M40 Cylinder head issues

[Jamesy]

I recently pulled my e30 out of the garage after standing for 3 years. The intention was to simply give it a bit of a service and book it in for MOT.

However, I notice once started it was ticking over on 3 cylinders (M40 1.6), I removed the spark plugs and water was evident on cylinder 4 plug, after a few further checks I suspected the head gasket was at fault. I’ve owned the vehicle for 14 years and to date it has never gone wrong, probably because I barely have time to use it but still it was running fine when I parked it up.

So, I’ve replaced the head gasket and every possible other seal plus new water outlets etc etc.

Unfortunately, despite my efforts the damn thing is not any better, I inspected the head for cracks or any other further damage whilst off, all appears OK.

The bit I'm confused about and there's probably not a great solution to this”¦.I'm hoping there is, but I’ve discovered water in the throttle body which is coming from the breather pipe on top of the rocker cover.

I've removed the rocker cover and discovered water droplets on top of the plastic cover over the camshaft yet there's no sign of water/oil mix underneath the cover neither is there any contamination in the sump oil, but still water droplets persistently appear in the throttle body from the breather pipe which obviously knocks cylinders off.

I guess the next step is to run a pressure test on the water system, but still if anyone has come across this over the years I'd really appreciate any help or ideas anyone has to offer.

Thanks in advance,

Andrew.

[Brianmoooore]

Burning petrol produces a lot of water, and inevitably some of this ends up in the oil, where it is removed by the breather system, so the odd water droplet in the intake system is normal, an shouldn't cause any problems.
If you've replaced the head gasket without skimming the head surface, then the problem could be corrosion around the crescent shaped coolant holes in the head face. If the corrosion creeps back under the fire rings of the gasket, then there will be problems.
As you say, a bit of testing should be the next step, either with a coolant system testing kit, or by using a leak down test adaptor into a spark plug hole, to feed compressed air into the cylinder.
If you use the coolant pressure tester, beware of cranking the engine over with the spark plugs in, in case sufficient water has entered a cylinder to cause a hydraulic lock.
If you use compressed air, watch for the level coming up in the coolant tank and/or bubbles.

[Jamesy]

The head was not skimmed, I opted not to skim the head as the engine had not suffered any kind of overheating etc.

There was a small amount of corrosion localised around a couple of the coolant ports on the head, but nothing I thought to be considered a problem, but I could be wrong!

From the poor condition of the head gasket it seemed it would be a straight forward job.

I think the compressed air in the cylinder is the better idea, as I want to focus on number 4 in particular.

I will try it tonight before I go any further.

Thank you for you help.

[Jamesy]

Just a bit of a conclusion Brian.

I didn't need to carry out any kind of cylinder or coolant system pressure check as I was greeted with a cylinder full of coolant before I started.

With that in mind, I removed the cylinder head again. On removal i couldn't see anything wrong at all, everything seems check out right.
I did notice however the inlet valve port on the cylinder head has been washed clean.

So that prompted me to remove rear water outlet from the back of the head to allow further access. There I found the problem, a nice corroded hole through water jacket into the inlet valve port.

Coolant must of been dripping into the cylinder all the time, mimicking what I thought was a straight forward head gasket swap.

Feeling pretty hacked off after all that wasted effort!

[Jamesy]

Just a bit of a conclusion Brian.

I didn't need to carry out any kind of cylinder or coolant system pressure check as I was greeted with a cylinder full of coolant before I started.

With that in mind, I removed the cylinder head again. On removal i couldn't see anything wrong at all, everything seems check out right.
I did notice however the inlet valve port on the cylinder head has been washed clean.

So that prompted me to remove rear water outlet from the back of the head to allow further access. There I found the problem, a nice corroded hole through water jacket into the inlet valve port.

Coolant must of been dripping into the cylinder all the time, mimicking what I thought was a straight forward head gasket swap.

Feeling pretty hacked off after all that wasted effort!

[Brianmoooore]

Sounds like a rare duff casting. Good news is that M40 heads are cheap and plentiful.
Note that 1.6 and 1.8 heads, cams and valves are identical.