no compression

[bubblegump]

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

 

[RonD]

Welcome to TRS

Something is wrong with description

1990-2000 4.0l OHV engine is non-interference, so at no time do pistons and open valves occupy the same space, it is not possible for bent/impacted valves in these engines, like other interference engines
Something could fall into the intake and into an open intake valve, i.e. nut, bolt, washer, ect.............but that would only effect that one cylinder

1997 to 2011 4.0l SOHC engines ARE interference engines, but Rangers didn't get these until 2001 model year
These can get bent valves if timing chains slip or if timed incorrectly

4.0l OHV engine looks like this:

https://imgur.com/KRAWQMS

4.0l SOHC looks like this: https://modd.me/wp-content/uploads/2014/02/4.0sohcRanger.jpg

If you have a 4.0l SOHC then timing has slipped after rebuild

If you have a 4.0l OHV then its not stock, has wrong pistons from a different year possibly, or otherwise modified in some way

So find out what we are dealing with, for sure, and we can help from there

 

[dvdswan]

Welcome to the site.

 

[2011Supercab]

Welcome to TRS

Something is wrong with description

I'm thinking he means recessed

 

[bubblegump]

Welcome to TRS

Something is wrong with description

1990-2000 4.0l OHV engine is non-interference, so at no time do pistons and open valves occupy the same space, it is not possible for bent/impacted valves in these engines, like other interference engines
Something could fall into the intake and into an open intake valve, i.e. nut, bolt, washer, ect.............but that would only effect that one cylinder

1997 to 2011 4.0l SOHC engines ARE interference engines, but Rangers didn't get these until 2001 model year
These can get bent valves if timing chains slip or if timed incorrectly

4.0l OHV engine looks like this:

https://imgur.com/KRAWQMS

4.0l SOHC looks like this: https://modd.me/wp-content/uploads/2014/02/4.0sohcRanger.jpg

If you have a 4.0l SOHC then timing has slipped after rebuild

If you have a 4.0l OHV then its not stock, has wrong pistons from a different year possibly, or otherwise modified in some way

So find out what we are dealing with, for sure, and we can help from there

it is an over head valve-the timing is right the heads are NEW not rebuilt-the lifters are NEW-the oil pump is NEW-it started and ran about 15 seconds until oil pressure was reached and then died and has no compression-some how the lifters are pumped up and holding the valves open-no one has ever seen this problem around here and no one has a solution

 

[RonD]

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"

 

[1990RangerinSK]

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

 

[pjtoledo]

what's the oil pressure?

 

[rusty ol ranger]

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

Also what caused the initial failure?

 

[bubblegump]

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"

the heads are not rebuilt - they are factory new-the lifters are identical to the ones that came out of it-nothing is adjustable on this engine

 

[bubblegump]

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

Also what caused the initial failure?

no one knows why it died-the exhaust valve seats being sunk was though to have been the problem but with factory new heads-lifters and oil pump it is doing the same thing

 

[bubblegump]

th

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

Also what caused the initial failure? They are the original pushrods they measure the same-

 

[bubblegump]

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"

the heads are new factory heads-

 

[rusty ol ranger]

no one knows why it died-the exhaust valve seats being sunk was though to have been the problem but with factory new heads-lifters and oil pump it is doing the same thing

You arnt going to lose 6 exhaust seats all at once and smoke the valves too.

If you had bent valves you either A) Jumped time or B) have some very very odd cam/oil circulation issue.

Im guessing all the top end damage was a result of what failed in the first place and now youve fixed the result without addressing the issue.

Basically you still have the original issue going on.

I think youre gonna have to dig deeper then the heads to figure this out.

 

[ekrampitzjr]

You arnt going to lose 6 exhaust seats all at once and smoke the valves too.

If you had bent valves you either A) Jumped time or B) have some very very odd cam/oil circulation issue.

Im guessing all the top end damage was a result of what failed in the first place and now youve fixed the result without addressing the issue.

Basically you still have the original issue going on.

I think youre gonna have to dig deeper then the heads to figure this out.

Check timing chain and sprockets for wear and jumped time. I'll bet that's at least part of the problem. Look closely at the lubrication system going to the chain, because if everything is sludged because of cheap oil and past lack of maintenance, that must be addressed too. The chain might not be getting any oil if the system is sludged.