Another radiator burp question...

Pilot · 10-02-2009, 09:59 PM

I took the car to an auto center that has a flushing machine and they tap into the front radiator hose. They then pump 5 gallons through the system, you see all the old stuff come out and when new antifreeze starts coming out, they are finished. They let it run for a few minutes and it did not need a top-off. They claim only a very minimal, if any, air gets into the system and it does not need to be burped. Is that correct?

Next newbie question, if the system DID have air in it, would that be detectable by a higher reading on the water temperature gauge or would I know when the engine froze-up from being overheated ?

YellowJacket · 10-02-2009, 10:33 PM

Where does the old stuff come out? The other rad hose? If so, they just flushed your radiator and thats it. Because this is a mid-engine car, the cooling system spans the entire vehicle.

If you have air, when the car gets hot, you usually notice the idle 'bouncing' or you might notice your temp gauge spike quickly as hot air pockets of steam roll past the temp. sender.

Regardless, if you want to own an MR2, you need to learn to burp the system yourself.... or else you could always annually budget for head gasket repair.

This picture of the cooling system in the Mk1 should help put things in perspective:

potatoe · 10-02-2009, 11:16 PM

haha, wow. thats awesome. coulda used that a few months ago when i just got my 2. lawl, but still helps even now.

Pilot · 10-03-2009, 08:22 AM

Quote:

Originally Posted by YellowJacket

This picture of the cooling system in the Mk1 should help put things in perspective:

http://k43.pbase.com/g1/01/187001/2/...5.46U9FauQ.jpg

Now this gives MEANING to "a picture is worth a thousand words" !

They disconnected the coolant line in the engine compartment next to the filer cap and they connect intake and outflow lines at this point to the machine. You can physically see what is going in and what is coming out--and the coming-out stuff was this dark brown really rank looking stuff. Eventually, after about 5-minutes, the dark brown stuff stopped coming out and the new stuff started coming through. In the days since, the coolant has remained that nice new color, if it had only been a partial flush, no doubt the new color would have degraded to something else.

At the same time the machine was running, the attendant attached a device to my wallet to suck-out $87.00 ;-)

The idle is smooth and the temp gauge does not spike, it stays in the 1/8 - 1/4 range on the gauge. When stepping out of the car, the engine has a slightly hot smell--but we have only owned the car a few days and we don't know if that is normal.

Thanks for the tips.

YellowJacket · 10-03-2009, 06:10 PM

Thats better than what I though from the front...

Although I believe the front radiator and and heater core would not have been flushed unless the car was at full warm, and the tstat open and the heater slider on hot... someone else will have to confirm or deny that. But what I am getting at is that it could have been just circulating the engine loop and would never have made it to the front, or heater core unless the tstat was open and the heater was on full hot..... if I am right, then at worst case, when the tstat does open, then the coolant just would have mixed with the older coolant at the front of the car... and same with the heater core when you turn the heat on full hot.

Again, I could be wrong.

Here are some more great pictures indicating flow of coolant. If you can figure this out, you are better than me!

Engine Bay:

Front end

Throttle body:

Tstat

Pilot · 10-03-2009, 07:17 PM

I attempted to follow the burping procedure in the OEM maintenance manual--with some difficulty--and here is what happened:

Vertically installed clear tubing on heater air bleeder cock and radiator air bleeder plugs per maintenance manual. When opening the radiator air bleeder plug, the coolant would go up the clear tube about 3", it did not come up the heater air bleeder line at all. The thermostat housing bleeder plug had fluid to the top of the opening, closed this plug. Started car, momentarily, fluid instantly came out heater air bleed and radiator air bleeder plug lines. Shut car off, coolant level dropped to about 4-6" above those two openings. I'm not sure, is that good enough or... ?

YellowJacket · 10-03-2009, 09:22 PM

Refilling and Bleeding
The first task is to slacken the bleed valves approximately three turns. The bleed valves are on top left of the radiator, on the heater piping in the middle of the front bulkhead (behind the spare wheel), and on top of the thermostat housing on the left side of the engine.

Attach lengths of clear plastic hose to the valves on the radiator and the heater. Originally these clear plastic hoses were supplied with the car and are stowed next to the heater piping, but over time they can go missing, in which case you can buy suitable piping from car accessory or DIY stores. Suspend them from the underside of the front boot. Remove the pressure cap (on top of coolant pipe in the right side of the engine bay) and fill with coolant until coolant flows out of the engine bleed valve. Close the engine bleed valve and continue filling until the levels in the two plastic hoses are level with the filler neck. Close the bleed valves and replace the pressure cap, but only to its first stop. This is important, do not close it fully to its second stop at this point. Fill the expansion tank to its maximum level mark.

Run the engine at fast idle for 3 minutes. Check the level at the filler neck - it probably will have dropped. Open the heater and radiator bleed valves again and fill until the levels in the plastic hoses are level with the filler neck once again. Close the valves and run the engine again. Repeat this loop until the level does not drop at the pressure cap.

Now replace the pressure cap to its normal second stop position. Check all the valves are closed and take the car for a run. Check for leaks from the bleed and drain valves. Check the coolant level in the filler neck when the engine has cooled fully.

from IMOC Articles - Mk1 Cooling System

Pilot · 10-03-2009, 10:33 PM

YellowJacket, that is a much better--more practical--description than what is in the official repair manual.

