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2008 C300 (sold), 1987 560SL, 2007 CLK350 Cabrio, 2011 E350 Coupe. ALL 040! :)
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Discussion Starter #1
Hi all

I think our 87 560 is getting to hot! I've read the threads that say variation in the temp is normal but sitting in traffic at a drawbridge the car started getting REALLY hot. It was only about 75 degrees today.. I've attached a pic of the temp gague and it actually went even higher than that, but never into the red.

I don't remember this happening before and we had the car in for a major service/ fluid flush recently. I checked and the fan behind the star WAS running so I'm not sure where to start troubleshooting.... or do I even need to and this is within normal operating specs?
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
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Hi all

I think our 87 560 is getting to hot! I've read the threads that say variation in the temp is normal but sitting in traffic at a drawbridge the car started getting REALLY hot. It was only about 75 degrees today.. I've attached a pic of the temp gague and it actually went even higher than that, but never into the red.

I don't remember this happening before and we had the car in for a major service/ fluid flush recently. I checked and the fan behind the star WAS running so I'm not sure where to start troubleshooting.... or do I even need to and this is within normal operating specs?
The pic of your temp is not as alarming as the oil pressure, which may be a function of engine temp in this case.

Things I'd check first , given you recently flushed fluids are:
1. air in the system http://www.startekinfo.com/StarTek/outside/11883/PROGRAM/Engine/107/M117_56/20-010.pdf
2. is Aux fan operable... should come on at engine temp of 105C (That what you mean by fan behind the star, I guess...)
3. Is the viscous-coupled clutch on your fan working properly. It has a 105 or close, temp cut-on wherein it will run at engine speed up to 3500rpm or so...

Usually, the fan clutch is weak/fubar, causing this kind of problem, but since you recently had the coolant flushed/filled, I can't help but think of air in teh system.

Thermostat is 85C in the 560, but is not fully open until 94C, so over-runs past 100 are common and acceptable. Yours is borderline high in the picture.

What oil viscosity are you running, and does the oil pressure return to 3 on the gauge above idle?
 

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87 560SL
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don't forget to check the actual temperature with an infrared sensor. Your sender may be going south.
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
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don't forget to check the actual temperature with an infrared sensor. Your sender may be going south.
Good point, but with his oil pressure, I think his temp gauge is reading at or low...
 

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2008 C300 (sold), 1987 560SL, 2007 CLK350 Cabrio, 2011 E350 Coupe. ALL 040! :)
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Discussion Starter #5
The oil pressure is basically pegged 3 when driving I think. When stopped the oil pressure goes down but not sure if it is usually as low as that. Should the oil pressure be maxed out at all times the engine is running?

I don't have access to an infra-red sensor... do you think the car needs to go into the doc? It just got a clear bill of heath from the independent MB guy..Did a 1000 tune up/ fluid change/ new plugs wires dist cap and rotor etc.. Said the car was in great health but now it's doing this? Hmm. the temp seemed more static when we brought it in.
 

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Always Remembered RIP
1979 280sl 4 sp w/ac 1957 MGA 1998 volvo xc/70 2004 F150
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I agree with EARS, air in the system and no the oil pressuse guage does not have to be pegged at idle. The high temp is probably causing the oil to be hot also causing a bit of a drop in pressure.
 

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500SLC #2624. Black on Black.
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If it has never gone into the red, you have nothing to worry about. If you had to worry about it nearly into the red, the red bit would start sooner.

That is just the temp these cars run at.

If at idle, that oil pressure looks fine to me, too.
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
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Benchmark for comparison...

Ambient Temp- 90F
Engine temp- 90C (fully warmed after several mile trip)
Oil Pressure at Idle 2.5-2.75bar (gauge)
idle rpm- 650-700

Oil- Cas 20w50

Even at 100C engine temp and idle, my oil pressure is above 2.25bar...

