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hi you all,

i had an engine overheat a while back and then it kept being white smoke through the exhaust pipe and i figured i might have blown the head gasket as ”internet” seemed to believe so. (i then also thought i might as well learn how to change one since i’ve never done it).

i took it all apart and it seems like the gasket is fine and here comes question 1: is it normally easily visible if the gasket is ruined or can it be such a tiny crack or so thats its hard to tell?

question 2: IF the gasket is fine, what else can cause coolant to leak into the cylinders?

question 3:
if its not coolant in the cylinders - is there anything else that can cause (pretty much) white smoke?

some further info:
when the engined overheated i had been driving 450 kms more or less without stopping and i saw it had lost super much of the coolant, i refilled and after another 550 kms it was still full to the top so no leaking the last 550 kms.

i had extra much white smoke like a big cloud puff when starting it after having stayed for food along the way.

when i took the top off the inside was pretty dirty like a thin layer of something sticky.

the engine is M10 in a 318i 1981.

The first question is why do you think water was entering the cylinders? Some white steam is fine while an engine is warming up, it doesn't mean the head gasket is gone, it's normal. If the engine is steaming when the engine is hot, after a 5 mile drive that may be a different matter. So was the coolant level going down at all?

Normally is a car has been run for a while with the head gasket leaking the affected cylinders will be very clean as the steam cleans away the carbon. Did you see this?

When a head gasket leaks it doesn't necessarily have a crack or a piece missing, it can leak quite subtly and close investigation of the gasket and making faces is required.

It's possible that the head itself could have distorted when it overheated, this could cause a leak past the gasket, back in the day the 6 cylinder engines were legendary for cracking the cylinder heads as well.

it is constantly white smoke even after driving for a while and its usually a bigger cloud just at start up.

the coolant level had gone down much as i wrote above, i think i refilled 2-3 liters after that 450 km drive.

i cannot really say that any of the cylinders/pistons were cleaner than any other, rather that they all looked kind of dirty, although i dont know exactly how it is supposed to look.

the head seem fine since i checked with a straight ruler and those 0.1 mm measuring ”sticks” or what to call them..

As you have the head off the car I'd recommend taking it to a machine shop for checking

Yup, pressure test on the head first now it's off anyway. Any color differences on the top of the pistons, the combustion chambers, valves, spark plugs?

Will be watching this post with interest
I experience some weird heating issues as well, which I can't yet exactly define. I don't have white smoke (except for the warming up some minutes, as keith said) but I notice the following: Especially during uphills, no matter if driving is spirited (well, most of the times it is, -lol) or not, car heats up (coolant temp gauge climbs to 3/4 and maybe more). Even if I have topped coolant up before I start the car. Also, usually coolant needs topping up, if I forget it for a couple of weeks, it may need more than 1 lt of coolant. Of course no need to mention if coolant is not topped up, heating issues get worse (it may heat up during other conditions apart form uphill, or, electric fan cannot cool it down easily etc)

I am wondering if just a radiator wash would solve the issue, is it a clogging rad issue? Or it might be anything more serious

More info on similar temp related issues in the FAQ as well. If you don't top up the coolant tank, does the level drop further or does ot stabilize at some point (preferably before the red section of the dial is reached)?

Yeah, I have read the Faq section, but this one seems to be a bit funny now:
We checked the cooler and it flows very well
We also saw that the ignition advance needed setting (especially after fitting the MSD)-so maybe this also might have to do with coolant circulation

Now, everything goes very well (and think I am mainly driving the car in Athens traffic, as I can't find the time to take it for country drives) until I start a fairly steep uphill, then temp rises to 3/4, and when I return to horizontal or even better downhill, then temp returns eventually to normal. A bit better than before I must admit, but still...

Outside temp has risen a bit in Athens as we are heading towards Greek summer alright, but it has a looong way to go (with temp rising even moe) until we reach the top, aka July-August difficult early afternoons. And this is what concerns me.

