Overheating Issues

[enildeR]

I fixed a number of problems on the car recently in order to pass smog.

Well. It failed, but I knew it was going to because I saw the needle at 3/4's. For some reason the front fan isn't kicking on, and when it rarely does, the whole damn car vibrates!
Anyway, the guy said I should take the thermostat out, check the fan clutch, and bleed the coolant.

I'm not familiar with bleeding the coolant.

Can anyone chime in on this process?
I would greatly appreciate it.

I guess I'll be doing a fan delete soon. That and prolly flush my coolant, but I'm wary of the shops that will do the flush/change for you in 15 minutes. I don't know if they use the right antifreeze that will not cause leaks (as discussed in a previous thread).

Also, I was changing the oil and noticed something in the lower front of the car was broken. It looked like a resistor (with the white block) inside a black plastic coupling. Does this thing control the front fan kickon? I'm going to look at replacing it, but I'm curious what it is.

[2002maniac]

your car is overheating and you want to do a fan delete?

Drain all the coolant, and fillit up with fresh stuff.  Run the motor for a while at varied revs with the bleed screw on the top of the radiator loosened a bit.  This will purge most of the air from the system.  Let it cool down before topping off the radiator, then bleed it again.  If it is still overheating I would suspect the waterpump or thermostat.

[enildeR]

I thought doing a fan delete meant taking off the belt driven fan and hooking up an eletric one? Hrmm. Oh well. my bad.

Now I recall that the person /only/ used the front fan. "Fan swap"? Well, I plan to put an electric fan on.

[D. Clay]

I think the front electric fan comes on with the A/C. Try wiggling the fan blade to check for fried bearing. Get a big fan that moves a lot of air (16" 2000 CFM or more).
The antifreeze thing is mainly from the days before aluminum heads were widely used. The first brand to make a big deal about this was Alu-gard in the 70's. They sponsored Rusty Wallace when he was still running short track and had a big Afro of curly red hair. ( I have pictures! ) Almost all brands are formulated for aluminum heads since the 90's but BMW stressed this going way back and it's a carry over from when they were first imported on a large scale.
Check realoem.com for the radiator vent screw. Let the rubber O-ring do the sealing. It's easy to crack that 15 year old plastic. I know because mine is epoxied and I have to bleed it pulling the top hose which works but is extremely messy. The temperature switch is high on the passenger side of the radiator.
My money would be on the fan clutch first. Warm up the car and see if a rolled up section of newspaper will stop the fan.

[enildeR]

What does it mean if the fan doesn't stop?

The bleed screw is right next to the fill cap, right? I was wondering what that was.

[enildeR]

The antifreeze thing is mainly from the days before aluminum heads were widely used. The first brand to make a big deal about this was Alu-gard in the 70's.

Almost all brands are formulated for aluminum heads since the 90's but BMW stressed this going way back and it's a carry over from when they were first imported on a large scale.

This was the thread I was talking about: http://m42club.com/forums/showthread.php?t=586

"Get phosphate free coolant."

That is my main concern. I'll land up asking them to see what their reply would be.

[D. Clay]

After reading a lot of the latest info on anti-freeze it seems the main difference is the ph and how long it stays alkaline. Additives mainly raise ph and extend it. Use in the car and time lower it. That's why they recommend changing it every 2-3 years. The main reason not to mix them is that you arrive at the lowest common denominator of alkaline life or, by using a partial mixture of propylene glycol, get inaccurate freezing point readings.
If you're like me you only have coolant in the car for two years anyway as it's alway's being drained for water pumps, radiators, hoses,  and hopefully no more serious problems than that. So I use Prestone green stuff and have for ever in all sorts of  aluminum head cars.

Instead of antifreeze, the main culprit is the water mixed with it. Use DISTILLED and if the fan doesn't stop that's good as far as the fan clutch goes but bad as it means your problem lies elsewhere.

[enildeR]

Thanks you for the input. I've always tried to stay away from tap water when it comes to filling up the coolant system.

The fan doesn't stop, and I bled the coolant system. Seems the thremostat is the problem. Picked one up from Kragen. Can you believe the dealer wanted f'n 55 bucks for it?! And that's just for the thermostat. He was trying to sell me the o-ring and paper gasket--all for about 80-something dollars. Screw that. I knew Kragen would have a cheaper thermo, and I could try to save the paper gasket as best I could. Either way, I would still simply use thermostat housing silicone. Such a rip off.

Anyhow. I'll see how long and how well it goes when I replace it. Have to buy some coolant and water. I think I'm going to go 25/75 on the coolant/water mix with water wetter.

Anyone know how many quarts are system holds?

[enildeR]

Well. I replaced the thermostat last week on thursday, let the silicone cure up on friday, and test ran the engine friday night. No leak. While idling, the temp needle stayed at 1/4s.

Unfortunately, it's still heating up when on the freeway. Though, it won't go above just past the 1/2 mark. The aux fan still kicks in. Figured out why it's vibrating the car. The PO had the car fixed after an accident, but the bumper wasn't pulled out far enough (or it was pushed in). The bolt on the center of the fan slightly touches the bumper.

Anyway. I took a trip to sacramento to do some camping/rafting. The car couldn't stay cool while cruising or going up a hill. The only time it would cool off was while coasting down the hills.
On my way back from my trip. I figured I'd try to buy some duct tape to cover a small 5in gash in the fan shroud, but that didn't help at all. It covered the gash fine, but it did nothing to help keep the temp down.

1. How can I tell if the radiator core is bad/clogged?

2. If it is bad/clogged, can I take it to a shop to be cleaned? Do I have to buy a new one?

The reason I think it's clogged is when I open the bleeder screw and rev the engine slightly, coolant gushes out. Also, when I take off the overflow tank cap, there is a little slit in the neck that squirts coolant into the overflow tank when I rev the engine. Or are both normal?
This is getting to be a pain in the ass.

[silverblades181]

Coolant coming out of the bleeding screw means theres no more air in the system. It's normal. Temperature being at the 1/2 mark is also normal. I didn't get the thing about the slit though...Check your water pump, is it making any weird sound? Also, why did you do 25/75 on the mix?

[enildeR]

Well. I know the temp at 1/2 mark is normal. Mine tends to stay just past that, particularly where the aux fan kicks in, and it'll stay there. I'll have to listen and see if it's making noise. I haven't noticed an new noises.

I went with 25/75 to have higher cooling efficiency while still preventing corrosion. Anything below 25%, and things begin to corrode. Second, higher percentages of antifreeze are to prevent the freezing of the coolant at lower temperatures. I live in SoCal, so that's not going to be an issue. The 25% will handle any drops below freezing that I would see here in California.
I was planning on putting water wetter in, but decided I'd wait till I know I won't have to drain or replace the coolant again, for whatever reason.

[enildeR]

Oh. As for the part about coolant squirting into the overflow tank... Do this: take off the rad cap/overflow cap and have the engine running. Using your finger to manipulate the throttle, while looking into the overflow tank, blip the throttle to 3k or more. I see coolant pouring/squirting back into the tank. I don't know if that's normal. Leads me to believe that it's due to blockage in the rad core.