QuestionQUESTION: I have a 1976 MGB, engine runs smooth and steady, no visible issues. Replace SU carb with a weber.
Yesterday I was checking the oil level after adding a zinc additive and noticed a gray creamy substance on the under side of the oil fill cap and some in the same area where the cap attaches to the valve cover. oil was changed less than 500 miles ago. Thoughts on the substance under the cap.
thanks, mike
ANSWER: Hi Mike,
Bad sign, check the color of the oil on the dip stick. If it is gray or brown you have water in the oil. If not remove the valve cover and see if the rockers are covered with this gray stuff and check the valve cover vent hose to see that it is vented to the air cleaner or to a PCV valve.
Howard
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QUESTION: The oil on the dip stick looks dark like it needs an oil change, it is deffently not gray and very dark brown to black, rockers look very clean and no gray stuff. Same under the valve cover. The top of the valve cover had some of the gray stuff, thin coat, and looks like condensation also. I also found the gray stuff in the tube going to the charcol evaporator. When I bought the car last fall the evaporator in the trunk was missing and both ends were open in the trunk. I also notice when running the car the hose that comes from the front of the engine and used to go to the air pump, I now have vented down under the car, at times clear "water" liquid drips from that hose.
Moisture is getting into the engine, PVC valve issue? Charcol issue. or something much worse?
thanks for your help.
mike
ANSWER: Mike, in my opinion you have a water leak into the oil. This can be tested by draining the oil (dark brown oil is a sure sign of water in the oil) Put the drain plug back in and get a coolant system pressure tester and apply about 15 to 30 PSI on the cooling system and leave it there. You will probably see the pressure drop after a while so keep applying the pressure. The pressure needs to be on the system for most of a day. Then remove the drain plug an see if any water comes out. Also remove all the spark plugs and spin the engine over to see if any water sprays out after it has set all day with pressure on the cooling system. If you don't have a pressure tester nor can borrow one, you should purchase one even though they are a little pricey you should consider it part of the cost of the repair.
They usually have adapters so they can be used on most any car so you can use it in the future to test for hose leaks gasket leaks etc.
Just be sure it has the adapter to fit your car unless you have an expansion tank with a conventional pressure cap which it will fit.
This is the procedure we had to use in the dealership when we found the valve cover tan colored oil and brown oil on a oil change. Check the side of the block where the oil filter to see if you have one of those oil coolers between the block and the filter. If you do, that is the first place I would look. Then a possible head gasket and last and the worst is a crack in the head or block. That is rare though.
Let me know,
Howard
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QUESTION: Howard: That is my conclusion also. Since I do not have an oil cooler should I go with the need to replace the head gasket and hope for the best? Or go through the testing?
mike
AnswerI have Murphy and his law following me around so I can never toss a coin and guess at what is wrong so if I were to just put a head gasket on and cross my fingers that it was what was wrong, it for sure would be something else.
I have been in this business for almost 50 years and I still have to test to find a problem. You may be luckier than I am and can just roll the dice to find a problem. Let me know how you make out.
Howard
