bad head gasket?
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Joined: Aug 2006
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bad head gasket?
ok so i just put a new 100k mile 4.2 into my 97 f-150...any ways i go to put a half quart of oil into today and when i take the top of the filler neck off i notice the filler neck and the bottom of the cap have the milkey coolent/oil mix caked to them..not a lot but just a little and its all on the top side of the filler neck towards the cap i put my finger farther down by the valve cover and theres none down there. checked the oil and there was no coolent contamination. so is this a head gasket or possible something else? by the way the motor is out of a 99. thanks
Postmaster
Joined: Aug 2001
Posts: 4,532
Likes: 5
From: Trussville, Alabama
Get a used oil analysis done next time you change your oil.
That will tell you for sure if you have coolant contamination.
I am assuming the oil currently in the engine is oil you installed during a previous oil change. If it is not, I'd drain it, refill with fresh oil, drive it a few 1000 miles -assuming you feel comfortable doing so and keep close watch on the coolant level- and then get a UOA done.
Point being, don't send off a sample of oil for which you do not know the complete history.
Two good choices:
http://www.oillab.com/
http://www.blackstone-labs.com/
That will tell you for sure if you have coolant contamination.
I am assuming the oil currently in the engine is oil you installed during a previous oil change. If it is not, I'd drain it, refill with fresh oil, drive it a few 1000 miles -assuming you feel comfortable doing so and keep close watch on the coolant level- and then get a UOA done.
Point being, don't send off a sample of oil for which you do not know the complete history.
Two good choices:
http://www.oillab.com/
http://www.blackstone-labs.com/
Cargo Master
Joined: Aug 2002
Posts: 2,013
Likes: 6
From: Cajun Country
Sounds like condensation.This happens when an engine is run for very short periods of time;like not letting the engine get up to fully operating temperature.Excessive stop and go driving for short periods of time. 
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
I think you are more concerned than you ought to be, unless... Do you have to add coolant on a regular basis? Have you cleaned the crud and it comes back? Give it some time would be my suggestion. The yogurt looking stuff forms from condensation on the coolest part of the crankcase when the engine is not taken to operating temp and run there for a while. You get a little blowby past the rings, leaving H2O in the oil. Running at normal temp for a half hour will boil the water out and it will be fed to the PCV and burned (burn water, anyone??). If you make a lot of short runs, the oil never gets hot enough to evaporate the water, and it make yoplait...
Wash it off, run it down the freeway for 20 miles to get the oil hot, and see if it comes back. I have never analyzed oil as the cost was high (IMO). If I had a $200K 18-wheeler, I'd think it worth the $, but I don't.
tom
Wash it off, run it down the freeway for 20 miles to get the oil hot, and see if it comes back. I have never analyzed oil as the cost was high (IMO). If I had a $200K 18-wheeler, I'd think it worth the $, but I don't.
tom
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smashclash
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
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