10-02-2009, 09:59 PM	#1 (permalink)
Pilot Master MotorcycleMechanic Join Date: Oct 2009 Posts: 81 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Another radiator burp question... I took the car to an auto center that has a flushing machine and they tap into the front radiator hose. They then pump 5 gallons through the system, you see all the old stuff come out and when new antifreeze starts coming out, they are finished. They let it run for a few minutes and it did not need a top-off. They claim only a very minimal, if any, air gets into the system and it does not need to be burped. Is that correct? Next newbie question, if the system DID have air in it, would that be detectable by a higher reading on the water temperature gauge or would I know when the engine froze-up from being overheated ?

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10-02-2009, 10:33 PM	#2 (permalink)
YellowJacket 1985 16v NA 6-speed Join Date: Sep 2008 Location: Nashville, TN Posts: 415 Thanks: 8 Thanked 31 Times in 24 Posts iTrader Rating: (1/100% )	Where does the old stuff come out? The other rad hose? If so, they just flushed your radiator and thats it. Because this is a mid-engine car, the cooling system spans the entire vehicle. If you have air, when the car gets hot, you usually notice the idle 'bouncing' or you might notice your temp gauge spike quickly as hot air pockets of steam roll past the temp. sender. Regardless, if you want to own an MR2, you need to learn to burp the system yourself.... or else you could always annually budget for head gasket repair. This picture of the cooling system in the Mk1 should help put things in perspective:

10-02-2009, 11:16 PM	#3 (permalink)
potatoe No Skills Join Date: Jun 2009 Location: san marcos, ca Posts: 47 Thanks: 1 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	haha, wow. thats awesome. coulda used that a few months ago when i just got my 2. lawl, but still helps even now.

10-03-2009, 06:10 PM	#5 (permalink)
YellowJacket 1985 16v NA 6-speed Join Date: Sep 2008 Location: Nashville, TN Posts: 415 Thanks: 8 Thanked 31 Times in 24 Posts iTrader Rating: (1/100% )	Thats better than what I though from the front... Although I believe the front radiator and and heater core would not have been flushed unless the car was at full warm, and the tstat open and the heater slider on hot... someone else will have to confirm or deny that. But what I am getting at is that it could have been just circulating the engine loop and would never have made it to the front, or heater core unless the tstat was open and the heater was on full hot..... if I am right, then at worst case, when the tstat does open, then the coolant just would have mixed with the older coolant at the front of the car... and same with the heater core when you turn the heat on full hot. Again, I could be wrong. Here are some more great pictures indicating flow of coolant. If you can figure this out, you are better than me! Engine Bay: Front end Throttle body: Tstat

10-03-2009, 07:17 PM	#6 (permalink)
Pilot Master MotorcycleMechanic Join Date: Oct 2009 Posts: 81 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	I attempted to follow the burping procedure in the OEM maintenance manual--with some difficulty--and here is what happened: Vertically installed clear tubing on heater air bleeder cock and radiator air bleeder plugs per maintenance manual. When opening the radiator air bleeder plug, the coolant would go up the clear tube about 3", it did not come up the heater air bleeder line at all. The thermostat housing bleeder plug had fluid to the top of the opening, closed this plug. Started car, momentarily, fluid instantly came out heater air bleed and radiator air bleeder plug lines. Shut car off, coolant level dropped to about 4-6" above those two openings. I'm not sure, is that good enough or... ?

10-03-2009, 09:22 PM	#7 (permalink)
YellowJacket 1985 16v NA 6-speed Join Date: Sep 2008 Location: Nashville, TN Posts: 415 Thanks: 8 Thanked 31 Times in 24 Posts iTrader Rating: (1/100% )	Refilling and Bleeding The first task is to slacken the bleed valves approximately three turns. The bleed valves are on top left of the radiator, on the heater piping in the middle of the front bulkhead (behind the spare wheel), and on top of the thermostat housing on the left side of the engine. Attach lengths of clear plastic hose to the valves on the radiator and the heater. Originally these clear plastic hoses were supplied with the car and are stowed next to the heater piping, but over time they can go missing, in which case you can buy suitable piping from car accessory or DIY stores. Suspend them from the underside of the front boot. Remove the pressure cap (on top of coolant pipe in the right side of the engine bay) and fill with coolant until coolant flows out of the engine bleed valve. Close the engine bleed valve and continue filling until the levels in the two plastic hoses are level with the filler neck. Close the bleed valves and replace the pressure cap, but only to its first stop. This is important, do not close it fully to its second stop at this point. Fill the expansion tank to its maximum level mark. Run the engine at fast idle for 3 minutes. Check the level at the filler neck - it probably will have dropped. Open the heater and radiator bleed valves again and fill until the levels in the plastic hoses are level with the filler neck once again. Close the valves and run the engine again. Repeat this loop until the level does not drop at the pressure cap. Now replace the pressure cap to its normal second stop position. Check all the valves are closed and take the car for a run. Check for leaks from the bleed and drain valves. Check the coolant level in the filler neck when the engine has cooled fully. from IMOC Articles - Mk1 Cooling System

10-03-2009, 10:33 PM	#8 (permalink)
Pilot Master MotorcycleMechanic Join Date: Oct 2009 Posts: 81 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	YellowJacket, that is a much better--more practical--description than what is in the official repair manual.