Overheating 108...please advise a solution

1965 - 1972: 250S, 250SE, 300SEb, 280S, 280SE, 280SEL, 280SE 3.5, 280SEL 3.5, 280SE 4.5, 280SEL 4.5, 300SEL, 300SEL 6.3, 300SEL 3.5, 300SEL 4.5
Post Reply
User avatar
SMOKEZ
C Class
Posts: 25
Joined: Sat 19 Nov, 2005 2:21 pm
Model you own: w901-905
Location: Melbourne

Overheating 108...please advise a solution

Post by SMOKEZ » Fri 02 Dec, 2005 11:54 pm

Hi everybody!

Down here in Melbourne we finally got over the 30C temp mark. i just had the 108's radiator flushed, new thermostat and fully tuned with new fluids a week ago

Anyway, the engine temp got extremely hot to the point where the needle on the temp gauge was very close to maximum.

knowing that this is a 35+ year car, what is the best way to tackle this problem??

The radiator looks to be in good shape with no visible leaks or damage and also the fan is defintely working.
When i had it flushed i also got it pressure tested to see if there were any possible leaks as i take my 1 and a half year old son cruisin in style as much as possible.......and the last thing i need is to be stuck in hot weather on the road.

Can anybody give me the best suggestion in regards to my problem??

I was thinking along the lines that maybe the orignal radiator design would not cope with our hot weather so therefore should i look towards a custom built radiator??

Could anyone recommend me on who to talk to as the 108 is my everyday driver so i would love to fix this problem in one go??

I truly appreciate everybody in advance on my problem.

Cheers!

User avatar
Hendrik
Mercedes Demigod
Posts: 5497
Joined: Thu 28 Jul, 2005 11:33 am
Model you own: w124
Location: Hawthorndene SA

Post by Hendrik » Sat 03 Dec, 2005 8:30 am

Perhaps you have a faulty thermostat. It does happen that brand new thermostats don't work. Can you take it out and run the 108 without it to see if the problem lies there?

User avatar
OzBenzHead
300 SLR
Posts: 2032
Joined: Mon 22 Aug, 2005 10:11 am
Model you own: w126
Location: Byron Shire, Northern NSW, Australia

Post by OzBenzHead » Sat 03 Dec, 2005 9:02 am

SMOKEZ: I'm inclined to go with Hendrik's suggestion re faulty (new) thermostat.

I live in far northern NSW, just below the Qld border, where summer temperatures are commonly in the high 30s every day and sometimes hit 40. Not infrequently I have taken long (1,000+ km) drives out west at high speeds in 40+ degree heat.

The only time any of my Benzes (and they're all elderly) has overheated was the time a slack mechanic failed to do up the clamps on the top radiator hose he'd replaced that day on my 108, and I drove a fast 50 km in ignorance of the fact. Then, once I hit 5 p.m. city traffic, the needle ran toward the red in a hurry. I got home, lifted the lid, and there was steam exiting the loose hose connection.

I removed the radiator cap, filled up with HOT water, tightened the hose clamp ... end of tale.

As for Benz radiators being unable to handle Oz climate? Nah - it's only cars "designed and built for Australian conditions, in Australia, by Australians" that you see decorating the summer roadside, plumes of steam gushing from their pathetically inadequate radiators, and the family - frequently one-and-a-half-year-olds amongst them - helpless and hapless, broiling in the merciless sun.
OzBenzHead
Currently owned:
1965 W112 300 SE/C
1983 C126 380 SEC

and formerly:
1955 W180 220a
1965 W111 220 S
1970 W108 280 SE (my first Benz)
1973 W116 280 SE Crayford Estate (previously owned by Rolf Harris)
1980 W116 280 SE
1989 W124 300 E
1992 W201 180 E
1992 W201 190 E 2.0
+ numerous W108 and W116 rolling spares

and prior to my M-B enlightenment:
53 other cars of many nations, but mostly British oil-leakers (including 14 Rovers of the 50s and 60s) cursed by Lucas the Prince of Darkness. First car owned (at age 13): 1953 Fiat. Learned to drive in: 1927 Nash utility paddock-basher & Grey Fergie tractor. Driven distance (logged as at 30 June 2016): 4.6 million km.

