Goo in heater core....

[sepehr]

I took out my 318is's heater core (royal PITA).

Draining the coolant, i noticed it was pretty dark in colour (is this normal?). Previous owner used regular prestone antifreeze, so it was green.

Flushing water through the heater core, I noticed that some small black gel like pieces came out.

Does anyone know why this would happen? Are the rest of the coolant passages/radiator gonna look like this? Is this related to the profile gasket (m42)?

thx in advance

[jlevie]

Over time small amounts of oil will get into the cooling system. That and mineral precipitates form a slighly oily sludge. It won't be limited to the heater core and will be throughout the cooling system. A flush using cooling system cleaner will get the majority (or even all) of it out. That will also remove a lot of the calcification that results from diluting anti-freeze with tap water instead of using distilled water.

I recently did this on the 87 325is that I'm turning into a track car. The car had no coolant in it when I got it because the waterpump seal & bearings were completely worn out and the PO had been using straight water because of the rate it leaked. The water that I drained was completely clear, but after running for about 15 minutes at temp with a jug of Zerex cleaner the first drain looked like weak coffee with tiny grains of black stuff in it.

The process that I use when doing a flush like this is:

1) Get the front of the car up on jackstands. You want the front wheels at least 6" off the ground. This will make the radiator and bleed screw the highest point and make it extremely easy to get air out of the cooling system each time you refill.

2) Drain the system from the radiator and block drains. Then remove the thermostat. I make a temporary gasket out of oiled paper to seal the housing.

3) Add the cleaner and dilute with water according to the package directions. I use hot water to cut down on the time it takes to bring the engine up to temp. Have the bleed screw open and fill until liquid flows from the bleed screw then get it finger tight. Leave the expansion tank cap loose so the system can't pressurize.

4) Run the engine with the heat set to max. Once the temp is out of the blue bring the engine up to 2000-2500rpm a couple of times to flush air from the heater core. Then check the bleed screw for air as the engine is warming up. You need to get the engine up to normal temp, which usually means blocking off some of the airflow into the radiator (a piece of cardboard works great). Once at temp run the engine for 10-15 minutes, keeping an eye on the temp and adjusting the airflow block if necessary. Don't allow the engine to overheat. Better to err a bit on the low side than risk and overheat.

5) Allow the engine to cool down to the point that you can keep your hand on the thermostat housing or head. That will avoid shocking the engine when you drain the cooling system and eliminate any risk of a scald. When cool enough drain the system.

6) Refill the system with water (like above). Again, using hot water will reduce the amount of time it takes for the engine to get to normal temp. You want to run the engine for about 15 minutes or until the temp gets near normal (remember to purge air from the heater core). That will keep from coking up the heads from lots of time with a rich starting mixture and give the alternator a chance to recharge the battery. Then drain per (5). Be sure to catch liquid from the radiator and block in a clean container so you can see what it looks like.

7) Repeat (6) and (5) until the drained liquid is completely clear. Depending on how dirty the cooling system was this may require 4 or more fill/drain cycles.

8) Re-install the thermostat. This would be a good time to put a new thermostat in if the one you took out has some age on it. In a like manner if the waterpump has 100k or more on it now would be a good time for a new one. Then refill the system with anti-freeze diluted 50:50 with distilled water. Fully bleed the system (like above) and you are done.

Note, before opening a drain make sure that the expansion tank cap is on tight. When you open a drain a bit of liquid will dribble out and then pretty much stop until you loosen the expansion tank cap. That will keep you from getting covered in liquid each time you drain the system.

[sepehr]

Thanks for the right-up.

I was just looking though the mess of coolant hoses at the firewall. Found a piece of waterpump impeller in the little safety thermostat. What sucks is there is probably a lot more where that came from. I put a new waterpump in a few weeks ago, and the old impeller was a third gone. :( I was hoping it was just from erosion, but i guess it just fractured.

Moral of the story: if you have an old plastic impeller waterpump, pull it out and swap it for a metal impeller one.

[92 mtechnic cabrio]

you should be replacing your water pump as often as your timing belt.

every 35-45k miles

[jlevie]

I believe BMW's recomendation is the change the pump every other timing belt change.

[PeaveyBassist]

I believe BMW's recomendation is the change the pump every other timing belt change.

Every timing belt change. You think the water pump will last 100k miles?

Will

[joshh]

It's also a good idea to use distilled water. Whatever you do, do not use hose water. Way too many minerals and solids.

[euroshark]

You think the water pump will last 100k miles?

I have 108k on my original water pump. My dad has at least 120k on his. That said, they are cheap, just replace the damn thing.

[jlevie]

Every timing belt change. You think the water pump will last 100k miles?

With an OE pump I would expect it to go past 100K. I've only known of a very, very, few BMW pumps that failed before then.

[sepehr]

Its a 318is, so I don't have a timing belt. It could use a new timing chain though.

[Jean]

How do I drain a 318i m10 block ? Does it not have an engine drain bolt ?

2) Drain the system from the radiator and block drains. Then remove the thermostat. I make a temporary gasket out of oiled paper to seal the housing.

[jlevie]

The 318 does have a block drain plug. I sort of think it is on the exhaust side of the block towards the front.

[Jean]

Here is a picture from the passenger side, no bolts that I can see. I checked with a local dealer and they think it might be under the timing chain cover but weren't sure (i don't know how a dealer can't be sure...)

[jlevie]

On an M20 and other BMW engines the drain is way towards the rear of the block. Is there a drain plug there on the M10?

Seems strange to but the drain under the timing cover, but I guess that's possible.

[Axxe]

According to the ETK, it's under the timing cover. Doesn't make too much sense, as it's pretty high up.