Coolant reservoir empty but no leaks

[calvainiac]

Hi all,

Recently I was driving and my check gauges light came on and my engine temp went almost all the way into the red. I parked and looked under the hood and saw no leaks or fluid on the ground. Later when I got home, I noticed the hose from the radiator cap to the reservoir was loose and I put it back on and it's tight. However, I drove about 30 miles after that and the engine temp stayed fine but when I checked it the next day the reservoir was empty. I haven't noticed any leaks and there's isn't any obvious cracks or seals broken. Could it be the thermostat giving faulty temp readings to the engine or is it potentially something more serious? It doesn't seem to be a head gasket issue as there aren't any external leaks. Thanks, any help is appreciated.

 

[Jcraig]

If you know the type of antifreeze to add, add to the full level. If the level falls again have a pressure test to see if it reveals a leak.

 

[astjp2]

You probably leaked out some and it will replenish from the reservoir when the engine cools down. If you have any air in the system, you will need to bleed it out.

 

[calvainiac]

If you know the type of antifreeze to add, add to the full level. If the level falls again have a pressure test to see if it reveals a leak.

I've filled it up and drove about 30 highway miles today and it seems alright. Is there a tool to do a pressure test?

 

[JEEPCJTJ]

There is a tool but I'm not familiar with it.

Since you filled it up and seemed to have no problems today I'd just check it the next few days and not even consider that tool until some of it is missing again. Maybe never, if lucky.

 

[calvainiac]

There is a tool but I'm not familiar with it.

Since you filled it up and seemed to have no problems today I'd just check it the next few days and not even consider that tool until some of it is missing again. Maybe never, if lucky.

Yeah I'm hoping it'll just go away haha.

 

[duncanator]

My 2001 has been experiencing the same issue, even after replacing the cap, radiator, water pump, upper and lower hoses. I even sent an oil sample off to get tested but my results came back clean with no coolant in the oil. Also, there is no sign of a heater core issue so about the only thing I have left is the reservoir and hose going to it. I think I got out all the air, but who knows! If the reservoir doesn't fix it, I'll take it to get tested.

It's very frustrating, but I feel much better knowing is not going into my engine.

 

[calvainiac]

My 2001 has been experiencing the same issue, even after replacing the cap, radiator, water pump, upper and lower hoses. I even sent an oil sample off to get tested but my results came back clean with no coolant in the oil. Also, there is no sign of a heater core issue so about the only thing I have left is the reservoir and hose going to it. I think I got out all the air, but who knows! If the reservoir doesn't fix it, I'll take it to get tested.

It's very frustrating, but I feel much better knowing is not going into my engine.

So your losing coolant level as well but it isn't going into the engine?

 

[duncanator]

That is correct. I have no idea where it's going!

 

[pagrey]

Buy a new radiator cap. They are a few bucks. It's good insurance and can cause your system to slowly boil out coolant.

 

[Halfstock]

I had a similar issue on my TJ 4.0. Turned out to be the hose from the radiator to the coolant recovery tank. The 21 year old hose was rotten, and leaking at the connection to the radiator at the filler neck. $1.83 worth of new hose, and a hose clamp cured the issue!

 

[calvainiac]

That is correct. I have no idea where it's going!

Well can you let know when you find out haha. I bet I have a similar problem.

 

[Flivver250]

One component in the cooling system that is often overlooked is the fan clutch. Don't be afraid to replace it. All your hoses should be replaced routinely as maintenance items. Every 5-7 years? While you are at it, don't be afraid to replace the belt, idler and tensioner. Coolant leaks are easy to find, keep looking.

https://www.amazon.com/dp/B0002SRGWU/?tag=wranglerorg-20

 

[jeepins]

I have the HF pressure kit.. used a coupon and sale and ended up getting it for around $65 but has already served me well twice on my Jeep and F150 in situations like this. Sometimes you can have leaks that you never see as the system gets heated, pressurized and leaks out as you're blazing down the highway.

 

[Jcraig]

I've filled it up and drove about 30 highway miles today and it seems alright. Is there a tool to do a pressure test?

Not sure how or what tool is employed for the test. Had the local garage do mine. If you're not having a problem, diminished fluid level, antifreeze smell, or an obvious leak maybe you should just wait and see. If it ain't broken.......

 

[MutantNinjaTJ]

A cracked head or a bad head gasket will let coolant into the cylinders and is burned up and exhausted as steam. If it's not leaking, or ending up in your oil which would be milkey looking, then it's getting into one of the cylinders.

 

[bobthetj03]

Another place to look is the bottom of the radiator where the lower plastic tank is crimped to the core. Coolant can pool up in that crimped galley and burn off as it gets hot. Look for evidence of dried coolant on steering components as the fan could likely blow some of that coolant around.

 

[Fakahatchee]

Another place to look is the bottom of the radiator where the lower plastic tank is crimped to the core. Coolant can pool up in that crimped galley and burn off as it gets hot. Look for evidence of dried coolant on steering components as the fan could likely blow some of that coolant around.

 

[Fakahatchee]

My 2001 was slowly loosing coolant because of a cracked head, my oil was fine it was leaking into the cylinder and being burnt off. Replaced with a new Clearwater head.