It appears that heat from the engine is entering the cabin of my 1986 R107 SL. After driving for an hour or so the cabin starts becoming oppressively hot, and after around two hours of driving the dashboard becomes almost too hot to touch. This is with all heater controls turned off, and very little hot air coming directly from the dash air-vents. Any thoughts on where the heat might be entering the cabin from?
R107 SL engine heat entering cabin
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Which engine? A lot of heat from the V8's. Has the bulkhead got the zinc heatshield on still on? Could also be a broken cable from the heater controls meaning the temp is stuck on hot - even with no fan on, it will still get hot.
Hi Carl, this is a 300SL. I'm not sure if the bulkhead has a heat-shield, how can I check? The cables do seem to be functioning properly but I'll check again.
The heat is beyond normal bounds as the cabin tends to get too warm for comfort and the dash would likely crack if exposed to such temperature for prolonged hours.
The heat is beyond normal bounds as the cabin tends to get too warm for comfort and the dash would likely crack if exposed to such temperature for prolonged hours.
Druk
Gone but not forgotten - RIP
- Joined
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- 5,300
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- Not far from Edinburgh.
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- 2011 S212 E350CDi. 1981 R107 300TurboDiesel.
The heater system on a 107 is by air mix rather than hot water regulation. There is a vacuum operated water valve on the right rear bulkhead which is purely on/off and is switched by the inner levers being in the full down position (iirc). There might be a vacuum line off which will give you hot water all the time regardless and you can check this by operating the levers and watching the valve. Check that the levers have not been pushed too far into their spring clips which will restrict total movement. Just grip them and pull gently out. The vacuum switch only works on the absolute full down position.
Notwithstanding this: if there is excess heat under the dash there will also be a problem with one of the flaps broken or a duct has come loose. Likely the latter. Taking the glovebox liner and/or the speedo cluster out will expose both sides of the heater box for examination. As a temporary fix and to prove that it is the heater (what else could it be?) if you clamp one of the rubber water pipes from the engine to the heater box it will cut off the supply and the heater will run cold whatever position the levers are in. A flexy brake line clamp will do this job well and cause no long term damage.
Come back if you need instructions on speedo removal but try the pipe trick first. At the least you'll get the summer out the car without having to strip it down.
One of these would work...
http://www.halfords.com/webapp/wcs/..._productId_214147_langId_-1_categoryId_255216
Although I think this type are better...
http://www.powertoolworld.co.uk/dra...p-11534.html?***id=COnn64bo6LACFU4lfAodBEpV0g
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Notwithstanding this: if there is excess heat under the dash there will also be a problem with one of the flaps broken or a duct has come loose. Likely the latter. Taking the glovebox liner and/or the speedo cluster out will expose both sides of the heater box for examination. As a temporary fix and to prove that it is the heater (what else could it be?) if you clamp one of the rubber water pipes from the engine to the heater box it will cut off the supply and the heater will run cold whatever position the levers are in. A flexy brake line clamp will do this job well and cause no long term damage.
Come back if you need instructions on speedo removal but try the pipe trick first. At the least you'll get the summer out the car without having to strip it down.
One of these would work...
http://www.halfords.com/webapp/wcs/..._productId_214147_langId_-1_categoryId_255216
Although I think this type are better...
http://www.powertoolworld.co.uk/dra...p-11534.html?***id=COnn64bo6LACFU4lfAodBEpV0g
.
.
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Druk
Gone but not forgotten - RIP
- Joined
- May 28, 2004
- Messages
- 5,300
- Location
- Not far from Edinburgh.
- Car
- 2011 S212 E350CDi. 1981 R107 300TurboDiesel.
ps. Are you anywhere near the West Midlands/ South Brum area? cos I can give you the contact of a very good Merc indie who specialises in 107s.
Derek.
Derek.
Also remember that R107 bulkheads rust badly... hope you havent got a big hole.
