Help- Sudden coolant leak from behind engine block on my 1997 Z3 2.8

[Rickypoos]

Would appreciate any ideas on where this leak could be coming from. Was OK when I set out locally today for the vet but the car started overheating on the way home and I found coolant running out of something central and behind the engine block when I stopped in the garage on my return - looks to be a pretty inaccessible area which is worrying. Will try to get to a garage this week for an inspection but , so I can sleep in the meantime, can anyone please tell me what the problem is likely to be. Had new coolant and water pump fitted only 6 months (and 200 mikes) ago so hoping it is only a hose or similar. Everything looks OK at the front with no issues at the radiator etc and the system only seems to have lost about half a litre from the coolant header tank before I switched the engine off. This, of course, reduced the pressure and allowed everything to cool down.
Views please. Thanks.

 

[Duncodin]

Is it a puddle you've seen under the car. In this heat any air conditioning will be producing a lot of condensation - ie water puddle under the car.

I'm sure you've thought of that already (if your car has aircon) but I just wanted to have said it.

 

[Althulas]

When you say the car was overheating was the temp gauge needle up towards the red for you to say this or was you concerned about it taking a leak as I had this today with the Mini and had a good check and realised it was the ac taking a wizz.

If it was the former can you some other descriptions, did you have fluids escaping from the expansion tank?

 

[Rickypoos]

Thanks for the interest guys. Had the a/c on as the weather was really hot. The journey was only 7 miles each way and no issues going. The sequence of events was that everything seemed OK on the return until I drove into my garage and switched the engine off. I got out and could hear liquid running onto the floor. Went behind the car and there was a line of blue coloured liquid which told me it was running from the car as I drove into my property and then the garage. It was definitely blue and, when I looked underneath, it was running from a point behind the engine block and central rather than to one side or the other. I looked at the temp gauge and it was at 75% ( maybe 1 min after switching off) ie half way between the normal vertical position and the red zone.
A minute later the liquid stopped running or dripping. I noticed some steam coming out from under the bonnet but at the rear of the space rather than forward near the radiator. Lifted the bonnet and everything looked OK. The screenwash container is still full whereas the radiator header tank level is low by around half a litre. I am hoping like hell that it will be a leaking connector or hose rather than a head gasket issue or anything else seriously expensive!!

 

[Andyboy]

There is an alloy coolant elbow on the back of the head, and that could be leaking. Either the hose or the elbow is corroded.

There is a steel coolant pipe that runs under the inlet manifold. It fits to the block behind the water pump and a few rubber pipes run from from it, to the heater etc.

 

[Rickypoos]

Thanks for that specific guidance Andyboy and I will go check it out now. The latest symptoms this morning are that I started the car and everything seemed OK with no leaks underneath. I drove it a couple of kms until it reached normal temperature and started to breathe a sigh of relative relief - but then the temp gauge started to rise quickly and I had the hissing again from behind the engine, some smoke/steam rising again from the rear of the engine and the leak had started again underneath. I did all this today with the A/C switched off (hoping that might isolate the problem) but it still occurred after that initial 5 or 10 mins while the engine warmed up wihout apparent issues!! Must be something similar to what Andyboy is suggesting - access not good in that area it would seem but hopefully it will be the elbow, a hose or whatever - anything other than the head gasket and the need for a top end strip!!

 

[Rickypoos]

Cant find elbow. This is the pre face-lift 6 cylinder 2.8 engine. What model do you have Andy?

 

[Andyboy]

On the back of the head, inlet side.

 

[Andyboy]

..

 

[Duncodin]

If it was me I'd put my finger in the puddle and lick it. Yeah. I know. Coolant isn't good for you. Get somebody else to lick it. A/C condensat drip is pure water. Coolant is sweet.

 

[Rickypoos]

That seems to be exactly where the coolant has been getting out because there is a little pool of coolant captured between fins on the block below that point. Well done Andyboy as I think we have probably found the problem point. If so relief that it is hopefully limited to that but dismay at trying to work out how I could access the elbow to replace it or install a new hose. Would much appreciate your advice on that please.

 

[Andyboy]

I would replace the hose. You’ll need a flexible hose clip driver and very flexible arms. The alloy elbow might be corroded but you’ll only know with the hose off.

 

[Rickypoos]

If it was me I'd put my finger in the puddle and lick it. Yeah. I know. Coolant isn't good for you. Get somebody else to lick it. A/C condensat drip is pure water. Coolant is sweet.

Thanks. Its blue coolant for sure!!

 

[Duncodin]

In that case ignore everything I said.

 

[Rickypoos]

I would replace the hose. You’ll need a flexible hose clip driver and very flexible arms. The alloy elbow might be corroded but you’ll only know with the hose off.

Sounds difficult for me but will look at it in more detail. One extra query. Will the hose be full of coolant if I remove it or does it only fill up when the engine and water pump are running?

 

[Rickypoos]

I would replace the hose. You’ll need a flexible hose clip driver and very flexible arms. The alloy elbow might be corroded but you’ll only know with the hose off.

My car is actually late 1997 albeit a 98 model and I see that some parts changed in 09/1998 so my hose would be for the 1997/early 1998 version. Does that change anything as the elbow may be in a different place perhaps?

 

[Andyboy]

Nope.

 

[Rickypoos]

Because it is the earlier version I think the part number for the engine inlet to heater radiator hose is 64218401809. Do you think that's right?

 

[Rickypoos]

I use Hubauer.de as the website for parts as I live in France and they have the full BMW parts list diagrams as I am sure others in UK do as well.

 

[Rickypoos]

Nope.

Hi Andyboy
Want to go on record with a huge thanks to you for correctly identifying my issue. Warmed up the engine again this afternoon and, sure enough, had coolant spirting from the junction you identified between the elbow and the hose. Hose ordered and will try to fix myself or get the local garage to do. Again many thanks for your prompt and really helpful assistance. Hoping the elbow itself is OK!!