I thought his looked a bit low, being under two, which is why I asked about oil viscosity. I also realized the oil pressure could be low due to engine temp, which is why I believe his temp gauge to be reading more or less correctly. He did not report any belching of coolant, so I did not mention the 18psi coolant tank cap or seal...

1.5-2bar is not all that low, but is low compared to my experiences. It equates to approx 24-30psi...
 

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1975 450SL
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Since the condition appeared after a Fluid change (I assume new coolant), my first thought would be that the cooling system may have air trapped in side it, and need to be 'burped'.

The procedure that I was told was this:

1) Raise the front end by about 10 to 12 inches. Driving the front end up on ramps is the safest way. Do this the 'night before', to let things cool off. You do NOT want to open a hot cooling system.:eek:

2) When cool, remove the pressure cap and fill coolant to proper level if not already.

3) With pressure cap still off, and heater on, start car. Check the coolant level and add more if needed as you go through these steps. Feel the small hose going from the top of the radiator to the reservoir. When this hose starts getting hot to the touch, top up the coolant level again, in necessary, and put the cap back on fully.

4) Back the car off the ramps, and go for a test drive, keeping an eye on the temperature gauge.

You may have to repeat a time or two, to make sure all air is out of the system.

Remember; the coolant can be OVER 212 F, so NEVER open the cooling system when hot. The heat will cause considerable pressure, and hot coolant will spray everywhere, including onto you.:eek: This is Not Good. Also, antifreeze is HIGHLY toxic, since it has a very sweet odor, it is attractive to animals. Do not leave any open containers or puddles out where they can be gotten to. Safety first.

Sorry if I got long winded, but it's such a simple procedure, even the most inexperienced newbie can use this as a 'first step' to working on their own car, and save a bit of cash in the process.

Scott
 

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87 560SL
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...
Even at 100C engine temp and idle, my oil pressure is above 2.25bar...

I thought his looked a bit low, being under two, which is why I asked about oil viscosity. ...
1.5-2bar is not all that low, but is low compared to my experiences. It equates to approx 24-30psi...
There are a lot of variables in engine oi pressure, especially at idle. No two engines behave the same way. Change in the way pressure behaves is much more significant than the numbers on the dial.

This is one of the reasons why manufacturers now shy away from direct gages, relying on the computer algorithms to decide if the pressure is suspicious.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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The temp your running at is not alarming and all SL's Ive driven run the oil pressure below pegged when hot and below 1000 RPM. The fact that your Aux fan is coming on in 75° ambient leads me to believe your primary fan is not doing its job. I understand the viscous clutches can be serviced, but I never did it myself. Do a search on how to check and service the clutch.
 

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Discussion Starter #12
Ok, I burped the system and it is still getting up to that temp when I have the car in drive and am standing on the brake, (as if I was in heavy traffic / not lots of air rushing through the grille)

One thing I DID notice after my test drive, is that the coolant level was pretty high in the reservoir (over about 3/4'?) and antifreeze was sputtering out from underneath the cap you could se it boiling under the cap It looks like it had been doing this for awhile as I could see residue from antifreeze bubbling out before on the hose and fresh-ish antifreeze on the side of the tank. I included pics. It looks like there is a little tube to relieve the pressure so do you think I possibly need a new radiator cap?

Regarding the oil pressure, its at approx 1.7 when the car is in drive and the brakes are on, hovers around 1.9 when in park idling and pegs when driving regularly.. Hope that is ok.

Thanks for everyone's help
 

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'80 450SLC Afro RHD Ikonengold
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there's a marker on the side of the tank, it may show that 1/2 tank @ cold is normal level.

After a couple of hot cycles, system should eject excess coolant and no more marks should be seen.

Have you replaced thermostat recently?
As much as it is common for them to be stuck open, many of them fault in delayed or partial opening
 

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It Is What It Is, Dude
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C300Brett said:
One thing I DID notice after my test drive, is that the coolant level was pretty high in the reservoir (over about 3/4'?) and antifreeze was sputtering out from underneath the cap you could se it boiling under the cap It looks like it had been doing this for awhile as I could see residue from antifreeze bubbling out before on the hose and fresh-ish antifreeze on the side of the tank. I included pics. It looks like there is a little tube to relieve the pressure so do you think I possibly need a new radiator cap?

