Letting the internet get you all freaked out about cracked heads

[barrys]

So, on the Ranger, I saw it wanting coolant top off with oil changes -- about an inch in the resevior every 3,500 mi/5 months) and the temp needle running a lot higher than I was used to (near "R" instead of below "N" where it sat for years).

I have a great indy mechanic -- 40+ years working on Fords only with two other mechanics that have been in that shop for 20+. So, I called them and told them what was on my mind. They know I'm a freak already and they're often telling me not to do services that I think I need.

Anyway, I spent the week freaking out that my heads were cracked and needed replacing, or maybe worse. Then I read a buttload of posts where people had spent 20 hours replacing their heads only to find out that that didn't solve their problems.

They took a quick look -- sniffed for exhaust gasses in the coolant with the exhaust tester (smog) rig and visual inspections. They did not pull plugs to inspect or do compression tests. From what they saw, there's nothing going on that warranted further explanation. They also said that, in their experience, the 4.0's like to crack heads and it's much more rare in the 3.0. And, that when the 3.0 heads crack, it's usually accompanied with some other failure in the rest of the engine.

With all that, they ended up not getting 1400 for putting in new heads and told me to come back sometime so they could test the thermostat and temp sender since those might explain the erratic guage behaviour.

Just thought I'd share that "I read it on the internet" story. In fact my heads might actually be cracked. But, for now, we'll explore other paths or none.

 

[McCormack]

From what I've noticed on the forums, water pump impeller wear on the 3.0 seems to be a semi-common occurrence - a worn impeller will reduce coolant circulation which can lead to higher coolant temperatures.

 

[psykostevo]

Good read

 

[jhammel85]

It happens...
I own a 2.9 thats notorious for cracking its heads. So, Im very paranoid about it cracking, even if I dont have a reason to be so worried..

 

[barrys]

> Im very paranoid about it cracking, even if I dont have a reason to be so worried..
That is the generic story of my life.

Now I'm thinking of replacing the water pump. If I'm going to look at it, it's no more work to replace it. But, I have the original service records. It mentioned that the water pump was replaced at about 50K (at 127 now). In those shop notes, they mention something about "repairing a stripped screw." So, who knows what that means. Did they helicoil or bore out and rethread (which would imply bigger than normal bolt). May be some trouble.
I think I'll try thermostat, sensor, and sender first.

 

[barrys]

Actually, a worn impeller would likely reduce cooling/raise temperature consistently. I'm seeing higher average temps, and the needle's moving a lot. So, perhaps the water pump is not the issue becuse that would not explain the needle fluctuation.

 

[McCormack]

If the temp needle is fluctuating then it sounds like it could be a case of thermostat failure. T-stats only cost a couple of bucks, so why not throw a new one in and eliminate that as a possibility?

 

[jhammel85]

I have some ideas:

You don't have any white smoke from the tailpipe right?
Is the oil milky looking? Almost like chocolate milk?
Is there any "snot" on the bottom of the oil cap?

These are easy symptoms of a bad HG or a head cracking...

Have you checked the water pump to see if its leaking from its "weep" hole?
Any noise coming from the pump? use an old piece of hose and with the car running, put it up to the pump and the other side to your ear.

 

[85_Ranger4x4]

And snot on the cap doesn't mean anything in colder weather, neither does a slight white smoke out the exhaust.

 

[jhammel85]

And snot on the cap doesn't mean anything in colder weather, neither does a slight white smoke out the exhaust.

Yup! Sorry I didnt mention that

 

[Beef52751]

NEVER NEVER NEVER Just Replace parts because someone on the net thought that they were bad, ALWAYS ALWAYS test them!!!!!!!! It'll save you alot of money in the long run. Thats the difference between a mechanic and a parts changer.

 

[Big Jim M]

Ahhh! Cracked heads again..

Ford has made us some really good heads. Them heads DO NOT crack all by themselves!!! What ALWAYS cracks them heads is LOW COOLANT!
So you are adding coolant...right?
Then the answer is SIMPLE! You have a coolant leak...somewhere.. So start looking for ONE DRIP of coolant on the outside of the engine.
Them little drips is what has cracked heads and burnt head gaskets in all cases.
In your case you are adding coolant...so it is going somewhere.. chances are about 99% that it is dripping down the outside of the engine.
What happens is: as the coolant gets low the engine has AIR in the place where the coolant used to be. Where is that air? Right there in the HEAD! Since the head is the hottest part of the engine, it over heats and cracks or burns the gasket, if you are lucky. Cause of the lack of coolant.
So crawl your ass up there under the engine with a light and spend an hour or so looking for that ONE DRIP.. That's how you do it.
Big JIm

 

[barrys]

There are no classic signs of cracked heads in the exhaust, coolant, or oil. There are no easily visible leaks and there's nothing on the ground. The cooling system is full.

I should do the "crawl my ass up there..."

I don't drive much so I'm adding about 1" to the reservoir every 4-5 months. The shop tech didn't think this was excessive. In my model year, the reservoir just has the push-on cap so I'm not convinced it's air tight.

I'm also suspicious of a thermostat that's getting old and lazy like me...

The one question I have after reading lots of posts is:
Doesn't the cooling system have a mechanism to bleed air out of a full cooling system?


I just want to trust Ford enough to have figured that one out.

 

[Big Jim M]

Yep!

There are no classic signs of cracked heads in the exhaust, coolant, or oil. There are no easily visible leaks and there's nothing on the ground. The cooling system is full.

I should do the "crawl my ass up there..."

I don't drive much so I'm adding about 1" to the reservoir every 4-5 months. The shop tech didn't think this was excessive. In my model year, the reservoir just has the push-on cap so I'm not convinced it's air tight.

I'm also suspicious of a thermostat that's getting old and lazy like me...

The one question I have after reading lots of posts is:
Doesn't the cooling system have a mechanism to bleed air out of a full cooling system?


I just want to trust Ford enough to have figured that one out.

The answer is the PRESSURE CAP.. As the engine cools a vacuum begins inside the cooling jack inside the engine. The cap allows that vacuum to pull a little coolant out of the reservoir and back into the engine.
HOWEVER this depends entirely on a SMALL amount of coolant at each "cool down". If there is a large amount of air inside the engine this vac does NOT OCCUR! It only occurs if there is almost NO AIR in the engine. Something to do with not being able to compress a liquid..
SO if the system has a fair amount of air in it that air STAYS in there. The system MUST be completely full for the coolant system to work as designed.

As a side note you seem to be adding such a small amount and so infrequently that I'd chalk it up to evaporation out of the resevoir.. I wouldn't worry about it.
Crawling under there WORKS! One drop of coolant can be found with a light.. One might have to cycle the heat cycle a couple of times to find that one drop but it does work.
Big JIm

 

[barrys]

Thanks Big Jim...
> I'd chalk it up to evaporation out of the resevoir..
That's what I think too. The tech said, "We top off coolant every time we do an oil change," which would be many/day -- Fords only.
I was hoping you'd say the radiator cap was the air evac mechanism. In the Helm shop manual, opening the cap to the "breather" position was part of the fill procedure to "get the air out of the system." So, I thought that would be it.

The 3.0's supposed to be a good and reliable motor. I do tend to it like it's a fancy new car.

I'm going to wait a month until my smog test and then replace the tstat and may
be the sender and sensor. Why wait? Because, in California, the smog test is so tough that a few extra degrees of engine warmth ("0" on the guage instead of "N") might just help a bit on the smog results.

P.S. Highly recommend the Helm manual and don't recommend Haynes or Chiltons unless they're being used as suppliments to the Helm.