Overflow bubbling/gurgling after shutdown

[pikapp504]

Ok, I've been having an on-going issue w/ coolant disappearing. Yes, I have a 2000 w/ the 0331 head, however I highly doubt it's cracked. Reason being: there are no visual signs of a crack when I look through the oil cap hole and the oil is still light brown in color and NOT milky. Here's what's happening: some weeks I'll drive every day and no change in coolant level in the overflow. Other weeks, I'll drive 2 days then notice it's 2" below the FULL mark. I'll top it back off and carry on about my business. After a long drive (couple hours or so) or even some shorter drives (few miles), after I shut it off, I can hear the overflow bubbling for a few seconds. Recently, after a long drive, it bubbled a little, then started bubbling a LOT. Again, I don't have any coolant leaks and the oil is still clean, but the loss of coolant is just making me "nervous" (i.e. I'm the type that worries about little stuff too much....trying to fix that. LOL). I've replaced the radiator cap a few times...maybe I just keep getting bad caps? A few months ago I did a full flush and replaced my water pump and the coolant is now clean and has stayed that way. Maybe I should try another cap? The radiator is only about a year old, ZJ fan clutch is about a year old, water pump is a couple months old, upper and lower hoses have been replaced (same time as water pump), and the thermostat is about a year old (replaced when radiator was replaced). I don't overheat while driving and if it ever does get up to 217*, the aux fan kicks on and it cools back down.

Any suggestions or is this "normal"?

[steph74]

overflow bottle cap or radiator cap.... this is the only thing that comes to my non expert mind ;)...
in the open system, i believe that it is important for the radiator cap to be able to keep pressure very precisely... I remember seeing a radiator for dummy explanation one day ;)

I would certainly start with exploring toward that direction... the radiator cap may look OK but I would just change to see... (get one at Autozone or other and try it... if it doesn;t solve the problem, just bring it back ;))


((and I just reread your post especially where you say that you have already tried to change the radiator cap lol... figured I would leave my comment nonetheless ;) )

[msmoorenburg]

Call a few shops in your area and see if they can do a block test. I would never rule out the head or headgasket. I have clean oil and clean antifreeze and I do have a blown headgasket. I had a buddy that has a block tester (looks for exaust gasses in the cooling system) check the link below

http://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm

[prerunner1982]

I am not sure that I would be worried about the bubbling sound too much. As hot as these things run when you turn it off the coolant is not longer flowing and the heat builds up a bit. I have had a couple vehicles that would do this and they had no issues. As long as it is not over heating and you do not see any leaks I think you are ok here..

As far as losing coolant, it just may not be making it into the coolant. Perhaps it is leaking into the cylinder and exiting the exhaust system. After a good drive you might check the exhaust and see if it smells sweet at all.

[pikapp504]

The last time the radiator was replaced, they pressurized the system and it held no problem (no leaks) and it was doing it then too. I'll see about getting the exhaust gas test and see if I have a bad headgasket. I don't see anything burning out the exhaust (i.e. no smoke), idles perfectly and the only issues I currently have are an oil leak (damn valve cover gasket) and the "houdini"/gurgling coolant after shutdown. When it's running, there are ZERO bubbles...only when I shut it off.

[prerunner1982]

When it is running the coolant is flowing so you wouldn't be able to hear the gurgling... and when it is flowing the coolant stays cooler.

[pikapp504]

I've gotten it nice and hot (up to temp) and then gotten out and watched the overflow and there are no bubbles...even when revved up.

[prerunner1982]

I've gotten it nice and hot (up to temp) and then gotten out and watched the overflow and there are no bubbles...even when revved up.

Was this while the engine is running? If so then you probably won't see/hear any bubbles as they are flowing through the engine/cooling system. It is not until you turn off the vehicle that the coolant stops moving and you can hear it bubble/boil.

[pikapp504]

In my original post, I was referring to hearing/seeing it bubble into the overflow tank, no where else...sorry, I should've been more specific. I only see/hear it in the overflow and only after it's been run for a little bit. While running, it's smooth as silk.

[prerunner1982]

In my original post, I was referring to hearing/seeing it bubble into the overflow tank, no where else...

Probably my mistake... I am at work and probably did not read your post as thorough as I should have. Disregard anything I said.. :fail:

[pikapp504]

No no, it's cool, and I do appreciate any/all suggestions. Just trying to get to the bottom of everything so I can stop worrying too damn much. LOL

[prcjeep]

while i was having this issue, someone recommended removing and checking the spark plugs, from what I remember, if any of the plus tips are cleaner than the others or look much whiter, then that signals that the water is leaking into the combustion chamber and exiting through the exhuast system

[Mudderoy]

Ok, I've been having an on-going issue w/ coolant disappearing. Yes, I have a 2000 w/ the 0331 head, however I highly doubt it's cracked. Reason being: there are no visual signs of a crack when I look through the oil cap hole and the oil is still light brown in color and NOT milky. Here's what's happening: some weeks I'll drive every day and no change in coolant level in the overflow. Other weeks, I'll drive 2 days then notice it's 2" below the FULL mark. I'll top it back off and carry on about my business. After a long drive (couple hours or so) or even some shorter drives (few miles), after I shut it off, I can hear the overflow bubbling for a few seconds. Recently, after a long drive, it bubbled a little, then started bubbling a LOT. Again, I don't have any coolant leaks and the oil is still clean, but the loss of coolant is just making me "nervous" (i.e. I'm the type that worries about little stuff too much....trying to fix that. LOL). I've replaced the radiator cap a few times...maybe I just keep getting bad caps? A few months ago I did a full flush and replaced my water pump and the coolant is now clean and has stayed that way. Maybe I should try another cap? The radiator is only about a year old, ZJ fan clutch is about a year old, water pump is a couple months old, upper and lower hoses have been replaced (same time as water pump), and the thermostat is about a year old (replaced when radiator was replaced). I don't overheat while driving and if it ever does get up to 217*, the aux fan kicks on and it cools back down.

