Oil cooler fan mod for 55

**DansSlk** · 05-07-2008

I'm thinking about fitting a new mod on my car that i hope will be cheap but effective if i can make it fit.

The E AMG's use a cooling fan for the engine oil cooler but the SLK just uses the airflow and the oil can get quite hot even if the coolant stays about level so the plan is to take the E fan install it over the oil cooler and connect it to the SAM that the 171 shares with the 211 and see what happens.

Just thought it would let you guy's know since it might interest some of you living in warmer climates than me.

**etyu** · 05-07-2008

Great idea Dan.
This wil be very helpful for those who are in hot climates or who track their vehicles. Something that is as close to plug-and-play as possible.

As an illustration:

1. Use existing mounts on oil cooler to mount the fan. Simple tools required.
2. Fan is an off-the-shelf item, e.g., the same fan already exist in the E AMG series. Hopefully the fan is of a compact size.
3. Simple wire harness to connect to existing SAM. Y-connectors perhaps.
4. No modification required on the body work or wheel liner.

Question: Does the oil flow through the cooler on the right side of the SLK 55 only when it reaches a certain temp? or is it a "dumb" system where it flows through no matter what the oil temp is?

**DansSlk** · 05-07-2008

That's about right Eddy mate.

The fan is in a duct on the E that covers the front of the cooler so that might have to come off for the SLK but i think it has space for the fan itself that is mounted to the cooler.

Its just 2 wires to power it, one goes to a ground point and the other to the SAM and the connector will be ready and waiting since the SAM is shared between the SLK and E so it wont need any splicing just slide the contact spring into the MB connector and insert it into the unit.

On the E the fan shares a relay with the electric air pump so when the ECU calls for the pump the fan comes on automatically and i hope to simply carry this over to the SLK but since it uses a N/A engine i don't think the ECU uses the pump once the engine is warm so i will look into it, if the pump is not used with a warm engine then i will find a spare ignition switched feed on the SAM that we can just plug right into without splicing anything and use a thermostatic switch on the metal feed line to the oil cooler so it wont be quite as accurate as ECU control but it will be close.

On the M113 engine the oil cooler is dumb it just pushes the oil out to the cooler as part of the normal flow so it takes the oil slightly longer to warm up after you start the car but once the oil is warm the airflow over the cooler keeps it at a nice temp but of course when you slow down in the SLK it can't get the airflow and it gets hot, the BS car's with additional coolers use thermostats in the lines to control the flow so i will make sure the fan mod is either ECU controlled via the air pump or thermostatically controlled via the line temp to avoid cooling the oil too much.

**F111F** · 05-08-2008

Yes Dan,
Let us know how this goes.
As you can imagine, it gets a little toasty here in Texas

**FishtailnZ** · 05-08-2008

Interesting, thanks Dan!

**DansSlk** · 05-08-2008

No worries, i wanted to try this today but the connector is on the bottom of the SAM so i will need to give it a few hours to get the thing out.

(The RHD car's have a different equipment box than the LHD's and the SAM is partially tucked under bodywork so it has to come up and to the right at the same time = PITA)

**DansSlk** · 05-09-2008

OK some more information for you, the N/A and S/C engine's are too different to carry this over with ECU control, every time you started the car you would get a CEL and end up in limp mode.

So plan B is to take ignition switched power this will be from the interior socket / ciggy lighter feeds and for fan control it could be one of the following (in order of complexity) -

1) In line thermostat mounted to the feed/return line for direct control
2) Tie it to one of the other heat switched motors (possibly, looking into this)
3) Line/sump mounted thermometer connected to a temp display that control's the fan

Personally i think the best option is to just install a stat on the power line and have it directly switch the fan that way we will only have 2 wires to think about, what do you guys think?

The downsides the downsides are -

1) If you have both the interior socket and the ciggy lighter fitted you would need to pick one to be disconnected.
2) The SLK SAM shares power internally from one fuse to feed both the interior socket and the ciggy lighter this fuse is rated at 15 amps and cannot be increased, the E fan is fused at 10 amps what it's actual in use draw is i don't know so if we assume its going right to the max at 10 that gives us 5 amps spare to the ciggy lighter / interior socket, i don't know how many amps the lighter draws and the interior socket is of course variable depending on what you plug in.

