My temp guage is registering very low, changed sensor no change...
Coolant overflowing the puke tank...
Newer waterpump...
Blackish looking residue floating in coolant...
Top radiator hose warm lower cold, radiator cold....
Heat works but not well and not at all at idle...

Some histrory here...
Replaced both heads, all was well for a month, suddenly missing, lost compression, burnt plug, coolant nasty black looking...
Had junker engine installed...
Now i have previously mentioned symptoms...
I pulled heads off the motor that was pulled, cracked head and intake valve missing a quarter of its top...
The coolant ports are lined thickly with some fine dark grey or blackish powdery residue... this residue matches the nasty looking head gaskets that looks like its just disintegrating...

my thoughts are that the cheap head gaskets i bought failed horribly and filled the head coolant ports causing the head to overheat and crack...
shop that swapped out the motors didnt flush the radiator and heater core and therefore coolant wont flow thru radiator... barely flows thru heater core...
this also means that residue has gotten into the head ports like before...

... what are the chances of flushing all this crap out of the heads and heater core? I dont wanna tear diwn the junker motor... thats why i put it in so i can work on the motor that just came out...
I can easlily replace the radiator but i dont wanna do that just to crud it up trying to flush the rest of the system...
i need some help here!!!
Will a chemical flush get this crap out?

 

What year Ranger?
It will matter for the heater core
If its a 1994 or earlier then you just replace the heater core, 4 screws and its out and new one in

You can flush the engine using heater hoses, but here's the problem with that
If you don't get heater core and radiator cleaned/replaced, then the crud in those will just go back into the engine

Remove both heater hoses at the firewall
Point one down at the ground
Put garden hose on the other
Flush
Then once its flowing out clean water, reverse the hoses

Have radiator hoses connected during this
Rad cap off
Once water is flowing clean put hand over hose pointed at the ground, this will force water thru lower hose and out of rad cap, maybe cleaning out some gunk from inside rad, maybe

Put garden hose on heater core ports, flush in BOTH directions

Remove lower rad hose to drain engine and rad once first flush is done
Then flush again
Flush radiator from rad cap opening

If you won't have freezing temps over the next week, refill with water, run it for a few days, then drain and see how water looks, if OK then refill with coolant

 

Problem was clogged radiator... replaced w a new one
Thermostat stuck open... replaced w new
Flushed heater core as suggested
Flushed engine with water and currently have the prestone total flush still in there...
i also believe it has a cracked head...
Trying to figure if i can replace just one cylinder head

 

Better to pull both heads and have them pressure tested at machine shop, unless crack between valve seats is obvious, but still test the other head
Over the years it has cost me more money and way more labor to guess at things, than to just have it tested

Of if you are building the other 4.0l just use those heads until, you are ready to swap it back in

The head gasket can't be reused of course, and also the head bolts once they have been tighten one time
The intake gaskets can be reused if they are newer




There is a simple free test called the Glove Test to test for blown head gasket or cracked head

Remove rad cap
Have water or coolant at least 2" below cap opening
Unplug coil pack's 4 wire connector, you want a no start
Use a vacuum cap(off the engine) or hose with bolt in it to block the overflow port on rad cap opening
Put a latex glove over rad cap opening and seal it with rubber band or ziptie
(or use a balloon, or even a condom in place of glove)

Cooling system is now sealed
The reason a blown head gasket or cracked head is bad is because it pushes AIR from the cylinder into the cooling system, this pushes out coolant and AIR is not good at cooling a head like these, so engine over heats

Crank the engine over and watch the "Glove"
If it starts to inflate and pulse then you have a leak from a cylinder to the cooling system
If so then do this
Remove 1 spark plug at a time and crank engine over, when pulsing stops, the last spark plug pulled was from the leaking cylinder, its no long pushing air into cooling system, you can put spark plug back in, hand tight, to confirm it starts pulsing again

If pulsing gets less but still there then you may have TWO leaking cylinders so keep pulling spark plugs

 

Yes i think im gonna go ahead and put heads on the original motor that came out of the truck and put it back in. I have one head that is newer and one that originally came off of it... im gonna have them tested and decked if needed...
i have fel pro gasket kit and new head bolts...
im told that the fel pro arent that great and to use multilateral metal head gaskets (???) and head studs instead of bolts...

 

What if:
motor running at idle, has miss that shakes the truck, gradually rev slowly up to 1500 then 2500 rpms and the miss doesnt go away...
coupled with a sucking in sound at the exhaust seemingly on one cylinder...
not as noticeable under harder acceleration with load...
would the glove test still show cracked head or gasket failure? No oil in coolant or coolant in oil?

 

Could be bad exhaust valve... but this was the exact same symptoms that started in the previous engine that got worse and worse and turned out to be a crack in the head between intake and exhaust valves...

 

No, Glove test would just show leaking cylinder, i..e blown head gasket or cracked head

Google: exhaust dollar bill test

This will show you if exhaust valve is leaking
A misfire from fuel or spark issue will not suck in the paper/dollar, just won't push it out, sucking in means exhaust valve is not sealed when that cylinder is on intake stroke so is sucking in air from exhaust side

 

Compression test shows fair compression... little lower on front 2, #s 1&4 at 125 and low on #6 which is about 120...
did glove test and sure enough... got a pulse... decided to start with #6 since its lower... pulled plug and turned starter over... no more pulsing of the glove... replace plug and pulsing again.... since its pushing air into coolant, and sucking air from the exhaust... im gonna guess its not just a gasket... luckily i have 2 heads that may be good (visually ok anyway) im gonna have them clean test and surfaced... new head gasket and intake gaskets....
should i do both heads or leave alone the one side that seems to be ok and just deal with the one showing a problem cylinder?

 

Because the labor to pull one head off means pulling the 2nd head is just 6 more exhaust bolts and 8 head bolts, its best to do both heads at the same time
But really up to you

But if one head blows a head gasket or cracks a head that means it was overheated at some point, so the "other head" will have suffered from the same overheating just hasn't "blown" YET, lol



Head gasket don't just "blow" and heads don't just crack, it always starts from overheating
In the case of head gaskets, when coolant gets low heads get hot because they are the highest point so lose coolant first

Metal expands when heated, the head and block metal expands and contracts every time engine is used, warmed up and cooled down, and all is fine, head gasket is made for this expansion and contraction
If head is overheated the metal expands more and it can't expand up, head bolts, so it expands down and crushes the head gasket between head and block, and that can cause head gasket to fail, as engine cools off the crushed area of head gasket can't expand back up, so cylinder breach

If head metal expands too much the head metal can crack from over-expansion, the 4.0l OHV heads have a thinner metal casting between Valve seats, most common place for them to crack when over heated

 

I dont even need to do the dollar bill test as i can hear the gasp of air being sucked in every revolution of the engine... and the glove test reveals that i have air escaping into the coolant... and have found the bad cylinder...