Coolant problem

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oldmercfan
Pagoda
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Model you own: w114
Location: Adelaide

Coolant problem

Post by oldmercfan » Fri 15 Sep, 2017 9:28 pm

Dear experts, any thoughts on a coolant problem with my M110 engine would be appreciated. Intermittently, I will head off for a drive and within a minute or so it wildly overheats. The radiator is cold, so its clear that water is not circulating. I used to be able to fix this by loosening the radiator cap, which would trigger a rush of water from the radiator into the block. Recently, this 'fix' is no longer working. I then discovered I could get water circulating by taking off the water inflow hose to the heater taps on the bulkhead, topping it up with coolant (at least a litre) and reconnecting. But even when I do that, a few days later while driving, water will come flooding out of the radiator overflow pipe. I have replaced the thermostat (installing it correctly with the arrow pointing rearwards). I have also had leaks fixed in the radiator. Any suggestions really appreciated!
1972 W114 280E (Tiefblau)

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Lance
Adenauer
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Joined: Thu 06 Mar, 2014 9:33 pm
Model you own: w114
Location: Altona Meadows, Melbourne

Re: Coolant problem

Post by Lance » Fri 15 Sep, 2017 11:55 pm

Me too, I had the same problem then it cleared by itself so is OK now, I changed the coolant but created an airlock and don't know how to clear it or prevent it happening.
Regards,
Lance Smart

W114 280E 5 speed manual
W123 280E

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Mercmad
Mercedes Demigod
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Re: Coolant problem

Post by Mercmad » Sat 16 Sep, 2017 7:58 am

Is the thermostat seized shut?

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markb
300 SLR
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Joined: Wed 20 Jul, 2005 1:54 pm
Model you own: w123
Location: Melbourne, Australia

Re: Coolant problem

Post by markb » Sat 16 Sep, 2017 8:41 am

Yes it sounds like an airlock.
The best way I have found to avoid this is by filling with coolant into the top hose rather than into just the radiator
Current Fleet
1985 C123 280CE Midnight Blue with blue MB Tex (234k klms, Daily Driver 2010- )
Past Benzes:
1972 W108 280SE 3.5 White (2002-2003 project)
1971 W108 280SE 3.5 White (1999-2006 Unmolested original & sadly missed)
1987 S124 230TE Diamond Blue (2002-2007 Family cruiser)
1983 W126 280SE Champagne 106k Klms (Custodian in 2013)
1969 W113 280SL Champagne (Custodian in 2000)
1988 W124 300E Diamond Blue (2016 project)

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Lance
Adenauer
Posts: 323
Joined: Thu 06 Mar, 2014 9:33 pm
Model you own: w114
Location: Altona Meadows, Melbourne

Re: Coolant problem

Post by Lance » Sat 16 Sep, 2017 11:32 am

Mercmad wrote:
Sat 16 Sep, 2017 7:58 am
Is the thermostat seized shut?
On mine the thermostat was new, but it behaved as if it was not working. After the airlock cleared it worked fine.
markb wrote:
Sat 16 Sep, 2017 8:41 am
The best way I have found to avoid this is by filling with coolant into the top hose rather than into just the radiator
I will try this on my W123 when I change the coolant (on the list of jobs to do).
Regards,
Lance Smart

W114 280E 5 speed manual
W123 280E

oldmercfan
Pagoda
Posts: 137
Joined: Mon 24 Mar, 2014 7:32 pm
Model you own: w114
Location: Adelaide

Re: Coolant problem

Post by oldmercfan » Sat 16 Sep, 2017 12:01 pm

Thanks, all. The thermostat is not seized shut as the cooling system will work fine for a few days (after filling up the heater hose) before spewing its guts out the overflow pipe. I will just have to keep doing things this way and hope it gets its act together eventually.
1972 W114 280E (Tiefblau)

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Mercmad
Mercedes Demigod
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Re: Coolant problem

Post by Mercmad » Wed 20 Sep, 2017 8:24 am

Before you cook your engine, go to a radiator shop and get them to test the coolant for carbon monoxide . It's a simple test and takes seconds to do . Temperature gauges running up rapidly then dropping is what happens when overheated coolant goes past the temperature gauge sensor, followed by a belch of coolant which makes it drop rapidly . Two things cause this, stuck or incorrectly fitted thermostats and cracked or corroded cylinder heads .A constant air lock is actually a leaking head gasket, because it shows coolant is being drained off somewhere. Is it a genuine behr thermostat or a cheap ebay version ? .

oldmercfan
Pagoda
Posts: 137
Joined: Mon 24 Mar, 2014 7:32 pm
Model you own: w114
Location: Adelaide

Re: Coolant problem

Post by oldmercfan » Fri 13 Oct, 2017 12:45 am

Thanks, all. The problem has fixed itself. The rush of coolant from the overflow pipe slowed to trickle over a few days and then ceased altogether. Have been driving it now for two weeks with coolant system working perfectly. I can only conclude it was an air lock as my trust mechanic in Adelaide, Barrie Green, had suggested. He says old BMWs had a similar issue, so now I know.
1972 W114 280E (Tiefblau)

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