Druk, many thanks for the detailed advice - I'll check the valve, and try the pipe trick if the valve checks out. I'm hoping it is just a flap not properly closing, don't want to find a rusty bulk-head causing the issue! I did open the heater compartment last week (heater motor decided to die randomly), and there was no indication of rust inside. I do know how to dis-assemble the cluster, but would leave that to the weekend if needed! Just spent the entire day getting the steering box sorted, so will work on it later this week - also getting the rear brakes sorted this week, and then the valve stems need to be checked... and...and... and... endless list....
Sorry to hijack this thread - i also have 107 heater issues - the car struggles to cut off hot air - i have checked the vaccum operated valve. It works. The levers were not closing it though when i checked it idling in the drive - i exercised it manually a few times and verified it by putting a hose on it and creating vacuum - then i went for a good drive and it opened and closed it fine. I took out the glovebox liner to check on the mechanism and it seems the far left of the levers has an issue. It tries to move a flap under the blower motor it seems but it wont budge, i can force it past an obstruction - then it moves freely. Has anyone had this usse before? At present though my car now isn't hot all the time which is an improvement!
The linkage that is not budging is in the middle of the photo.
Any ideas - thanks!
The linkage that is not budging is in the middle of the photo.
Any ideas - thanks!
Druk
Gone but not forgotten - RIP
- Joined
- May 28, 2004
- Messages
- 5,300
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- Not far from Edinburgh.
- Car
- 2011 S212 E350CDi. 1981 R107 300TurboDiesel.
Check first that the black inner levers aren't pushed too far into their sockets. They can be gripped and pulled out from the slots. If they're too far in they won't go to the bottom of the slot which is where the vacuum microswitch is. The last 2 or 3 mm of travel makes all the difference.
A jammed lever is almost certainly caused by the foam lining on the heater flaps disintegrating. This causes the flaps to close too far and the levers to go over-center. Check first if the 10mm screw on the lever adjuster is tight. (center of photo)
If you're car is not aircon the fix is relatively straightforward involving removing the plastic cover at the rear of the engine bay, removing the heater fan, then the flaps and sticking new thin foam to them and re-assembling. If you have aircon it's dashboard out. There are four 10mm bolts holding down the fan unit. Soak these well in WD40 beforehand cos they often snap. Access is much easier if the bonnet is removed first.
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A jammed lever is almost certainly caused by the foam lining on the heater flaps disintegrating. This causes the flaps to close too far and the levers to go over-center. Check first if the 10mm screw on the lever adjuster is tight. (center of photo)
If you're car is not aircon the fix is relatively straightforward involving removing the plastic cover at the rear of the engine bay, removing the heater fan, then the flaps and sticking new thin foam to them and re-assembling. If you have aircon it's dashboard out. There are four 10mm bolts holding down the fan unit. Soak these well in WD40 beforehand cos they often snap. Access is much easier if the bonnet is removed first.
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Hey Druk,
many thanks, yes the levers go all the way down and aren't too far in. The 10mm bolt is tight so i think its the foam you mention. I will have a peer into the heater box - i now only have 3 bolts securing the blower as i had to change it a few years back and wasnt patient enough with the wd40!
Funny thing is i can get cold air very fast via the lever now and i would have thought the vaccum switch would take a while to give cool air.
thanks,
Rohan
many thanks, yes the levers go all the way down and aren't too far in. The 10mm bolt is tight so i think its the foam you mention. I will have a peer into the heater box - i now only have 3 bolts securing the blower as i had to change it a few years back and wasnt patient enough with the wd40
!Funny thing is i can get cold air very fast via the lever now and i would have thought the vaccum switch would take a while to give cool air.
thanks,
Rohan
Druk
Gone but not forgotten - RIP
- Joined
- May 28, 2004
- Messages
- 5,300
- Location
- Not far from Edinburgh.
- Car
- 2011 S212 E350CDi. 1981 R107 300TurboDiesel.
