Question - When replacing M30 water pump

[Mitch90535im]

Do you use:

1) No additional sealant, only the gasket
2) Sealant only, no gasket
3) Sealant on one side of the gasket only
4) Sealant on both sides of the gasket

[Bill R.]

need to take it back apart later, but seals well also....
That said, I dont think your pump will help the overheating problem..

Do you use:

1) No additional sealant, only the gasket
2) Sealant only, no gasket
3) Sealant on one side of the gasket only
4) Sealant on both sides of the gasket

[Mitch90535im]

need to take it back apart later, but seals well also....
That said, I dont think your pump will help the overheating problem..

I'm not convinced it will help either, but we're working out way up the chain least expensive to most expensive, and the water pump is next.

What's your opinion as to what the problem is Bill?

[Bill R.]

And did it start only after you changed the coolant?

I'm not convinced it will help either, but we're working out way up the chain least expensive to most expensive, and the water pump is next.

What's your opinion as to what the problem is Bill?

[Mitch90535im]

Sorry for the wordeness Bill , but here it is start to finish -

Started after a drain/flush/fill:

Temp went between 1/5 - 3/4 next morning on the way to work, waiting in line for a biscuit.

I suspected air, so I bled, topped, bled, bled, bled, etc. (at least a couple dozen times)

Thought things were ok then a couple of weeks later overheated in mall parking lot (slow traffic)

Suspected air again - bled, topped, bled, topped... (didn't appear to be any trapped air)

Seemed to get worse over the next week or so. I only work 2-3 minutes from home, so it would basically heat to normal in time it took to get to/from the office. I tried to avoid slow traffic or any extra mileage because I really don't like to run it at all when over 1/2, (I'm honestly not sure if overheating occurs at high speeds or not)

At that point I suspected either a stuck thermostat or fan clutch, or aux fan. (since top hose is hot and hard I assumed thermostat is OK. Since fan spun when turned off hot (2-3 revolutions when I was expecting abrupt stop, I replaced the fan clutch.) No change.

Next, tested the aux fan. It at least works with the A/C on. (I haven't tested both speeds yet, but with A/C on, overheating still happening) Doesn't appear to be air flow problem based on that, right?

Next, replaced thermostat with a cheapie from auto zone.

After replacing thermostat, when bleeding, noticed something different. Just about scalded myself. After warming up to normal temp and opening the bleed screw it blew coolant (at high pressure) all over the place. Actually blew until it was dry. Noticed that heater was blowing cold inside and radiator feels cool to touch.

That is leading me to believe that the water pump is not moving coolant. I couldn't find a reasonable way to test the water pump on the car, so I have one on order from BMA. I'll put my original thermostat back in when I do the water pump.

Of course I also suspect that it could be a crack or head gasket, but the system is definetly pressurizing. Local independent wants $60 to check the cooling system pressure, so I'm saving that for last. Oil looks good.

[Jr ///M5]

Don't mean to barge in, but it sounds like it has an air lock. Did you have the heater on full with the key in the "on" position when filling? Did you drain the complete system by pulling the drain plug in the side of the block under #6 cylinder?

You might try draining the system again, jack the car up on ramps, fill the system with the bleeder open until fluid runs out, fill very slowly. You might have to remove the Coolant Temperature switch to help burp the system. With the front end up in the elevated position, it helps to purge the air in the system.

Jr

[Mitch90535im]

Don't mean to barge in, but it sounds like it has an air lock. Did you have the heater on full with the key in the "on" position when filling? Did you drain the complete system by pulling the drain plug in the side of the block under #6 cylinder?

You might try draining the system again, jack the car up on ramps, fill the system with the bleeder open until fluid runs out, fill very slowly. You might have to remove the Coolant Temperature switch to help burp the system. With the front end up in the elevated position, it helps to purge the air in the system.

Jr

I'll take any advise I can get and I certaintly suspected air JR.

When I changed the coolant, I did not remove the block plug. Reason being that the radiator was only 2 months old and I had been running straight water for those 2 months until I had a chance to get by the stealer (not one in my town) and pick up some blue stuff.

'You might try draining the system again, jack the car up on ramps, fill the system with the bleeder open until fluid runs out"

Will coolant ever run out the bleeder hole if the front end is elevated?

When I filled it here is how I did it - I set both heater controls to full warm, filled with 50/50 (slowly) . I filled it until overtank was full, then opened the bleed screw, filled it until coolant flowed out, closed bleed screw, warmed it up, then bled it. It did have some air at this point, but seemed to bleed OK, then topped off. Once the overheating started I bled and topped at least a couple dozen more times, and didn't see amy more air.

When I replaced the radiator in Sept., it bled good, and ran fine until after I drained and refilled with 50/50.

[GS535i]

For what it may be worth, at one point my 535i rapidly overheated without any prior warning signs: It blew most of its coolant out through the overflow, etc. Thinking it was a stuck thermostat, I opened the 'rad' cap, refilled, and limped home with the cap still open. Replaced the thermostat, and the problem repeated - replaced the rad cap, and the temp needle has sat perfectly on mid scale ever since ... (the OE cap was stamped 1.4 bar, the new was 2.0 bar [release pressure], but works just fine).
Test the thermostat by slowly bringing to a boil in a pot of water: it should be ~1/4 open at 83C, and fully open just prior to boiling. You can make your own cooling system pressure tester any number of ways: cut out a section of a bicycle inner tube with the air valve, and clamp it in-line with any coolant hose, or epoxy a similar fitting on the rad cap you are going to replace, etc.
This is worthwhile doing, for hoses and plastic end tanks (especially the hose nipples) can fail rapidly after a diet of steam - if the overheating became severe.

[winfred]

ill almost bet that the pisser line that goes from the top of the radiator to the coolent tank is plugged, with motor cool remove cap and disconnect the line from the radiator and try to blow through it into the bottle, if this line is plugged the system will not burp internally and the coolent will not flow properly. i just did a 91 535 yesterday and a few months ago we got a 91 735il that belongs to a mechanic friend of mine's parents for me to do a head gasket (as it was diagnosed by a generally top quality bmw shop) (he wanted me to do it because i've done so many, and i guess he's lazy) i didn't see anything wrong with it so i checked the pisser and sure enough it was clogged and was the only problem with the car. i always check to see if water is flowing into the bottle before going further into a cooling system as i've seen it too many times

[632 Regal]

I dont know...the more that time goes on Im glad I got the optional Nikasil option. No weed no bleed.