User avatar
Hendrik
Mercedes Demigod
Posts: 5497
Joined: Thu 28 Jul, 2005 11:33 am
Model you own: w124
Location: Hawthorndene SA

Post by Hendrik » Sat 03 Dec, 2005 9:39 am

Later model Mercs can overheat if the electro magnetic clutch stops working.
This happened on the 190E last summer, pulled out the clutch and after a bit of fiddling/testing I resoldered the terminals and away it went again.

User avatar
SMOKEZ
C Class
Posts: 25
Joined: Sat 19 Nov, 2005 2:21 pm
Model you own: w901-905
Location: Melbourne

Post by SMOKEZ » Sat 03 Dec, 2005 11:23 am

Thank you Hendrick and OzBenzHead.

i truly appreciate your feedback.

im going to check the thermostat next week to see if its faulty.

As with the tightening of clamps, i had that double checked and all clamps are tight.

All terminals are fine. nothing loose in that department!

Its good to hear from everybody that does not have a major issue with overheating!

i'll keep u posted as to my next step.

Thank you again!

User avatar
WarrenM
Zeppelin
Posts: 401
Joined: Mon 20 Jun, 2005 7:15 pm
Model you own: w114
Location: Western Australia
Contact:

Testing thermostat

Post by WarrenM » Sat 03 Dec, 2005 11:40 am

You can do a quick test on thermostat by putting it pot of water or similar and heating until it opens-you will need a thermometer of course.

Don't drive far without a thermostat as it is designed to keep engine at correct temp.

We drove our 108 250S across Nullabor with temps around 45ºC many years ago and we were one of few cars to get across without trouble.

Many of Australia's own were stopped. especailly after removing radiator cap to check water and losing most of it.
http://mercedesbenzw114swtroke8.myfanforum.orgImage
1972 MB 280E
1995 MB E280

1976 Mercedes Benz 0309D Camper-gone but not forgotten

User avatar
bruceT
OZBENZ Admin
Posts: 839
Joined: Mon 20 Jun, 2005 9:21 pm
Model you own: w124
Location: East Maitland, NSW, Australia
Contact:

Post by bruceT » Sat 03 Dec, 2005 10:05 pm

It is NOT a good idea to drive without the thermostat as coolant may not cycle through the radiator as it should. Instead coolant can, in some cases, cycle straight back into the engine without being cooled. Not very good for an engine......

I was having similar issues with my W123 300d a couple of months back. I was begining to suspect the water pump, but it turned out to be the gauge that was faulty. Every now and again it goes beserk, but it is recognisable as the fuel gauge also acts up simultaneously.

Is your pump not making any noises? I presume you've checked the fan is operational?

Just a tip. If the gauge goes up to the red mark, turn on the heater to max, and wind the windows down!
Cheers
Bruce

http://oztayls.blogspot.com/
http://oztayls-shesha.blogspot.com/

Past Benzs:
1976 W123 300D (Running on SVO (Straight Veg Oil) since June 2006-Sold in Nov 2008)
1982 W126 280SE - Unregistered (Free to a good home!)
1993 W124 300D (running on 100% used cooking oil, no conversion and no glow plugs!)

User avatar
SMOKEZ
C Class
Posts: 25
Joined: Sat 19 Nov, 2005 2:21 pm
Model you own: w901-905
Location: Melbourne

Post by SMOKEZ » Sun 04 Dec, 2005 12:58 pm

Thank you again everybody for responding!

i checked the fans and they are definetly working. Once it gets over the 3/4 mark, the fans switch on.

i have to double check the thermostat as that seems to be the weakess link as i have just fitted a brand new waterpump and new hoses.

thanks again everybody!