The coolant is either boiling, or bubbling.

Boiling coolant means the temp gauge is wrong, and reading low. Confirm or disavow the temp gauge with an IR thermometer.

Best case, bubbling coolant means air in the system. Burp it as suggested above.

Worst case, the bubbling is cylinder gases.


And yes, if the cap leaks, replace it.
 

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The cooling system in the 560SL is a royal pain to bleed air from to atmosphere. You might do it again a time or two. While it doesn't have much excess capacity, 75f should have your temp gage at no more than 100c.
 

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1975 450SL
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Just as a point of interest: When was the last time the thermostat was changed? If it has gone on you, and is not opening or closing fully, you could be getting this symptom.

When your mechanic did the fluid change, did he flush the system? It looks like he used the green coolant, this is usually not the stuff you want to use in aluminum engines.

Check to see if the temp really is that high. If it is, you may need to start some system troubleshooting. Has the engine been tuned properly? A mis-tuned engine can run hot. Are there any hoses that are leaking? Low coolant level can result in high temps. Is the cap good? Most auto parts stores can test them for free.

When 'burping' the engine, I forgot to mention that the heater should be turned ON, this will get the air out of the heater core and associated plumbing. I forget to mention this because my heater core is bypassed, due to a leak in the system somewhere.

I tend to suspect that something went wrong due to the work your mechanic did, but that could just be a coincidence.

Just a few thoughts,
Scott
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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The last time I saw coolant bubbling out of a reservoir.........I was changing a head gasket not long after.
 

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One of the BW Old Guard/R129, W204 Moderator
1997 SL500- 40th Anniversary
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560's are notorious for leaking around the neck of the reservoir... Either cap or a leak around the neck is probable in your case. If cap, replace. If neck, replace reservoir.

Oil pressure sounds fine... just lower than mine, but I am using dinosaur syrup.

Head gasket is possible... but not probable that it would just start now. I am still leaning toward air, but a leaking cap may not be holding pressure as well as it should. 1.2BAR is spec, if I remember correctly (approx 18psi), which is a lot compared to comparable detroit iron. Still, if it was working properly before, likely still air in the system. Burping procedure is in the link in my first response... other methods do work, but why not do what the manual sez?

Do you have copious amounts of heat when the heater is turned on?

I agree with others... get rid of the green stuff.

You mentioned not much air rushing thru the grill... Symptom of viscous clutch fubar on engine fan? Don't stick anything in there to check (rolled up newspaper or shop towel). Find, rent , borrow, steal a non-contact tach and measure to see if running at engine speed when the engine temp is above 100C.
http://www.benzworld.org/forums/r-c107-sl-slc-class/1548907-viscous-fan-clutch.html

I don't think I question the temp gauge, but I would verify with a non-contact thermometer if possible, or a contact thermometer if that is all you can muster, to verify.

Good luck sorting it out...
 

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Discussion Starter #19 (Edited)
**UPDATE**

So the Thermostat was replaced today and the problem was not fixed. Mechanic says we should next replace the Radiator as it may be bad (?) or perhaps the water pump. It seems to me that as long as the radiator is not leaking how can it be "bad" since it is essentially just a vessel right? The Water Pump he says is aftermarket and advises putting a MB one in to replace it however it is 6 hours of labor (!)

Any advice on the mechanic's advice would be appreciated!

Mech is nice enough to let us supply our own radiator if we like to save $. Where is the best place to buy a BEHR Radiator if we are advised to go that route?

Thanks as always!
 

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Always Remembered RIP
1979 280sl 4 sp w/ac 1957 MGA 1998 volvo xc/70 2004 F150
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The glycol in the anti-freeze crystalizes in the core of the radiator reducing it's cooling capacity. How long was it in there? Does the car run hot at speed?
 
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