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Tiny Bubbles in my coolant...98 Caravan 3.8 V-6


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jj94auto
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Jun 21, 2012, 10:20 PM

Post #1 of 19 (1972 views)
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Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 Sign In

Hello everyone...

The vehicle is a 1998 Dodge Caravan with a 3.8 V-6 AWD with 135k miles.

I bought the car about a year ago and noticed a neverending stream of small bubbles in the coolant. I noticed that the rear head was cracked and covered with something that looked like JB Weld. The JB Weld had failed and you could see the coolant oozing around it but not really coming out. After removing the head, I could see that the crack was from the inside to the outside of one of the water jackets.

I replaced the rear cylinder head with a remanufactured one and put a new head gasket in. To my dissapointment, this did not fix the problem.

Other Symptoms:

No overheating, no coolant in the oil, no oil in the coolant, No smell of coolant from the exhaust, no visible leaks.

I have done the following:
  • Replaced the radiator with a new one
  • Replaced the rear cylinder head with a new one and a new head gasket.
  • New Water Pump
  • Input 100 psi of compressed air using a leakdown adapter into each cylinder. Moved each cylinder to TDC to test. This yielded no bubbles in the radiator.
  • Bypassed the water pump by pulling the serpentine belt. This yielded no bubbles and convinced me to put a new water pump in which didn't fix the problem
  • Input compressed air to the radiator overflow hose to the radiator. (Both new radiator caps I purchased leaked like crazy so I had to hold the radiator cap down to listen for leaks...didn't hear any though.
  • Ran the vehicle with the heater on and radiator cap off for an hour to see if the bubbles would go away.
  • Ran the vehicle for weeks to see if the bubbles would go away.

I have also removed the thermostat to see when the bubbling starts and it starts immediately after turning it on even if the vehicle is cold. The bubbles NEVER stop so I don't believe it is trapped air.

I have 2 mechanics that I have known for a long time telling me that this nothing to worry about.

I am worried about it, my wife drives the vehicle with my kids on it and we plan to take 2000 mile round trip road trips since it is a nice vehicle in every other way.

I don't know what else to do. Please help.

Thank you!


(This post was edited by jj94auto on Jun 21, 2012, 10:35 PM)


Hammer Time
Ultimate Carjunky / Moderator


Jun 21, 2012, 10:28 PM

Post #2 of 19 (1963 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In


Quote
No overheating, no coolant in the oil, no oil in the coolant, No smell of coolant from the exhaust, no visible leaks.


Then why do you think you have a problem?
Are you losing coolant over time?




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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jj94auto
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Jun 21, 2012, 10:34 PM

Post #3 of 19 (1958 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

To be honest, the level is not a condition that I have monitored closely so I can't give you an honest answer. I do BELIEVE that if I run it for a few days, the radiator level drops down by about an inch but was wondering whether or not that would taper off. I was going to post that information but didn't want to because I wasn't sure. Sorry about that. I paid alot more attention to the bubbles themselves.

I also own 4 other vehicles and none of them act like this. The bubbles go away on their own after running the vehicle without the radiator cap. I am afraid these little bubbles are hot spots that cracked the head in the first place.


(This post was edited by jj94auto on Jun 21, 2012, 10:42 PM)


Discretesignals
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Jun 21, 2012, 11:51 PM

Post #4 of 19 (1914 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

You mentioned that the bubbles went away when you took the serpentine belt off and ran the engine. That should tell you that you don't have combustion gases getting into the coolant system.

Have you tried pressure testing the coolant system?

Wondering if your getting air into the suction side of the water pump from somewhere. Seen that happen on a few power steering systems when air gets sucked into the return side of the system from cracks in a return hose or loose clamp on a return hose.

You really don't want air getting into the coolant system, because that will create air pockets and cause hot spots and possible overheating.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jun 21, 2012, 11:56 PM)


Hammer Time
Ultimate Carjunky / Moderator


Jun 22, 2012, 6:07 AM

Post #5 of 19 (1881 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

You don't seem to have any symptom that should cause concern. The bubbles alone don't really mean much unless they are causing other issues which they don't seem to be. You may just have some air trapped in the system that will eventually work out but pressure test it anyway to find out if the system is sealed tight.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jj94auto
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Jun 22, 2012, 10:03 AM

Post #6 of 19 (1872 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

I pressure tested the cooling system by sending 15 psi with compressed air to the radiator overflow hose after disconnecting the hose from the overflow. I really did have a hard time. Either new radiator cap that I had (autozone/advance auto) caps leaked like crazy with only about 5 psi applied to either. I had to use alot of force to hold the caps down...so much force in fact that I couldn't really get under the vehicle to check for other leaks. My neighbor, (one of the 2 mechanics who says don't worry about it) (now 3 lol) is going to bring his pressure tester from work.

