e21 m10 coolant in oil but no oil in coolant

[mr.vang]

The car doesn't over heat and no oil in the coolant, but there are coolant in the oil. If it was a blown head gasket, wouldn't there be oil in the coolant as well?

The only way I can think of is, if there is coolant in the oil but not the other way around would be that coolant is leaking into the cylinder and down the rings into the block. I would hate to pulled the head to find out it is leaking from the water pump passage under the timing chain cover. I know m42 have problem with coolant leaking through the water passage into the block. I'm not sure about m10 since its my first m10 and I'm not familiar with it.


The previous owner did put in some stop leak into the radiator. I can see the gold looking flakes floating around. Also it does misfire under load from one cylinder. So, i'm leaning more toward a blown head gasket. What do you guys think?

[loki_]

most common suspects are a cracked head, cracked block, or blown head gasket. if the previous owner put in stop leak then it wouldn't be out of the realm of possibilities that they overheated it. how much water are you having to add after how much driving? in the interest of starting small, i'd begin with a compression test and then go from there.

[e30davie]

All depends how the gasket blew. Ive had coolant in oil a number of times over the years. You can blow between an oil drain passage and a coolant passage. Coolant at higher pressure than oil drain thus coolant goes down oil drain:)

[mr.vang]

most common suspects are a cracked head, cracked block, or blown head gasket. if the previous owner put in stop leak then it wouldn't be out of the realm of possibilities that they overheated it. how much water are you having to add after how much driving? in the interest of starting small, i'd begin with a compression test and then go from there.

When I bought the car, it was running and drove 2 hours home with no issue at all, so water was never added. I think the stop leak finally give in after I drove it hard couple times. I haven't drive the car since I parked it and drained all the fluids out. The head look very clean inside, like it has been replaced recently. I'm leaning toward a bad head gasket job from the previous owner. I'm going to pulled the head tomorrow and see where the head gasket blown.

All depends how the gasket blew. Ive had coolant in oil a number of times over the years. You can blow between an oil drain passage and a coolant passage. Coolant at higher pressure than oil drain thus coolant goes down oil drain:)

You are correct. That may be the case thats why only coolant is found in the block and not the other way around.

[thebutterson]

Everything flows from high to low. Air, heat, electricity, fluids, etc. The coolant system is pressurized. If the crack/leak is in a location where the pressure on the opposite side is lower than coolant system pressure, coolant will only flow out and nothing will flow in to the coolant system. Oil pressure drops off as soon as you shut the engine down, but coolant pressure remains for a while so I guess its possible you could have a crack in a location where the oil system pressure is higher when the engine is at higher rpms but at lower rpms or when the engine is off the coolant pressure is higher. This would cause flow both ways. Not sure where this would happen though.

I had a cracked head on an S52 that leaked water above the intake valve. The water then flowed into the cylinder and down into the oil pan making the famous milkshake.

[mr.vang]

Everything flows from high to low. Air, heat, electricity, fluids, etc. The coolant system is pressurized. If the crack/leak is in a location where the pressure on the opposite side is lower than coolant system pressure, coolant will only flow out and nothing will flow in to the coolant system. Oil pressure drops off as soon as you shut the engine down, but coolant pressure remains for a while so I guess its possible you could have a crack in a location where the oil system pressure is higher when the engine is at higher rpms but at lower rpms or when the engine is off the coolant pressure is higher. This would cause flow both ways. Not sure where this would happen though.

I had a cracked head on an S52 that leaked water above the intake valve. The water then flowed into the cylinder and down into the oil pan making the famous milkshake.

I just pulled the head and what a surprise. The 6 middle head bolts hole cracked into the water channels. Just like what you mentioned, the head bolts doesnt have any pressure that is why the coolant isn't milky.

So can over tightening the head bolts cause these cracks? Who ever did a head gasket job on this car suck. Almost every bolts and nuts in the engine bay are loose.


This suck, now i need a new engine. Anyone have a good running m10 laying around?

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[thebutterson]

The cracks could have been caused by not cleaning/drying the holes before installing the bolts.

There should be an M10 available somewhere close to you. Many people chuck them when doing a swap. You can use an E30 or E21 block but you'll need an E21 head and pistons that match it if you keep CIS.

[mr.vang]

The cracks could have been caused by not cleaning/drying the holes before installing the bolts.

There should be an M10 available somewhere close to you. Many people chuck them when doing a swap. You can use an E30 or E21 block but you'll need an E21 head and pistons that match it if you keep CIS.

Thanks for the info. I hope someone around here have a m10 laying around. If not, I will have to get one from the junkyard and hope its still runs.

[TobyB]

The head was probably swapped because the one that was on there had chunks out
of it from the massive overheat.

The ONLY M10 I've ever seen crack a block was run without water for multiple overheats.

t

[Jean]

My original M10B18 when I pulled the head to installed a rebuilt head had the same cracks and more than two. From what I recall it was original head on the engine, I just wanted at the time to put a rebuilt head on it since I've refreshed everything else but gave up on it when I saw the cracks .

Time for an engine swap ;)

[superj]

I ran an m10 that was mixing water/oil for a year before it finally started overheating. those are damn good engines. since you are going to be looking, look for a 2.0 m10, just for the heck of it.