Are these spark plugs toast?

[Eric93se]

There is no need to empty the coolant and start over, that's silly.

Drive it short distances with the heat on and feel for hot air at the floor. Let the car sit over night and inspect the next day what the level is. When the coolant is cold never fill over the cold line.

Only when your initially filling the system is it ok to fill well over the cold line to help fluid move to the high spots in the engine.

[zellamay]

There is no need to empty the coolant and start over, that's silly.

Drive it short distances with the heat on and feel for hot air at the floor. Let the car sit over night and inspect the next day what the level is. When the coolant is cold never fill over the cold line.

Only when your initially filling the system is it ok to fill well over the cold line to help fluid move to the high spots in the engine.

"silly"? Are you sure? People do it all the time.

[Eric93se]

I don't know, emptying the coolant to refill !? I don't know, doesn't sound needed.

[R Shaffner]

Often I've heard BMW owners say they filled and bled the system, but then they'd get all the symptoms of a system that was low on coolant. I was concerned about that when I heard that you didn't get heat in the cabin. Now it sounds like you've been bleeding it well enough, so the lack of cabin heat could be a separate issue.

The cabin heater should get warm and then hot coolant flow as soon as the engine makes it, so long as the temp setting is high enough and that system is working properly. In other words, plenty of heat should be sent to the cabin by the time the thermostat opens and makes the top radiator hose hot. So you might have a faulty switch/valve, or a blockage in the heater. (Has anyone ever put some kind of stop-leak in the system? I hope not.)

As others have noted here, coolant expands as it gets hot creating pressure in the system (when the cap and bleed screw are closed). That pressure also raises the boiling point. If you crack open the cap or bleed screw on a hot engine you'll release some of that pressure as air and/or coolant comes out. The loss of pressure will cause some of the coolant to boil, creating steam, and that steam will make it's way to the top of the radiator and the bleed screw area.

The only reason I can think of for cracking open the cap or bleed screw on a hot engine is to verify that the system is building and holding pressure, by noting that air/coolant comes out as soon as the cap isn't tight.

There's no reason I can think of to remove the bleed screw on a hot engine, and it would be futile to try to bleed a hot engine because the coolant would just keep turning to steam that came out as bubbles from the bleed screw. You also don't need to worry about bleeding the steam out. If it's just steam, it will condense as soon as it cools a bit and turn back into liquid coolant.

And again, these systems are somewhat self-bleeding. If your radiator has an inch of air at the top of it, it won't cause a problem and that air will eventually be bled out to the expansion tank after several hot and cold cycles.

And finally, if you're draining and refilling the system (which shouldn't be necessary), and if you have an issue with the heater not opening/flowing properly, then that might be where some air is getting trapped temporarily. That might create some lingering bubbles. But again, the system will bleed that much out over time. (Just keeping checking and topping up the coolant level up when it's cold.)

So, back to the second overheating event... Do you think the system was pretty full then? Could it have overheated from low coolant? (If the aux pump isn't working, that might explain why the cabin heat is low at idle and why the system might not have been bled well enough after the 1st overheating event.)

If you think the system is full now, I'd go ahead and take it on short drives. Just keep a close eye on the temp gauge and be prepared to stop if it gets hot. (Normally turning the heat on high temp and high fan will help cool down a hot engine. Not sure about your heater but it would be worth a try.)

[jmo69]

Wait! That's a big warning sign that your coolant system isn't right and probably isn't full of coolant. Whatever bleeding you're doing might not be right, or enough.

Personally, I don't like to rely on the aux pump. With a cool engine, I'll start with the cap and bleed screw off, the cabin heat on high but the fan on low. Then I'll start the car, add coolant whenever it drops below full, and watch it as it warms up. I'll look for leaks as I keep adding coolant. If the thermostat is working properly, it will take a while (maybe 5 minutes or more) before the top radiator hose starts to get warm. At that point warmer air should be coming from the cabin heater and you can turn it back down or off. Keep adding coolant whenever needed. At first just air will come out of the bleed screw, then coolant with bubbles (sputtering), then just coolant. When the top hose is hot and just coolant comes out of the bleed screw opening, you'll know both the pump and thermostat are working. Then put on the screw and cap (again making sure it is at least at the full mark). Then I let it continue to idle to make sure the system builds and holds pressure, and that no leaks emerge as the pressure builds. I'll also let it idle long enough to see if the electric fan comes on as it should. If all looks good, then I'll take it for a drive and check again for leaks when I return. You'll prob need to add a little more coolant after the engine cools and the coolant contracts.

