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  #1  
Old 09-15-2010, 03:16 PM
zeke's Avatar
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Location: The Alamo City, TEXAS
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Help me find where my coolant is going

Wifey overheated the wagon today. No damage apparent, once it cooled it started and ran fine, but was down almost 2 gal. of coolant. It's not coming out of the tail pipe, it's not in the crankcase. Radiator looks good - no rust or anything else. No leaks in any hoses that I can see.

The only thing is that occasionally, it benches alot of coolant out of the overflow tube from the tank.

It had done this several times over the past few months, including last night.

What is the problem here?

Thanks!
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1979 maple yellow 240D 4-speed


Gone and fondly remembered:
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Gone and NOT fondly remembered:
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  #2  
Old 09-15-2010, 03:35 PM
benhogan's Avatar
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you have a blown head gasket.

the coolant is getting into the oil and the oil is getting into the coolant (hence oil in the overflow tank).

you can do a compression test to be sure.
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  #3  
Old 09-15-2010, 03:36 PM
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I suspect blown head gasket.

If the car was badly overheated and then cold water pouring in without a cool down, then maybe a cracked head.
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  #4  
Old 09-15-2010, 03:40 PM
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There is no oil in the coolant, and no coolant in the oil....

The belching coolant does happen during cooldown, though. I suppose it could also be happening under load, but I wouldn't see it from inside the cabin.
__________________

Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #5  
Old 09-15-2010, 11:02 PM
vstech's Avatar
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Location: Mount Holly, NC
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I hesitate to mention it... but have you checked your transmission fluid? hope it's not pink...
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #6  
Old 09-15-2010, 11:07 PM
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Quote:
Originally Posted by zeke View Post
There is no oil in the coolant, and no coolant in the oil....

The belching coolant does happen during cooldown, though. I suppose it could also be happening under load, but I wouldn't see it from inside the cabin.
The first thing to check is the coolant tank cap, that determines the pressure at which coolant exits the overflow. If that is not sealing correctly or not in spec it will allow overflow at less than designed pressures.
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  #7  
Old 09-15-2010, 11:13 PM
vstech's Avatar
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yeah, and I added a belch capture tank to my SD... I don't like dumping that wonderful G05~~~ on the ground!
look closely at your cap! the rubber can be perfect and the rest of the cap totally useless! I've got a thread on here with closeup pics of my shattered cap. blew my mind!
I found it!
OK silly question I think...should the hose build any pressure?
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #8  
Old 09-16-2010, 01:35 AM
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VStech, I always look forward to your comments on my threads b/c you always come up with something thought provoking....

I did go out and check the tranny fluid...i looks ok...red and clear compared to the pictures I found on the internet of pink milkshake. Feels oily (not watery) and smells pretty good - not like new, but not bad or burnt. I changed it and the filter in June.

Sooo, I checked my rad cap, and the shim part looks good, but I noticed some little warped looking bits on the rubber part on the end that points down into the tank, VERY gently picked at it and the whole rubber piece came apart - also the rubber just disintegrated onto my fingers as I touched it, so it was clearly compromised....So maybe that's it.

I will start with the rad cap and go from there. Hopefully as Billybob says coolant was moving through the seal at lower pressures that it should...
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Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #9  
Old 09-16-2010, 03:38 AM
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Quote:
Originally Posted by Beagle View Post
This looks to me like a classic case of your cooling system not being properly bled.
The 617 turbo engine is self-bleeding.
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  #10  
Old 09-16-2010, 03:44 AM
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r
Quote:
Originally Posted by zeke View Post
it benches a lot of coolant out of the overflow tube from the tank.

It had done this several times over the past few months,
This looks to me like a classic case of your cooling system not being properly bled. Isolated pockets of air in the cyl.head/block water jacket can cause very localized boiling that can blow half your coolant out in a matter of seconds, even before engine is fully warmed up. I was once following one of these cars and saw it happen - I managed to stop him!
Quote:
Originally Posted by zeke View Post
The belching coolant does happen during cool down, though.
And this would seem to confirm it. Engine temp can be 10 to 20 deg above coolant - enough to boil locally after switch off.

I have found that the best way to fill the system is to get the front aised on an incline at least 20 up. Half fill it and top up with the engine idling and the bleed plug (on thermostat housing) removed until all air is out.
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  #11  
Old 09-16-2010, 12:43 PM
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While they system may be self bleeding, it's not self burping! When you refill the cooling system, burp it along the way.
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  #12  
Old 09-16-2010, 02:28 PM
zeke's Avatar
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I will replace the rad cap AND burp the baby tonight!

:p
__________________

Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #13  
Old 09-16-2010, 02:57 PM
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Quote:
Originally Posted by zeke View Post
I will replace the rad cap AND burp the baby tonight!

:p
You would be wise to do one or the other seperately, that way you can note if one addresses the problem condition or the other to better ascertain the root of the problem, if you can.
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  #14  
Old 09-16-2010, 06:41 PM
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Quote:
Originally Posted by Billybob View Post
You would be wise to do one or the other seperately, that way you can note if one addresses the problem condition or the other to better ascertain the root of the problem, if you can.
Good call billybob..will start with cap.since I know it is broken
__________________

Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #15  
Old 09-16-2010, 06:57 PM
winmutt's Avatar
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With the heat on do you smell coolant?
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