assumption of worst case scenario

[braino]

I've been dealing with all sorts of coolant issues recently with my '78 530i.

I replaced the radiator, expansion tank and various hoses, been coping with leak after leak from cracking hoses (now mostly replaced)...

Now, just as I was about to drive into the city, I noticed that the coolant in the expansion tank was bubbling while idling. My assumption is that this indicates exhaust gases blowing through to the water jacket.

Could someone quickly confirm my suspicions on this, please? Coolant in the expansion tank should not be churning about.

I haven't had an overheating event since the one I had in early March and the car has been running cool and well since then. There is no discoloration in the coolant yet but I wonder if it wouldn't take a little while for particulate exhaust to accumulate?

Your experience and insight is appreciated.

cheers,
Brian

[braino]

So, I finished work and checked on the car again. The engine was cool enough that I could open the expansion tank. There was a decent amount of pressure and a little vapor.

I drove the car in traffic a bit and it was holding steady. One thing I notice about this motor - the temp swings quite bit between driving and idling. Driving it quickly drops down almost to the second line. While idling, it holds just slightly below dead center...

Is this a typical temp range for 530i's in warm weather? It must be in the high seventies today...

cheers,
Brian

[alotawatts]

Your temp gauge is not in the red correct ?
My 79 circulates very fast.....you could call it churning. I attribute it to a healthy water pump.

[T.Hanson]

I know there is a coolant drain (bolt ?) on the block, which I've never drained. I have taken the radiator out and flushed it clean from both ends.

All new hoses, checked the clamping ends of all the pumps and tubes clean, rust, corrosion free. New water pump, and the heater works fine.

What else can there be ? If coolant isn't leaking, or smoking white out the exhaust, or steam from the manifold, head gasket, or oil turning milky.

My temp gauge moves just a needle width over half on a warm day idling, to drop just the other side driving. I think that's the thermostat and difference in gauges.

Don't know if it helps. Just gossip, 530's with exchangers, old style heads, but if it's all clean inside and never pegged the needle to suspect something cracked, about all that's left is to rooter rotor the block passages.

[braino]

Interesting, so it's not entirely typical to have so much movement in engine temp. Good to know.

The head on this car is a later one - based on what I read in the Tech FAQ it's a '79. I have a Spanish, sand-cast head on the engine I'm going to rebuild. The rebuild will be an L-Jet conversion. I'll be glad to be done with concerns about overheating.

Thanks for the note about churning coolant in the expansion tank. That makes sense. I have to go about 100 miles in the 530i today so I'll know for sure what's up by the end of the evening.

cheers,
Brian

[Mike W.]

Either is possible, churning or bubbles. With it not too warm, take the cap off and start the car up. You should be able to tell the difference between bubbles, which is bad, and turbulance, which is normal from the bleeder hose from the radiator. Especially at idle.

[GripGreg]

From what both Tom & Mike said, I would go with a new water pump. And change the bleeder valve on top of the water pump to the one that has to be opened/closed with a wrench rather than a screw driver. This is one of the few things I recommend buying from the 'stearlership'. But not the water pump! Go online for the water pump. And, make sure it has a metal fan. I heard the plastic fan is cr#p!
I'll betcha, if everything else is done,(as in, nothing else is clogged up) this'll do it IMHO. Remember, it's been sitting for a spell.
There is a stamp on the side of the head, inside a tri-angle, I think. This tells you what year the head was manufactured. Post '80, I'm sure is safe. The water jackets are larger & a lil farther apart than pre '80; or was it pre '79? The later stamped head is better, along with the fact that a Spanish Head (I'm not sure how to know a Spanish-built head from??) is supposed to be a very reliable after market head. Plus, a LOT cheaper than the BMW head along with the reliability issue. Greg

[alotawatts]

And change the bleeder valve on top of the water pump to the one that has to be opened/closed with a wrench rather than a screw driver. Greg

I think Greg meant to say bleeder bolt on top of the thermostat.....
Good info

[GripGreg]

Right;right!! The thermostat! Greg

[Mike W.]

Post '80, I'm sure is safe. The water jackets are larger & a lil farther apart than pre '80; or was it pre '79? The later stamped head is better, along with the fact that a Spanish Head (I'm not sure how to know a Spanish-built head from??) is supposed to be a very reliable after market head. Plus, a LOT cheaper than the BMW head along with the reliability issue. Greg

Later heads, or the AMC Spanish heads are much better than early ones or middle ones, but especially on a car with thermos any of them can crack. It's just that the early ones are pretty much guaranteed to crack and the later ones might or might not crack.

[Blaise]

While I do not have much to help you with your predicament, I thought it might be helpful for me to share my own experience.

I have had my e12 for a couple weeks now. When I first got it, it would overheat unless at a good freeway clip.

I bought a high flow water pump from metric mechanic, but have not installed it.

My first step was to flush and clean the system. A friend of mine sent me a link to another forum, where one member recommended using an oxalic acid mix to clean the cooling system. If you are not familiar with oxalic acid, it is often used to clean the tannins off of woods such as redwood or teak. I also use it to clean metals.

Anyway, back to the car. I drained my system, including the engine block plug and filled it with water and about 200ml of oxalic acid. I have run the car for about 100 miles and flushed again with water. I will flush a few times like this before putting a coolant mixture back in. You would be amazed at the junk that comes out.

Here is the interesting news. My car now runs so cool that it does not reach the normal operating temperature. Even if I leave it idling in the parking lot on an 80 degree day. The reason is that the previous owner had installed a 71 degree thermostat to combat the overheating issue. Obviously I will have to go back to the stock thermostat.

Here is the post that I was referring to....hope it helps (see post #5):

http://www.e9coupe.com/forum/showthread.php?t=6114

[GripGreg]

Oxalic acid. HUMMMM! How much is 200ml. I'm guessing 1/4 cup?
Would it be at a hardware store? Thanx In Advance,,,,Greg

[grumpsjr]

If my metric is correct, 200ml is about 6.5 oz, or just over 3/4 cup.  Should be able to find it in the paint section of the hardware store.  My E12 has cooling issues too, so I'm going to give this a try.

Brian

On Thu, May 6, 2010 at 12:44 PM, GripGreg <gripgreg@aol.com (gripgreg@aol.com)> wrote:

Oxalic acid. HUMMMM! How much is 200ml. I'm guessing 1/4 cup?
Would it be at a hardware store? Thanx In Advance,,,,Greg

Post generated using Mail2Forum (http://www.mail2forum.com)

[braino]

Cool stuff. Thanks for that post. I'm going to try that with one of my other cars, too.

I flushed the radiator with a hose before I installed it - no acid, though. Great idea.

cheers,
Brian

[Blaise]

Sorry guys, I should have provided a little more information.

If you want to know more about it:

http://en.wikipedia.org/wiki/Oxalic_acid

Oxalic acid is usually sold as "wood bleach". You can find it at hardware stores, lumber yards and marine supply stores.

I bought some for a project at a local lumber yard recently. The stuff that I just put in my car came from West Marine. It comes in the form of a powder that you mix with water.

http://www.dap.com/images/products/hire ... BLEACH.jpg





http://www.westmarine.com/1/1/19952-oxalic-acid.html