Recently traded Tahoe for 03 f.150 5.4 triton vin L head that means somethin. I got the truck 6/29/19 it’s got about 275xxx miles drove 2-3hrs ran good noticed oil and water has mixed before has I noticed milky stuff on oil cap wiped off came back done and wiped again just appeared to be a little bit water changed oil on7/5/19 didn’t come out milky just a little dark and no milk on dipstick either. I also cleaned their air filter with the air filter kit as it has after market air filter from previous owner. I’ve been driving the truck for about week now and noticed starting rough a little rough and a misfire just wondering if it could be from previous water oil mixture or something simple. I know the truck has new radiator, water pump, alternator and starter. So far I’ve just flushed the radiator out couple times and changed oil planning on doing another oil change in a week or so just to flush motor out a bit.

 

When an engine has a lot of blowby, the water in the exhaust gases may cause a white deposit on the oil fill cap. I would not assume there has been water in the oil.

Clean the throttle body and change the plugs. Torque the plugs to 28 ft lbs. Put a couple bottles of chevron techron in the gas.

 

Thanks imma give them things a shot. What would be the best sparks I should use should I go with the platinum or iridium plugs any suggestions on coil packs also I’m sure it wouldn’t hurt to replace them either. Any advice on taking them out has I’ve heard these 5.4 motors like to break the spark plug off

 

Buy motorcraft plugs. The 2003 engines don't have the plugs that break. Thats 2004 thru 2008 3V engines. It just has a few threads to hold the plug in so you need to torque them to 28 ft lbs not 12 that the manual says because they have been known to blow out. Coils recommended are motorcraft, denso, or delphi available from rockauto for the best prices.

 

When you have the plugs out, do a compression test. With that many miles, it may be on its last legs. Spark plugs are Motorcraft SP479. Coils can get expensive, try just the plugs first. Use a small amount of dielectric grease inside the coil boots. The cheap Ebay Chinese coils are a crapshoot, hence the above recommendation.