Coolant level dropping

[yippee]

Hello all,

Performed a little engine work on the Liberty today, after finishing it up I started the Liberty and let it run for a little bit to see how it ran after the work. I let it run and idle a little bit to get warmed up, while standing looking into the engine bay I decided to open the throttle body slightly to allow the engine to run at a higher RPM as if it were driving at regular road speeds.

When I revved the engine up I noticed the level in the reservoir on the firewall dropped. When you let off the throttle and let it drop back to idle it goes back up to normal levels. Is this normal or a sign of something wrong? I'm not used to this style coolant system, my other two vehicles have a radiator with a cap and then overflow boxes - I've never noticed the same thing from them.

I'm hoping it's normal for this type of setup, but fear it may be something more. I just want to check with everyone to see if it is normal, and if not where to go from here.

Thanks in advance.

 

[tjkj2002]

Normal.

 

[LibertyTC]

Still check the coolant level after sitting all night, & make sure it is at the cold line for a few days. Otherwise top it up to the cold line then.
What engine work did you do?

 

[RenKJ]

When you rev the engine the water pump is sucking more fluid and pressurize the water jackets in the engine, when you let off the pressure equalized and eztra fluid comes back to the reservoir

Sent from my A0001 using Tapatalk

 

[yippee]

Great news! I was hoping that was something normal. I've never had a system setup exactly like this, so I've never noticed this issue. I'll check the levels in the morning after it has sat all night to make sure they're still where they're supposed to be. Outside of that, I suppose I won't worry about it.

I wouldn't really say engine work per say, and probably overstated it the first time. I had a spark plug hole that had some threads that were a little wonky. I chased the threads and cleaned them up and installed a new spark plug in that hole. I mostly just meant I had been working in the engine bay, nothing exciting.

 

[yippee]

Checked the coolant level this morning after she sat all night, before starting her up for the day. Under cool conditions the coolant level was right on the mark.

 

[uss2defiant]

wait till it cools overnight or wait a few hours then crack the overflow cap open to let the pressure out.

 

[yippee]

wait till it cools overnight or wait a few hours then crack the overflow cap open to let the pressure out.

I let the Jeep sit over night, and in the morning before I started it I opened the overflow cap to vent any pressure that might be in there. I didn't notice any pressure being released from this procedure, is this a bad thing?

 

[uss2defiant]

i don't think it's an issue.
There will be less pressure when it cools off so maybe you didn't noticed the slight pressure.

 

[HoosierJeeper]

Yeah there will be very little pressure if it's been sitting for awhile, you're good.

 

[yippee]

I drove the Jeep this morning and parked it once I got back home. I let the Jeep sit probably 2.5 hours after returning home. I got under the hood to check the fluids, etc. and decided to crack the coolant reservoir cap to release the pressure. This time I did notice some pressure spew out upon removing the cap. What does this procedure do exactly?

 

[HoosierJeeper]

It just means that it's working as it should...you have pressure. Which is good.

 

[uss2defiant]

if you're unsure if you have a leak, you can pick up a pressure tool from your LAPS loaner program.