how to tell when engine is bad

[imtired111]

does anyone know how to tell when an engine is bad? my 2.5 runs like a bat-outta-hell in the high rpms but if i start off idle my truck takes about 4-5 seconds to get into power. i know my fuel tank has a minor leak but the loss is only in the low end.

i looked at my piston and sleeve and i see some really really small scratches on the sleeve but they dont look bad.

 

[cwal1774]

How far can you push the piston up the sleeve before it stops? It's supposed to be 1/8 of an inch from the top of the sleeve. If you can push it flush or all the way through the sleeve with little or no resistance then its time for a new piston and sleeve.

 

[imtired111]

How far can you push the piston up the sleeve before it stops? It's supposed to be 1/8 of an inch from the top of the sleeve. If you can push it flush or all the way through the sleeve with little or no resistance then its time for a new piston and sleeve.

it stops at a little less than an eighth of an inch.

 

[cwal1774]

Then the engine is still good. I'd say the leaky fuel tank is your problem any loss in pressure will result in poor fuel delivery to the carb especially at low rpm because the exhaust is what pressurizes the tank. At high rpm the pressure is a lot greater than it is at idle or low rpm so the fuel delivery would be affected more in the lower rpm range because ther is less pressure in the in the tank at idle and low rpm.