Then you know all key parts of the system are working and that it's full of coolant.

According to the Bentley manual you fill and bleed cold, I do my e46 that way whenever I service the cooling system. I also do my e36 that way. I usually have to adjust the levels over the next few days. Where is this auxiliary pump you mentioned, I've never found one on either of my cars, e34s have one IIRC.

[spyderg0d]

No auxilary pump on e36 or e46. Auxillary fan is in front of the rad, in the front end support frame system encased in a fan box of sorts of plastic pieces.

[R Shaffner]

According to the Bentley manual you fill and bleed cold, I do my e46 that way whenever I service the cooling system. I also do my e36 that way. I usually have to adjust the levels over the next few days. Where is this auxiliary pump you mentioned, I've never found one on either of my cars, e34s have one IIRC.

Here's a picture of an auxiliary water pump. When mounted the metal cylinders point up. I've seen them near the brake master cylinder on an e34. On my e39 they're in the engine bay near the driver front wheel well.
s-l300.jpg

The main purpose of the pump is to help hot coolant flow to the cabin heater at idle (think of cold German winters). The Bentley manual says to turn the key on, motor off, and cabin temp on high -- that should turn on the aux water pump which will then help bleed air from the system.

Personally, when I refill and bleed the system I like to see whether and how well the thermostat opens and the primary water pumps sends hot coolant to the radiator. If the aux pump isn't working right, the system won't bleed well unless one starts the engine and uses the primary water pump.

And yes, because some of the coolant gets hot before I finish bleeding, that means I have to add a little more when it cools off. Just the way I like to do it, but might help here if the aux pump/heater valve isn't working right.

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No auxilary pump on e36 or e46. Auxillary fan is in front of the rad, in the front end support frame system encased in a fan box of sorts of plastic pieces.

Are you sure? Just saw one listed on realoem for a 1996 e36 (the OP's car).

[jmo69]

I think what you think is an aux pump on the e36 is the heater valve. If there was a pump you should hear it when under the hood.

Sent from my SM-G950U using Tapatalk

[spyderg0d]

Thats the heater valve. Not a pump.

[spyderg0d]

That does open when you turn the heater on though. The valve redirects hot coolant to the heater core from the engine. Obviously if it doesn't open there will be a constant air bubble in the heater system since the coolant cant back track to fill the space in the heater core. Although, it wouldnt make coolant disapear could indeed be an issue to consider. If you chose to delete the valve, its best to delete the valve and block off the heater core, rather than leave the flow unchecked, as it does steal some flow from the radiator system and could cause further cooling issues.

[jmo69]

That does open when you turn the heater on though. The valve redirects hot coolant to the heater core from the engine. Obviously if it doesn't open there will be a constant air bubble in the heater system since the coolant cant back track to fill the space in the heater core. Although, it wouldnt make coolant disapear could indeed be an issue to consider. If you chose to delete the valve, its best to delete the valve and block off the heater core, rather than leave the flow unchecked, as it does steal some flow from the radiator system and could cause further cooling issues.

The way I understand the heater valve is open by default and closes from signals from the HVAC, at least on the e46

[R Shaffner]

Sorry guys if I got some of the model details wrong. Most of my experience is with the 5 series; I know I'm not up to speed on all the e36 variations.

However...are you all sure no e36 328i has an auxillary water pump? I could be wrong but I thought I helped someone replace his heater valve and aux water pump together, like this one shown for sale on eBay. And I know I've worked on a similar valve/pump set-up on an e34 525i.

https://www.ebay.com/itm/New-Heater-....c100005.m1851

But all this is a diversion. The real issue for the OP is whether his car has enough coolant now and whether he can drive it without overheating. I hope we get an update.

[jmo69]

The link you listed won't work for an e36 or e46 non M according to their compatibility listing for what it's worth. It does fit the M3 and Z3.

[R Shaffner]

Come to think of it, it was probably a same-period 318i that I worked on with one of those. Still an e36 but different engine. (A neighbor gave a convertible one to his wife a year before he passed away with ALS. Later she was shocked at the cost of repairs so I offered to fix it for the cost of the parts.) Sorry again my mistake.

