coolant flush help - engine overheated

[Wiker Man]

hey folks, long time, havent used the car lately due to not needing one, I know i still got that diy fog light to post up, never found the time but oh well, one of these days. i promises

anyway, I just started to get my m42 fired up after sitting for almost a year, replaced the automatic trans oil, added about 1l on engine oil(hope didn't add too much?) and reset the inspection light. And realized that apart from a few electrical issues, the engine was having some over heating issues as well..

Engine seems to be overheating up to 3/4 of the OEM temp sensor after a 20 ~ 30min drive.I know normal is 2/4. So I came back and it was quite warm later on i opened up the radiator cap and saw a lot of green goo inside the tank, So thinking of doing a coolant flush and bleed tomorrow hoping it fixes my issue. I am keeping the thermostat and water pump replacement in my to do list early next year.

So I am reading this, http://www.pelicanparts.com/bmw/techarticles/E36-Coolant_Flush/E36-Coolant-Flush.htm

I was thinking the job was simpler then that above and I could simply drain the radiator with the blue cap and refill, but it sounds like I have to take out a drain bolt on the engine under the car near the exhaust headers while the heater is running? This is to drain the water inside the engine? Can anybody please confirm this or tell me where this bolt is? and then I take off the little blue cap on the radiator? drain it and fill it up with some antifreeze and distilled water? I bought a regular 5L of average anti freeze so I will do a 50 50 mix or something. 2.5 liters of the anti freeze and 2.5 liters of the distilled water.

also i dont have a crush washer can i just reuse the old one for now as I will be going for a long trip (few hundred km's) in a weeks time?

not getting much feedback in bfC so need some help & input from fellow m42 ers as I will do this tomorrow 

thanks

[DesktopDave]

To do a thorough job, you should definitely flush out the radiator, heater core and block. The block drain is a requirement as the thermostat is closed, blocking much of the old coolant in the motor. The bolt is on the rear half of the engine block, about halfway down. IIRC it's between exhaust runners 3 & 4. I've never replaced the crush washer, but they're not hard to find. Any parts store should have both aluminum (cooling system) and copper (lubrication system) crush washers.

That article just notes that the heater valve has to be open to do a good job. It's not necessary to have the heater valve open to drain the block.

I've also found it very helpful to pre-fill as many of the hoses as I can before I reinstall them - especially the radiator hoses. Bleeding is a lot easier that way. And be very careful with the bleed screw. It's easy to break. Use a large straight-bladed screwdriver (no cross-blade phillips types!) and only tighten it until coolant just stops flowing. I've broken them before...the car can't run with a broken screw and extracting them is not fun.

[Nick_318is]

Hi, I hope I can help, I did this over the summer when I cleaned up the mess under the intake. 

You don't need to have the heater on in the car when removing the drain plug on the engine block. The plug is on the passenger side of the car behind the exhaust headers, it's a little tough to get to but manageable.  They recommend a fresh crush washer and you probably want one but if it's only going to be a few weeks I suppose you're likely okay.  If you remove the block drain plug you can get most of the old coolant out between the radiator plug and removing the in/outlet hoses from the thermostat.  When I did it I think I drained the radiator, then the radiator hoses, and then the block drain plug.  Put it all together and filled the system with as much coolant as I could get in (filled the upper radiator hose before connecting it back to the thermostat), then filled the radiator to the cold line, left the radiator cap off, turned the car on, turned the heat and fan all the way up and filled the radiator until it stopped taking coolant.  Then bleed the system.

The cars can be a pain to bleed and it helps to elevate the left front of the car as it helps with the process.  Also be careful with the bleed screw, you don't need much pressure to close them up, I stripped mine and ended up buying a new radiator.  Someone suggested using a quarter to tighten it that way you can't torque it too much, I will always do this in the future.

Good luck, I hope that fresh coolant and a bleed solve your problems.

[Wiker Man]

hey guys thanks for your reply, So I went with a different approach since I couldn't jack up the car properly due to not having jack stands and almost had an accident.  I went on to drain the radiator and dark muddy water inside. at first I thought it might had been my head gasket or something which might have caused some oil and water mixing. I continued to flush the radiator using my garden hose, I would turn the heater on then fill it up, check for bubbles and then would run the car/idle for like 5 - 10 mins. and let the water coolant flow through the system. Drained and refilled and went through this 5 times and then the water started to become clear.

So I came to the conclusion that it couldn't be the  head gasket or the engine or some oil mixing into the water as the color would remain the same and not clear up after so many flushes. It actually seemed to be some rust and corrosion. anyway since then I filled and bled the system with 50% Green Anti Freeze and 50% Distilled Water. Took it for a 10KM Drive around town and the temp stayed normal.

Then I realized my aux fan was never working and the clutch on my mechanical fan is probably bad too. I found the AUX fan to be the problem of the temperature sensor on the radiator which I fixed for the time being by jumping it with a small wire. Will take it to the mechanic to have both the fans sorted. I think the water pump and thermostat are good though.

attached some pictures.

[monty23psk]

Green anti freeze which has phosphate, can leave these corrosive bits. You need to use phosphate free anti freeze like the BMW brand. Also orange ones will work.

[DesktopDave]

That coolant looks to have some oil in it. I'd take a sample of the coolant to your mechanic as well. He'll be able to tell for sure. That's a significant problem, and must be repaired before your bearings are permanently damaged by contaminated oil. A compression test would be a great idea, along with a 2.0 bar (28psi) pressure test on your cooling system.

Do you have an E30? If so, have your mechanic pull the lower oil pan and check the upper oil pan front bolts, if you haven't done that already. They should be reinstalled with a tough locking compound like Loctite Red.

I'd also recommend using BMW OEM coolant mixed with distilled water. Excellent stuff. I have used Zerex G-06 in the past, also excellent stuff. Avoid any type of Dex-Cool antifreeze until it's been proven to work well.