Expansion tank leak?

[Brian James]

Hi
I have a leaking expansion tank on my 99 1.9 Z3 and I suspect it is a common problem due to the square shaped gasket at the bottom of the tank. As I am new to this website, I have tried to find a "How to" guide to help me take the tank off and replace the square black seal.
At the same time I need to replace the antifreeze but would like advice on the brand type used successfully by others.
All guidance help at finding my way round the website plus some help with these tech issues would be gratefully received.
Many Thanks
Brian

 

[2bmws]

Not sure if yours is the same as mine as mine is a p reg. But when mine was leaking I had to replace the radiator

 

[2bmws]

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[jonco]

Just to confirm do you have the M44 engine with expansion tank on side of the rad or the M43?
Have look at this https://www.pelicanparts.com/BMW/te...-WATER-Coolant_Expansion_Tank_Replacement.htm

 

[Ian Wilcox]

I had the same problem for quite a while and after trying new expansion tanks and different seals I replaced the radiator which wasn't very difficult or very expensive and it solved the problem straight away

 

[t-tony]

It's likely that all the parts are the same age and condition so it makes sense to change the lot while you're at it Brian.

Tony.

 

[AthensGA]

I had a leaky tank and went to the trouble of changing the “square” gasket and it still leaked. A mechanic explained the over time the black plastic parts of the original cooling systems would develop microscopic cracks that would only leak when hot and under pressure, then close back up when you were looking for leaks.

 

[Brian James]

Many thanks guys - to Jonco it is a M43 engine with the expansion tank on the side. Extreme thanks to the Pelican link and ebay article!

I will remove the tank and radiator to do a close examination but I really like the idea of using the ebay item (coolparts) just for added security.
Seeing the ebay feedback on this radiator it seems a very good buy - do others have OK experiences with this product? 5yr warranty seems unbeatable!
Kind Regards
Brian

 

[Mazza]

I had a similar problem on my M44 with the seal leaking…. Had a go replacing it but never got it to seal again, so bought a new rad (£56.00) and been ok ever since. I think the plastic had deteriorated as well as the rubber seal.

 

[2bmws]

Many thanks guys - to Jonco it is a M43 engine with the expansion tank on the side. Extreme thanks to the Pelican link and ebay article!

I will remove the tank and radiator to do a close examination but I really like the idea of using the ebay item (coolparts) just for added security.
Seeing the ebay feedback on this radiator it seems a very good buy - do others have OK experiences with this product? 5yr warranty seems unbeatable!
Kind Regards
Brian

Bought it last year was cheaper then think I gave 50 odd for it, haven't had a problem since not a big job, and didn't take long.

 

[Brian James]

That's GREAT feedback - looks like a busy weekend ahead.
MANY thanks!!

 

[Brian James]

Hi,
I have now replaced the radiator (Nissen) as advised on this and other related threads.

However, I am having some difficulty in understanding the coolant filling and bleeding procedure - possibly because this engine (M43) is not covered in the Haynes or Bentley manuals but I have tried to adapt the principles described therein. The coolant expansion tank is an integral part of the radiator. I understand there is a coolant capacity of 6.5lts.

The procedure I seem to have devised is as follows:
0. Check engine cold
1. Drain system of coolant from using radiator drain valve and block drain plug. Close drain and refit block drain plug. Note the system holds ca. 0.8lts residual.
2. Check all hoses connected and tight
3. Turn the heat switch to full on at the console, turn fan to 1
4. Remove bleed screw from radiator coolant tank (There is no bleed screw on the thermostat),Remove coolant filling cap on expansion tank
5. Using a 50:50 mix ethanediol antifreeze : deionised water, slowly fill the expansion tank with ca 5.5 lts so that the air is expelled from the bleed screw and fluid fluid free of air bubbles flows out. Tighten the bleed screw.
6. Replace the coolant expansion tank cap.
7. Start the engine and allow the temp to rise to mid gauge. Check heat emitted from air vents
8. Allow to cool.
9. Remove the expansion tank cap and fill with antifreeze/water until the KALT/COLD mark (ca. 1/2 way up the expansion tank) - this takes ca. 0.3lt
10.Replace cap and restart engine till mid gauge.
11.Allow to cool (overnight) and check level at KALT/COLD.

I would be grateful for your comments

Kind Regards
Brian

 

[2bmws]

I usually park on a hill, so the radiators up a bit fill it with coolant, open bleed screw on top fill till coolant comes out of the bleed screw start it wait for the thermostat to open and no air comes out of screw topping up as required then nip it off check level. Leave cool then recheck and keep an eye on it a couple of days

 

[colb]

As advised before get the front of the car as high as you can get it so the filler is highest point of the system when adding your coolant mix. Once you have some coolant in start the engine and bleed it as per your list of instructions. I did use a vaccum filler kit I bought on ebay on a M43 engined car and that worked very well, no air lock problems encountered. You do need a compressor to run the vaccum bleeder.

 

[Brian James]

Many thanks for the comments - as usual very much appreciated so will incorporate these comments into the procedure.
Kind Regards
Brian