Count yourself lucky. I know of some guys who can't get cold air even with the pipes clamped off
. I have my own car modified to a variable opening electric valve but that's another story.BTW. You can drill a clearance hole in the fanbox flange a bit below the snapped bolt and a smaller one through the steel underneath and refix the fan corner with a selftapper.
Last edited:
manlikejohnny
New Member
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- Apr 30, 2014
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- 1
- Car
- mercedes slc 380 (c107)
Hi there Druk
I am having the same problem with my slc 380 so I am planning clamp the rubber water pipe from the engine to the heater box. I am new to cars I'm afraid and am wondering where exactly I should clamp and which is the right pipe?
I'd be grateful for your help
Cheers!
I am having the same problem with my slc 380 so I am planning clamp the rubber water pipe from the engine to the heater box. I am new to cars I'm afraid and am wondering where exactly I should clamp and which is the right pipe?
I'd be grateful for your help
Cheers!
Druk
Gone but not forgotten - RIP
- Joined
- May 28, 2004
- Messages
- 5,300
- Location
- Not far from Edinburgh.
- Car
- 2011 S212 E350CDi. 1981 R107 300TurboDiesel.
Have you checked the operation of the vacuum heater valve on the right side of the bulkhead. It defaults to open and if there is a vacuum failure or the module is faulty then it wont work and hot water will always get to the heater matrix.
I like the comment that "if not aircon the fix is relatively straightforward" followed by "remove the flaps". Not aircon and the fan is out but cant see how to remove the flaps (which dont move withthe levers!). Any ideas please.
The heater valves on these cars are vacuum controlled and there should be a bunch of little check valves on the firewall (at the engine side). Check to make sure that they're functioning properly. If your car is catalyst equipped, your catalytic converter could be cooking due to incorrect mixture.
Thanks
Thanks
Al, thanks. Vacuum system definitely suspect as door and boot central locking doesn't always work especially after car hasnt been used for a while. At the moment have fan out and can see that the foam on the flaps needs replacing but cant see how to remove the flaps. Just noticed that NEITHER OF THE FLAPS MOVE WHEN THE LEVERS IN THE CABIN ARE OPERATED. Any suggestions for next step. NB it is European model with no aircon and no catalyst.
Had similar problems when I had my 450sl. Replaced the heater vacuum control with a 12v solenoid operated arm and two position switch. Total cost about £12 . Also fitted a switch operated fan at the front of radiator for better cooling.( pulling the hot air out ). Not original, but effective.
Al, thanks, fresh air flaps OK, with the fan removed I can see daylight when the flaps are open.
Nomoneybutamerc. Thanks,. new vacuum valve on the heater control valve so can test when I re-assemble as the switches are now within reach.
I have dived in at the deep end. Drivers seat out, handbrake removed, radio out, gear change cover, tunnel cover and walnut trim around gears and flap levers out.
Currently staring at a jumble of wires and can see that the flaps aren't moving so trying to decide whether to go deeper and remove the whole ventilation flaps and heater box.
One thing noticed is that 2 plastic covers (100mm x 100mm) at the bottom of the ventilation box have dropped off. Assume they must be blanks for the floor vent trunking on the more upmarket versions.
Suspect that this is where the excess heat was coming from, but they wont clip back into place.
Nomoneybutamerc. Thanks,. new vacuum valve on the heater control valve so can test when I re-assemble as the switches are now within reach.
I have dived in at the deep end. Drivers seat out, handbrake removed, radio out, gear change cover, tunnel cover and walnut trim around gears and flap levers out.
Currently staring at a jumble of wires and can see that the flaps aren't moving so trying to decide whether to go deeper and remove the whole ventilation flaps and heater box.
One thing noticed is that 2 plastic covers (100mm x 100mm) at the bottom of the ventilation box have dropped off. Assume they must be blanks for the floor vent trunking on the more upmarket versions.
Suspect that this is where the excess heat was coming from, but they wont clip back into place.
