Cracked Head / Head Gasket Gone

[Danstable]

The garage tells me that my steam and water incident is down to a cracked head or a bust head gasket. Apparently they can tell this from the fact that when running at temperature it spews water out of the water reservoir and also there is water coming out of the exhaust.

Now I'm no expert but this doesn't sound good!

I want to make sure I'm not being fed a load of bull so can anyone list the symptoms of a cracked head / bust head gasket? As far as I could see, the water continued to escape from wherever it was coming from at the rear of the engine, for a long time after the engine was switched off and cooled down, is this right?

Also, there seemed to be no loss of power or odd running at all, I saw the steam, then went straight home, about 3 miles. I'd have expected that if water was getting into various places that it shouldn't then you'd lose power/smoothness?

Also, does anyone have a head going spare for a 325 M20?

[PeteE30Tourer]

I guess the symptoms can be very different depending on where the leak is, how big it is and whether it's oil or water leaking through it.

In my case, i noticed a gradual, steady loss of coolant, clouds of steam from the exhaust for first few miles of each journey and rough running for the first 30 seconds or so. I gather these all indicate that there's a leak of water into one of the combustion chambers, so that pot wont fire until it's been sucked out, then it's boiling off the moisture through the exhaust. I noticed no difference in power and no oil in the water or vice versa for ages, then i noticed a bit of mayonaise in the oil. Things had obviously got a lot worse over time, so i've taken it off the road until i can get my replacement head fitted.

There have been no end of people on here with cracked M20 heads lately - almost one a week. Seems like it's always the head too, seldom just the gasket.

[psychochild187]

engins produce water from burning fuel . its why i see steam comming out the exhaust mostly from start up where its hot water vapour , then when the engines hot u cant see the steam as its super heated and its not visible .bit like aircraft and there vapour trails
eg .you see a realy slow driver infront creaping away from the lights and u see water fall out the exhaust(coz there that slow its built up over the last few miles from there gental driving/sleeping), and also why exhaust rot from the inside out . when the cars turned off the water sits and rusts over time

but just saying this b4 eveyone freaks out coz they can see steam!

[Rowen]

ok, last week i had the head on my car done, ported /polished bla bla..
i fetched the car from the tuner, all was well, ran on the car on the dyno etc, big improvement, anywayz driving home the coolant light comes on, so pull ouver at the next gas station, about 500m from where the light came on, wait for the car to cool down , before opening up the water bottle..

the car didnt over heat, no visible sign etc, and the temp gauge was normal, car needed almost a litre of water...after feilling water, i drove the car, it seemed fine all the power was still there etc,, took the car in, this morning to find water and oil mixing, striiped of the head, removed the cam, there she was, a crack...but prior to that the car seem fine, no smoke/over heating etc....so...just check correctly

[Adammcf]

Mine started with a tiny amount of mayo on the edges of the oil dipstick. This slowly started getting worse until the car started using water.
It never over heated or anything.

I took my head to get tested and it was porous! I got a new one from www.linwar.com

Good luck!

[Danstable]

I'm confused as to how there is water leaking from somewhere at the rear of the engine....especially when the engine isn't running and has cooled down. When I switched the engine off after the 3 mile drive home, there was a very small amount of water under the car and the coolant light wasn't on. A day and a half later and there was a far larger pool of water under the car and the coolant light was on.

I'd have thought that once the engine was off, there should have been less, if indeed any leakage. Also, if water is coming directly from the engine, wouldn't this suggest a gasket failure rather than a cracked head?

I realise I'm probably clutching at straws, just praying I can remove the head and replace the gasket.....job done.

Finally, I saw no steam coming out of the exhaust.

[Martinaston]

Hi Dan
Are you sure it's not coming from the rear coolent out let on the back of the head (perished hose)

Part 15
http://www.realoem.com/bmw/showparts.do ... g=11&fg=15

[Danstable]

That's the sort of pointer I was after, cheers mate I'll have a look what I can see. Any idea if this hose is likely to be visible? Looked very tight back there when I had a nosey when it was going dark.

[Martinaston]

I'm not sure. I know on the 318 i had the rear elbow that bolted to the engine was leaking because i'd managed to scratch the smooth finnish on the back of the head (ali) and was cured by a bit of instant gasket to fill in the scratch. The 318 is a smaller unit that sits further forward so your best to have a look when the engine is cold or you'll get burnt.
If the problem is there you may have to drop the engine a bit to get to it.
If it's coming from the head gasket and your still not sure if its that or the head just strip the thing and expect the worst.

[Templ8e30]

Dan, the rear hose is just about visible from the top.

When I rebuilt the 2.7 the threads had corroded away for the metal pipe and I had to re-tap them to a larger size (6mm).

It'll be impossible to remove the metal pipe from the head with the head still on.

However you may be lucky and find it's just a bust hose. It's the short one feeding the heater matrix iirc.

Cheers,

Iain T