My '03 ranger with only 24k miles on it began smoking white smoke out of exhaust and losing coolant, it seems to get worse the longer it sits. The oil looks light brown so i think coolant is getting in the oil too. I took to a local shop and they told me it failed the block test and told me it would need $7000 worth of work and wouldn't even let me talk to a mechanic. It didn't have this problem when I first bought it and it's never over heated. However, I had a problem with the thermostat where it caused the gage to fluctuate up and down so I replaced the thermostat and I think the problems started after this. Would a bad thermostat cause it too overheat that quickly? I'm just wondering what my options are and if I can determine if it's really the block that is bad or if it is the head gaskets.

 

Welcome to the forum

Yes, reads like a blown head gasket

I never trusted the Block test, its a chemical test for exhaust in the coolant, can get false positives


Way simpler test is the Glove test and its FREE which is why shops won't use it, and 100% accurate

This is the gross test to see if you need glove test
Cold engine
Remove radiator cap
top up radiator if its low, tap water is fine
Start engine rad cap off
If coolant level drops add more water until its topped up

Watch rad cap opening, if water/coolant starts to over flow after a few seconds to 1 min you have a head gasket leak or cracked head, no way to tell which
For sure

If coolant level stays the same then you can do the Glove test just incase, or do it just to do it, lol
Shut off engine
Pull off overflow hose, and block that port on radiator with vacuum cap, putty, gum, ???
Put a latex glove over the rad cap opening and seal it in place with rubber band or zap strap
(you can also use a balloon or even a condom in place of the glove)
Pull the 4 wire connector off of the coil pack, so no spark and no start
Crank engine over and watch the "glove", if it starts to bounce you have a head gasket leak or cracked head
For sure 100%
At this point you can ID which cylinder/head has the leak if you want, but both heads needs to be serviced regardless

Pull out 1 spark plug
Crank engine over
If "glove" still bounces pull out the next spark plug
Repeat
When "glove" stops bouncing the last spark plug removed was from the leaking cylinder
Put it back in, retest to confirm

There can be more than 1 cylinder effected so "less bouncing" can occur, judgment call on your part


Head gasket separates the cylinders from the cooling system, main function
Each cylinder has 150psi when cranking and 1,000+ psi when running, its what pushes the piston down
Cooling system is 0psi when cold and at most 16psi when warm, rad cap rating
So a breach in a head gasket forces the pressure inside a cylinder OUT and into the cooling system, this displaces the coolant, replaces it with air/exhaust, then as coolant is forced out of the head you get overheating, because the air/exhaust can't cool the head
The while smoke occurs because coolant is sucked in the intake stroke and hot cylinder temps vaporizes it and sends it out the exhaust pipe
The Block Test looks for the chemical traces from exhaust gases, which shouldn't be in the coolant
Glove test looks for the pressure being forced into cooling system from a cylinder leak

Coolant in the oil can still happen but not like it did in pre-1980 engines
It also has to do with where the breach occurs, only 3 or 4 oil passages in a head


You have a 4.0l SOHC engine so it should be pulled out to do the repair, but can be done without pulling it, DIY, a shop will have to pull it to give a warranty
Should be 6 hours to pull the engine and 8 hours to re-install, so 14 hours, at $125/hour that $1,750

Head swaps and timing chains 6 hours, $750
So you already have $2,500 in labor

Parts are parts, lol,
Rebuilt 4.0l SOHC head complete with cam runs $350-$400 each, test and surface existing heads $150 each
Motorcraft tensioners, set of 2 $100
Head gasket kits $150, includes intake and exhaust gaskets
Head bolts, $60
Oil, filter and coolant $100

The $7,000 seems on the high side of check with another shop, lol
So call around after you confirm blown head gasket

A rebuilt 4.0l SOHC long block is $3,500
So brand new rebuilt engine installed is $6,000 on the high side, should be closer to $5,000 installed

 

I did the trouble shooting test and it immediately over flowed, but with the glove test cranking the engine over with the over flow port blocked i didn't see any bouncing at all. What does that mean? Maybe i wasn't cranking long enough?

 

I pulled the heads off and it turns out it was corroded on the left head around one of the rear water ports so that is what was letting the water into the cylinder.

 

Have your local machine go over the heads to make sure they are straight and true.

 

I dropped them off today, we'll see what they say. Going back together what types of lubricants, gasket sealers,etc. Should I be using to put all the new seals in place?