Overheating issue with m42

[Joseph.]

Hey guys, my names Joseph. I've been lurking around here for some time and I finally decided to join. Glad to be here. I currently own two e30's. One is a 1989 325i
And the other car is a 1991 318is that I just picked up as a project. Long story short, I got the car for $640 and I want to fix it up for then enjoyment of doing so (Will potentially do a drift build) here's the car:
Now here's the issue, I've got the car running an driving, but it keeps over heating. I've already flushed the radiator and block as well as replaced the thermostat. The car smokes a little bit, but I do not see any traces of oil in the coolant or any loss of coolant. No signs of coolant in the oil either. Passengers side floor was wet and heating wasn't working (not blowing hot) so I originally thought it was the heater core and re routed the hoses to bypass it, still overheating though. What's weird though is when the car is fully heated up past halfway, the hose from the top of the radiator going to the heater core is hot, but there's no coolant going through it. Also, the hose from the bottom of the radiator directly underneath the hose going to the thermostat housing is cold. The hoses that I rerouted for the heater core are cold as well. It seems like there is a block somewhere or that the thermostat isn't opening up, but I just replaced it. What do you guys think?


Cliffs:
-Sorry that was really long, this was my introductory post as well as first issue haha.
-Flushed block and radiator and replaced thermostat but car still overheats
-Under operating temp the hose from the top of the radiator is hot, but no coolant flows through it. Hose directly underneath this one (bottom radiator hose) is cold. Hoses that I rerouted to bypass the heater core are cold

[jlevie]

That could be air in the cooling system collecting in the vicinity of pump and preventing circulation. Which in turn could be from a failure to fully bleed the system or air being pumped in from a leaking head gasket. If the heater loop is hot but the radiator not flowing a bad thermostat or a plugged radiator would be possibilities, but those don't affect the heater hoses.

The first action should be to properly bleed the cooling system to get all of the air out (procedure below). Then there are a couple of easy DIY checks for a leaking head gasket. The first is to drive the car for a bit after bleeding and re-bleed. Release of a significant amount of air then or on a subsequent bleed is evidence of a head gasket problem. The other is to remove the cap when the engine is completely cold (the hoses will then be soft), drive the car for a bit, and allow the the engine to get completely cold. If those hoses are hard, air is being pumped into the cooling system from a head gasket leak.
The definitive test is to pressurize each cylinder with 175-180psi air for several minutes while monitoring coolin system pressure with a sensitive gauge. A rise in pressure is evidence of a head gasket leak or a cracked head. A negative result on a cold requires the test to be repeated on a hot engine.

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.

[Joseph.]

Could it be the head gasket though if there's no signs of oil and coolant mixing and no white smoke? There's no loss of coolant either. I filled the coolant level to the "cold fill" line when the car was cold. I removed the radiator cap and bleed screw and started to bleed the system. The car ran for like 30-40 minutes and released a lot of steam from the little vent near the bleed screw. The radiator never bubbled over though when bleeding, just a lot of steam. During this time though (like 30-40 minutes) the temp of the car overheated to 3/4 before I turned it off. Not sure what it could be. What does this sound like to you guys? What would make it do this when I was bleeding it? Thanks

[FLG]

Do EXACTLY has Jim said then report back. We can take guesses all night, but you need to do as stated first before we go further.

Im not sure on m42's but did you make sure you put the thermostat in facing the correct direction?

[roguetoaster]

If it's not a bleeding issue it often turns out that someone installed the thermostat backwards! While you are checking that make sure the bypass line in the inner face of the thermostat housing is clear of RTV or debris.

[Joseph.]

Ok guys so I followed the proper procedure to bleed the system. Put the car up on ramps and followed the instructions. I did re connect the hoses to the input and output to the heater core and removed the bypass line that I had there originally. I filled the coolant up to the "cold fill" level and started to bleed. The car only started to release steam at the 3/4 to red mark when it was starting to overheat. During this entire time, the only two hoses that got hot were: the hose from the top of the radiator leading to the thermostat housing, and the hose from the bottom of the radiator leading to the other side of the thermostat housing. All the other hoses were cold. I had the heat on full and and the entire time it did not blow out any hot air. At normal operating temp, I tried stopping the fan with a couple sheets of newspaper and it stopped easily. There was also a screeching sound I kept hearing near the fan or water pump. I did include some videos so it would be easier for you guys to see. I know I did install the thermostat the right way, I also installed a new thermostat housing gasket and there is no leaks. Please let me know what you think. Thank you.

http://www.youtube.com/watch?v=MocJYOwinqE

This video shows the fan at operating temp being stopped by a newspaper.

http://www.youtube.com/watch?v=Vll8ZZK6uP0

This video has the screeching.

Sorry for the poor video quality, they were filmed with an iPhone.

[e30 vert]

my car had a same problem replace the fan clutch and bleed the air from cooling system solve the problem

[Joseph.]

my car had a same problem replace the fan clutch and bleed the air from cooling system solve the problem

So you think the water pump is good but the fan clutch is bad? I know the newspaper way to test the fan, but is there any other way? It seems like coolant isn't being pushed through the system though because there is no hot air from the heater and hoses are cold.

[jlevie]

The heater hoses being cold is a major clue. Regardless of the thermostat or radiator there should be circulation through the heater hoses. The most likely explanation for the lack of heat in the hoses would be failure of the water pump impeller.

[Joseph.]

The heater hoses being cold is a major clue. Regardless of the thermostat or radiator there should be circulation through the heater hoses. The most likely explanation for the lack of heat in the hoses would be failure of the water pump impeller.

Thank you very much. Would a failed water pump have any effect on the fan? Like it easily being stopped by a couple sheets of newspaper when the car is at normal operating temp?

[jlevie]

The water pump and the fan clutch are separate issues. You can't at this point tell if the fan clutch is good because the radiator isn't getting hot. But the smart person that follows best practice will replace the entire cooling system (radiator, expansion tank, cap, thermostat, water pump, fan clutch, and all hoses) every 10yr/100k. I'll bet your fan clutch is well past that. Pull the pump and see what it looks like. My guess is that the impeller has failed and the pump needs to be replaced. Replace the clutch while the fan is off.

[Joseph.]

Thank you. Pulling the water pump out as we speak. So far I have everything disconnected and drained. Fan is off finally after some work with an adjustable wrench and a hammer! Will update you guys when I pull the pump out.

[Joseph.]

Well guys, pulled the pump out today and saw this. Looks like the plastic impeller broke off inside. I think I grabbed all the broken plastic pieces from in the block. Going to be replacing the pump with one that has a metal impeller. Any recommendations on which brand pump to buy and from where? Thanks guys.

[Joseph.]

Thank you guys for all your help. It was definitely the water pump. Installed the new water pump and bled the system and car is running properly.