lifters

[bubblegump]

Does any one here know what would cause the lifters on a 2000 4.0 to pump up enough to hold the valves open? new lifters-new heads-new oil pump-but no compression

 

[89Twincharge]

Ohv or sohc???

 

[bubblegump]

ohv-

 

[89Twincharge]

Kinda figured... Lifters only pump up to "take slack"(oil controlled valve lash adjuster) up from push rods to rocker arms they should not extend enough to open a valve until cam lobe dictates it.. are pushrods seated properly in lifters? Are all cylinders no comp? Did you compare new and old lifters to ensure proper length?

 

[89Twincharge]

Also why were these parts replaced?

 

[Uncle Gump]

Push rods are too long.

 

[89Twincharge]

Push rods are too long.

Most likely something along that line just need more info to really help... Its funny I get paid $90 an hour for diag but for a TRS member I'll do it for a thanks!!!

 

[bubblegump]

Also why were these parts replaced?

it died going down the road and when the timing was checked and found to be correct the compression was checked and it had none and when the rocker shafts were loosened it had compression-so the engine was pulled and they thought the lifters were bad so they replaced all of them and put in a new oil pump and the exhaust valves were seen to have the seats beat out so they sent them to a machine shop which found them to have the seats out but they also found the heads were cracked so they bought a new set of heads-replaced the lifters with new ones and replaced the oil pump because they though perhaps the bypass valve was sticking-it started and ran about 15 seconds and died and now has no compression again

 

[bubblegump]

Most likely something along that line just need more info to really help... Its funny I get paid $90 an hour for diag but for a TRS member I'll do it for a thanks!!!

Your help is really appreciated - the poor kid has spent 2000 dollars on parts now and it still won't run-his grand father has done the work for free but has about 15 hours of labor in it

 

[bubblegump]

Push rods are too long.

they are stock push rods and the lifters and heads are both new-he is mad enough to grind the valve stems off but I told him he better try to figure out the problem before resorting to such drastic measures

 

[89Twincharge]

Need to remove lower intake and turn over by hand to watch lifters, I think the cam gear is probably spinning on the camshaft it will show good timing but not be timed... Hopefully I'm wrong as they may have destroyed new heads.. well im off to bed. Let me know what they find out when you can!