold/hot cycle will eventually purge the air.



Henri
1980 TR8, Platinum
1971 MGB GT, Midnight Blue



Edited 1 time(s). Last edit at 2017-11-04 10:45 AM by TeeR8.

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POW Peter Wirth
HEBRON, NH - New Hampshire, USA   USA
The header tank is kind of but not really an overflow reservoir. I added a true reservoir by mounting a pint canning jar in the location for the former FI airbox. If you still have this you still should be able find a suitable location somewhat on the same plane as the header tank. By running the overflow hose that now goes through the right fender into the jar lid about 1/2" and using a like hose from the header tank again through the lid but to the bottom the jar, you will have your overflow system. Still try to get as much air as possible out of the system but what is left will self purge. As the coolant expands out of the header tank it will go into the jar instead of on the floor. As the system cools the contents will be drawn back into the header tank. Next day top up the header tank and if necessary bring level of overflow jar to around 2" or so. This works just like a modern system in that coolant expands to around 2" from top of overflow jar when hot, and contracts back down to around 2" level in the morning, all the while keeping the header tank full with no chance of drawing air. Here is a bit more about purging the system with post #4 showing what I put together. - Pete

http://www.triumphexp.com/phorum/read.php?3,1471791

Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, Oregon, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1495829 by erictr6 In a 1981 TR8, a little background, the header tank had a leak around the top seal. Removed it and had a rad shop, tin it and resolder, being careful not to go near the low coolant sensor since I wasn't able to find a replacement at the time. He pressure tested to 15psi and held nicely. Installed the tank added coolant, went for a ride last night under the full moon for about 40 minutes.When I returned and pulled into the garage the overflow tube blasted coolant all over the floor. Cleaned up and called it a night This morning added coolant, let the car idle with rad cap off until the coolant level in the header tank went down, shut down, added more coolant, ran again till hot and then the header tank overflowed. Repeated the process and same results. The correct thermostat and water pump were installed within the past 18 months along with new hoses, Wedge Shops aluminum radiator and electric fan. There is no sign of coolant in the oil. I'm thinking its air in the cooling system. The red book does not have a detailed process to bleed air. Can someone advise the procedure?
Could it be something else?

Thank you in advance for your reply.

Eric:

Without being there, it sounds like you are simply overfilling the header tank. The tank is intended to handle the inevitable expansion of the coolant during warm up. As such it must not be full when cold.

With the engine cold, the header tank should have enough coolant to cover the low coolant sensor and no more. If you fill it to the bottom of the filler neck, it will definitely vent coolant when hot, as it is designed to do that when overfilled.

When cold it should be roughly half full. When hot it will be much closer to the filler neck, but as the engine cools the coolant will once again drop. This is what it is supposed to do.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

REXUK Rex Holford
Southampton, Hampshire, UK   GBR
The method I have used in the past is to first ensure that the heater lever is in the hot position so that water can flow through the heater without trapping air. Next when working from a cold engine fill the top up tank to the halfway mark. Then, with the cap removed, start the engine and allow it to idle until the water in the tank begins to rise. Switch off the engine for a few minutes to allow the air to escape and the water level to lower, if necessary then top up tank to half way. Repeat this procedure allowing the temperature to rise to a quarter of the way up the gauge. Switch off the engine and allow it to settle for about five minutes. Top up the tank again, start the engine and allow it to run up to operating temperature (just under halfway up the gauge). All the air should now be expelled. Replace the cap and leave engine running for a few minutes to make sure everything has settled down. When the engine is cold check the level in the top up tank, fill as necessary to halfway.
Enjoy your motoring.
Rex

Bergie Bob Berg
Powell, Ohio, USA   USA
fill header tank 1 inch below top...run car until it slowly reaches the top of tank as car warms up and thermostat slowly opens releasing air...cap it...drive around with heater on and off...check cold again, repeat a and or refill 1 inch below..3-4 times then you should be done bleeding/burping it...

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hdeyong Harry DeYong
Bargemon, PACA, France   FRA
I agree with TeeR8.
I had the same problem recently with another car. Filled the cooling system for the first time and there was an air pocket stuck behind the thermostat, and the air wasn't hot or dense enough to open it. So, the engine started running too hot with the thermostat still closed. Drilled a 3/16" hole in the stat and the problem was solved.



Edited 1 time(s). Last edit at 2017-11-09 01:03 AM by hdeyong.

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