Faux Cylinder Head Leak Bruce Giller

I'm not a mechanic but I play one at home. Sometimes the diagnostic skills of Dr. Kildare along with the intuitive reasoning of Sherlock Holmes are required to be an auto mechanic of any worth. And with the each more advanced model, there are multitudes of new ways for a car to 'misbehave'. This is just one of those ways.

I have an '86 Spider which I drive every day and I try to do all the maintenance/repair work. One day, whilst checking the dipstick when I was filling the tank, I noticed that there was oily foam on the end of the dipstick. There were also drops of water up the length of the dipstick. I've seen oily foam on dipsticks before when head gaskets leak radiator fluid into the oil but usually the oil has a milky color to it. This one did not have the same look to it as before but then again this was an Italian car and the other was French (Peugeot). There wasn't any foam on the timing chain that I could see when I looked through the oil filler cap opening. Wishfully, I lied to myself saying that this was just moisture from the air since it had been raining steadily for quite awhile. But I did start to check the dipstick more often; the foam was always there no matter how many times I wiped it off ('Out damned, spot!').

After about 3 months of fearing that my engine would seize up at any minute and images of winged dollar bills flying from my wallet, I decided that I'd have to replace the head gasket to fix this leak. After pulling the head, I couldn't find any tears or rips in the head gasket that would indicate where the water leak had occurred. But I did get some much needed work done on the exhaust valves and I got to see how much fun it was to adjust the valves (I can now mic those shims with the best of them). Back on went the head and the oily foam did not reappear.........until about 6 months later!

I wasn't too pleased with this since it wasn't a whole lot of fun removing and replacing the head with all those hoses, fuel injectors, belts, wires etc. I thought that this was another aberration and would soon go away. It did not, but it never got worse either, most perplexing.

Then I started looking in my Alfa manual for some hints as a last resort. When I was dismantling the head, I remembered that the oily foam was inside a small, bolt on tube on the left hand side of the valve cover whose hose disappeared in a tangle of other hoses by the FI plenum. I thought that this might be a good place to start my investigation. I then started tracing the hose and found out that it went to a small black canister on the left hand side of the engine compartment near the fire wall. My manual said that this was the 'oil separator'. It's purpose was to suck in air from inside the value cover, get the oil out of it and return it to the engine and then return the air back into the air induction system to be recycled. There were 4 hoses attached to the oil separator; (1) crankcase ventilation hose, (2) oil vapor return hose that goes to the air intake duct (3) idle oil vapor return hose that goes to the FI plenum and the (4) oil return hose that goes to the bottom of the dipstick. A call to the dealer got the information that the oil separator would need to be cleaned out at about 50K miles. My mileage was a bit higher.

I took off all the hoses that went to the separator and removed the unit from the car. The dealer said that there wasn't anything that could be damaged by gasoline, so I poured a bit into it and swirled it around. All kinds of nasty looking stuff came out. I did this about 10 times, until the gas got somewhat clear and I got tired doing it. I then let it dry out. To clean out the hoses, I detached the other ends from the car and using the business end of my garden hose, washed out the hoses except for the oil vapor return and idle oil vapor return hoses which were not contaminated. The worst one was the crankcase ventilation hose. Then I used my vacuum cleaner in reverse to blow-dry the insides of the hoses. I removed the rubber dipstick 'grommet' from the block; this 'grommet' is the transition from the dipstick tube to the block. Here I used a rag and paper towels to swab it out instead of water. The oily film hasn't returned since then and it has been almost a year

I found out later that Alfas' usually exhibit head gasket leaks by having oil in the radiator water and not water in the oil because of the higher oil pressure (> 50 lbs) compared to the 15 lbs of water pressure. So if you have an Alfa with Bosch FI and you get an oily foam on your dipstick, it is probably that the oil separator needs to be cleaned and not your head gasket replaced.

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1996