Now, my electric fan can be connected with two different heat sensors (both fitted on the car). One is a on-off sensor, and the second one gives two speeds, high and low. We have the second sensor connected for winter and we disconnect this and connect the on-off one for summer, as I think that the high speed of the No2 sensor is a bit lower than the "on" speed of the on-off one. So a guess is that the outside temp has risen enough to switch the sensors, but I did not believe this, I would guess that this would happen in May at least.
Well I will try this and see...

Got a question anyway: When should I start worrying about a possibility that my cylinder head gasket have failed?
At the moment car gets overheated whenever it needs extra cooling and it seems it can't get it, like I wrote: on uphills, and also (last night checked: on motorway if I drive a bit more than just spirited, 160-180 kmh, then the temp indication climbs up to 3/4, then when I slow down again, temp goes back to normal.)
However, what I noticed is that after last cooler flushing and checking, and then toping up with fluid, these temp rises I described, never climbed more than 3/4, which I guess is good.

So, returning to my question, in case there was a gasket issue, shouldn't I be experiencing more severe temp problems?

Today we will apply some pressure to the cooling circuit
In order to see, if we make it, whether there is indeed some coolant loss or am I dreaming

From my previous experience, overheating when climbing a steep hill or spirited driving has been because of a partially blocked radiator or failure of a viscous fan (if you have one) perhaps a lazy thermostat. In any case it has been because of a lack of flow of air or water, not a head gasket, although prolonged driving with this issue can case a failed gasket.

Mechanic checked almost everything found nothing.
Applied pressure on cooler, and on cooler lid. Both OK
Checked coolant circulation, seemed fine
No signs of water in the engine (phew!!)
My thermostat is 75 deg, and replaced fairly recently (fitted new during engine swap, so less than 10000 km)

Changed the switch of the electric fan (see description above) to the "summer" (on off, but "on" is powerful)
Also opened the rocker cover, to see if more tightening might be required (so valves have again been adjusted before retightening.)

Found out this, however: 2 spark plugs with their electrodes melted !
Replaced by 4 new NGK Laser Platinum Premium

Now, as iirc the overheating problems started after fitting the msd ignition, might this be due to very strong spark combined with the wrong spark plugs? And after the melting of the two, problem started going worse perhaps (because it was going worse : last two weeks, I used to leave the parking lot with the cooler topped up, and overheating would start at the first uphill)

And, then, my possible explanation to the loss of coolant: Could it be, that some coolant was lost, in form of vapor, each time system was overheated, from the overflow hole of the cooler ?
The quantity seems a bit larger than this (I was loosing about 250 ml per 50 km, which means 1 lt per 200 km) and I know the issue is similar to the question "Hen made the egg first, or did the hen come from the egg ?" But I really can't think of anything else.

Anyway issue seems to be solved at the moment. So keeping my fingers crossed...

Could be the coolant overflow valve opened and let some out while overheating indeed.

Sounds like a huge mismatch between MSD and spark plugs, hope that's solved now!

Indeed
I do hope as well.
It seems that msd need quite cool plugs to go with.
A friend who has it (in his highly tuned 1602) claims that these ngk I have now, are not the best choice according to his opinion, he found that the best for our cars are some very cheap champion

Yesterday was actually my first test on the road of what had been done (as described in the last post), as, last time, I only took the car home from the mechanic, and everything seemed all right.
Car is going better in general, but I am afraid that this is due to the cooling capacity of the fan, which is increased now (connected to the "summer" switch, which gives it a higher speed. On my known testing route, in general as I wrote it was keeping a bit cooler (not chance for fast driving though, because of traffic), but when I drove up that steep uphill, temp rose up to almost 3/4 again (just a bit lower this time). The only difference was that the system was cooled down afterwards, a bit faster than it used to before last service.

Did not check the coolant level, as it should normally be full from last time (I only drove for half an hour last time, and another half hour yesterday, so everything should be in place)

Now, I am wondering whether this is still a problem of (still hot?) spark plugs (maybe we need even colder plugs?), or it may have to do with fuel mixture/timing, as all other cases (concerning cooling system seem to have been examined)

Do you suggest I should refit the car's factory belt driven fan (and leave the electric fan as well, thus having two fans) ?