Blown Head Gasket or Cracked Block??

BryanG · Feb 26, 2017

My son's 2000 4.0 with 120k miles had a major malfunction. He was almost to work when the check gauge light came on, temp spiked to high and the motor started to hop. He was less than a block from work and managed to limp it to the parkinglot. I was assuming either a stuck thermostat or fluid leak. Got there and the overflow resivour was empty so I popped the radiator cap and it was bone dry. (We did a complete radiator flush and service before winter and all was good). I grabbed the oil dipstick and sure enough creamy milk all the way up. It's now at the mechanic shop since this is way out of my ability to fix. They hope to know this week if it is a blown head or something more catastrophic like a cracked block. Looking at big repair price tag!! Truck is in such good shape but if it's the motor do you put $4k into a truck worth $3500? He is very upset and the wait is killing us all.

Mark_88 · Feb 26, 2017

It's a tough call...personally I would do it myself...depending on the shape of the frame and cab. If it's not too rusty and it has sentimental value to you or your son then it makes it even harder...

You can probably buy a running and road worthy Ranger for less than what the shop wants for an engine...

Finding a 4.0 from that year might pose a bigger problem...

85_Ranger4x4 · Feb 26, 2017

Used engine time...

DangerRanger37 · Feb 26, 2017

5.0 time?

I doubt the block is cracked. More likely the head went. But again, very strange it just let go like that usually there is a little warning, missing coolant and all that good stuff.

I would just find a donor motor. There's a ton up here.

EDIT: Has it ever been overheated before? if the heads not cracked, that might just be an OHV thing, bring it to a machine shop have it trued out and pop it back on. Might be worth doing that and the timing chain (its time) and keeping the same motor.

Die.Fledermaus · Feb 26, 2017

It is not going to be the fault of the shop if the repair is higher than the street value of the truck. Labors of love are always that way.
Price tags are not often assigned to heart and soul.

Also if you walk away, keep in mind the enthusiast that wants also faces this expense it so don't all of his/hers money.

RonD · Feb 26, 2017

He was most likely loosing coolant from a leak before hand.
That caused the over heating

Then limping a little farther caused the head gasket breach or the head to crack
4.0l OHV heads have a weak spot between valve seats and will crack there, if over heated.

Never seen or even read about a 4.0l OHV engine with cracked block, I image it could happen just never heard of it happening

But coolant in the oil means head gasket breach for sure, cracked head won't/can't do that.

To R&R the heads is about an 8 hour job the first time, not counting time at machine shop to test and surface the heads, they may be fine.

How full is the "oil" level on the dip stick?

Coolant in the oil can hurt the bearings, but seems like it wasn't run long enough to do that.

1998-2000 4.0l OHV used different heads than 1997 and earlier, different exhaust port shapes.

Used 4.0l OHV should be priced out, but you could be buying someone else problem, lol.

adsm08 · Feb 26, 2017

Die.Fledermaus said:
Also if you walk away, keep in mind the enthusiast that wants also faces this expense it so don't all of his/hers money.

Don't drink and type kids.

BryanG · Feb 27, 2017

RonD said:
He was most likely loosing coolant from a leak before hand.
That caused the over heating

Then limping a little farther caused the head gasket breach or the head to crack
4.0l OHV heads have a weak spot between valve seats and will crack there, if over heated.

Never seen or even read about a 4.0l OHV engine with cracked block, I image it could happen just never heard of it happening

But coolant in the oil means head gasket breach for sure, cracked head won't/can't do that.

To R&R the heads is about an 8 hour job the first time, not counting time at machine shop to test and surface the heads, they may be fine.

How full is the "oil" level on the dip stick?

Coolant in the oil can hurt the bearings, but seems like it wasn't run long enough to do that.

1998-2000 4.0l OHV used different heads than 1997 and earlier, different exhaust port shapes.

Used 4.0l OHV should be priced out, but you could be buying someone else problem, lol.

The oil/coolant level was all the way up the dipstick except the last 4-6". He did a really good job getting it turned off. I would say it has less than 5 minutes running after the failure. The truck was owned by an older guy who took good care of it so I'm hoping it's just a head gasket. The plan is a full repair at this point but still waiting for the diagnosis. I'm sure new heads ior new motor is going to cost more than the truck is worth but I could go buy another vehicle and have the same thing happen. I will keep you all posted and thank you all for the replies.

Mac · Feb 27, 2017

I had same problem with my 2000 with only 66K on it. Guy at work had same also with 78K on his. 5.0 swap for me, he swapped motors. My other 2000 has over 184K with not a sign of problems.
Dave

Shran · Feb 27, 2017

If it was a high mileage truck then my answer might be different but even $3500 is cheaper than a new truck or new truck payments and hopefully fixing it means you'll have a reliable rig for quite a while. Although from the sounds of it you might just be looking at head gaskets plus labor, nowhere near $3500.

RonD · Feb 27, 2017

4.0l OHV had cast iron heads and aluminum intake which did cause a problem if coolant wasn't changed every two years.

Electrolysis, if coolant PH levels dropped below 9 then coolant flowing thru the intake from one head to the other would eat away at the intake, where it meets the heads.
That could cause intake gasket failure and coolant could flow into Cam Valley and down to oil pan.

Usually it will leak externally at passenger side front or driver side rear of intake, but no reason it couldn't do that internally

BryanG · Mar 1, 2017

RonD said:
4.0l OHV had cast iron heads and aluminum intake which did cause a problem if coolant wasn't changed every two years.

Electrolysis, if coolant PH levels dropped below 9 then coolant flowing thru the intake from one head to the other would eat away at the intake, where it meets the heads.
That could cause intake gasket failure and coolant could flow into Cam Valley and down to oil pan.

Usually it will leak externally at passenger side front or driver side rear of intake, but no reason it couldn't do that internally

You may be right on the money! Shop called this morning and said the intake gasket is definitely blown out and they see no signs of a blown head gasket. They are changing out the intake gasket, flushing the entire system numerous times, new antifreeze and oil changes in hopes to clean everything out really good. So fingers crossed we might have dodged the head gasket issue. Will update you all when I know for certain it was a success.

RonD · Mar 1, 2017

That would be a bit of good news

Tell them to use lock-tite on the intake bolts, they only have 14-18ft/lb torque so had a tendency to loosen up, never heard of that causing coolant leak but it did cause Lean code on the loose bank/side.

BryanG · Mar 4, 2017

Final Diagnosis

In the process of tearing the top of the motor down they found the intake gasket blown out and was allowing the coolant to mix with the engine oil. They did not remove the heads because they were very confidant the intake was the issue. They replaced the valve cover and intake gaskets, added all new coolant, flushed out the crank case and changed the oil twice. At this point it seems to have fixed the issue. Fingers crossed this was the problem and the issue has been corrected. Truck started a little funny this morning and died a couple times but once it remained running it has been. $635 repair is way better than new head gaskets or new engine cost. Thanks for everyone's help!!!

cal74 · Mar 4, 2017

Hope that was all that happened and limping it further didn't do any damage.

Replacing the heads really isn't all that hard and you don't need a lot of tools. I did a 2000 4.0 a few months ago and it went pretty smooth.

Today I started the tear down on a '97 4.0 and whoever came up with the EGR set-up on it should be taken out back and shot. Absolutely no clearance to get to the back drivers side manifold stud/nut.

400.00 for a set of new, supposedly heavier heads. Another 100-120 for a gasket set with new head studs.

Blown Head Gasket or Cracked Block??

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