Would you mind giving up either the socket or the lighter if you have both fitted and would you mind telling me how many of you use the interior socket and what the rating is of the appliances you plug into it, i will set up a poll in 171 General if you guys would be kind enough to answer.

Does the plan still sound acceptable to you guys?

**alroumi** · 05-09-2008

Thanks dan, sounds like an interesting modification. I cant wait to know the outcomes if they are substantial after a track days worth of driving.

**etyu** · 05-09-2008

Quote:

Originally Posted by DansSlk

.....

So plan B is to take ignition switched power this will be from the interior socket / ciggy lighter feeds and for fan control it could be one of the following (in order of complexity) -

1) In line thermostat mounted to the feed/return line for direct control
2) Tie it to one of the other heat switched motors (possibly, looking into this)
3) Line/sump mounted thermometer connected to a temp display that control's the fan

Personally i think the best option is to just install a stat on the power line and have it directly switch the fan that way we will only have 2 wires to think about, what do you guys think?

The downsides the downsides are -

1) If you have both the interior socket and the ciggy lighter fitted you would need to pick one to be disconnected.
2) The SLK SAM shares power internally from one fuse to feed both the interior socket and the ciggy lighter this fuse is rated at 15 amps and cannot be increased, the E fan is fused at 10 amps what it's actual in use draw is i don't know so if we assume its going right to the max at 10 that gives us 5 amps spare to the ciggy lighter / interior socket, i don't know how many amps the lighter draws and the interior socket is of course variable depending on what you plug in.

Would you mind giving up either the socket or the lighter if you have both fitted and would you mind telling me how many of you use the interior socket and what the rating is of the appliances you plug into it, i will set up a poll in 171 General if you guys would be kind enough to answer.

Does the plan still sound acceptable to you guys?

Personal thoughts and opinion:

1. The simpler the set-up the better, 2 wires is as simple as it gets I think.
2. If the thermostat switch is not installed, how about a toggle switch to turn the oil cooler fan on-or-off by the vehicle operator, who can decide based on oil temp. in the MFD.
3. Cigarette smoking is not recommended, ergo, the cigarette lighter can go.
4. I personally don't attach any accessories to the 12V socket on the passenger side.

**FishtailnZ** · 05-09-2008

Quote:

Originally Posted by DansSlk

OK some more information for you, the N/A and S/C engine's are too different to carry this over with ECU control, every time you started the car you would get a CEL and end up in limp mode...

Guess your sig rings true...again...here Dan!

P.S. I don't use the cig socket Dan, and have used the power socket for an air pump only (at the track).

**DansSlk** · 05-09-2008

Thanks guys.

Eddy in answer to point 2 mate, that certainly could be an option it's simple enough to do but you would have to route a fairly substantial cable into the cabin and back out again.

**got_power55** · 05-10-2008

Dan don't smoke and if I did it wouldn't be happen in the car under any conditions, that said can't think of a better use for the cig. lighter.This mod will be great if you can make it come together,helping to cool down the oil in turn less stress and helping to prolong the life of the engine.

**etyu** · 05-10-2008

Quote:

Originally Posted by DansSlk

..Eddy in answer to point 2 mate, that certainly could be an option it's simple enough to do but you would have to route a fairly substantial cable into the cabin and back out again.

Return to point 1.

**DansSlk** · 05-10-2008

Was talking with one of the guys i work with today about this and we spotted a small problem, if you are using a thermostatic switch then the fan would not start until the oil is warm so you can assume the engine is running but if you switch the engine off and then go to start it again before the engine cools that would place extra load on the battery because the fan would start before the engine.

We don't think with a healthy battery it would have any effect but we are going to have a look into it anyways, best case is this is not an issue and the worse case is we perhaps use a timer in the loop to wait say a minute before starting the fan to let the engine start or we use the alternator OK line with a relay.

I have a pic I'm gonna upload of the fan and a quick wiring diagram to give you an idea what i mean.

