how do you elininate this air lock?The initial overheating problem would have been due to an air lock under the thermostat caused by replacing the heater core.
Over heating dramas LONGWINDED
Started by
REDA9X
, Jan 06 2007 09:47 AM
50 replies to this topic
#26
makka
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Posted 08 January 2007 - 01:12 PM
#27
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Posted 08 January 2007 - 01:43 PM
Some cooling systems are sensitive to airlocks some are not. If for example you fit a heater to a red 6 and dont bleed the system so the heater pipe and hoses are full, all that will happen is that after running the motor for a minute or two, the system will need topping up at the radiator. The only issue would be if running a gas convertor where it may freeze up near instantly if there is no water in the hoses to start with. Havent had experience with the v8 to know if that is similar. Have had experience with an ea falcon that was extremely sensitive to this and would need careful bleeding when adding extra coolant if it had got low, it would take weeks for the air to bleed out by itself.....and run hot in the meantime.
To eliminate the airlocks, bleed the system, one way is to disconnect the top heater hose at the engine end and fill it directly with a hose so that the system then fills firstly through the heater core, then return which leads to bottom hose of the rad, have the cap open and your finger over the heater outlet pipe and let the water flow out the top of the rad. Then put the rad cap on and let the water flow out the top heater outlet till there is a solid flow, then put the heater hose back on losing as little water as possible. There are also typically drain holes on cylinder blocks that allow you to do this, but often they are corroded, not easy to get at and may leak after using them. Also consider if the car is on a slope, best to fill with nose of car uphill.
To eliminate the airlocks, bleed the system, one way is to disconnect the top heater hose at the engine end and fill it directly with a hose so that the system then fills firstly through the heater core, then return which leads to bottom hose of the rad, have the cap open and your finger over the heater outlet pipe and let the water flow out the top of the rad. Then put the rad cap on and let the water flow out the top heater outlet till there is a solid flow, then put the heater hose back on losing as little water as possible. There are also typically drain holes on cylinder blocks that allow you to do this, but often they are corroded, not easy to get at and may leak after using them. Also consider if the car is on a slope, best to fill with nose of car uphill.
Edited by devilsadvocate, 08 January 2007 - 01:57 PM.
#28
REDA9X
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Posted 12 January 2007 - 01:28 PM
Well it's a stinking hot day today, I took t for a drive. It ran at 1/4 on 80, but on the M4 at 100-110 it ran at 1/2. I pulled up at the servo and ran the lazer over it while still running and got 80c in the top hose and about the same in the bottom, the top tank read 100 though......
#29
TerrA LX
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Posted 12 January 2007 - 02:33 PM
lazer maynot be as accurate as a probe, M4 servo is close to me, arrange a time if you want and we will give your motor a poke.
EDIT i find it a lil strange for the top of the motor to be 20 deg cooler than the rad after a freeway sprint.
EDIT i find it a lil strange for the top of the motor to be 20 deg cooler than the rad after a freeway sprint.
Edited by ALX76, 12 January 2007 - 02:34 PM.
#30
REDA9X
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Posted 12 January 2007 - 02:56 PM
it has me buggered, I have a big 3 core one here, might see how that goes in it.
#31
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Posted 12 January 2007 - 03:39 PM
I think he said top hose ^, not the motor. Is this the first time the laser has given inconsistent readings from engine block to hose to top tank. The thermostat cover, top hose and top tank should all be within a deg or so with full coolant flow, Id believe what the top tank reading says, given your temp gauge reading........what was the bottom hose temp. Shiny things can give poor readings, but a rad hose.....possible. For best possible diagnosis, temps need to be measured with the conditions the engine is running too hot in , ie dynamically(the effect of airflow at speed is the big factor)......a sensor which can give you readings on the move in the bottom hose or bottom tank of the rad. Typically the temp of the coolant will increase when you reduce the motor to idle after a run on the highway, much like heatsoak after shutdown. This is because the cylinder head itself becomes much hotter than the coolant at 100kmh than it would at 60kmh, you can see this by looking at oil temperature. Once you stop the coolant circulating quickly, idling the motor, the coolant is in much longer contact with the block and will become hotter, even the temp in the radiator can increase in the short term if you come to a stop due to relatively no airflow through the rad. Its a little like if youve been running outside or even riding a push bike hard, stop and park yourself and you start to perspire more than when you were actually moving.
#32
View GaragePosted 12 January 2007 - 03:48 PM
RED - I know you have already checked the rad - but from what i have read this is "classic" blocked radiator. Had a very similar problem with a rodeo - fine city driving even some freeway driving - but with a load the temp would climb. It steadily got worse - radiator was 60% blocked. When you try the 3 core have the std one check out properly. Also double check your overflow hose and make sure its not blocked.
