Car making a loud noise intermittanly, my friend had me change to a high viscosity oil and sub 1 qt stp oil additive for 1 qt oil. After the oil change we started the truck to find the noise the same. We ran it a few minutes several times, then the noise stopped but there was a milky white to grayish goo under the oil cap. He immediately said head gasket or cracked head. The car did over heat like 2 mos. ago and the coolant was empty in the resevoir but fine since and the noise didnt start til one week ago.No white smoke, no overheating no power loss, and no anitfreeze smell with heater on. And the weather has been 80s. The milky goo only appeared after the oil change, looked at it several times after the noise started and the dip stick looks like normal oil. HELP!!!!

 

Does the vehicle get driven hard enough to get it hot each time it is driven? Clean the cap and take the car? truck? out and drive it 'till it gets and stays at normal operating temperature for a while. It does have a thermostat, does it not?

 

It has a thermostat, havent changed it since it over heated. It has only been on one short trip since we saw that on the oil cap and cranked and idled several times. Also that day we saw what was prob. coolant on the valve cover never there before or since. Little scared to drive it. oh its an 03 expedition. 159000 mi.

 

It has a thermostat, havent changed it since it over heated. It has only been on one short trip since we saw that on the oil cap and cranked and idled several times. Also that day we saw what was prob. coolant on the valve cover never there before or since. Little scared to drive it. oh its an 03 expedition. 159000 mi.

 

Get a loaner pressure test kit from a parts store and test the cooling system. You should also have a cylinder leak down test done by a competent shop or mechanic to find any possible leaks before condemning the engine. You can clean the cap off and run or drive it a bit and see if the milkiness reappears, it is not uncommon for some milkiness to be there if the truck is not driven in cycles long enough to fully warm up and evaporate the moisture that accumulates in the engine.

 

(Expedition XLT, 4.6L V8 159,000 miles) Took the truck to my mechanic. He said the milky oil is condensation, the coolant on the valve cover is a leaking, stopped up PC valve. Have not had that repaired yet. He also said I need a tensioner pulley(? the top pulley) and serpentine belt. All easy fairly inexpensive fixes. Then the bad news..he said the tap, tap, tap, I hear that speeds up with acceration is the timing chain going bad. The noise is reallly loud but it def. there. He said he usually does not see this problem before 300,000 miles. He did not to my knowledge hook it up to a timing light, they just listened with a stethescope. Could it possibly be something else? I dont seem to be loosing any power or have a rough idle and the truck runs fine other wise. This is ALOT of money, so I want to be as sure as I can before fixing or getting rid of it.

 

should have said the tap, tap, tap is not super loud

 

Metallic sounds heard in an engine have a tendancy to telegraph throughout the engine and I suggest that you ask your mechanic to put the truck on a lift and listen to the bottom of the engine for noise that could be coming from #4 and #8 connecting rods, which would indicate a spun bearing. I had a very similar noise in a '98 Expedition when I bought it and I felt sure the noise was either the chain and guides or possibly a broken valve spring, which for me, are fairly easy repairs. I bought the truck, brought it home and started checking. The noise proved to be at the rear of the engine and at the bottom. I removed the oil pan and then the rod caps and found the problem was spun bearings on #4 and #8 rods. I was shocked as the truck ran and drove fine and the noise was just barely audible. The mileage was about 20,000 more than yours so the same problem could be yours.
If the noise is in the bottom end I suggest selling or trading it as the repair cost even with a used engine will be pretty expensive. If the noise is in the timing chains and guides just live with it, but do get the new belt and pulley as he suggested.
Also ask him to let you hear the noise with the stethescope when he checks it again.
Keep in touch and let us know the results.

 

Milky oil in the oil cap usually is condensation , happens when the weather is cold.
Replace your thermostat and flush the cooling system, that should have been done after the overheat anyway.
Check the antifreeze , after few hundred miles, if you see oil or if it is milky then it could be the headgasket.