cant tell whats wrong with my 4.7 no compression in 2 cylinders, wont start

[josephzielinski1]

any other suggestions

 

[josephzielinski1]

well i pulled my injectors and they are most definetly shooting fuel out, and i checked my spark plugs and they are sparking nice and blueish

 

[NYCruiser]

Still could be one of the timing chains.

 

[josephzielinski1]

im pulling the radiator and front section of the truck off now, and i guess gonna work my way thru the engine.....ughhh

 

[josephzielinski1]

some pics

 

[josephzielinski1]

this is what i found, i dont know why but my front and back piston are toasted, any ideas why only those two pistons where toasted?

 

[MegaMouseGW]

this is what i found, i dont know why but my front and back piston are toasted, any ideas why only those two pistons where toasted?

There is the problem like I had said. Burnt pistons which in turn burnt the top rings which is why fuel is getting into your oil pan. Only recourse is to rebuild. Get the pistons from AirRam that I linked for you earlier in this post. Not sure what may have caused the problem for you but it is somethinghtat every owner of the 4.7l needs to know about. The upper rings on the stock 4.7l pistons is only 1/8 of an inch from the top of the piston, which is too close for any modfications. Now while you have the engine apart best thing to do is to check everything else to be sure there are no other broken parts. Replace what needs to be, but be sure you get some good pistons to replace all of the stock ones you have.

Again here is the link to AirRam for you:

AirRam - Cold Air Induction System

These are the pistons you need:

AirRam - Cold Air Induction System

These are a better set but only get them if you really want them:
AirRam - Cold Air Induction System

 

[josephzielinski1]

thanks for the link, im gonna take a look at the pistons, the front and back pistons are horrible, they are eaten up, and have metal missing, on the top edge of the piston its missing close to 3/16 of an inch of metal. im gonna put a salvage yard engine in it for now, and do a full rebuild on this one, maybe some modification as well

 

[NYCruiser]

Well that sure explains the rough idle........but why wouldn't it fire?

 

[MegaMouseGW]

Well that sure explains the rough idle........but why wouldn't it fire?

Sometimes if the compression in even one cylinder is not right the engine will not run at all. He had 2 burnt pistons which meant something was big time going wrong. Best thing to do is to rebuild the motor and upgrade parts while at it. Stock rebuild kits for the 4.7l are stupidly weak.

 

[josephzielinski1]

agreed, i couldnt figure out why it wouldnt fire either, it only seemed logical to fire, im assuming those two damaged piston there rings were shot in them, also one cylinder a valve seat came loose and had the valve stuck open, the 2 cylinders with the damaged piston im assuming the pistons had too much play in them and thats what the ratteling dieseling noise was shortly before the engine failed, im putting a junk yard motor in tomorrow with 130xxx and either rebuilding or selling this one for rebuild

 

[MegaMouseGW]

agreed, i couldnt figure out why it wouldnt fire either, it only seemed logical to fire, im assuming those two damaged piston there rings were shot in them, also one cylinder a valve seat came loose and had the valve stuck open, the 2 cylinders with the damaged piston im assuming the pistons had too much play in them and thats what the ratteling dieseling noise was shortly before the engine failed, im putting a junk yard motor in tomorrow with 130xxx and either rebuilding or selling this one for rebuild

Rebuild the old one. But do not go stock parts. Get everything from AirRam if you can. That is what I did when I had to do before I gave the 06 1500 to my daughter. She now ahs a motor that should last 200k+ miles before it needs anything else done to it.

 

[ercmesser]

Rebuild the old one. But do not go stock parts. Get everything from AirRam if you can. That is what I did when I had to do before I gave the 06 1500 to my daughter. She now ahs a motor that should last 200k+ miles before it needs anything else done to it.

Or if she drives it threw a puddle as i did. Mega thanks for the advice on the rebuild I'm going a head and buying an rebuilt long block for about 1800.

 

[MegaMouseGW]

Or if she drives it threw a puddle as i did. Mega thanks for the advice on the rebuild I'm going a head and buying an rebuilt long block for about 1800.

No problem. Bullet proofing the 4.7l is easy if you know where to get the right parts. And RamAir has them.