So if I did have combustion gases in the system, would they work their way up to the radiator filler hole without the water pump turning? I wasn't 1000% sure about that.

I too am curious about the suction side of the water pump.

I also believe that I might have made a "mistake" when I put the new head gasket on but not sure if it really was a mistake. The Felpro intake manifold gasket called for some RTV around the 2 coolant ports on the intake manifold as well as the intake manifold.

Since Felpro didn't get it right in other areas (like adding exhaust manifolds to my kit when they weren't required) and did not mention that I needed RTV on the factory intake manifold gaskets, I added no RTV there and left the gasket dry. I believe the factory gasket might had had some embedded sealant around the ports now that I think about it. I'll probably go back down there since things are half way apart and add the RTV.


In Reply To
You mentioned that the bubbles went away when you took the serpentine belt off and ran the engine. That should tell you that you don't have combustion gases getting into the coolant system.

Have you tried pressure testing the coolant system?

Wondering if your getting air into the suction side of the water pump from somewhere. Seen that happen on a few power steering systems when air gets sucked into the return side of the system from cracks in a return hose or loose clamp on a return hose.

You really don't want air getting into the coolant system, because that will create air pockets and cause hot spots and possible overheating.



jj94auto
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Jun 22, 2012, 10:07 AM

Post #7 of 19 (1871 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Thanks, will pressure test it tonight to be sure. Should a successful pressure test eliminate any possibility of air entering the system?


In Reply To
You don't seem to have any symptom that should cause concern. The bubbles alone don't really mean much unless they are causing other issues which they don't seem to be. You may just have some air trapped in the system that will eventually work out but pressure test it anyway to find out if the system is sealed tight.



Hammer Time
Ultimate Carjunky / Moderator


Jun 22, 2012, 10:49 AM

Post #8 of 19 (1866 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In


Quote
I pressure tested the cooling system by sending 15 psi with compressed air to the radiator overflow hose after disconnecting the hose from the overflow.


No, that's not how a pressure test is done. Ive heard of a lot of wild creations, but never that one.




~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jj94auto
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Jun 22, 2012, 11:07 AM

Post #9 of 19 (1858 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Laughing with me or at me? :) lol


In Reply To

Quote
I pressure tested the cooling system by sending 15 psi with compressed air to the radiator overflow hose after disconnecting the hose from the overflow.


No, that's not how a pressure test is done. Ive heard of a lot of wild creations, but never that one.



Tom Greenleaf
Ultimate Carjunky / Moderator


Jun 22, 2012, 12:04 PM

Post #10 of 19 (1852 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Pressure test is done where the pressure cap goes specially made to fit and should test pressure cap also. Don't exceed a cooling system's pressure rating, usually around 15lbs and stated on pressure cap if it's the right one.

Didn't re-read whole thread but tiny bubbles noted could be some air still in there, lousy grade of antifreeze that should not bubble like soapy water, air getting in from where coolant mix is being sucked into water pump and more,

T
_________________________________________
Long retired now


jj94auto
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Jun 22, 2012, 12:44 PM

Post #11 of 19 (1847 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Thanks, the bubbles aren't soapy. They are more like champagne bubbles. Coolant was pretty good grade IMHO, peak blue 50/50. Will pressure test the right way tonight. In the meantime, I am putting down a new IM manifold gasket and RTV for the ports.

Where does a pump suck water in from? I know that is probably model specific but any generalization would help.

I really like this forum...I must admit. Have posted in other places and everyone gave up super fast!






In Reply To
Pressure test is done where the pressure cap goes specially made to fit and should test pressure cap also. Don't exceed a cooling system's pressure rating, usually around 15lbs and stated on pressure cap if it's the right one.

Didn't re-read whole thread but tiny bubbles noted could be some air still in there, lousy grade of antifreeze that should not bubble like soapy water, air getting in from where coolant mix is being sucked into water pump and more,

T



Tom Greenleaf
Ultimate Carjunky / Moderator


Jun 22, 2012, 1:26 PM

Post #12 of 19 (1842 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Champagne bubbles? Didn't think is was making shaving creme! Pressure tester may be rent-able for free. Mine older by Stant Co. and has been old reliable for a long time. It checks caps too which should hold at the rating and spit out excess of the rating.

Peak brand is no generic IMO and does make a variety including clear/no color, concentrate and premixed.

Off the wall if everything else is proper and working fine probably just leave it alone or if bugging you they make defoamer but meant for hot tubs which I've had and shockingly one tablespoon of the dang stuff and it stops the annoying foam they can make. Absolutely untested so don't use that unless you can boil just a bit down in water and see what happens. I'm not fast to nor really suggesting that and if a literal thimbleful of it didn't cut this out fast I wouldn't put more in. If there was a problem with the water if you changed it with tap water that might be it.

