slow loss of coolant

[uss2defiant]

Hi all,

I have a slow loss of coolant.
The level have gone down to the bottom of the 'cold' lettering.
I don't remember how long but I want to say about half a year.

I'm going to start with testing if it's a HG issue with a block test w/ the blue fluid.

• Pressure testing in the past have shown no leaks and the pressure has held for an hour.
• Water pump and thermostat are about 1-2 years old.
• Radiator cap seem fine. It was replaced about 5-6 years ago.
• System was flushed about 1-2 years ago. Hoses were fine so didn't replace them.

Other tests I can think of are compression test and using UV dye in the coolant if the HG test comes back negative.

Has anyone used UV dye in their coolant system?
https://www.amazon.com/Interdynamics-375CS-Radiator-Coolant-Dye/dp/B002M4E0VC

Any other thoughts?

Thanks

 

[kejobe]

I lose about a quart a month (1000ish miles) and it's the radiator. Has a small hairline crack. Going to replace it this summer.

The only way I seen the crack is it'll seep out slowly. Seen the wet and dried it with a paper towel and a couple days later it was wet again.

 

[LibertyTC]

Another idea is to perform an oil analysis and look for % of antifreeze in oil.
Blackstone lab results: Gas Engine Sample Report 1
How many psi was used on the pressure test ?

 

[uss2defiant]

I lose about a quart a month (1000ish miles) and it's the radiator. Has a small hairline crack. Going to replace it this summer.

The only way I seen the crack is it'll seep out slowly. Seen the wet and dried it with a paper towel and a couple days later it was wet again.

I'll go through with a UV light again. Dried coolant is fluorescent.
Radiator is fairly new too. 4 years old.

I am hoping it is something happening when running at normal/peak temp and not a HG issue.

 

[uss2defiant]

Another idea is to perform an oil analysis and look for % of antifreeze in oil.
Blackstone lab results: Gas Engine Sample Report 1
How many psi was used on the pressure test ?

Good idea. I have to change my oil.

Pressure tested at 16 psi. Tested for an hour and pressure held.

 

[Conundrum2006]

I've had radiator fluid loss do to seeping o-rings to the heater core, a radiator hose clamp that some how loosened up in the winter just enough for a small drip. Those were the less obvious and hard to catch. Easy for a pin hole leak only at certain temperatures or pressures to be impossible to find. Freeze plugs starting to fail. Had a car where the a leak disappeared because the freeze plug resealed for awhile.

Without obvious symptoms of A blown head gasket the oil test is the best diagnosis.

The blue fluid test will only work if it is bad enough to actually get exhaust gasses to burp out of the cooling system.




Sent from my iPhone using Tapatalk Pro

 

[uss2defiant]

I've had radiator fluid loss do to seeping o-rings to the heater core, a radiator hose clamp that some how loosened up in the winter just enough for a small drip. Those were the less obvious and hard to catch. Easy for a pin hole leak only at certain temperatures or pressures to be impossible to find. Freeze plugs starting to fail. Had a car where the a leak disappeared because the freeze plug resealed for awhile.

Without obvious symptoms of A blown head gasket the oil test is the best diagnosis.

The blue fluid test will only work if it is bad enough to actually get exhaust gasses to burp out of the cooling system.




Sent from my iPhone using Tapatalk Pro

That's a good point.

 

[uss2defiant]

Has anyone used UV dye in their coolant system?
https://www.amazon.com/Interdynamics-375CS-Radiator-Coolant-Dye/dp/B002M4E0VC

Thanks

 

[uss2defiant]

nothing on the UV inspection.

However, closer inspection of the rad. cap, there's a crack on the upper seal/outer seal.
fingers crossed.

 

[ltd02]

nothing on the UV inspection.

However, closer inspection of the rad. cap, there's a crack on the upper seal/outer seal.
fingers crossed.

Never used the UV dye but that cap might be it. I've had that happen before on my 02 and it took me a while to find the cracked cap seal. Seemed to hold decent pressure when running but not for long after shut down. I didn't say anything earlier since you said you changed it a while back and mine was the original (10 year old at the time) cap.

 

[HoosierJeeper]

I read somewhere on BITOG forum that coolant loss, a minimal amount (like having to top off once a year) is normal, it evaporates a bit.