So to get facts straight for the e36 328i, does the normal bleed procedure say to turn the ignition on while bleeding, or not?

[Nanniepoo]

Sorry guys if I got some of the model details wrong. Most of my experience is with the 5 series; I know I'm not up to speed on all the e36 variations.

However...are you all sure no e36 328i has an auxillary water pump? I could be wrong but I thought I helped someone replace his heater valve and aux water pump together, like this one shown for sale on eBay. And I know I've worked on a similar valve/pump set-up on an e34 525i.

https://www.ebay.com/itm/New-Heater-....c100005.m1851

But all this is a diversion. The real issue for the OP is whether his car has enough coolant now and whether he can drive it without overheating. I hope we get an update.

100% positive. Although I've fortunately never had to mess with my heating system on either a '94 325i or '98 323is, I've never heard of an aux pump and it's never come up as a part when doing cooling system work. Perhaps BMW had fancier heater "valves" on their other cars that include a pump, but on E36s they're just a valve.

Come to think of it, it was probably a same-period 318i that I worked on with one of those. Still an e36 but different engine. (A neighbor gave a convertible one to his wife a year before he passed away with ALS. Later she was shocked at the cost of repairs so I offered to fix it for the cost of the parts.) Sorry again my mistake.

So to get facts straight for the e36 328i, does the normal bleed procedure say to turn the ignition on while bleeding, or not?

Never owned a 318 nor worked on them, but searching through realoem I'm only seeing heater valve, no pump. Additionally searching on parts websites, no hits for aux water pump.

I don't think I've left the ignition on while filling before. Once it's full as I can get it I start the engine and bleed with the engine running. For whatever it's worth, I've followed the same process on an E70 as well which has an aux pump.

[Eric93se]

That newer bmw design is interesting, adding an aux pump to the heater control valve. But I kinda like our design, if we get no heat when we expect it then we know something is wrong and if it's a coolant leak then we better fix it asap. lol

[spyderg0d]

No e36 or e34 or non m e46 came with an auxillary water pump. Many people install them for track purposes or for the extra protection in hot climates, but not from factory. I think hybrids e46 m cars, and m package z3 and most of the turbocharged cars come with them now, but thats really phased in after 2012 i think.

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But yes, you need the key on, so the heater can be on. Otherwise you cant bleed the system properly.
It does help to have the car running as you add coolant. If the coolant starts rising, put the cap on, turn the car off and wait for it to cool. I usually squish the upper and lower coolant hoses to prime the coolant through and force any air into the radiator where the system can them bleed itself. If you prime the engine full of coolant, a couple heat cycles will certainly finish bleeding the system.

[R Shaffner]

No e36 or e34 or non m e46 came with an auxillary water pump. Many people install them for track purposes or for the extra protection in hot climates, but not from factory. I think hybrids e46 m cars, and m package z3 and most of the turbocharged cars come with them now, but thats really phased in after 2012 i think.

- - - Updated - - -

But yes, you need the key on, so the heater can be on. Otherwise you cant bleed the system properly.
It does help to have the car running as you add coolant. If the coolant starts rising, put the cap on, turn the car off and wait for it to cool. I usually squish the upper and lower coolant hoses to prime the coolant through and force any air into the radiator where the system can them bleed itself. If you prime the engine full of coolant, a couple heat cycles will certainly finish bleeding the system.

Thx. Not a big deal, but at least several e34s had them. Here's a pic from realoem for a '92 525i. Part 1 is listed as an Additional Water Pump.

diag_6nf.png
Here's a link to that page: http://www.realoem.com/bmw/enUS/show...diagId=64_0114

And here's a video discussing how one owner repaired his aux water pump on a e34 540i: https://www.youtube.com/watch?v=844XIOjpFt0

I guess I was wrong about e36's, except possibly the M3. My apologies.

[shadze36]

I’ve tried bleeding the system again. I followed this procedure:
Open expansion tank and bleeder screw.
Fill expansion tank with coolant until air bubbles stop coming from bleeder screw.
With expansion tank filled to top, close and tighten expansion tank cap and also bleeder screw.
Turn car on with heater and fans on full blast.
5 minutes in, still no heat from fans.
Open bleed screw, small amount of coolant and air bubbles come out and then stops. Then closed bleeder screw.
Car reaches operating temp, I shut it off.