Most use plain tap water which varies depending on your source so will suggest distilled water to almost anyone who asks. I can find it for 88 cents a gallon still. The water out of tap that I use has never been a problem but for a couple bucks I'll use only distilled now and three to do this year known ready for a routine change.

Smile/frown - I see this "Life Time" label on some with no changes needed. Hmmm - does that mean I'm not going to live for another change or the cars wont?

Can't verify that claim and suggest changing it on suggested schedule,

T
_________________________________________
Long retired now


Sidom
Veteran / Moderator


Jun 22, 2012, 3:02 PM

Post #13 of 19 (1832 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

One thing you can look at would be the timing cover. It's been a while but I had a few 3.8 where the O rings in the cover would leak coolant.
There are a few O rings in there but if I remember correctly the ones that were leaking for me were on the left side of the engine at the bottom & a little tough to see. Really the only reason I remember those is because when I got the cover off the O ring looked as though it was "sucked in" instead of just being round or blown out......

Those were leaking coolant but may have had a small bubble problem prior.....Honestly those bubble sound like they are pretty small & would be easy to miss if you weren't specifically looking for them....






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jj94auto
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Jun 22, 2012, 4:00 PM

Post #14 of 19 (1819 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Thank you...any need to pull the timing cover to see them?


In Reply To
One thing you can look at would be the timing cover. It's been a while but I had a few 3.8 where the O rings in the cover would leak coolant.
There are a few O rings in there but if I remember correctly the ones that were leaking for me were on the left side of the engine at the bottom & a little tough to see. Really the only reason I remember those is because when I got the cover off the O ring looked as though it was "sucked in" instead of just being round or blown out......

Those were leaking coolant but may have had a small bubble problem prior.....Honestly those bubble sound like they are pretty small & would be easy to miss if you weren't specifically looking for them....



Sidom
Veteran / Moderator


Jun 22, 2012, 4:16 PM

Post #15 of 19 (1814 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

I would want to 1st verify there was a problem before pulling the cover. The ones I had were leaking on the left side by the a/c compressor. I would want to look at the cover to block area and see some coolant corrosion or something that would indicate a leak before pulling the cover. Since yours isn't leaking coolant it may be harder to nail down but I would think there would be some kind of evidence of leak you could see.

I cheated & used a boroscope but you can see it by eye if you twist right & use a flashlight....






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jj94auto
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Jun 22, 2012, 5:27 PM

Post #16 of 19 (1801 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Thank you.


In Reply To
I would want to 1st verify there was a problem before pulling the cover. The ones I had were leaking on the left side by the a/c compressor. I would want to look at the cover to block area and see some coolant corrosion or something that would indicate a leak before pulling the cover. Since yours isn't leaking coolant it may be harder to nail down but I would think there would be some kind of evidence of leak you could see.

I cheated & used a boroscope but you can see it by eye if you twist right & use a flashlight....



jj94auto
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Jun 22, 2012, 5:29 PM

Post #17 of 19 (1800 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Well, I pulled the intake manifold and followed Felpros instructions for RTV on both side of the gasket just to be sure. That wasn't it lol.

Still waiting for the pressure test to come my way tonight and the mightyvac.


jj94auto
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Jun 22, 2012, 8:53 PM

Post #18 of 19 (1780 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

All, the bubbles seem to have gone away....had to have been either 1 of 2 things:

1) Putting RTV around the intake ports and coolant ports for both the head and the top of the valley gasket. Last time I left it dry.

2) Changed my brand of coolant...fresh coolant/water mix now.

It will probably come back with my luck but wanted to share this with you in case it doesn't. I left the cap off and the thermostat was definitely open. Couldn't observe it that way for long because it would have rose over the radiator filler. No bubbles out of the overflow now though (since I had to close the cap). Not even one...let it idle about 30 minutes and no bubbles.

I hate eating my words so I am not confirming anything.


jj94auto
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Jun 23, 2012, 5:53 PM

Post #19 of 19 (1749 views)
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Re: Tiny Bubbles in my coolant...98 Caravan 3.8 V-6 [In reply to] Sign In

Update:

Ran it again until the thermostat opened again. Some large bubbles came out of the overflow. Noticed that one of my new radiator caps was going bad (wasn't sealing the radiator and coolant was trickling past the neck).

Soon bubbles started coming out every 3-5 minutes. The would last about 5 seconds and then stop. That frequency just seems like trapped air at this point.

I think that I can call this fixed. Another thing I replaced was the water pump bypass hose. It was in shoddy shape and ripped when I put things back together. Could that have been the problem or a contributor?

Thank you




Tiny Bubbles in my coolant...98 Caravan 3.8 V-6


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