Bleeding coolant system e30 M52 swap

[aldur99]

Hi guys,

Back again for some advice on how to bleed the coolant system on my m52 swap. I am currently using a late model rad from an e30 automatic with an external res.

I have been trying for 3 days with no success. I have followed the many suggestions currently in the forums: (except I do not have a bleed screw)

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

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 2000-2500 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.

What happens, heater is blowing heat as it should, but when the temperature reaches the mid point on the temperature guage, the coolant level rises in the external res until it flows out the little drain tube.

I have driven it as well, but when I stop and check the coolant, there is so much pressure the res is showing signs of stress.

There is no obvious signs of coolant in the oil, and no oil in the coolant. I have no idea what to do.

Any suggestions? Thanks again for the help.

Ed

[frankie591]

Could try massaging your coolant hoses while its running to try and force any air pockets upwards. Not really much help as I had no issues bleeding my m52 swap.

[badvibrations]

Get(make) a vacuum bleeder.

[hwy84]

Did you overfill the coolant res? On the external res, it should only be filled to the line marked with an arrow when cold (about halfway).

The late model e30 syetem is self-bleeding. All that crap with jacking the front of the car, thats all for the M42 rad, which is notoriously hard to bleed. Even a stock e36 is hard to bleed (they have a similar system).

The stock e30 stuff should work without any of that jazz. Fill to the appropriate level when cold, put the cap on, and go drive. Any bubbles will work their way up and into the res, and the coolant level will go down a commensuate amount. If the light comes on, add more coolant after the car cools down. If not, you didn't have many bubbles, and only may have to top up slightly.

[Adrian_Visser]

Late model m20's still have a bleeder screw on the thermo housing and you do need to use it sometimes.

OP: Some coolant being pushed out is normal as you will have probably overfilled it initially and as the coolant heats up it does expand. If you really think that the reservoir is over-pressurizing you could try a new cap for it. They are a wear item and should be replaced periodically anyway. I think what you are describing is normal though.

If you let the car run does it continue to heat up past the half way point on the temp gauge? If the temp needle keeps climbing skyward you have a problem if not the cooling system is bled of airlocks and functioning normally.

[aldur99]

Thanks for info and the proper procedure. Also, I have found that the original aux fan is blowing the 30A fuse now, so have ordered a new spal. I will give it another go when the fan comes in.

I believe I did overfill the reservoir as originally I was following the instructions for the m42 rads. But have ordered a new cap to be safe. I was just worried the pressure was building at too high a rate as the reservoir was showing signs of stretching after a drive.

The car will heat up to the mid point, but over a fairly long period of time, at which time the fan was supposed to kick in and cool it down. I found on drives, the temp guage was below the half way mark, actually, it stays just above the 1/4 mark. Is that temp too low? It may partially explain why I failed aircare with a high CO2 score.

@Adrian_Visser, the m20s have a bleeder on the thermo housing, but does the m52? I will check.

Thanks again for the help.

[BBDirtbiking]

I didn't read the whole post, or replies, but from skimming I did not read what I am about to say.

This is something that I have had to do on EVERY M5X/S5X system I have had to bleed...

With the engine cool, remove the TOP hose at the radiator and fill THE HOSE with coolant until it gets close to overflowing. Re-install the hose onto the radiator neck. Be Gentle. Then follow bleeding procedures with the elevated front end and squeezing bottom hose to get air out, yatta yatta.

[5Toes]

I bleed mine the other day. I took a bike intertube and cut it in half.

Then I tied one end in half, and stretched the other over the nozzle of the expansion tank. With a bike handpump I pressurized the system and then opened the bleeder on the t-stat housing. Lots of air came out, and when water started to pour out I had my neighbor close it while I was still pumping. Add the appropriate amount of water after you forced the air out

I repeated the procedure for the overflow hose on the top of the radiator. Then I started the car and let it idle with some revving with the expansion tank cap off. I noticed some air bubbles coming out and what not. I massaged (squeezed) the coolant hoses to get more air to come out.

Anybody have any feedback on my technique?

[5Toes]

Also, amke sure the heater is set to full blast and highest heat setting

[Roysneon]

I bleed mine the other day. I took a bike intertube and cut it in half.

Then I tied one end in half, and stretched the other over the nozzle of the expansion tank. With a bike handpump I pressurized the system and then opened the bleeder on the t-stat housing. Lots of air came out, and when water started to pour out I had my neighbor close it while I was still pumping. Add the appropriate amount of water after you forced the air out

I repeated the procedure for the overflow hose on the top of the radiator. Then I started the car and let it idle with some revving with the expansion tank cap off. I noticed some air bubbles coming out and what not. I massaged (squeezed) the coolant hoses to get more air to come out.

Anybody have any feedback on my technique?

Yeah, it's useless to OP, he doesn't have an m20 and doesn't have the blender screw.

[blackhawkimpact]

Bump.
What if you don't have a heater core? Did a coolant flush but looks like I still have air in the system. I did what op posted but only I don't have a heater core (heater core delete).