Can't bleed the system!

[nunezfrancisco30]

Hope someone on this forum can help out with this dilemma. Trying to bleed the air out of the cooling system on the fresh m20 swap into the 318is. With the m42 radiator. When I first start the car it idles at 2500 rpm, once it gets warm it drops to 2000 rpm. The strange thing is that it takes about 4 min for it to reach the red line on the gauge that reads the temperature!!! by that point, steam starts coming out quite aggressively out of the bleeder on the thermo housing. By this point I turn off the engine, I dont want it to overheat or anything since its on the redline by the time this starts to happen, any advice?

[jlevie]

Bleed procedure is below, but you need to find out why the engine is idling so high. Intake leaks, a stuck ICV, or the throttle being open are obvious places to look.


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.

[nunezfrancisco30]

Thanks for the advice, Will definetly check the idle problem, just one quick question, how do you know when ICV is sticking?

[jlevie]

Because the idle will be too low, too high, or unstable. But other things like intake leaks can cause the same symptoms. The ICV can be removed and cleaned with carb cleaner until the vane moves freely, the idle switch in the TPS can be checked for correct operation, and the intake can be smoke tested to look for leaks.

[paperplane94]

Also make sure the bleeder isn't blocked with junk, run a wire through it.

[Billy325is]

I bought an air lift kit (UVIEW 550000) for my nissan frontier it was around $100.(amazon)couple years ago. I was having problems with air in my e30, it worked great. Air compressor hook to it it'll collapse most hoses, put coolant in a bucket, it'll draw coolant in the system. if a hose or the bleeder screw loose you know, it suppose to hold 25psi on gauge until you switch valve. I hate to spend more than $10 on a tool that I probably use once. But this one I'm glad to have. There are some a little less expensive that will work just as good. Google "coolant air lift".

[nunezfrancisco30]

OK so today I payed attention to the way the throttle was positioned, and noticed that the accelerator cable was pulling on it just a tab bit! I adjusted it and the rpm dropped to 1500, I think its still high, but better than before at 2500 that's for sure. Whats the spec rpm at which it should be at idle? As for the smoke test whats the best vacuum line to use?

[jlevie]

The right way to do a smoke test is to replace the AFM with plug containing a nipple for smoke injection.