**DansSlk** · 05-10-2008

OK here we go this is the as built config
(SAM is N10/1, X58/1 is the interior socket, R3 is the lighter - If not fitted to the car wiring will not be present)

Now the modded config
(Lighter disconnected from socket's 22 and 19 - if installed, Motor(fan) added along with a 10A in line fuse but if you do not use the socket then you could remove the 15A on the SAM and replace with a 10 for a simpler install without the in-line fuse, the red section is where we plan on putting the control)

And the fan itself

**DansSlk** · 05-10-2008

Found another option for this that will not require the removal of either the interior socket or the ciggy lighter but will require a relay to switch the fan, we can use the front pre-fuse box (thats the box with the red + flap on it) that contains the main fuses that take power from the battery and send it to the SAM's.

We could simply install another ring connector onto one of the fuses (I've picked the one going to the Driver SAM because it has the highest rating) then install a 10A fuse and relay in the line to the thermostat and fan.

Still a very simple option i think, the wiring diagram with the fan installed is attached.

What do you guys think?

**etyu** · 05-10-2008

Looks simple enough (wiring wise).

Is the fan going on the back part of the oil cooler so it draws air from front to back?

The reason for the above question is that there's a black plastic chamber/housing in front of the oil cooler right behind the right fog light that directs air to the oil cooler. There seems to more room behind the oil cooler but not in front.

**DansSlk** · 05-10-2008

Normally it draws air toward itself so it would go on the front but we will see what we can do mate.

Probably going to be some fitment modding going on.

05-07-2008	#1 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	Oil cooler fan mod for 55 I'm thinking about fitting a new mod on my car that i hope will be cheap but effective if i can make it fit. The E AMG's use a cooling fan for the engine oil cooler but the SLK just uses the airflow and the oil can get quite hot even if the coolant stays about level so the plan is to take the E fan install it over the oil cooler and connect it to the SAM that the 171 shares with the 211 and see what happens. Just thought it would let you guy's know since it might interest some of you living in warmer climates than me. __________________ One thing you will learn with German cars - If it's simple it ain't happening.
	http://www.slkworld.com/

05-07-2008	#2 (permalink)
etyu Founding Member #2 / Ambassador Of Good Will Join Date: Jun 2006 Location: Orange County, CA Vehicle: 2008 SLK 55 Posts: 5,131 Country: Thanks: 377 Thanked 243 Times in 139 Posts	Great idea Dan. This wil be very helpful for those who are in hot climates or who track their vehicles. Something that is as close to plug-and-play as possible. As an illustration: 1. Use existing mounts on oil cooler to mount the fan. Simple tools required. 2. Fan is an off-the-shelf item, e.g., the same fan already exist in the E AMG series. Hopefully the fan is of a compact size. 3. Simple wire harness to connect to existing SAM. Y-connectors perhaps. 4. No modification required on the body work or wheel liner. Question: Does the oil flow through the cooler on the right side of the SLK 55 only when it reaches a certain temp? or is it a "dumb" system where it flows through no matter what the oil temp is? __________________ *Eddy* To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Pewter/Beige, PIII package, Airscarf, Hands-Free Communication System, Lighting package Designo Black Leather Cover on e-brake handle, ( To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Bill T), SmartTop v1.0, Kleyman 3BFM (NoRegret Custom), Green Air Filters, *Mod. R170 ant.* EuroClear sidemarkers w/PIAA PlasmaIon lamps, chromed front & rear turn indicator lamps, PIAA SuperPlasmaGTX front parking lamps, HyperWhite license plate lamps ( To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Scott), bilateral rear fog lamps enabled.

05-07-2008	#3 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	That's about right Eddy mate. The fan is in a duct on the E that covers the front of the cooler so that might have to come off for the SLK but i think it has space for the fan itself that is mounted to the cooler. Its just 2 wires to power it, one goes to a ground point and the other to the SAM and the connector will be ready and waiting since the SAM is shared between the SLK and E so it wont need any splicing just slide the contact spring into the MB connector and insert it into the unit. On the E the fan shares a relay with the electric air pump so when the ECU calls for the pump the fan comes on automatically and i hope to simply carry this over to the SLK but since it uses a N/A engine i don't think the ECU uses the pump once the engine is warm so i will look into it, if the pump is not used with a warm engine then i will find a spare ignition switched feed on the SAM that we can just plug right into without splicing anything and use a thermostatic switch on the metal feed line to the oil cooler so it wont be quite as accurate as ECU control but it will be close. On the M113 engine the oil cooler is dumb it just pushes the oil out to the cooler as part of the normal flow so it takes the oil slightly longer to warm up after you start the car but once the oil is warm the airflow over the cooler keeps it at a nice temp but of course when you slow down in the SLK it can't get the airflow and it gets hot, the BS car's with additional coolers use thermostats in the lines to control the flow so i will make sure the fan mod is either ECU controlled via the air pump or thermostatically controlled via the line temp to avoid cooling the oil too much. __________________ One thing you will learn with German cars - If it's simple it ain't happening.