Any suggestions or is this "normal"?

Do the chemical test for exhaust gases in your coolant and then you'll know for sure if that is, or is not the problem.

http://youtu.be/xwba3iOHuac

[jccatt]

To check for blown head gasket we used to run truck up to temp with radiator cap off and you can see any bubbles easy. Yes the spark plug test is also a good one. My friends car has no milky oil but a wet plug, blown head gasket or cracket head. It also runs a bit ruff on start up for a second or so. Thats a reputable mechanics diagnosis.

Good luck

[Mudderoy]

To check for blown head gasket we used to run truck up to temp with radiator cap off and you can see any bubbles easy. Yes the spark plug test is also a good one. My friends car has no milky oil but a wet plug, blown head gasket or cracket head. It also runs a bit ruff on start up for a second or so. Thats a reputable mechanics diagnosis.

Good luck

The 99 was doing a lot of bubbles for a few days. It stopped. I ran the chemical test on it weeks later and no sign of head leak.

My 98 ran rough for the first few seconds for months. I replaced the fuel pump, regulator, filter combo this past weekend. No more rough running for the first few seconds. The 98 tested positive for a head leak, but it doesn't show any signs of it except running hot on the highway. Spark plugs look normal, no milky oil and no chocolate in my peanut butter. (old commercial)

My point? Do the chemical test to see if you have exhaust gases in your coolant.

[pikapp504]

Ok, new development. I checked it last night while it was running, and I noticed some bubbles :FML: So it's now bubbling while running and when it's off for a minute or 2. Now, with that being said, I did a little test this morning: popped the hood while it was running, noticed bubbles in the overflow tank, tapped on the radiator cap, and it bubbled even more. If I juggled the cap (well, more like tried to jiggle it..it's on pretty tight), it bubbles even more. I'm starting to think it's just a bad cap. Concur/Disagree?

[Mudderoy]

Ok, new development. I checked it last night while it was running, and I noticed some bubbles :FML: So it's now bubbling while running and when it's off for a minute or 2. Now, with that being said, I did a little test this morning: popped the hood while it was running, noticed bubbles in the overflow tank, tapped on the radiator cap, and it bubbled even more. If I juggled the cap (well, more like tried to jiggle it..it's on pretty tight), it bubbles even more. I'm starting to think it's just a bad cap. Concur/Disagree?

I had the host that runs to the over flow crack and break at the radiator neck. I don't recall any symptoms I just noticed it was broken. This was the bottom of the rubber hose.

[pikapp504]

I even tried jiggling the hose a bit....little/no change.

[Mudderoy]

I even tried jiggling the hose a bit....little/no change.

I think you have more than pressure than the radiator cap can hold back. When you jiggle it you are changing the seal and you get more or less bubbles.

You may have air in your system. It took several days for my 99 to stop bubbling after the lower hose split.

[pikapp504]

I last flushed my system about 2 months ago when I replaced the water pump. It took a few days for it to even out, but the bubbles while running only recently reappeared. I'm thinking more air in the system due to the "bad" cap and even if it bubbles, it's still "cycling" air. It never overheats, I have great heat, oil isn't discolored, coolant isn't discolored, no loss in power, no smoke...

[pikapp504]

Drove home last night from work, stopped to get a new cap, got home, popped the hood...NO BUBBLING/GURGLING! WTF?!?! Didn't even do it when I tapped on the cap or when I shut it off. I'm baffled!!!! It's like a totally random issue....

[Mudderoy]

Drove home last night from work, stopped to get a new cap, got home, popped the hood...NO BUBBLING/GURGLING! WTF?!?! Didn't even do it when I tapped on the cap or when I shut it off. I'm baffled!!!! It's like a totally random issue....

It's taunting you... :popcorn:

[pikapp504]

Yes...and I'm about to BIWP! LOL I bought a new cap, so I'll probably swap that out tonight after it cools down anyway...cheap insurance. :-) But, if it's not doing it anymore, I may leave it alone...

[pikapp504]

Swapped in a new Stant cap...still no change. No overheating, no leaks, oil is clean (no milkshake), coolant is clean (no oily residue), no white/blue smoke, runs great. I don't get it!?!?!?! Any other suggestions other than the block test?

[pikapp504]

Ok, I think I have a faulty radiator. I've narrowed it down to the radiator cap. When I got home from work today, I took a look while it was running. No bubbles...so I tapped the radiator cap, heard a "gurgle" then started to see little bubbles start to come up in the overflow tank about 1-2 bubbles every second. Only thing I can think of is that the radiator fill cap area isn't "flat" or flush...