Coolant loss, bubbling coolant

Hi All,

Here's a good one. Bought used Jeep 2000 wrangler with 4L. Over the
past few years replaced radiator, thermostat, water pump. Now I have a
mysterious coolant loss. No visible leaks. Did compression test (not
leak down). All cyclinders are 185 +- 10 psi.

What I noticed is that if I take the rad cap off and start the
engine...as it warms up the coolant starts to rise out of the top.
When I rev up the motor the coolant goes down and does not over flow.
However if I then release the throttle the coolant rises and over
flows. I then watched more closely at it looks like there are bubbles
that come up ver so often.

This to me is pointing to a bad head gasket or head.

What are your thoughts? Any other things to try before I pull the head
off and spend the $250 for all the gaskets?

Help!

Loren

If you pull the plugs and look at them, a plug that has seen coolant
will be super clean.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

wrote:
>
> Hi All,
>
> Here's a good one. Bought used Jeep 2000 wrangler with 4L. Over the
> past few years replaced radiator, thermostat, water pump. Now I have a
> mysterious coolant loss. No visible leaks. Did compression test (not
> leak down). All cyclinders are 185 +- 10 psi.
>
> What I noticed is that if I take the rad cap off and start the
> engine...as it warms up the coolant starts to rise out of the top.
> When I rev up the motor the coolant goes down and does not over flow.
> However if I then release the throttle the coolant rises and over
> flows. I then watched more closely at it looks like there are bubbles
> that come up ver so often.
>
> This to me is pointing to a bad head gasket or head.
>
> What are your thoughts? Any other things to try before I pull the head
> off and spend the $250 for all the gaskets?
>
> Help!
>
> Loren

Thanks Mike,

I pulled all the plugs and they all looked clean. I replaced them
around a month ago. One of the plugs had more carbon on the outer rim
then the others but not a noticeable difference on the electrodes.


Mike Romain wrote:
> If you pull the plugs and look at them, a plug that has seen coolant
> will be super clean.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)
>
> wrote:
> >
> > Hi All,
> >
> > Here's a good one. Bought used Jeep 2000 wrangler with 4L. Over the
> > past few years replaced radiator, thermostat, water pump. Now I have a
> > mysterious coolant loss. No visible leaks. Did compression test (not
> > leak down). All cyclinders are 185 +- 10 psi.
> >
> > What I noticed is that if I take the rad cap off and start the
> > engine...as it warms up the coolant starts to rise out of the top.
> > When I rev up the motor the coolant goes down and does not over flow.
> > However if I then release the throttle the coolant rises and over
> > flows. I then watched more closely at it looks like there are bubbles
> > that come up ver so often.
> >
> > This to me is pointing to a bad head gasket or head.
> >
> > What are your thoughts? Any other things to try before I pull the head
> > off and spend the $250 for all the gaskets?
> >
> > Help!
> >
> > Loren

I mean a leak into a cylinder will make the plug look clean like new.

You can have leaks into the exhaust. Usually you can actually see smoke
coming out the rad or smell it when that happens. You also might be
able to feel puffs of compression if you put your hand over the rad
opening when it is first going.

I had a head gasket go like that an the coolant foamed up like a wash
machine with dish soap in it. Here is a photo:
http://www.imagestation.com/album/pi...?id=4290636987

Mike

bbb wrote:
>
> Thanks Mike,
>
> I pulled all the plugs and they all looked clean. I replaced them
> around a month ago. One of the plugs had more carbon on the outer rim
> then the others but not a noticeable difference on the electrodes.
>
> Mike Romain wrote:
> > If you pull the plugs and look at them, a plug that has seen coolant
> > will be super clean.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> > Canadian Off Road Trips Photos: Non members can still view!
> > Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> > (More Off Road album links at bottom of the view page)
> >
> > wrote:
> > >
> > > Hi All,
> > >
> > > Here's a good one. Bought used Jeep 2000 wrangler with 4L. Over the
> > > past few years replaced radiator, thermostat, water pump. Now I have a
> > > mysterious coolant loss. No visible leaks. Did compression test (not
> > > leak down). All cyclinders are 185 +- 10 psi.
> > >
> > > What I noticed is that if I take the rad cap off and start the
> > > engine...as it warms up the coolant starts to rise out of the top.
> > > When I rev up the motor the coolant goes down and does not over flow.
> > > However if I then release the throttle the coolant rises and over
> > > flows. I then watched more closely at it looks like there are bubbles
> > > that come up ver so often.
> > >
> > > This to me is pointing to a bad head gasket or head.
> > >
> > > What are your thoughts? Any other things to try before I pull the head
> > > off and spend the $250 for all the gaskets?
> > >
> > > Help!
> > >
> > > Loren

