500 sl overheating and using coolant

[demetrios]

Morning all

I purchased a K Reg r129 500sl with 95000 kmh on it (wwell the jury's out on this as the odo is in kmh but it's not an import)
Cars been superb. 4 weeks ago i took it on a 34mile run to Birmingham as usual and noticed after the 50mph roadworks on m6 that coolant light lit up when punched it to 80mph.temp rose to over 90°c then light went out when I settled to cruise at 75mph. Checked coolant when I arrived in Birmingham and it was very low so picked up a bottle of ready mixed pink coolant and topped up.

Yesterday again to Birmingham same thing happened so checked when I arrived and coolant was low again. Drove another 35 miles further on and then on the 73 miles home trip the light didn't come on but engine was at 100°c at 75mph all the way. Touched the bonnet when we got home and on side where coolant is the bonnet was very very very hot.
Just taken a look at coolant level and it's dropped from full but maybe to 3/4 full

I'm guessing I have a leak for coolant to be going that quick but any other ideas??

 

[camerafodder]

Hopefully its just a leak from a pipe or a union. However, have you checked for 'bubbling' in the radiator/header tank whilst the engine is running (be careful)? This could be a sign you have a head gasket problem.

 

[demetrios]

Thanks for reply but I have no idea on how to check anything like that. I can check oil, coolant, windscreen water levels and change some fuses but I know nothing about engines.

 

[W210Virgin]

Then you're a bit stumped. Go to an Indy for advice but chances are Camerafodder is on the money.

 

[BTB 500]

Head gasket would be unusual on a V8, but it's possible. Look for drips under the car after a run.

 

[demetrios]

Then you're a bit stumped. Go to an Indy for advice but chances are Camerafodder is on the money.

Camera fodder? ???
Got it booked in to a high performance garage in stafford this thursday to take discs on rear wheel apart and the owner used to be an engine tech for Mclaren I believe upto the 90 ' s. Does lot of full engine builds and upgrades for subarea and evos as well as testerrosa and some s classes parked outside so hopefully get something figured

 

[savinda92]

Must be a leak from the path of radiator outflow line. So the water is not flowing into the engine. But when you accelerate that means the water pump rotates faster. So the rate of flow of water is high. Thats what i think. Try checkin for leaks using a radiator pressure gauge. Good luck

 

[jaymanek]

When you say you filled the coolant, you know that you cant fill it to the top? If you do it will just flow out of the over flow when it gets hot...

There are min and max markings on the bottle.

As has been said, HG failure is extremely rare on these.

Water pumps fail, leaks occur but rarely anything major.

Someone with a coolant pressure tester will soon diagnose..

90 degree's in traffic is normal on the original water pump, radiator etc.

I changed the water pump, radiator, thermostat etc on mine when temps started creeping up and above 100.. now it runs at 80-85 no matter what.

p.s. usually the coolant is blue, use the same colour as whatever is in there.

 

[demetrios]

When you say you filled the coolant, you know that you cant fill it to the top? If you do it will just flow out of the over flow when it gets hot...

There are min and max markings on the bottle.

As has been said, HG failure is extremely rare on these.

Water pumps fail, leaks occur but rarely anything major.

Someone with a coolant pressure tester will soon diagnose..

90 degree's in traffic is normal on the original water pump, radiator etc.

I changed the water pump, radiator, thermostat etc on mine when temps started creeping up and above 100.. now it runs at 80-85 no matter what.

p.s. usually the coolant is blue, use the same colour as whatever is in there.

When I checked the coolant first time it was pink so I got the ready mixed pink coolant.
I don't fill it all the way but first time it was very low.
So someone that knows his engines will find a leak without a problem if it is indeed a leak.

Have any of you fellow r129 owners used aftermarket radiators and pumps or always original (helps with classic value of these I'm guessing)

 

[jaymanek]

You can buy oem quality from parts suppliers saving a bit on mb price. From memory I bought it all from mb though as wasn't convinced by the brands on offer by the aftermarket supplier.

There is copious information with all the options, part numbers etc on the 500e forum. Although this is a w124 model, The radiators may not be the same but other parts are.

My motto is you want to do these large jobs only once!

 

[demetrios]

You can buy oem quality from parts suppliers saving a bit on mb price. From memory I bought it all from mb though as wasn't convinced by the brands on offer by the aftermarket supplier.

There is copious information with all the options, part numbers etc on the 500e forum. Although this is a w124 model, The radiators may not be the same but other parts are.

My motto is you want to do these large jobs only once!

I agree. I'd rather pay extra for parts that will do the job than save money and buy the part twice.
Things like the wiper relay and electric window motors I may purchase non original as it's not a massive thing but anything engine has to be done properly for the health of the car and my anger

 

[GH421]

Just a punt but check your oil cap and dipstick for milky residue. This will rule out head gasket

 

[grober]

As Jay recommends check --pressure cap, thermostat, water pump, radiator in that order. My guess is leaking water pump. You can sometimes check a radiator manually for cold spots [ i.e. if certain sections remain colder than others its an indication they may be choked] can sometimes be cleared by back flushing but usually the cure is replacement.
OEM was BEHR part no (8MK376711181) MB part no possibly A 129 500 01 03
Nissens [ Danish] are a suitable substitute 62532 ? but double check with supplier

 

[demetrios]

I checked the oil this morning and dipstick oil had nothing odd. Just nice oil
It's in on Thursday so will call garage tomorrow to add this job to the clicking wheel one.

Also who do you guys recommend for service as an Indy around stafford way?
Was gonna use sl shop in warwick when service needed as I know they are very good but just wondering if there are any more that are recommended around Birmingham/wolves/walsall even derby way?

 

[demetrios]

Right, garage called me up earlier and said thermostat and water pump as well as hoses are fine so suspect a leak or cracks in radiator. Can't be flow tested til Monday and I need the car for weekend.
So, how much is replacement radiator? Part number and best place to buy

 

[Vlad]

See if Euro Car Parts have got a Nissens radiator in stock.

 

[demetrios]

Guys quick question.
I'm picking my car up later so I've got it for weekend then it's back in on Monday.
Is there a danger of engine damage if the radiator is cracked? I've read briefly in another mercedes forum about coolant going into the gearbox??
Or have I got it completely wrong?

 

[buster651]

remember there are some other pipes one across bottom of screen and im told the washer bottle has heater pipe

 

[BTB 500]

Guys quick question.
I'm picking my car up later so I've got it for weekend then it's back in on Monday.
Is there a danger of engine damage if the radiator is cracked? I've read briefly in another mercedes forum about coolant going into the gearbox??
Or have I got it completely wrong?

That's a different issue, where the pipe that carries transmission fluid through the radiator (to cool it) corrodes ... letting water seep into the ATF. Not a known issue with the R129.

 

[demetrios]

That's a different issue, where the pipe that carries transmission fluid through the radiator (to cool it) corrodes ... letting water seep into the ATF. Not a known issue with the R129.

So really if I take it easy ie no hard acceleration and stick to around 75mph on m6 should be fine for 80 mile round trip on Sunday