Overflow Coolant cap on E36

[Mercenary(FH)]

Just curious, does our E36 have an overflow cap. because when i got my water pump changed, they obviously topped off my coolant, but I've noticed after driving it hard (new suspension :-D had to take advtange of it)
that the coolant had dropped some at hot level.

im assuming that when they filled it up the coolant was cold, and my "spirited driving" and plus the coolant raises when hot. so im assuming somew would go through the overflow cap?

just checking to see if it had an overflow cap and my situation makes "sense"

[desperate 4 help]

I'm not an expert but I had a failed water pump once on my 320. It caused the coolant to bubble through the rad cap due to the excessive temp and pressure. Although I have a european car I'm sure yours is similar, and would say it does act as an overflow.

The line on the rad states cold level, after you've blasted down the highway the water warms up but it shouldn't foam through the rad cap since the cap will hold in any reasonable pressure.

If I were you I would bleed the coolant system a little (5 min job) just to see if there are any serious airlocks. There is a bleed on the top of the rad (black plastic crosshead) and also a 17mm or similar on the exhaust side of the engine block, easily accesed from beneath the car. easwe of the bleed bolt and let some coolant flow out (only a little is required). Hopefully you will here a hissing noise as air is escaping. These motors are bar stewards for airlocks if not filled properly.

Always fill your rad very slowly too, will prevent air locks.

I think that no matter how hard you drive it shouldn't overflow (but i might be wrong).

Also make sure when your filling from empty the fans have been left in the hot and on position in order to open the solenoid valve for the heater matrix.

An airlock may warp your head if its stopping flow to the head but I doubt this is the prob, more likely something smaller. run the car till hot and Sqeeze all the hoses you can see. If they are solid (feel like a over inflated tyre) youve found your lock. A normal coolant hose will still be squidgy upon sqeezing but a air locked hose will be closer to rock solid after a good run, but be careful.

Pete (the ews ratsnest)

[Mercenary(FH)]

well I mean the temp has never gone up. but don jacbos (bmw dealership) just basically poured a shiitton of coolant in there, like all the way to the top. and now it's a lil below. So who knows. but I figured if it was cold when they poured it in and the coolant expanded when it was hot, obviously some is going to leak out......cause where else would it go

[Dudesky]

Why don't you take the cap off and look at it?

You'll see it says "2 BAR". That means it's designed to release the pressure when it exceeds 2 BAR (or 29 PSI).

[Mercenary(FH)]

oh well that explains that. I mean I know don jacobs jsut poured a bunch in there without care so im sure their were air pockets, so ill prolly bleed the system anyways, cause when I take the cap off, the coolant goes up considerably

[Dudesky]

Pressure does not mean you have air in the system. If you took the cap off while the engine was hot, then you should expect the coolant to rise, because you're releasing the pressure, and the coolant is replacing that volume in the expansion tank. BMW's cooling system is pressurized- it's supposed to be. The pressure increase raises the boiling point of the coolant, thereby keeping the engine cooler.

It's simple: if your heater isn't blowing hot air, then you probably have air in the system that's not supposed to be there. And always check the level when the engine is cold. Don't worry about what level it is when the engine is warm.

[desperate 4 help]

good luck pal. only look at the rad fill line when cold. A healthy sys shouldnt blow water though the cap as it operates below 2 bar.

dudesky can you help me with my "ews 320 into 328" post? I'm fapped. am looking to put the 320 back in this weekend .

[Dudesky]

^^^Yea, I looked at that, but I'm not too familiar with the EWS system. hang out, tho- maybe someone else can help you out

[B_w.]

how many threads have you posted about stupid coolant problems? THERE IS NOTHING WRONG WITH YOUR COOLANT SYSTEM! RELAX!

[3050rpm]

It's been my experience that adding new coolant, such as after a system flush, needs to be done rather slowly, and carefully (such as by massaging the coolant hoses), to minimize the formation of air pockets, and even after that, the level should be monitored for a week or two after regular driving to see if any "burps" materialize. Also, be sure to have had the heater valve turned fully open. Undo the bleed screw next to the radiator cap (when cold), and add coolant as necessary until it consistently stays at the right level.

[Mercenary(FH)]

thats what i figured, but knowing don jacobs they prolly just poured shit in, altho once it drops it tends to stay at that level.