Mystified: Requesting Cooling System Guru's

[Zreberlcoe]

I know this looks like a novel but I just have to explain my process.

So I replaced my starter the other day so I drained my whole cooling system so I could move the heater core hoses out of the way. So When I got it started and stuff I put the car on a the slanted driveway facing up hill and unscrewed the bleed screw on top of the thermostat housing. So the car started to just stream air while engine temperature was sitting just a bit above half and then kept streaming air... and kept streaming air... and kept going. About five minutes later not a drop came out of the damn bleed screw and the reservoir was full of water as well. So I kept the bleed screw unscrewed slightly and drove 3 or 4 blocks and pulled over, popped the hood, checked the screw and water was spilling out with bubbles and stuff. Then after about 30 seconds of idle the damn thing kept streaming air! I also noticed that when I drive the temperature creeps up, and I have no heat inside the car. I'm 99% positive I put the heater core hoses back on in the same manner they were in before. I know the temperature switch works because I can hear the difference in air speed through the fan when I switch it from hot to cold and cold to hot. I have no idea what is wrong so I need someone to help me out!

[Cletonius]

Did you drain the block?

If you drain everything it takes almost 2 gallons to refill. How much did you fill with? Did you remove hoses other than the heater core ones?

[TurboJake]

Sometimes they can be a bitch taking a couple tries and heat cycles.

Also, driving with the bleeder screw loose and if you have no pressure in the system allows air right back in.

[Zreberlcoe]

Well I unscrewed the hoses that lead to the intake butterfly valve thingy.

[merlinfe]

When I bled my M20 after replacing the waterpump and timing belt, I lifted the front end as far as i possibly could, put it on jack stands and bled the system.

It seems like the higher up these cars are in the front the easier it is to bleed them.

Try lifting the car and slowly adding the coolant mixture. I usually squeeze the coolant hoses while I'm doing this with the bleed screw open to force as much air out before turning the motor over.

[Zreberlcoe]

When I bled my M20 after replacing the waterpump and timing belt, I lifted the front end as far as i possibly could, put it on jack stands and bled the system.

It seems like the higher up these cars are in the front the easier it is to bleed them.

Try lifting the car and slowly adding the coolant mixture. I usually squeeze the coolant hoses while I'm doing this with the bleed screw open to force as much air out before turning the motor over.

Yeah I lifted it way up in the air as well! Is there somewhere it can be pulling air in? For some reason water isn't reaching the top:/

[jlevie]

I suspect there is a bigger problem, but could be that you just haven't yet properly bled the system. The best way is to use a vacuum fill system, but in the absence of that the following will work almost as well.


1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

If when doing the bleed correctly it is extremely difficult to clear the system of air or a subsequent bleed releases a significant amount of air, there is a head gasket leak that is pumping air into the cooling system.

[Zreberlcoe]

Well it wasn't doing this when I wrote the thread but now it's leaking from the front of the motor. By the water pump.

[ScHpAnKy]

Couple questions

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

Do you mean, fill the reservoir until the coolant comes out of the bleed screw? How much typically comes out before the bubbles are completely bled?

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

With the engine-bay side valve deleted, Wouldn't unplugging the heater core valve on the cabin side (footwell) , which defaults to flow-through when unpowered accomplish the same thing as max temp/speed?

How loose is loose for the cap? Couple threads on? Couple threads off?
I've found that no matter what, with the coolant cap loose, I always find that the reservoir level will rise and rise without ceasing once the thermostat opens. Is this typical?
How long between cycles should we wait?

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

When you rev the coolant level will continue to rise and rise and more and more steam just keeps on coming, I filled my reservoir with water a while back before I replaced everything in my cooling system - even with all the flushes, is it possible that I still have some in the system somewhere which is what's causing the level rise and steam?
I've probably done this process 15+ times with the same result, still no HOT air through the vents, but the heater core + pipes are HOT.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

If when doing the bleed correctly it is extremely difficult to clear the system of air or a subsequent bleed releases a significant amount of air, there is a head gasket leak that is pumping air into the cooling system.

Compression is good across all cylinders and when cruising the temp never goes above 1\4 - everything is brand new (heatercore, heater valve, radiator, water pump, thermostat, housing, hoses...)

which is pretty confusing.

setup: m50 / m42 rad / 88C thermostat

[Zreberlcoe]

I pulled the drain plug to the radiator to just restart and try again. But then I found a little bit of black murkiness when it was on my hand. Idk if its oil or mung from sitting for two months. But if I had oil in there that means a gasket failed right?

[603Racing]

Oil in the system shouldn't be black, it will mix with the coolant and look like a chocolate milk shake. I suppose if it weren't mixed it would be black and seperated. If oil is in the coolant you should see a lot of it (or at least residue) in the expansion tank.

When bleeding the system, I've had it work on the first try and I've also had it take 4 or 5 attempts to get the air out.

[Zreberlcoe]

So we did the water pump and timing belt! Did everything slow, made 100% sure we had our timing marks spot on. Once we got her running let it idle and jacked up the front a little and let the air out of the bleed valve. The air went on forever and the overflow tanks started boiling as well. And we put in new drive belts. But the damn thing won't cool down behind half like it used to run. This car is mystifying me. We drained the block plug as well, would that make bleeding the air out take a long time?

[jlevie]

I really can't tell at this point whether you are filling and bleeding the system correctly. Your last post seems to clearly indicate that you aren't. The nose of the car has to be at least a foot higher than the rear (not just a little higher) at the start of the fill/bleed procedure. It it isn't up in the air as you fill the system, a pretty large air bubble can get trapped in system and make bleeding difficult.

When executed correctly the whole process should take no more than 30 minutes. If at the end of that time you are still betting air out of the bleed screw, the head gasket is leaking.

[Zreberlcoe]

I really can't tell at this point whether you are filling and bleeding the system correctly. Your last post seems to clearly indicate that you aren't. The nose of the car has to be at least a foot higher than the rear (not just a little higher) at the start of the fill/bleed procedure. It it isn't up in the air as you fill the system, a pretty large air bubble can get trapped in system and make bleeding difficult.

When executed correctly the whole process should take no more than 30 minutes. If at the end of that time you are still betting air out of the bleed screw, the head gasket is leaking.

Welp I got it. Just was questioning myself.

[barbierij]

best way is to fill the radiator (upper radiator hose), then fill the engine block until fluid starts to fill the reservoir. it helps to have a 3/16" hole in the thermostat toward the top so you dont have to wait for it to open for bleeding.

http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=3981