Replacement fan clutch needed for AMG M117 engine in 500GE

[Vesken]

What I learned through all of this, as a general rule of thumb, was the following:

Cooling temp problems are either caused by airflow issues, or coolant circulation issues.

Airflow-related components that can cause problems are: aux fans and associated temp sensors, relays, fuses, etc.; fan clutch; radiator (if externally clogged with bugs/detritus, or otherwise physically/externally blocked from flowing air efficiently by debris); or fan shroud (directs air properly)

Coolant circulation components that can cause problems are: thermostat; radiator (if old and blocked/clogged internally with scale inside the tubes, or leaking, etc.); water pump (impeller not circulating coolant efficiently); coolant expansion tank cap (not maintaining system pressure).

Since this is my first post here, I've just got to say thank you very much for all your amazing walktroughs on all sorts of repairs. I've been lurking here a long time, and used a lot of your M117 posts as reference when I've been working on my own. It's been a real lifesaver.

As for this post; I had most of the problems you mentioned on my M117, and have now finally fixed pretty much all of them. However, in the process, I've had to pull my condenser, plug the AC lines, and disconnect the compressor (for the time being). I'm also down one fan clutch and primary engine fan, so the aux fans are my only option for active cooling for now.

My question is: Would there be any downsides to me just shorting the red pressure sensor switch, bypassing it completely, so that the aux fans always run on low setting?

 

[gerryvz]

I recommend that you just get a new fan clutch for your M117. They are pretty cheap and easily available as Behr aftermarket products.

Running the fans is a Band-Aid to having the cooling system work correctly. You can use a resistor (you can google CoolHarness) to jumper the fan and turn it on at a somewhat lower temperature. This is one option.
However, I recommend that you just take the time and spend the money to fix things so that they work as the factory intended.
That means ensuring that all components, including the thermostat, fan clutch, radiator, and coolant temp switches and cooling fans are working correctly.

 

[Vesken]

Thank you! Yes, getting everything up to factory standard is the goal. Sadly, replacing the fan clutch is not an option – mine is a special AMG version (HWA part number) which went out of production around when my car left the factory, and which was never made in sufficient quantities for spares to exist anywhere in the world. I literally checked everywhere, up to and including the Affalterbach plant. That's why I need the band-aid

My radiator and thermostat are brand new, but from what I've read in this thread and the previously linked mandatory reading one on aux fans, there won't be any pressure to trigger the low setting without the AC compressor? The CoolHarness idea seems to be a great way of lowering High Speed kick-in, but it seems it wouldn't do much to get Low Speed engaged...? Or am I wrong?

 

[TerryA]

Why won’t a STOCK FAN cLUTCH work?

Can’t be that different. Stock spec has to be close to the AMG spec. I don’t know but the AMG fan clutch might even be a re-badged stock part.

Bottom line the stock fan clutch is got to be better than NO fan clutch.

Just Saying

 

[Vesken]

Why won’t a STOCK FAN cLUTCH work?

Can’t be that different. Stock spec has to be close to the AMG spec. I don’t know but the AMG fan clutch might even be a re-badged stock part.

Believe me, I wish it was that easy! Daimler brought AMG on board for this car in part to get around space constraints, and a slimmer, wider diameter fan clutch was one of the things they engineered in as a solution.

A stock unit won't physically fit, and while I'll get my old one repaired somehow, some day, I need a stopgap measure until I do. Slow-speed aux fans would fit the ticket very well, since I'm not really seeing any heat issues at even moderate speed.

 

[Jlaa]

Believe me, I wish it was that easy! Daimler brought AMG on board for this car in part to get around space constraints, and a slimmer, wider diameter fan clutch was one of the things they engineered in as a solution.

A stock unit won't physically fit, and while I'll get my old one repaired somehow, some day, I need a stopgap measure until I do. Slow-speed aux fans would fit the ticket very well, since I'm not really seeing any heat issues at even moderate speed.

