Temp Reading on 300SL

[MM]

Greetings all !

I have a 1992 300SL - had it for about three months now and have noticed the temp needle rising from its usual place of abode...

All the other mercs i've ever had - the temp needle sits normally a degree or so above the 80 mark. My one has started sitting just below 100 and in traffic will go a few degree's past 100 - is this right ? should it be doing that :?

I have changed the coolant, and thermostat - no difference !

P.S it is an import from singapore - dont know if that makes a difference.

All answers appreciated.

MM

 

[talbir]

You are right to be concerned - the straight six in your car should be at 85-90degC most of the time and only in high ambient temps and long traffi, should it approach and rise above 100.

IS the fan kicking in at 100degC ?

If not, then the viscous clutch may be suspect (given that you have already changed the thermostat)

If it is kicking in fine and you still have high temps, then it is most likely to be the radiator. Given that your radiator is likely to be the original item that has now seen twelve years of service, it is most likely getting clogged. Worthwhile having it changed if the service book/invoices show no proof of this having been done since the car was built.

Also, check for any leaks of coolant - if there are any leaks in any of the rubber hoses, this will also lead to high temps and of course loss of coolant.

 

[landover]

TEMP

It might be worth changing the temp sender unit first

This would be the cheapest option.

If it has no effect you have not lost a lot of time or money.

good luck.

 

[justin1820]

why dont you all get your sef a laser thermometer and then we will know how hot all are bits of engine are geteing rather than the needle on the dash which is up and down as often as a knickers.

 

[NormanB]

why dont you all get your sef a laser thermometer and then we will know how hot all are bits of engine are geteing rather than the needle on the dash which is up and down as often as a knickers.

The temperature indicator on the Merc is fine and is actually quite accurate - so believe what it tells you.

As has been posted in the more helpful responses check the operation of your viscous clutch (bridge the plug on the sensor lead) and with ignition on engine off the clutch should lock up and you will be unable to turn by hand - if you can the clutch is knackered and you will require a replacement.

If you prove the clutch is OK run the engine and observe if the fan cuts in - if it does not change the sensor (about £12).

Of course if the above all checks out then the problem lays elsewhere and the radiator (as has been suggested) is worth investigating.

 

[justin1820]

that engine has a viscous fan not an electromagnetic fan so there is no sensor!

 

[NormanB]

that engine has a viscous fan not an electromagnetic fan so there is no sensor!

Good point

My unreserved apologies.

 

[landover]

temp sender

that engine has a viscous fan not an electromagnetic fan so there is no sensor!

no but it has a temp gauge sensor. thats what i said.. i know it has a viscous fan ..i thought it was the gauge that was the problem???the sensor you are on about is for electric fan

 

[MM]

Thanks chaps for all your helpful responses 1

I have the viscous fan changed at a cost of £90 + labour - and job done !

The temp needle is now back home at 85 degrees !

Just for your info - George Fraser of Wembley knows his business, his garage specialise in MERcs and his prices are very reasonable.

Give him a call before sending your motor to Merc - he is always very helpful.

Tel 0208 795 1055

Again - thank you very much !
MM :lol: :lol:

 

[landover]

fast

That WAS QUICK if it had went into a merc garage it would have taken a few days.and they do not work on sundays .good you got it sorted.