#33
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Posted 12 January 2007 - 05:06 PM
iv often found those laser to be to inconsistant,givin heat readins from other things ,with a slight movement a complete diff reading.We now use a expensive temp probe with far better results.Rubber hoses wont transfer heat like brass will and will give a lower reading.
What motor do you have?If its a 308 you will need the big tank 3 row as the two rows are only for the 253,6cyls.
What motor do you have?If its a 308 you will need the big tank 3 row as the two rows are only for the 253,6cyls.
#35
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Posted 12 January 2007 - 07:22 PM
its still only a 308 isnt it, or are we looking at something with bigger cubes
#36
REDA9X
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Posted 13 January 2007 - 01:10 PM
It's a bog stock 308 as it left the factory. Original radiator was a 2 core, the current one is the same size as the 2 core, but it has a 3 core installed. The spare I have is the original factory 3 core as fitted to the Aircon versions, it's physically larger. The lazer is consistant, it's not a cheap one , I borrowed it from work. We used to use it for engine running. The temp on the thermostat housing was about 79, the hoses were both 80 and the top tank was 100. This was after driving down the M4 to the Caltex, pulling up and with engine and fan running. The car got past 3/4 quickley and then began to run rough. Once getting back on the M4 the car ran at just over half, and once in the 80 zone it ran at about 3/8. I'm going to pull the radiator and get it cleaned out anyway, I just wanted to cover every angle before throwing $110 into a wasted cause.
#37
boomfunk
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Posted 13 January 2007 - 01:55 PM
get them to poke every core out with wire, no use just blowing it clean or some other method, get them to poke it clean then you no it is totaly unblocked....
its well worth it
its well worth it
#38
REDA9X
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Posted 13 January 2007 - 02:32 PM
Yeah they do, I've had it done before, it's like a file or wire brush
#39
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Posted 13 January 2007 - 04:44 PM
its just a thin flat rod,comes in different size deppending on the tube width.The only way to get the things clean.
#40
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Posted 13 January 2007 - 05:31 PM
What was your temperature gauge saying when the IR sensor said the thermostat cover was at 79C?The temp on the thermostat housing was about 79, the hoses were both 80 and the top tank was 100. Once getting back on the M4 the car ran at just over half, and once in the 80 zone it ran at about 3/8.
I gather you have learnt what temp the motor is for certain positions of the gauge, not sure on the calibration of the gauge in the A9X, but in the UC maybe the LX too, they deliberately desensitised the gauges so that ~12 oclock was 100C.
#41
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Posted 13 January 2007 - 06:06 PM
One thing to keep in mind when using "laser" thermometers is that the laser is not used to read the temperature it is to tell you where you are pointing the infrared sensor which reads the temperature.
The area read by the infrared sensor gets larger the further away from the object you are. The reading is the average temperature within the infrared sensor circle. My Raytek minitemp has a 25mm sensor area at 2m.
The area read by the infrared sensor gets larger the further away from the object you are. The reading is the average temperature within the infrared sensor circle. My Raytek minitemp has a 25mm sensor area at 2m.
Edited by AndyCullen, 13 January 2007 - 06:09 PM.
#42
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Posted 13 January 2007 - 09:58 PM
Bummer Red. My L31 runs hot on 10 degrees static advance, have to run 12. Might be worth a shot. Does sound like blocked radiator though, maybe dislodged some build-up on the sides of the rubber hoses, which ended up in the radiator.
To rule out running lean, pop into a dyno place and just get them to stick it on the dyno with the gas analyser on it. Check both sides unless you are running a balance pipe (I'm not). Carburettor's get a gum build up which does eventually block up jets.
From what I've seen, does seem like blocked radiator.
To rule out running lean, pop into a dyno place and just get them to stick it on the dyno with the gas analyser on it. Check both sides unless you are running a balance pipe (I'm not). Carburettor's get a gum build up which does eventually block up jets.
From what I've seen, does seem like blocked radiator.
#43
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Posted 13 January 2007 - 10:10 PM
At the point where I pulled up, the gauge was on just over 1/2, so I guess around 80c is 1/2.... . Anyway, Even if the gauge was buggered and the lazer didn't work, the car has always reached a point where once it gets to about 3/4 or more the car runs rough and the revs come up, so it's definately getting hot because at 3/4 on the gauge it started to run rough and the revs came up. And Andy, yes I did know that about the lazer.