did pass the time by typing:
> Hi All,
>
> Here's a good one. Bought used Jeep 2000 wrangler with 4L. Over the
> past few years replaced radiator, thermostat, water pump. Now I have a
> mysterious coolant loss. No visible leaks. Did compression test (not
> leak down). All cyclinders are 185 +- 10 psi.
>
> What I noticed is that if I take the rad cap off and start the
> engine...as it warms up the coolant starts to rise out of the top.
> When I rev up the motor the coolant goes down and does not over flow.
> However if I then release the throttle the coolant rises and over
> flows. I then watched more closely at it looks like there are bubbles
> that come up ver so often.
>
> This to me is pointing to a bad head gasket or head.


Gonna give you another thing to look at. Especially if you
don't have water in the oil or a grey cloud following you,
I'd suspect a leak in the overflow system.

The coolant system in your jeep is a closed/airless system. i.e. the
coolant should be even with the radiator cap when you take the cap off
a cold radiator. The overflow bottle should have a low and high mark.
With the engine cold the coolant should be about in the middle or just
a bit below the high mark.

What can happen is a crack in the overflow bottle or in the hose that
runs to it. As you drive the expansion drives some coolant out and it
dribbles down on the road. When the engine cools down air (rather
than coolant) gets sucked back into the system.

As air gets into the system this problem gets progressively worse.

You check the overflow bottle by filling it up. and looking for leaks
Generally what ever is remaining indicates where the crack is. The
hose is just a matter of looking.


--
DougW

Thanks for the great ideas. The coolant is not bubbling like the
picture. It is more like a burp.

I will double check the over flow bottle and hose. I can go through a
liter of coolant in around 1.5 weeks.

There definately are no visible leaks on the over flow...what I mean is
nothing is leaking on the ground.


DougW wrote:
> did pass the time by typing:
> > Hi All,
> >
> > Here's a good one. Bought used Jeep 2000 wrangler with 4L. Over the
> > past few years replaced radiator, thermostat, water pump. Now I have a
> > mysterious coolant loss. No visible leaks. Did compression test (not
> > leak down). All cyclinders are 185 +- 10 psi.
> >
> > What I noticed is that if I take the rad cap off and start the
> > engine...as it warms up the coolant starts to rise out of the top.
> > When I rev up the motor the coolant goes down and does not over flow.
> > However if I then release the throttle the coolant rises and over
> > flows. I then watched more closely at it looks like there are bubbles
> > that come up ver so often.
> >
> > This to me is pointing to a bad head gasket or head.
>
>
> Gonna give you another thing to look at. Especially if you
> don't have water in the oil or a grey cloud following you,
> I'd suspect a leak in the overflow system.
>
> The coolant system in your jeep is a closed/airless system. i.e. the
> coolant should be even with the radiator cap when you take the cap off
> a cold radiator. The overflow bottle should have a low and high mark.
> With the engine cold the coolant should be about in the middle or just
> a bit below the high mark.
>
> What can happen is a crack in the overflow bottle or in the hose that
> runs to it. As you drive the expansion drives some coolant out and it
> dribbles down on the road. When the engine cools down air (rather
> than coolant) gets sucked back into the system.
>
> As air gets into the system this problem gets progressively worse.
>
> You check the overflow bottle by filling it up. and looking for leaks
> Generally what ever is remaining indicates where the crack is. The
> hose is just a matter of looking.
>
>
> --
> DougW

Just checked the coolant bottle and hose. There are no visible leaks.
I took them off, filled with water, pluged the hose and upper outlet
and blew in the top. Nothing came out.

