im having serious trouble with my 4.2. when i first got the truck a few months after it blew a head gasket. i basically rebuilt the top oft he motor got the heads and lower intake redone at a machine shop. lately ive been having some problems. first it was my oil pressure. my idiot light in the dash would go down when the engine is warm and idling. today i replaced the sending unit and i still lose pressure. my cel is on too. its code p0402. excessive egr flow. when u put your foot on the gads it kinda hesitates at 2000 rpm and then kicks up. then i started it up like an hour ago and when i went to put my foot on the gas it studdered at about 1000 rpm. the engine is lacking serious power. and when it idles i swear i can hear a tad bit of knocking. what do you guys think i am i screwed or what. the engine has 193,000 miles on it.

 

Did u drain all the fulids after the head gasket let loose? Did u drop the oil pan to get all of the pieces of the gasket out? When mine blew all the junk and sludge was at the bottom of the pan and the oil pick up tube was getting plugged making for poor pressure. I had about 3" of sludge in the bottom of the pan. I no long have oil pressuer issues and my 98 4.2 has 307,xxx miles

 

I had an instructor explain why synthetic oil is better. he said that real oil has different size molecules and when new, the bearings ride on the larger sized molecules and grinds them down till they are all the same size, the part ground off is what causes sludge. Synthetic oil is all the same size thus reducing sludge. I have had a 98 I put 400k on it when I sold it, an 01 that had 250k when I totaled it and now have an 03 with 325k. All 4.2 V6's. I used them for my wife's hotshot job, We had to quit that the first time gas went to $4. I want that new V6 with the cam advance, not the boosted one, I might even get electric windows this time. No car for me. The only thing slightly major I had done on any of them was the fuel pump. The last GM I had you had to replace Alt., Water Pump, and Starter at 60k intervals like clockwork. Go Ford!!

 

yeah i drained everything but i didnt remove the oil pan because iw ould of had o pull the motor. the gasket wasnt neccesary blown apart it was leaking through the layers.

 

U should not have to pull the motor. Just remove the cross member support and remove the motor mount bolts and jack the motor and trannyup for clearence. That is how I removed my 98.

 

im gonna try to flush it with to try to remove some of the sludge and im going to change the oil. im using a thicker weight.