#44
TerrA LX
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Posted 14 January 2007 - 02:38 AM
runs rough AND the revs come up. sounds stupid but next time rip the air cleaner off and have a look at the choke and carb linkages, shouldnt matter how hot they get, the revs dont usually go up.
#45
REDA9X
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Posted 15 March 2007 - 07:52 AM
I got my hands on a nice clean genuine factory air large 3 core unit a few weeks ago, a mate loaned it to me. I put it in yesterday and ran the car for about half an hour or more at idle and it didn't get past half, very unusual for this car. It sat consistantly at about 82degrees at idle, now for the test on Sunday when I drive to Newcastle.
#46
REDA9X
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Posted 15 March 2007 - 10:18 PM
I did some interesting tests today with the factory aircon radiator fitted at idle and the fan on.
at idle with the auto choke still engauged the car idled at 1000rpm
at 1/4 on the gauge it sat on
74Degrees C at the thermostat housing
top hose was 73 to 70 DC (moving from thermostat housing towards the radiator)
top tank 82-75DC ( moving from the inlet across the top of the tank)
bottom hose was 75DC.
At idle of 750rpm at 3/8 on the gauge it was (as above)
78
77-75
85-79
78
At idle at 1/2 on the gauge
80
80-78
88-81
80
At idle at 5/8 on the gauge
88
88-83
88-81
80
to get the car to go to 3/4 I had to turn the fan off ( thats a first)
When it reached 3/4 the revs automatically came up to 1000RPM and the fan automatically kicked in. The switch says 95 degees C (which it was exactly)
temps were
93
91-89
100-96
92.
Looks like it's working correctly now to me, the test will be going for a drive along the M4 and seeing what it does at speed. It was interesting to get a good comparison between the gauge markings and actual temp.
180-190 degees F is the correct running temp, so about 82-88DC, so looks good so far.
at idle with the auto choke still engauged the car idled at 1000rpm
at 1/4 on the gauge it sat on
74Degrees C at the thermostat housing
top hose was 73 to 70 DC (moving from thermostat housing towards the radiator)
top tank 82-75DC ( moving from the inlet across the top of the tank)
bottom hose was 75DC.
At idle of 750rpm at 3/8 on the gauge it was (as above)
78
77-75
85-79
78
At idle at 1/2 on the gauge
80
80-78
88-81
80
At idle at 5/8 on the gauge
88
88-83
88-81
80
to get the car to go to 3/4 I had to turn the fan off ( thats a first)
When it reached 3/4 the revs automatically came up to 1000RPM and the fan automatically kicked in. The switch says 95 degees C (which it was exactly)
temps were
93
91-89
100-96
92.
Looks like it's working correctly now to me, the test will be going for a drive along the M4 and seeing what it does at speed. It was interesting to get a good comparison between the gauge markings and actual temp.
180-190 degees F is the correct running temp, so about 82-88DC, so looks good so far.
#47
REDA9X
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Posted 16 March 2007 - 03:58 PM
Drove it today, ran fine, sat on 1/4 at 80 and all the way to 110kmh along the freeway. Now all I should need to do is get the radiator that came out cleaned.
#48
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Posted 16 March 2007 - 07:19 PM
First time I read this thread was today. I know the pain you share as do many. Nothing worse than an overheating car and not being able to find the problem why.
Looks as though it may be solved with this other radiator so my fingers are crossed for you, Good luck!
Looks as though it may be solved with this other radiator so my fingers are crossed for you, Good luck!
#49
LXCHEV
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Posted 16 March 2007 - 11:52 PM
RED - congrats on finally fixing the problem!!! What a relief.
I've been thinking about it - it's so strange how the problem suddenly appeared, only after you changed the heater core. Perhaps the new core had some debris or muck in it, which was instantly introduced to the system, and therefore started blocking your previously good radiator? It's the only thing that makes sense to me.
When you do get your old radiator pulled apart - make sure you ask them to visually inspect it first and tell you if it is blocked or not.
Either way, well done!
I've been thinking about it - it's so strange how the problem suddenly appeared, only after you changed the heater core. Perhaps the new core had some debris or muck in it, which was instantly introduced to the system, and therefore started blocking your previously good radiator? It's the only thing that makes sense to me.
When you do get your old radiator pulled apart - make sure you ask them to visually inspect it first and tell you if it is blocked or not.
Either way, well done!
#50
REDA9X
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Posted 17 March 2007 - 05:10 PM
The heater core was brand new and I flushed it. I'd say it's had a build up of crystals when the car sat around for a while when I used to use coolant. They must be trapped in some of the cores. I'll find out once I take it to get it cleaned I guess.
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