M20 Water Pump - telling if it's good or bad or a donkey?

[doogie]

OK, I've pulled the water pump from my M20 (which was waaaaay harder than I was expecting :'() - is there any way I can tell if it's broke before shelling out for a replacement? It visibly looks fine if a little rusty, and spins pretty ok, although it does have a little grind every so often.

I've tried to disassemble it (there's an exploded diagram on the ETK) but I can't for the life of me get it apart (rigger gloves and twisting really hard!)

Should I just bite the bullet and buy a new one assuming it's broke or what?

(and yes I've now realised that although I drained the rad I didn't drain the engine block - I obviously skim read that and assumed I knew what I was doing, LOL!)

[632 Regal]

Ok Doogie, I am assuming you need or want advice so I will go from that standpoint.

The waterpump, thermostat, belts and hoses on a BMW are regular maintenance items. This goes against common knowledge of american cars where you run them til something breaks and then fix it, such as a waterpump when you are 350 miles away from home. Wonder what that would cost after towing to the nearest facility that can take care of that small problem for you on your BMW I see $$$$$ and so do they.

Other things that are maintenance items include replacing the brake fluid evey 2 years, rear end fluid, trans fluid (argumentative on the autos) and antifreeze. I'm skimming now.

That being said you should be able to decide for yourself if you want to bite the bullet or not on an old waterpump that was a PITA to simply remove. Read up on scedule 1 and 2 mauntenance and get an idea what is done and at what times and I think you will realize why these cars can go for an easy 300K miles before BMW recommends replacing the engine. The vehicle itself should last forever unless rust or a collision supersedes.

I am not trying to be a smartass although I usually am on here but trying to get you to see the grand design of a BMW. There are a lot of newbies here giving false advice (or bad guesses) and that was not why this board is here.

After reading on your initial post I believe I suggested that you had cavitation causing the overheating which was probably initially caused by replacing some sensor. In other words air got in the system, you didnt bleed it correctly and the water did not circulate. Others advised you that you had a bad waterpump and you went and pulled it. You are probably due a new waterpump along with other items but since you didnt get good advice you pulled the pump instead of looking at the other most likley cause...air in the system.

After you replace the waterpump you will have to PROPERLY bleed the system or you will overheat. There is more than enough information on here about bleeding if you search and also on Brunos site.

I am here to help and so are most others, heed advice and use common sence and you will be a happy BMW owner. I did not try to offend you but enlighten you.

Good luck!

[doogie]

Thanks for your advice, don't worry I'm not offended, just trying to get my car back on the road. :)

I think I will probably just buy a new water pump since it's out now and it's not *that* expensive for a new one - will go down to a parts store tomorrow morning and get one and then leave work early and try to put the car back together the same way it was before I took it apart, LOL!

Thanks

[632 Regal]

dont get a GEBA pump...try to get a LASO if possible, they are one of the better ones. Get a new thermostat, make sure its a BMW stat or you will have to drill an 1/8 hole to get it to bleed.

Do you have BMW coolant? I like it but others like the green crap...BMW blue for me. You didnt drain the block so are you going to drain it or flush the old crap out? No use having to do this twice for double the price! If you do it right the first time you wont even have to think about it for at least 2 years (everything else being equal) If you dont drain the block add 1/2 the amount of antifreeze first as the system takes for protection and then add your "distilled" water to top it off.

Read up on bleeding that system, Winfred says its a bitch to do it right, others have raised the front wheels up on ramps to get the air to purge and yet others dont heed anything and just crack heads and head gaskets. The choice is yours on that one.

No matter what action or direction you take, please at least do a full review on bleeding your system properly, you dont want to be one of those people we refer to by name when things go bad. There have been several really bad examples this last year and after remortgaging their houses failed to simply get things right. I havent heard from many of them lately.

Good luck tomorow!

[doogie]

Thanks :-) I've drilled a hole in the current stat and I did confirm in a pan of water on the cooker that it opened when the temperature went up and closed when it went cold again. I might just get one anyway to be safe.

I don't currently have any coolant.... I'll drain the block and do a flush (although I don't have a garden hose/ outside water - can I do this with loads of jugs of water or will the pressure not be good enough? Do I have to use distilled water to fill it up or is tap water ok (I'll have a read around on that one)

I've currently got the front up on axle stands (don't have any ramps) so hopefully that'll help a bit with the bleeding.

Thanks!

[doogie]

Right I have the new pump and have a question - is there some knack to getting the pump, the spring & pin and the bottom bolt in all at the same time????

I've played about with remounting the old pump a bit so I don't damage the shiny new one, and I think I'll manage it, but it's not going to be easy... am I missing something obvious ? (like an orc sword or something ;))