Help before i junk this engine

[farmboi1066]

I have a 84 ranger with the 2.8 with 4 speed in it 4wd. i recently taken the engine out of the truck and replaced some gaskets and put a set of rod and main bearings in it and a new cap and rotor and plug wires. i started driving the truck and went from 21mpg to about 12 mpg ,all highway with a light foot, after i put the engine back in. also i have plenty of power in the first 2 gears, decent in 3rd but it can't get out of its own way in 4th gear. the timing is dead on and the advance is working. I also have a good bit of blow-by coming out of the valve cover into the air filter. what could i look for next. any suggestions

 

[The Man]

It could be a vacume leak.

 

[cckc135r]

Could be a combination of bad ring seal and bad valve guide seals which are known to go bad on 2.8's. Look on the tech page for the 2.8 and it will tell you how to change them without having to remove the heads. Also if the cylinders are either our of round or have a decent amount of tapper you could be looking boring the cylinders to the next bigger size which of course means new pistons, rings, another gasket set.....not trying to be Debbie Downer but that could be another cause of blow by.

 

[kimcrwbr1]

Check the compression and vacuum pressure. Have you changed the PCV it could be plugged giving you the blowby. Dont try and clean it just get a new one. Do the compression test when the engine is up to temp. Get back to us with the results with both tests.