no compression

[2011Supercab]

The reason it ran was because until the lifter was completely pumped up... the valves closed. Once fully pumped up... the push rods are holding the valves open.

What caused the old lifters and the new lifters to do the same thing?

 

[2011Supercab]

I still think the camshaft sprocket has slipped, no way to tell without removing it.

 

[Uncle Gump]

I still think the camshaft sprocket has slipped, no way to tell without removing it.

Well they didn't do the same thing... the exhaust valves were trashed and the heads were cracked.

 

[2011Supercab]

Well they didn't do the same thing... the exhaust valves were trashed and the heads were cracked.

So this truck was running just fine down the road and all the exhaust valves went out at once?

 

[Uncle Gump]

So this truck was running just fine down the road and all the exhaust valves went out at once?

With cracked heads... I would think it was over heated.

 

[Uncle Gump]

there is only one length pushrod available for this engine

Smith Brothers will make push rods any length you need.

 

[Uncle Gump]

I still think the camshaft sprocket has slipped, no way to tell without removing it.

He said he took the cover off and valve timing is correct.

 

[2011Supercab]

He said he took the cover off and valve timing is correct.

According to the timing marks it would be, but is the camshaft sprocket still timed to the camshaft?

Is the keyway still lined up properly on the sprockets? , no way to tell with out removing and inspecting
.

 

[Uncle Gump]

According to the timing marks it would be, but is the camshaft sprocket still timed to the camshaft?

Is the keyway still lined up properly on the sprockets? , no way to tell with out removing and inspecting
.View attachment 84667View attachment 84668

He said it ran after he put it together. If the cam gear slipped on the cam... good chance it would have never started and ran.

 

[RonD]

that is true-but where do they bleed off to? something is wrong but no one knows where to go now

Lifters have a hole in the side where oil comes in from the passages, ONLY the oil pressure holds the oil IN the lifter, via that hole
When engine is shut off any oil, under pressure in the lifter, would come out that hole, nothing holding it in

Any engine oil system is "open ended", bearings and rocker assembly are all open where the oil comes out so any remaining oil pressure in the engine after its shut off just bleeds off pretty quickly
There is no way to "hold" oil pressure in an engine when the pump is off

Oil Pressure is the oil the engine CAN NOT USE at that moment, its back pressure
The Oil pump pumps more oil than the engine can use, as it should, so oil pressure you see at any time is the Back Pressure in the Main oil passage just after the oil filter

Oil pressure goes up with RPMs because Pump Volume goes up but engine doesn't need that much more oil, bearings, rocker assembly and lifter passages can only pass a limited volume of oil under any pressure, its why there is oil pressure to begin with


You forgot the "new" heads
Everything is "stock"
But something is wrong

CHECK THE PRE-LOAD, then take that off the table or................find out it is the issue

 

[2011Supercab]

He said it ran after he put it together. If the cam gear slipped on the cam... good chance it would have never started and ran.

If the pushrods are to long, why won't it start again after the lifters collapse after being shut off?

 

[1990RangerinSK]

okay-here's the deal-My cousin has a 2000 4.0 ranger that quit while driving down the road-a compression test showed it had less than 20 pounds of pressure so the heads were pulled and the exhaust valves were beat down in the head about 1/8 of an inch so the heads were sent to a machine shop and found to be cracked so a brand new set of heads were ordered as well as a new set of lifters and oil pump-when the engine was reassembled it started and ran about 15 seconds until it built full oil pressure and died-no compression again-what could anyone suggest as could be the cause? we are at our wits end-to edit- the valve seats were beat out on the exhaust valves-the valves were not bent-the seat were beat out so the valves were sunk into the head and the stems were about an eight of an inch higher than the intake so we figured the exhaust valves were being held open but the new heads and lifters and oil pump have the same problem-it seems they are being pumped up and holding the valves open

So 4.0l OHV

So wrong lifters, or new heads have been rebuilt and milled one too many times
Possibly wrong valve stem height after rebuild

Problem is not "pumped up" lifters
Problem is most likely too much "pre-load" because of distance issue between rocker and cam, i.e. lifter/pushrod length

Remove a valve cover and test the pre-load by loosening rocker assembly
Pre-load is about 1/10" if that, so less than 1/16"
You should be able to spin a pushrod with your fingers, if that valve is closed

If the head has been surfaced/milled then push rods are now too long, so pre-load would be too much and valves wouldn't close all the way once lifters are filled with oil

Each hydraulic lifter has a spring that holds it open all the way, pre-load pushes that spring down slightly
Oil pressure just fills the lifters with oil, each lifter has a check valve that releases the oil as the lifter is compressed and released by cam, so it shouldn't "pump up"

I'm going to go out on a limb, here, and suggest wrong lifters.

Did you replace the pushrods? Are they same length as the old ones?

Also what caused the initial failure?

I'm going to go out on a limb again. There are two different 4.0 engines for the Ranger. Generally, the SOHC didn't appear until 2001 model year, prior had the OHV. There are two possibilities I see, here:

1. Your truck is a late 2000 model, manufactured late in the model year, and Ford equipped some late model year trucks with the SOHC, but you installed lifters for the OHV engine. Before y'all get your underwear in a knot, Ford has been known to do similar. On the Taurus, the AX4N transaxle was not officially available until 1996, but some 1995 models got it. Same goes for OBDII, not officially available until 1996 on the Taurus but some late 1995 cars got it.
2. Your truck originally had the OHV (as it should have), but the engine was replaced with a SOHC, and the lifters installed were the lifters for the OHV. This SHOULD have been caught by whomever installed the lifters in the heads (which would have been for the right engine, and should have been obvious).

Both are far fetched, but possible.

 

[pjtoledo]

where are you going to put the pushrods in an over head cam engine?

 

[2011Supercab]

With cracked heads... I would think it was over heated.

So the heads cracked and all the exhaust valves recessed at the same time ?

Cracked heads wouldn't explain all 6 cylinders having 20 psi at once, maybe a couple neighboring cylinders, but not all 6.

 

[Uncle Gump]

If the pushrods are to long, why won't it start again after the lifters collapse after being shut off?

So you think hydraulic lifters bleed all the oil out after you shut the engine off? They don't. If that were true... everytime you started an engine with them it would clatter on start up. Again they don't.

So the heads cracked and all the exhaust valves recessed at the same time ?

Cracked heads wouldn't explain all 6 cylinders having 20 psi at once, maybe a couple neighboring cylinders, but not all 6.

Do you know what it run like a week before it quit? Do you know it wasn't overheated and driven to the ragged edge of destruction?

But you could tell me how it would have started if the cam gear actually spun on the cam...