How about the ACM clutch? It is thinner than OE and it works too.

 

[gsxr]

Jlaa, this is the M117 engine, with an AMG fan clutch... not sure how or why it's different, but I don't know if there's an ACM version available that is thinner than the stock/standard M117 AMG clutch.

Vesken, can you post a photo of your HWA- fan clutch?

 

[Jlaa]

Jlaa, this is the M117 engine, with an AMG fan clutch... not sure how or why it's different, but I don't know if there's an ACM version available that is thinner than the stock/standard M117 AMG clutch.

Oops sorry. I thought this post was previously in the M119 section or perhaps I'm just confused.

 

[gsxr]

Oops sorry. I thought this post was previously in the M119 section or perhaps I'm just confused.

The post was originally in the M119 section... a helpful admin must have relocated it.

 

[gerryvz]

Good to know there are admins who are moderating the forum, moving posts to appropriate forums and keeping the trolls at bay.

i don’t recall an ACM clutch being available for the M117; only Behr.

if you take the dimensions of your special AMG clutch, I wonder if you could adapt a similar sized clutch from another engine application. Chances are something can be found.

I recently learned that the clutch from a Nissan QashQai (Rogue in the US) is an identical fit for the M103, and is much cheaper to boot.

 

[jhodg5ck]

Since this is my first post here, I've just got to say thank you very much for all your amazing walktroughs on all sorts of repairs. I've been lurking here a long time, and used a lot of your M117 posts as reference when I've been working on my own. It's been a real lifesaver.

As for this post; I had most of the problems you mentioned on my M117, and have now finally fixed pretty much all of them. However, in the process, I've had to pull my condenser, plug the AC lines, and disconnect the compressor (for the time being). I'm also down one fan clutch and primary engine fan, so the aux fans are my only option for active cooling for now.

My question is: Would there be any downsides to me just shorting the red pressure sensor switch, bypassing it completely, so that the aux fans always run on low setting?

What M117 in which chassis? We don't have this issue with any of the M117 equipped AMG's that we have. Curious what you have going there...



Jono

 

[Vesken]

What M117 in which chassis? We don't have this issue with any of the M117 equipped AMG's that we have. Curious what you have going there...

It's, ah, not technically an E-class at all - it's a 500 GE, with the 117.965. Hope that's all right! There's very little information for them, so I gather what I can wherever I can.

 

[gerryvz]

Ah yes, so there was a lot of special stuff on that engine. I have a 1995 G320 from the same era. It takes a special fan clutch for the M104 that is only applicable for the G-wagen, not for regular M103/104 engines.

I have a friend in Germany who has the same G that you do. I will get you in touch with him as it is VERY likely he can help you.

 

[Vesken]

Wow, that would be something! And yes, no kidding about the special stuff. My favorites so far are the radiator hoses which uses (and are stamped with) the exact same part numbers as the corresponding regular Mercedes-Benz ones... except that the tubes you actually want come with "HWA" instead of just "A" before the string of numbers. This prefix, of course, is not included in the stamped-on number. Thanks, AMG!

 

[gerryvz]

There were only ~500 of the M117 G’s built so they are rare. I have only seen two of them in person. They are painted in a special blue/purple color. An AMG model would even be rarer.

my friend can definitely help you. He is one of the best experts on G-wagens in Germany. His name is Fabian. I’ll get you his information. He speaks good English and has a lot of sources for parts and much knowledge about the G.

 

[TerryA]

Vesken,

If Gerry’s friend Fabian can help you, please report back the solution to us.

 

[Vesken]

That I will certainly do! This board has provided me with a wealth of information on the details of less obscure parts of my engine, so if I can help someone else resolve this problem when another such fan clutch inevitably fails somewhere down the line, I'll just be glad to have shared a solution here myself.

 

[gerryvz]

I sent you Fabian's information via private conversation.