Still blowing cold air, what am I doing wrong?

[zellamay]

Sorry for sticking my nose in without knowing all you've said, but: Could it be that your heater control valve is simply not letting any water into the heater? I have determined that is the problem on my wife's 94 325i.

[shadze36]

Im not sure, maybe it is a heater control valve issue, but I’m more worried about overheating my car again.

Im not sure what the cause of the 2nd overheat was. It’s possible there could have been low coolant, but the car had been running fine for many days until that happened. And it overheated on a pretty short drive.

If it was overfilled, could that also be a reason it overheated? Remember the 2nd overheat was when coolant was spraying out of the expansion tank cap as I raised the hood to look.

[shadze36]

Also worth noting that the heaters were working fine before the 2nd overheat if I remember correctly.

[shadze36]

Okay guys another update:
Just took the car for a test drive around the block to see if it holds pressure. After 10-15 minutes of stop and go around the block, the needle starts the move towards the right. I quickly pulled into my driveway before it passed the 3/4 mark and then popped the hood. Immediately I see coolant is splattered along the expansion tank and nearby components. I didn’t physically see coolant spraying anywhere but I could hear a hiss coming from the bleed screw and lots of coolant around it. It looks to me like the bleed screw definitely needs to be replace since it’s not holding pressure, I might’ve over tightened it. Gonna go ahead and replace the expansion tank cap as well.

Is it safe to assume that the coolant boiled over since it wasn’t holding pressure? And does this mean I just created more air bubbles in my cooling system?

[zellamay]

Okay guys another update:
Just took the car for a test drive around the block to see if it holds pressure. After 10-15 minutes of stop and go around the block, the needle starts the move towards the right. I quickly pulled into my driveway before it passed the 3/4 mark and then popped the hood. Immediately I see coolant is splattered along the expansion tank and nearby components. I didn’t physically see coolant spraying anywhere but I could hear a hiss coming from the bleed screw and lots of coolant around it. It looks to me like the bleed screw definitely needs to be replace since it’s not holding pressure, I might’ve over tightened it. Gonna go ahead and replace the expansion tank cap as well.

Is it safe to assume that the coolant boiled over since it wasn’t holding pressure? And does this mean I just created more air bubbles in my cooling system?

Yes, if it boiled out there is now less coolant in there. You will need to add and bleed. .... There's an O ring on that bleeder screw. It does not need to be very tight: moderate push with a screwdriver. ... Make sure you haven't damaged the expansion tank where the bleed screw goes. I just bought an expansion tank for about $25, and it included a new cap, so, if in doubt, that's the way to go. Obviously, you've got to stop all leaking before diagnosing any further. ... And I don't get the worry about whether the heater works while diagnosing cooling problems. If the heater is not leaking water, it's not part of the problem.

[R Shaffner]

You're using coolant that is 50/50, right? Not just water, I hope. The antifreeze will raise the boiling point somewhat. Without pressure it will boil faster than with pressure, but that alone (not holding pressure) shouldn't cause it to overheat -- at least not until it boils out so much coolant that the engine can't keep itself at normal temp.

This time when you bleed the system, fill it and bleed it as you did before. Set the heat on high and the fan on LOW. Put the cap and screw on, start the car and watch it as it warms up. The first thing that you should notice is warmer and then hot air in the cabin. If/when that happens turn the cabin heat back down, and keep watching.

As the engine continues to idle, the upper radiator hose should get warm and then hot. That tells you two things: that the thermostat is opening and that the water pump is sending coolant through the system and out to the radiator. If you don't notice the top hose getting hot, DO NOT DRIVE THE CAR. It will just overheat again if you do. You'd need to figure out whether the pump of the thermostat is bad (or both).

If the hose gets hot it should also be getting tighter, as the system builds pressure. Leave the bleed screw alone! A few bubbles won't cause any problems. Let it continue to get hot and build pressure on it's own (without letting it out). Then keep watching for another 10-15 minutes. If the system is working as it should you will notice that the top hose is getting tight and real hot. The air being pulled through the radiator is getting warm and then hot. And finally, when the radiator gets hot enough the electric fan will cycle on and you'll notice a lot of heat coming from the radiator. Test drive it only if you confirm ALL those things.

(And do that warm-up with the cabin fan on low, or off once you've decided to turn the heat back down.)