Any other ideas? I'm looking for all options before I take the head
off.



bbb wrote:
> Thanks for the great ideas. The coolant is not bubbling like the
> picture. It is more like a burp.
>
> I will double check the over flow bottle and hose. I can go through a
> liter of coolant in around 1.5 weeks.
>
> There definately are no visible leaks on the over flow...what I mean is
> nothing is leaking on the ground.
>
>
> DougW wrote:
> > did pass the time by typing:
> > > Hi All,
> > >
> > > Here's a good one. Bought used Jeep 2000 wrangler with 4L. Over the
> > > past few years replaced radiator, thermostat, water pump. Now I have a
> > > mysterious coolant loss. No visible leaks. Did compression test (not
> > > leak down). All cyclinders are 185 +- 10 psi.
> > >
> > > What I noticed is that if I take the rad cap off and start the
> > > engine...as it warms up the coolant starts to rise out of the top.
> > > When I rev up the motor the coolant goes down and does not over flow.
> > > However if I then release the throttle the coolant rises and over
> > > flows. I then watched more closely at it looks like there are bubbles
> > > that come up ver so often.
> > >
> > > This to me is pointing to a bad head gasket or head.
> >
> >
> > Gonna give you another thing to look at. Especially if you
> > don't have water in the oil or a grey cloud following you,
> > I'd suspect a leak in the overflow system.
> >
> > The coolant system in your jeep is a closed/airless system. i.e. the
> > coolant should be even with the radiator cap when you take the cap off
> > a cold radiator. The overflow bottle should have a low and high mark.
> > With the engine cold the coolant should be about in the middle or just
> > a bit below the high mark.
> >
> > What can happen is a crack in the overflow bottle or in the hose that
> > runs to it. As you drive the expansion drives some coolant out and it
> > dribbles down on the road. When the engine cools down air (rather
> > than coolant) gets sucked back into the system.
> >
> > As air gets into the system this problem gets progressively worse.
> >
> > You check the overflow bottle by filling it up. and looking for leaks
> > Generally what ever is remaining indicates where the crack is. The
> > hose is just a matter of looking.
> >
> >
> > --
> > DougW

bbb did pass the time by typing:
> Just checked the coolant bottle and hose. There are no visible leaks.
> I took them off, filled with water, pluged the hose and upper outlet
> and blew in the top. Nothing came out.
>
> Any other ideas? I'm looking for all options before I take the head
> off.

Possibly a teeny leak in one of the hoses that's only spraying when
the system is under pressure?

--
DougW

DougW wrote:
>
> bbb did pass the time by typing:
> > Just checked the coolant bottle and hose. There are no visible leaks.
> > I took them off, filled with water, pluged the hose and upper outlet
> > and blew in the top. Nothing came out.
> >
> > Any other ideas? I'm looking for all options before I take the head
> > off.
>
> Possibly a teeny leak in one of the hoses that's only spraying when
> the system is under pressure?
>
> --
> DougW

I had one like that too. I was losing coolant but could never figure
out where until I noticed my battery was 'wet' one day. It was a
pinhole in a core that finally got big enough to make it to the battery
on the firewall. Before that it was just spraying on the ground under
acceleration when the pressure was highest.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

"Mike Romain" > wrote in message
...
> DougW wrote:
>>
>> bbb did pass the time by typing:
>> > Just checked the coolant bottle and hose. There are no visible leaks.
>> > I took them off, filled with water, pluged the hose and upper outlet
>> > and blew in the top. Nothing came out.
>> >
>> > Any other ideas? I'm looking for all options before I take the head
>> > off.
>>
>> Possibly a teeny leak in one of the hoses that's only spraying when
>> the system is under pressure?
>>
>> --
>> DougW
>
> I had one like that too. I was losing coolant but could never figure
> out where until I noticed my battery was 'wet' one day. It was a
> pinhole in a core that finally got big enough to make it to the battery
> on the firewall. Before that it was just spraying on the ground under
> acceleration when the pressure was highest.
>
> Mike

I had one too on a Chevy truck. Got so frustrating that I took it to my
buddies shop where he specializes in cooling systems and AC. The thing would
hold pressure with a pressure tester, and he even put the UV dye in the
coolant, but still nothing. Only after letting it run for about 2 hours did
it start to leak. It sprayed a stream about the same size as a piece of
thread from the upper hose.

Chris