User avatar
bruceT
OZBENZ Admin
Posts: 839
Joined: Mon 20 Jun, 2005 9:21 pm
Model you own: w124
Location: East Maitland, NSW, Australia
Contact:

Post by bruceT » Sun 04 Dec, 2005 1:57 pm

Yes, from what you have written so far, it does appear that the thermostat could be the most likely culprit.

By the way, was your radiator reverse flushed? This is necessary to make sure that any blockages are removed. Also, the engine water jacket should also be flushed. If there was a lot of crud and oxide build up there, it could have made its way back to the radiator and blocked the core again.
Cheers
Bruce

http://oztayls.blogspot.com/
http://oztayls-shesha.blogspot.com/

Past Benzs:
1976 W123 300D (Running on SVO (Straight Veg Oil) since June 2006-Sold in Nov 2008)
1982 W126 280SE - Unregistered (Free to a good home!)
1993 W124 300D (running on 100% used cooking oil, no conversion and no glow plugs!)

User avatar
SMOKEZ
C Class
Posts: 25
Joined: Sat 19 Nov, 2005 2:21 pm
Model you own: w901-905
Location: Melbourne

Post by SMOKEZ » Sun 04 Dec, 2005 11:46 pm

Hi BruceT,

i had the mechanic fully flush the system. He spent roughly 30 mins physically flushing the radiator and all associated parts off the system which i witnessed as any car which is over 30 years old should not have any short cuts done to it.

So hopefully it'll get warm enough down here in Melbourne to check to see if the thermostat was the culprit.

Big thnx to all!

User avatar
O319-coach
Mercedes Guru/Admin
Posts: 456
Joined: Mon 20 Jun, 2005 6:29 pm
Model you own: w901-905
Location: Canberra, center of the known universe.
Contact:

Post by O319-coach » Tue 06 Dec, 2005 12:57 pm

What temperature thermostat did you fit?

Have you done a check for a blown head gasket?
John Green
Independent importer of discounted genuine Mercedes-Benz parts.
Restorer of Concours winning cars.
Sponsor of this forum.
http://www.mbspares.com.au Toll free phone 1300 787 300

User avatar
ADow
C 111
Posts: 850
Joined: Tue 21 Jun, 2005 5:25 pm
Model you own: w108
Location: Gilberton, Adelaide, SA
Contact:

Post by ADow » Thu 08 Dec, 2005 11:32 pm

Is it losing coolant? Is it steaming out the exhaust or is there a creamy sludge under the oil filler cap? These can be signs of a head gasket failure or cracked head.

Other possibilities
Incorrect ignition timing
Mixture too lean - check plugs for colour.

Smokez, I wasn't clear from your posts which fan or fans you have been checking, but I suggest that you check for a defective viscosity coupling for the main cooling fan (not the electric fan).

The main cooling fan (driven by a fan belt) is fitted with an 'intelligent' viscosity coupling operated by a thermostat so that the fan does not take full power when it is not required. The fan runs at a minimum of 25% of engine speed at all times (even when cold), but as the engine and the fan coupling heat up the amount of 'slip' in the viscous coupling reduces and the fan speed increases in relation to the speed of the engine. In other words, the hotter the engine gets, the less slip in the viscous coupling and the faster the fan turns.
You can test the coupling as follows. Drive the car until it reaches normal operating temperature (above 62C), then stop the engine. Open the bonnet and try to spin the fan by hand. If the fan spins freely, the viscosity coupling is almost certainly stuffed and it means that the fan is not operating at the proper speed, even if it appears to be turning when the engine is running. This will show up in hot running in the city - but less hot running on the open road when the air flow compensates for the failure of the fan.

These couplings do fail.
Alastair
1971 280SE 3.5 - Don Ottavio - sold
1980 300D (formerly daughter's) - Heidi - sold
1999 C200 Elegance (currently daughter's)
1981 300D (son's) - Hektor
1998 Puma Clubman with 225 RWKW SR20DET - Percy
http://www.youtube.com/user/adow77

CraigB
OZBENZ Admin
Posts: 4810
Joined: Thu 23 Jun, 2005 2:18 pm
Model you own: I own multiple different models
Location: Hawthorndene (Adelaide)

Post by CraigB » Tue 13 Dec, 2005 1:13 pm

All the posts here seem relevant to me and cover everything I can think of.

