[st]

Hi there,

I've got a very small coolant leak somewhere bu I can't find where.

• All hoses are new, all new clamps.
• All small tubes thoroughly cleaned.
• New waterpump
• Coolant: deminiralised water with anti freeze
• Coolant color: clear
• No bubbles with open expansion tank when engine is running and hot
• No smell in the interior

I need to fill around 1/10 of liter every 100 km or so








Any ideas? Pressurizing the system somewhere to see where it pops out?

Willem

Actually...yes!
BMW was kind enough to give you a schrader valve onm your expansion tank - don't take it for granted, its a luxury.
Turn your compressor down to 1 bar.
Remove the oil fill cap.
Put the tire filler on.
Put your ear close to the cam cover.
Pray to your higher power that you don't hear anything there.
Finally - look for leaks that DON"T make you want to commit suicide.:haha:

 

[Crash & Burn]

Am i being fooled? What's a schrader valve and what do you mean with onm?

Willem

Sent from my Desire HD using Tapatalk

 

[AlexA]

I think the schrader valve is only for the 3.6. No such valve on my 92 Touring anyway.

 

[mottati]

i'm in agreement with alex. The 3.8 didn't have the valve on the expansion tank. In fact, none of the new expansion tanks have the valve. (it looks like a valve that you'd fill a tire with, so you could pressurize the cooling system). When i replaced my expansion tank, there was no valve, and from what i've read it's not necessary.


Regarding the leak, is the inside of the filler cap clean? no moisture residue or anything that looks like chocolate milk? No coolant smells in the cabin with the heater on?

 

[joeywx]

from which point is it dripping from on the floor? From the back near the expansion tank or near the front close to the pipes and waterpump? If it's the latter then leaking is likely coming from one of the pipes connecting to the new waterpump/thermostat housing; in my experience--that means a busted O-ring in the housing. Check your coolant hoses and make sure the clamps are tight. If there's still a leak--it's the expansion tank and it'll need replacing. Good luck

 

[Crash & Burn]

Gents, appreciate your comments but.....as i stated in my first post. Nothing is dripping....if that wasthe case i would have found it already. I'll check the filler cap but i sure nothing is there. No smells in the interior eiter witb heater full open....

Willem

Sent from my Desire HD using Tapatalk

 

[Blitzkrieg Bob]

schrader valve was on some early 3.6s... later and replacement tanks did away with it.

 

[Alan Archer]

Small head gasket leak (internal) or small heater matrix weep.

Such a small amount could easily go undetected on the garage floor.

Does the heater smell "sweet" when you set both dials to full heat and
switch the fan on ?

These heater matrix cores are getting on in age now.....


Alan.

 

[mottati]

i think Willem is going to smack the next person who asks about any smells in the interior!

I had a head gasket leaking on an old 525, used a similar amount of coolant, never a drip on the floor. Some time lying on my back with a flashlight found a dried trail down the side of the block. Not a great answer, but was better than a cracked head (which would be my big concern).

Have you tried pressure testing? Perhaps a used engine oil analysis looking for coolant ingress?

 

[Crash & Burn]

Coolant video

Hi there gents, here a short video I made this morning after the car had run ofr about half an hour. You can clearly see the clear coolant and the spraying of the little tubes coming off the radiator and Thermostat housing (Thermostat is also new by the way).
One thing I didn't change where the tubes going to the heater valves next to the fusebox. Will update you on what I find overthere....hoping it's not the head gasket but if so...it has to come off doing all the things in there that need to done......ouich

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/bjRanPxJUJw?hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/bjRanPxJUJw?hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

 

[Dan Kelly]

Glad you found the leak.

Just for information there was no smell in the cabin when my heater matrix failed. Just all the windows steamed up and wouldn't clear. There are drainage holes that let any leaking coolant escape just above the gearbox to save your carpets getting soaked.

 

[Crash & Burn]

Glad you found the leak.

I didn't find it just yet but I will in the end...hopefully!

 

[Dan Kelly]

Sorry, didn't watch the video and then misunderstood your post.

 

[Crash & Burn]

Updated: Vaporizing coolant

Gents,

I've problaby found the cause. 1,5 years ago I refilled the cooling system with demineralised water with some anti freeze. I've used very little anti freeze because I didn't had enough at that time:sad3:. Around 2 litres of anti freeze on the total amount.

So what probably happens is that the boiling temp of the total fluid is to low causing early vaporizing through the expansion filler cap and some foaming on the top level of the fluid.
No signs of mayonaise or chocolate on the oil filler cap, dipstick or expansion filler cap....luckily.
Yesterday I bought 5 litres of red coolant (G12+) which is the best at this moment. Tonight I fill her up with the red / pink stuff and see what happens.

Any tips how I can totally remove the old stuff from engine and heater matrix?

Cheers

 

[Alan Archer]

I can't see this being the case.

The valve on the system cap is designed to only vent
when the fluid (whatever quantity or mix it is) pressure
exceeds the given value.
This is to prevent hose and gasket damage if the engine gets too hot.

Unless the seal or valve is faulty on the expansion tank cap
there is no way you are loosing fluid past it unless the coolant
is boiling away in the tank.

It doesn't matter what mix of water or coolant you have in the system,
the pressure cap works the same way.

It is however, worth checking the vent pipe from the cap
to see if it is moist or wet in any way.
This would suggest a faulty cap seal or valve.

Regards,


Alan.

 

[Crash & Burn]

Found something......

Alan, Of course I understand that the pressure valve is working the same whatever fluid mix is used but because of the lower boiling temp the pressure is built up earlier then should and therefor pushing it through the cap earlier then should. Maybe I'm wrong here.....did have an A on physics back then but now I'n not so sure anymore.........


Anyways: I found wet spot on the ground for the second time right under the outside temp sensor. First I thought it was just a pool of rain but noticing it was on the exact smae spot made me curious.......and then I suddenly remember something what happened 3 weeks ago when I was driving in traffic.
The coolant temp was normal (just before 12:00 o'clock), so was the oil temp (80 degrees) but the suudenly the outside temp started rising rather quick to around 28 degrees (it came form 13, it was a nice day in Holland). It stayed there for a around 5 minutes to drop again to nomal.

I'm thinking I made have a smalll leak on the radiator or the hose on the right lower side. Strange thing is that I don't see anything dripping.....

Keep you posted

 

[Alan Archer]

Glad it looks like you've found the leak :M5thumbs:

Even with tap water in the system alone you should
not see the condition of water boiling in the expansion tank so
the theory of boiling water escaping through the vent just because
of the mix doesn't hold true.

The system is pressurised...therefore even plain water will not boil
until way above 100'C.

Many race engines don't bother using expensive coolant as they
don't sit outside during winter !

Even with tap water or a weak mix of coolant you should not
have any problems of loss due to fluid boiling off.

Hence there was a genuine leak and you found it !


Regards,


Alan.

 

[Crash & Burn]

@Alan,, thx a lot. This afternoon I saw the small pool again and I've located it. It's the return hose from radiator to Thermostat housing. Hose is now but problably not tied enough on the T-housing.
Easy fix...will do it tonight. After that I fill her up with G12 longlife (Better for the pump anyway)

THX again...

Willem