05-08-2008	#5 (permalink)
FishtailnZ Buckle up shut up hold on / Moderator Join Date: Jul 2006 Location: Nfld., Canada Vehicle: 20?? SLK?? Other Toys: Wife, kids, dogs... Posts: 1,435 Country: Thanks: 289 Thanked 181 Times in 77 Posts	Interesting, thanks Dan! __________________ - Bill R.I.P. 2006 SLK55 Caspian Blue/Beige Stock 1/4 mile results: ET 12.72, trap 110.80, 60' 1.80 Some guys they just give up living and start dying little by little, piece by piece. Some guys come home from work and wash up and go racin' in the street... - B. Springsteen

05-08-2008	#6 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	No worries, i wanted to try this today but the connector is on the bottom of the SAM so i will need to give it a few hours to get the thing out. (The RHD car's have a different equipment box than the LHD's and the SAM is partially tucked under bodywork so it has to come up and to the right at the same time = PITA) __________________ One thing you will learn with German cars - If it's simple it ain't happening.

05-08-2008	#4 (permalink)
F111F Elite SLK World Member Join Date: Oct 2006 Location: Plano, TX Vehicle: SLK55 Black Mocha Designo Posts: 283 Country: Thanks: 37 Thanked 16 Times in 6 Posts	Yes Dan, Let us know how this goes. As you can imagine, it gets a little toasty here in Texas

05-09-2008	#7 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	OK some more information for you, the N/A and S/C engine's are too different to carry this over with ECU control, every time you started the car you would get a CEL and end up in limp mode. So plan B is to take ignition switched power this will be from the interior socket / ciggy lighter feeds and for fan control it could be one of the following (in order of complexity) - 1) In line thermostat mounted to the feed/return line for direct control 2) Tie it to one of the other heat switched motors (possibly, looking into this) 3) Line/sump mounted thermometer connected to a temp display that control's the fan Personally i think the best option is to just install a stat on the power line and have it directly switch the fan that way we will only have 2 wires to think about, what do you guys think? The downsides the downsides are - 1) If you have both the interior socket and the ciggy lighter fitted you would need to pick one to be disconnected. 2) The SLK SAM shares power internally from one fuse to feed both the interior socket and the ciggy lighter this fuse is rated at 15 amps and cannot be increased, the E fan is fused at 10 amps what it's actual in use draw is i don't know so if we assume its going right to the max at 10 that gives us 5 amps spare to the ciggy lighter / interior socket, i don't know how many amps the lighter draws and the interior socket is of course variable depending on what you plug in. Would you mind giving up either the socket or the lighter if you have both fitted and would you mind telling me how many of you use the interior socket and what the rating is of the appliances you plug into it, i will set up a poll in 171 General if you guys would be kind enough to answer. Does the plan still sound acceptable to you guys? __________________ One thing you will learn with German cars - If it's simple it ain't happening.

05-09-2008	#8 (permalink)
alroumi Moderator Join Date: Jun 2006 Location: Kuwait City, Kuwait Vehicle: 2006 Kleemann Designo Mocha Black SLK55 AMG Other Toys: 2007 Ebony Jaguar XKR Coupe' and 06 Black Cayenne S Posts: 6,208 Country: Thanks: 287 Thanked 221 Times in 132 Posts	Thanks dan, sounds like an interesting modification. I cant wait to know the outcomes if they are substantial after a track days worth of driving. __________________ 06 Kleemann Designo Mocha Black SLK55 AMG 06 Porsche Cayenne S 07 Jaguar XKR Coupe' I use the Torque and keep the HP for my Steak Sauce!