Just a short cut test you can do (and I am also interested if any experienced people think this is incorrect). Open your bonnet, remove the cap from the radiator, then start the engine (from cold) and go back and watch down the hole. If your thermostat is basically working, you should see the water sitting still and then as the engine warms up and the thermostat opens, you will start to see water moving as it starts to circulate. Also while you are there, if it is topped right to the top and you see bubbles, this is an indication of a blown head gasket.

Hope this helps in the diagnosis and doesn't require dismantling anything, but also be aware that the thermostat may still work but be working in the wrong temp range for the car and I have an idea I have heard that you can have a blown gasket and not get bubbles also.
Craig Baulderstone
Lurch
280s's
280SE3.5
280SL
350SL
500SEC's
560SEL's

User avatar
SMOKEZ
C Class
Posts: 25
Joined: Sat 19 Nov, 2005 2:21 pm
Model you own: w901-905
Location: Melbourne

Post by SMOKEZ » Tue 13 Dec, 2005 1:22 pm

Thnx Craig for the tip.

Unfortunetly, the cars been sitting here for a week as i cant start it.

My younger brother wanted to install my TV/DVD/NAV system but somwhere along the way he burnt out some wires within the engine bay :cry:

I've tried to start it up but the engine cranks over but wont start!
Its like if you ran out of fuel!!!!

So hopefully i've booked an electrician to check all the electricals are fine!

Hoping then, once it starts again, i can diagnose the overheating problem by trying everyones ideas.

CraigB
OZBENZ Admin
Posts: 4810
Joined: Thu 23 Jun, 2005 2:18 pm
Model you own: I own multiple different models
Location: Hawthorndene (Adelaide)

Post by CraigB » Thu 15 Dec, 2005 10:40 am

just a comment on the wiring. You are probably only looking at one wire that has been grounded and therefore melted. In the process it may have melted insulation on wires around it. I would get myself a wiring diagram and then look for the melted wire on it. If you can trace back where it comes from and also physically follow where it appears melted, you might save yourself some time and money with the electrician.

My guess is that there is a fuel solenoid or something like that. Ignition isn't usually fused but I am not familiar with the 8. Have you pulled a plug lead off while someone turns it over to see if you have a spark? Also stating the obvious, but have you checked your fuses? Having said all that, if you can see phsically melted wires, you will want to make sure they are insulated again before going any further.

Also speaking from experience, i had a neg earth radio I fitted to my pos earth first car. It stuffed the radio by getting the polarity wrong. Just something to keep in mind if when you finally fit the thing and find it doesnt work. Hopefully the damage was just due to earthing some live wire and didn't involve your new unit
Craig Baulderstone
Lurch
280s's
280SE3.5
280SL
350SL
500SEC's
560SEL's

User avatar
SMOKEZ
C Class
Posts: 25
Joined: Sat 19 Nov, 2005 2:21 pm
Model you own: w901-905
Location: Melbourne

Post by SMOKEZ » Sat 17 Dec, 2005 12:12 am

Thnx for the advice Craig,

Checked all wiring, fuses and spark and all is good except for the one wire.

With the burnt out wire, all i did was cut off the melted wire from the alternatar to the battery and re-routed a new wire. Easy fix!
Lucky for me it didnt effect my head unit! its installed now and i must admit, the sound quality is fantastic.

Car starts now, with a new dellima though :(

As with Allistair, mate! you were right with the defective viscosity coupling for the main cooling fan!
Will get someone to look over it in the next week!

Thnx again to you guys for helping me out!

Its embarrassing asking all these questions..........Which leads me to my next question! But, i'll start a new post on this one :oops:

Post Reply

Return to “W108/109”