Coolant boiling

[Laine D]

I made a mistake in the beginning of August when I put my engine back in after doing the oil pan seal. The first gallon of coolant I put in was pre diluted and (I admit it’s completely my fault and I should’ve paid more attention), then the rest of it was not diluted. Fast forward to now, I have an issue that I am 99% sure is the head gasket but some threads I’ve read recently have me wondering if it’s something more simple. I have a 13 pound radiator cap, 3 row champion radiator, and a Napa thermostat. The truck’s temp will fluctuate between 180-200. Never goes over 200. Every once in a while when I park, the coolant will be boiling in the overflow tank. If I start it in the morning with the cap off the radiator it doesn't bubble. It doesn’t lose coolant.

now I’m pretty sure it’s the head gasket and I have all the stuff to fix it, but I don’t want to pull it apart if it’s something stupid that I’m overlooking. What do you guys think?

 

[asmith]

So do you have 100% undiluted coolant in your truck except for that first gallon? That really shouldn’t cause any issues other than being more expensive and it won’t cool as well.


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[Laine D]

So do you have 100% undiluted coolant in your truck except for that first gallon? That really shouldn’t cause any issues other than being more expensive and it won’t cool as well.


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Yes, it’s undiluted. I read that undiluted coolant won’t cool as well and the boiling point would be affected

 

[FrozenMerc]

See charts below (You may have to do some conversions if you don't speak metric on the 2nd - 760 mm Hg = 14.7 psi or atmospheric pressure) That said, You should be fine at ~95%. What you are describing sounds like a potential head gasket issue. Does the coolant temp continue to climb while idling? You may want to perform a leak down test or have some one do one to know for sure.

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[ih8minimumwage]

So its it boiling the coolant in the overflow tank or are air bubbles coming from the overflow tube into the tank? Those are two pretty different things, so just want to narrow it down.

 

[FrozenMerc]

I assumed the comment of "boiling" by the OP was the gases coming out of solution in the coolant in the overflow tank since the tank is not under pressure. Is that correct? Another sign of a bad head gasket if so.

 

[Laine D]

So its it boiling the coolant in the overflow tank or are air bubbles coming from the overflow tube into the tank? Those are two pretty different things, so just want to narrow it down.

I believe that it was boiling the water. Sorry for the confusion

 

[Laine D]

I assumed the comment of "boiling" by the OP was the gases coming out of solution in the coolant in the overflow tank since the tank is not under pressure. Is that correct? Another sign of a bad head gasket if so.

Like I said in the initial post, I’m almost 99% sure it was the head gasket because of this stuff, but also wanted to weed out anything I could be overlooking. Thanks for that chart, and the temperature does not continue to rise. It always stays between 180-200. But it rarely gets up to 200.

 

[FrozenMerc]

Could be a cracked or pin holed cylinder wall was well, something that is leading to combustion gases getting dissolved into the coolant. This was much more common on 7.3's than 6.9's due to the thinner cylinder walls.

 

[franklin2]

Like I said in the initial post, I’m almost 99% sure it was the head gasket because of this stuff, but also wanted to weed out anything I could be overlooking. Thanks for that chart, and the temperature does not continue to rise. It always stays between 180-200. But it rarely gets up to 200.

Keep driving it. If it gets worse, then start thinking about your options. If it doesn't get worse, then don't worry about it.

 

[Laine D]

Keep driving it. If it gets worse, then start thinking about your options. If it doesn't get worse, then don't worry about it.

Well the only issue is this summer I plan to take it up to Washington from California so I’m hoping to fix it first. This is the only real thing holding me back, just not knowing for sure.

 

[CDX825]

Number one thing you need to do is ditch that napa thermostat and get a motorcraft or one from an International truck dealer. Aftermarket thermostats are very problematic in these engines.

Second thing is drain the antifreeze and refill with a 50/50 mixture of coolant and distilled water. Running almost straight antifreeze is no good because it doesn't transfer heat well.

Your temperatures don't sound bad but something is going on. If it was a blown head gasket you would have coolant loss one way or another.

 

[IDIBRONCO]

Your temperatures don't sound bad but something is going on. If it was a blown head gasket you would have coolant loss one way or another.

I agree with this. You don't have coolant loss, and it only "boils" coolant once in a while. I don't see how compression wouldn't leak into the cooling system all of the time. Even a slow leak would have more than the 13 PSI that you radiator cap is rated at. I also don't see where a compression leak wouldn't leak on a cold start up. Maybe your first move should be to get a test kit that lets you test the coolant for combustion gasses. That will tell you for sure if it's a head gasket. Test first before replacing parts to see if the new part helps. This can save you A LOT of money. Then, if replacing parts to see if it helps, start with the cheapest first: thermostat. Either way, just make sure that you end up with a Motorcraft thermostat and 50/50 antifreeze.

 

[lotzagoodstuff]

Go get a OEM radiator cap and an OEM thermostat. Change them one at a time (I'd start with the radiator cap) and see if either fixes your issue.

If your cap is weak, it will cause the symptom you are describing. CDX825 explained it very clearly: aftermarket thermostats don't work well in IDIs.

Good luck, and stay away from Washington state: it's getting just like California up here, without the benefit of nice weather

 

[Laine D]

Number one thing you need to do is ditch that napa thermostat and get a motorcraft or one from an International truck dealer. Aftermarket thermostats are very problematic in these engines.

Second thing is drain the antifreeze and refill with a 50/50 mixture of coolant and distilled water. Running almost straight antifreeze is no good because it doesn't transfer heat well.

Your temperatures don't sound bad but something is going on. If it was a blown head gasket you would have coolant loss one way or another.

I almost think that it is a slow start to a head gasket. That’s why I’m ready for it when it happens. In the mean time I’m definitely going to fix the coolant and thermostat