Ah feck, overheating and suspected water pump failure

[doogie]

Ugh, after replacing the temp sensor the other day I had a massive overheating problem today (after driving really slowly round a car park for ages :() - had steam shooting from the top of the rad cap, which I waited till had cooled etc then topped up with plain water trying to get home, then 10 mins later had steam coming out from the engine around the spark plug area - got the AA out and although there was water/coolant in the expansion tank, there was none flowing through the system and so rad was not getting hot - took apart to check thermostat which physically looked fine, so AA mechanic reckons it's probably a water pump.

I've got the procedure for taking out water pump in my Bentley and in Haynes, and hopefully the impeler is going to be noticeably broken so I can buy a new pump. Anyone any pointers/ gotchas on the replacement ? I see I need a 32mm spanner which I don't have - hopefully my adjustable one wont be too fat to get in the space!

Cheers

[doogie]

OK an observation/ question - because the system was full of plain water and it's blooming cold here, I went out to drain it so that there's nothing there to freeze overnight. I removed the rad cap, and undid the drain plug (it didn't come out - was it supposed to, did I just not twist it enough?) and some water came out. I then messed around with other hoses and eventually removed the hose at the bottom of the rad at the other side from the expansion tank and loads of water came out - should that have happened?

Does that suggest that I might have a rad problem rather than a pumping problem?

Thanks

[Scott C]

OK an observation/ question - because the system was full of plain water and it's blooming cold here, I went out to drain it so that there's nothing there to freeze overnight. I removed the rad cap, and undid the drain plug (it didn't come out - was it supposed to, did I just not twist it enough?) and some water came out. I then messed around with other hoses and eventually removed the hose at the bottom of the rad at the other side from the expansion tank and loads of water came out - should that have happened?

Does that suggest that I might have a rad problem rather than a pumping problem?

Thanks
Change the pump - relatively common problem with the plastic impeller
Scott

[Scott C]

Change the pump - relatively common problem with the plastic impeller
Scott

Do search here for water pump and anti-freeze.... A lot of people won't use anything other than BMW antifreeze

[632 Regal]

dude what you experienced is called an air pocket. The engine has to be bled thouroughly after adding or removing water. Do a search on "bleeding" in this place and you will find all you ever wanted to know about it. You may not even have a bad waterpump.

[winfred]

a m20 doesn't have the impeller problem, id be looking at a new tstat and bleed any air from the system, a m20 is a bitch to bleed unless you drill a small hole in the thermostat to burp the air from the block, the radiator can collaps internally and cause problems, you said the radiator was cold so id guess you had a air bubble at the thermostat, usually after gotten hot the thermostat gets unreliable

[doogie]

Right.... took the stat out and checked it in a pan, opened fine. Drilled a hole in the stat and put it back together. Poured a couple of litres of water in till it started coming out the rad bottom hose (on the opposite side from the expansion tank) then reconnected that hose - I think that means that the flow through the rad is fine - ???

Poured another 3 litres in and I can't seem to get it to take anymore (it should take 10 litres yes?) - tried turning the engine over and still no change to the level, up to the top of the expansion tank, but only max 5 litres in there and nothing in the top hoses.

I've just realised that I don't have a big enough spanner for the blooming water pump so I'm trying to borrow/ buy one as we speak.

[doogie]

I've now taken the water pump off (blooming heck that took a lot longer than I expected!) and physically it looks fine to me (but what do I know!) - it doesn't seem to come apart so I can inspect it further - should it and is there a knack?

When I took the water pump off a fair amount of water came out - is that normal or does that suggest a blockage somewhere?

Thanks