05-09-2008	#11 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	Thanks guys. Eddy in answer to point 2 mate, that certainly could be an option it's simple enough to do but you would have to route a fairly substantial cable into the cabin and back out again. __________________ One thing you will learn with German cars - If it's simple it ain't happening.

05-10-2008	#12 (permalink)
got_power55 SLK World Member Join Date: Feb 2008 Vehicle: 2005 slk55 amg Posts: 46 Country: Thanks: 17 Thanked 2 Times in 2 Posts	Dan don't smoke and if I did it wouldn't be happen in the car under any conditions, that said can't think of a better use for the cig. lighter.This mod will be great if you can make it come together,helping to cool down the oil in turn less stress and helping to prolong the life of the engine. __________________ Fast Ken To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.

05-10-2008	#14 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	Was talking with one of the guys i work with today about this and we spotted a small problem, if you are using a thermostatic switch then the fan would not start until the oil is warm so you can assume the engine is running but if you switch the engine off and then go to start it again before the engine cools that would place extra load on the battery because the fan would start before the engine. We don't think with a healthy battery it would have any effect but we are going to have a look into it anyways, best case is this is not an issue and the worse case is we perhaps use a timer in the loop to wait say a minute before starting the fan to let the engine start or we use the alternator OK line with a relay. I have a pic I'm gonna upload of the fan and a quick wiring diagram to give you an idea what i mean. __________________ One thing you will learn with German cars - If it's simple it ain't happening.

05-10-2008	#15 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	OK here we go this is the as built config (SAM is N10/1, X58/1 is the interior socket, R3 is the lighter - If not fitted to the car wiring will not be present) Now the modded config (Lighter disconnected from socket's 22 and 19 - if installed, Motor(fan) added along with a 10A in line fuse but if you do not use the socket then you could remove the 15A on the SAM and replace with a 10 for a simpler install without the in-line fuse, the red section is where we plan on putting the control) And the fan itself __________________ One thing you will learn with German cars - If it's simple it ain't happening.

05-10-2008	#16 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	Found another option for this that will not require the removal of either the interior socket or the ciggy lighter but will require a relay to switch the fan, we can use the front pre-fuse box (thats the box with the red + flap on it) that contains the main fuses that take power from the battery and send it to the SAM's. We could simply install another ring connector onto one of the fuses (I've picked the one going to the Driver SAM because it has the highest rating) then install a 10A fuse and relay in the line to the thermostat and fan. Still a very simple option i think, the wiring diagram with the fan installed is attached. What do you guys think? __________________ One thing you will learn with German cars - If it's simple it ain't happening.

05-10-2008	#17 (permalink)
etyu Founding Member #2 / Ambassador Of Good Will Join Date: Jun 2006 Location: Orange County, CA Vehicle: 2008 SLK 55 Posts: 5,131 Country: Thanks: 377 Thanked 243 Times in 139 Posts	Looks simple enough (wiring wise). Is the fan going on the back part of the oil cooler so it draws air from front to back? The reason for the above question is that there's a black plastic chamber/housing in front of the oil cooler right behind the right fog light that directs air to the oil cooler. There seems to more room behind the oil cooler but not in front. __________________ *Eddy* To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Pewter/Beige, PIII package, Airscarf, Hands-Free Communication System, Lighting package Designo Black Leather Cover on e-brake handle, ( To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Bill T), SmartTop v1.0, Kleyman 3BFM (NoRegret Custom), Green Air Filters, *Mod. R170 ant.* EuroClear sidemarkers w/PIAA PlasmaIon lamps, chromed front & rear turn indicator lamps, PIAA SuperPlasmaGTX front parking lamps, HyperWhite license plate lamps ( To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. Scott), bilateral rear fog lamps enabled. Last edited by etyu; 05-10-2008 at 09:51 PM. Reason: corrected location of fog light

05-10-2008	#18 (permalink)
DansSlk Super Moderator Join Date: Jun 2006 Location: Wales Vehicle: 05 B55S (Brabus 6.1 S) Posts: 6,622 Country: Thanks: 91 Thanked 182 Times in 139 Posts	Normally it draws air toward itself so it would go on the front but we will see what we can do mate. Probably going to be some fitment modding going on. __________________ One thing you will learn with German cars - If it's simple it ain't happening.