I'd do the oil analysis. You'll have to do a few. They'll look for elevated sodium levels. Some oils (like Valvoline) are higher in sodium, but if that's your "baseline", then nothing to worry about. Just don't switch oils during the testing period!

 

[Conundrum2006]

I had a new rad cap from crown that looked great but didn't seal, no idea if the cap of faulty of if the previous owner had the radiator changed. It didn't leak for a few miles, looked fine at first inspection too. It didn't clampdown hard enough, I think the dog ears on the cap were too tall.

Looking for signs of a BHG can drive you crazy, I was convinced our old gunked up 3.7 had to have a head gasket leak, because of the gunk and very slight coolant lost. Turned out the head gaskets were fine, except for extreme neglect so was the engine.

I'd try a new rad cap and trust a little in your engine (keeping a eye on the temp gauge and res levels) until you see something more definite.


Sent from my iPhone using Tapatalk Pro

 

[uss2defiant]

Never used the UV dye but that cap might be it. I've had that happen before on my 02 and it took me a while to find the cracked cap seal. Seemed to hold decent pressure when running but not for long after shut down. I didn't say anything earlier since you said you changed it a while back and mine was the original (10 year old at the time) cap.

yeah. I looked at it the last time but i didn't pay too much attention to the outer or upper seal. It was a 'hairline' crack. Had to push around the seals to see it.

 

[uss2defiant]

I read somewhere on BITOG forum that coolant loss, a minimal amount (like having to top off once a year) is normal, it evaporates a bit.

I'd do the oil analysis. You'll have to do a few. They'll look for elevated sodium levels. Some oils (like Valvoline) are higher in sodium, but if that's your "baseline", then nothing to worry about. Just don't switch oils during the testing period!

Darn.... I was hoping to only just do one....
I'll give them a holler.

 

[uss2defiant]

I had a new rad cap from crown that looked great but didn't seal, no idea if the cap of faulty of if the previous owner had the radiator changed. It didn't leak for a few miles, looked fine at first inspection too. It didn't clampdown hard enough, I think the dog ears on the cap were too tall.

Looking for signs of a BHG can drive you crazy, I was convinced our old gunked up 3.7 had to have a head gasket leak, because of the gunk and very slight coolant lost. Turned out the head gaskets were fine, except for extreme neglect so was the engine.

I'd try a new rad cap and trust a little in your engine (keeping a eye on the temp gauge and res levels) until you see something more definite.


Sent from my iPhone using Tapatalk Pro

Jeep$......

 

[HoosierJeeper]

Darn.... I was hoping to only just do one....
I'll give them a holler.

I wish that were true! But I'm guessing they'll want to do 3.

 

[Conundrum2006]

Well with a bad leak it will not take much for the test to show it.
If it's new oil I'd go a few thousand miles before sending it in for one test, if your doing a series of tests I dunno.


Sent from my iPhone using Tapatalk Pro

 

[Conundrum2006]

Jeep$......

True. in our case the motor flush we had done was the final issue for that motor. Too much crud and gunk in the pan to leave it alone. Probably was easier to remove the engine than do in vehicle repair. I do know that rotella and other recommended high detergent oils will start to cut the gunk after miles and miles . They'll work as long as enough oil flow exists.

I thinking the pressure test should give you some peace of mind.

Also compression test and leak down test could help prove it one way or another. The oil test i think is a better indicator, well easier.
Leak down test is a bit of a pain to get each cylinder correctly lined up but you'll find the issue if there is one.


Sent from my iPhone using Tapatalk Pro

 

[uss2defiant]

I don't have the necessary equipment to do a leak down test.

I'll definitely do a pressure test again after I pick up the loaner tool and new radiator cap.

just sent Blackstone an email.

 

[uss2defiant]

pressure test seems okay.
Held at 16 psi for 25 mins and dropped to 15 psi. Stayed there for about 45 minutes.
I was doing multiple pressure tests as I did an oil change and some basic inspection around.
All had similar results as previously mentioned.

Didn't see any white smoke out the tail pipe after all those tests so I think the definitive answer would be from the oil analysis.

new Motorad 16 psi radiator cap. a lil skeptical of this new cap. not as much resistance screwing it on as the old one.

any thoughts are much appreciated.
Thanks.