M42 losing water

[martyyn]

My e30 m42 decided to start over heating the other day when I was stuck in traffic with the weather being nice and hot.

I pulled over after 30 mins of going nowhere with the gauge between 3/4 and the red. I gave it 20 mins to cool down, filled the header tank to the 'cold' mark (it didnt take much), gave it a burp and went on my way.

Another 10 mins on with an open road and it started rising again, so I pulled over for nearly 40 minutes for it to cool completely, had an ice cream on the beach, refilled (this time it took 2 litres) burped it again and all seemed ok.

I was only 10 mins from home so felt confident I would get there so tried again but 50 yards from home it got very hot very very quickly. I must have still had air in it somewhere because the radiator top hose appeared to have nothing in it but air.

Anyway, I left it till the morning, stuck the nose in the air, filled the header tank, let it get to temperature, opened the bleed value and definitely got all the air out this time and it was all good.

I cant find any leaks under the car, the hoses all 'look' ok and it loses nothing when sat still. So I drove it for 20 mins yesterday with no problems, but when I checked it this morning the header tank was again empty.

I know about the profile gasket but I have none of the other symptons. It starts first time and idles beautifully. There is no water in the cabin (at least the carpets not wet) so Ive ruled out the heater matrix.

So apart from removing all the hoses is there anything else I can check before handing it over to my mechanic ?

[appletree]

Check for water/mayo in the oil?

Have good check of the rad front and back.

Maybe you hadnt got all the air out? Have you topped it up and ran it again?

[mrLEE30]

sounds like all the symptoms of a blown head gasket, unfortuately the water does not always play the game and mix with the oil, as it can find its way into the combustion chamber and out the exhaust - thus not giving any indication of where the leak is.

I assume you are running with coolant and not just water?

As it overhats while running then we can assume the fan clutch is not to blame (plus you are loosing water)

if i were you i would:
Free bits!!
1. remove the spark plugs and look for one that is obviously cleaner or a different colour yes then signs of water in the combustion chamber and an blown HG.
2. check the oil filler cap for signs of white residue in the oil - water and oil mixing then also HG!!

not so free bits
1. have the cooling system pressure tested - pin prick leaks can be found or hopefully its the waterpump
2. check or change the cooling system pressure cap -

last bits
1. remove the head

[DHFiS]

I had a tiny leak in the rad that was really hard to see until it was out of the car.

[mrLEE30]

me too on my sport, no visible signs of green stuff and even when i removed the rad it was not too evident, but in this case 2 litres in 20 mins, followed by two consequtive days of an empty header tank does not smell like a small leak!!

and only a pressure test will tell him for sure, i assume he does not have this gear at home so he can remove the plugs and oil filler cap to get an idea, then he must get a pressure check before he proceeds futher.

before you remove the head i would also ask for a compression check as if water is leaking into the combustion chamber, the compression on that pot will be low.

[martyyn]

Thanks guys.

There is no evidence of water in the oil, the filler cap and everywhere I can see inside is all ok. I had a quick look at the radiator side facing the engine but couldnt see anything at all. Havent checked the front yet though.

There was initially coolant, but the last couple of days has just been water. I only bought the car a couple of months ago and although Ive dont the plugs, oil, filter etc I havent got around to the coolant yet....now is my chance !

In terms of the fan clutch, whats the best way of testing that ?

I was talking to a friend last night who also said the best idea would be to pressure test the system because some leaks just cant be seen like Ive been doing by poking my head under the bonnet.

[DHFiS]

only a pressure test will tell him for sure.

yup

[mrLEE30]

so he can remove the plugs

what do you see when you do this?

[martyyn]

Well it turns out its the radiator. I couldnt see anything whilst stuck on the side of the road, but as soon as my mechanic started with a pressure test it just started pouring out of the top.

A direct replacement isnt cheap down here, so Ive been searching to see if anything else can be used. Ive found a six cylinder e36 will fit, but it needs more modifications than its worth from what I can see......anyone know if I can fit a standard radiator from anything else ?

[mrLEE30]

a recore is genrally cheaper then a new rad

[DHFiS]

same part number on all these cars

http://www.realoem.com/bmw/partxref.do?part=17111712982

EDIT that is a Euro spec rad