Noticed that coolant was coming out the cap from the overflow.

stuck my finger in the oil fill neck and found white substance which I’m pretty sure indicates coolant in the oil.

Is that definitely the head gasket?

 

not really. it could just be condensation.
or it could be a bad oil cooler.

 

Did you check the dipstick for the same substance or a (coffee with milk) tan color? Your condition is typically caused by moisture which could be the start of a leak but can be caused if you have short runs and you are not getting the engine up to temp or your vent isn't working properly. In the 1980's, I've seen hundreds of engines with this problem and the engine was fine. Keep an eye on your coolant level and check for oil residue in the coolant system. Best bet can be pressure tests and dye tests if you are really concerned.

 

Oil Cooler leaking.

I had oil in my Coolant Bottle one morning...Black yuck. The morning before all was good.
Started a thread I thought the same thing..."Head Gasket"... three guys came back and
said "Oil Cooler" which it was. OH, and the same time of year.
Hope it is something simple for you.

I took it to the local Diesel shop all the big boy take their jacked up Diesels..."OH!!!...
we don`t work on something that old"

Here is the thread I started if you want to read up on it.
https://www.ford-trucks.com/forums/1...oh-goodie.html


Charlie

 

Okay well I definitely drive my truck for short runs and probably doesn’t reach temperature. Kind of explains the white substance in the oil fill neck.

But still trying to understand why I’m having coolant come out the cap from the overflow. It’s a big amount but it’s definitely still lowing my coolant level.

You said oring on the oil cooler is a reason why oil may enter coolant. But will the oil cooler allow coolant into oil?

will a bad oil cooler cause extra pressure in the cooling system which could be a reason why it’s pushing coolant out of the overflow cap?

Its only pushing coolant out the cap when the truck is driving. Whenever I open the hood while the truck is running I don’t see the coolant coming out. I could just see that it is coming out from there because it’s wet.

Thanks guys,
7.3B*tchImFree

 

I saw that in your text but wasn't sure if you meant the overflow reservoir was overflowing. If you have NO oil/residue in the coolant, you should be ok. Sometimes a gasket will fail and push oil into the coolant or fail and remove coolant into the cylinder or the oil.
Ok! The over low reservoir has a "cold level" when cold. Make sure you are not above that level when cold.
Could be a few things.
1. I would check to see if the top of your radiator core is plugged. Also check the exterior fins for cleanliness. Given our mild temperatures here, I would think a diesel would idle all day and not overflow- and not "overheat". Is it overheating and boiling over or just overflowing when driving? When you cruise you get extra heat from the engine and if your radiator is restricted/plugged your volume to the top of the radiator will be more than the overflow can handle and overflow and overheat.
[Edit- When **COLD** and the radiator cap off, a full radiator will have extra volume at the top as it starts to warm up and may overflow. Once it is at operating temperature, you should see the water flowing quickly which "should" indicate the pump propeller is not deteriorated.]
2. Bad/worn/improper radiator cap not holding pressure.
3. Thermal fan, if equipped, has failed or does not fully lock up or your belt is loose. **Technically**, if there is dampness at the seal it should be failed, but I have seen newer units that were damp and worked just fine.

 

please clarify the line I highlighted in red.
a bad oil cooler will make the coolant look like chocolate milk.

 

a cheap test for a blown head gasket

 

Please read through all pages of the below linked article:

Part 1 -BAD Fan Clutch Troubleshooting Case Study (GM 4.8L, 5.3L, 6.0L) (troubleshootmyvehicle.com)

The van had been to two prior mechanic's who said "Bad Head Gasket", but the coolant issue was the result of a faulty Fan Clutch.
Our first notion is "Head Gasket", but we need to pressure test the cooling system.
Maybe the pressure test should be done both with engine-cold and engine-warm ?

when mentioned that you have coolant coming out of the overflow bottle cap, it made me think your cooling system had too much pressure. Then we must determine if the pressure is coming from combustion pressure working past a head gasket or from the cooling system not being cooled properly by the fan not pulling sufficient air through the radiator core.

I recently had two instances of suspect head gasket, and both wound up being a faulty Fan Clutch.
1. Isuzu 3.2L V-6 in a '95 Honda Passport
2. Ford 460 (7.5L) in a '78 E-250

The Isuzu would pressurize the cooling system so much it ruptured the plastic composite heater core nipples, blowing them off of the heater core.
The Ford 460 would pressurize the cooling system so much it ruptured the plastic body of the vacuum operated heater control valve.

OK, for the Isuzu: I had changed out the badly worn rocker arms (exhaust rockers) and shafts which were badly worn. Upon post-repair shakedown, I started the engine and checked the coolant temps with a candy thermometer (the wife's), and the thermostat opened at 180 degrees. Nice !
Then, I allowed the engine to idle for 25-minutes as I did some errands out back. Suddenly, I remembered, oh *****, the Isuzu is running, and ran to the garage to have a looksie.
Hmm, not good. What I found when stepping into the garage was steam shooting from the opening for the radiator cap opening (cap was left off for temp checking), and the floor below the Passport was covered in a huge puddle of green coolant. Dang, and double Dang.
I promptly shut off the engine to cool down, and mucked-up the brand new lost coolant. Dang
According to the above article, I checked the mechanical lock-up of the Fan Clutch and it failed the spin test as described in the article. Aha !!!
Basically, the Ford 460 did a similar stunt with radiator cap in place, and engine idling for 20-minutes.
The weak pressure link in the system was the above mentioned plastic body of the heater control valve.

Good luck on solving your coolant and condensation issue.

 

Thanks for posting. Yes, that article brings up some old forgotten memories. You could lube the shaft on that particular design and use pliers to makes sure that shaft turns freely. If it doesn't it will not engage. Anyway, if the shaft is frozen and you free it up the thermal clutch will work until it fails again.