Can I get by without aux fans? 1995 W124 E300D - Page 2 - PeachParts Mercedes-Benz Forum

shertex · #16 07-15-2013, 07:11 AM

Quote:

Originally Posted by zakatekaluka

Oh word of caution, my friend. I love my diesels, but I also own a 95 e320...same fan system, same gauge system and I can tell you for a fact that those gauges are merely feel goods. My engine was overheating like you wouldn't believe and the gauge didn't move over 100. Don't trust the gauge. NEVER trust just the gauge! However, if you know the other signs of an overheating engine, I'm with ya on simply being careful. Use common sense and you should be just fine.

What are the other signs? I'd be grateful to have as complete a list as possible.

ah-kay · #17 07-15-2013, 11:40 AM

Quote:

Originally Posted by EDBSO

In my opinion the aux fans when seized block a lot of air from entering the rad. If you are not going to repair then I would remove them to increase air flow to the cooling system. Just my opinion.

What is the difference between a STOP and a seized aux fan? They are all in front of the radiator, with the same number of blades partially blocking the radiator. It does not make sense to remove it.

I am not familiar with the OM606 but the OM603 aux fan serves 2 functions - turns on at slow speed for AC and at high speed at 100C ( or 105C ). If your car has NO working AC and it is NOT overheating then it can be deemed unnecessary.

compu_85 · #18 07-15-2013, 11:53 AM

Actually while you're moving the airflow will make the fans spin. If they're dead, I'd get them out of the way.

Zulfiqar · #19 07-15-2013, 12:51 PM

The fans work from A/C pressure switch (low side) and high temperature of the engine (high speed).

You can replace the pair with genuine MB items or even stick a pair of aftermarket ones on there. You can also ditch the clutched fan and use one large electric fan with a variable speed controller to cool the whole thing down. The later MBs have that.

Chris W. · #20 07-15-2013, 12:57 PM

Pulling the fans for additional airflow aside, if you pull them, you then have the opportunity to clean out all the built up crud which is lodged in the radiator (or is it the condenser... doesn't matter) fins behind the front fan shroud. I'm not kidding that my normal operating temperature dropped a few degrees just by cleaning out that mess of built up bugs, sticks, and leaves.

Rgds,
Chris W.
'95 E300D, 398K

chronometers · #21 07-15-2013, 02:42 PM

My aux fans hardly if ever come on. I run my AC in summer.

When I pulled the temp. sensor plug at front of block they both came on high.

My temp gauge is normally a bit above 80C and hardly ever climbs above 90C.

gsxr · #22 07-16-2013, 11:49 AM

Shertex, what makes you think the fans are bad? Most of the time the problem is either a blown 30A strip fuse, or a broken wire at the ceramic resistor below the ABS pump.

The fans should run on low speed when the AC is on (based on refrigerant pressure), they trigger on high speed when engine temp exceeds 107C. The easy test is to disconnect the 2-pin sensor on the top/front of the engine with the engine running, this normally should kick the fans on high speed. If they don't engage, check the fuse, then check the wires at the resistor.

BTW, the dash temp gauge is VERY accurate on the W124, and other models which use a similar gauge (W201, W123, etc). If it's not accurate, either the sender or gauge is bad. A new sender is cheap insurance after 20+ years, just make sure to only get OE/OEM sender (Hella, VDO, Beru, etc) and not the Chinese junk senders (Uro, FAE, APA, etc). This isn't the place to try and save five or ten bucks. OE is ~$25, Beru is ~$15, Chinese junk is under $10. How much is your engine worth to you, including labor to replace it?

shertex · #23 07-16-2013, 12:41 PM

Quote:

Originally Posted by gsxr

Shertex, what makes you think the fans are bad? Most of the time the problem is either a blown 30A strip fuse, or a broken wire at the ceramic resistor below the ABS pump.

Thanks, Dave. Wire looks good. Where's the 30A strip fuse located? I had assumed that the 16A fuse designated aux fan was the fuse.

gsxr · #24 07-16-2013, 12:50 PM

Quote:

Originally Posted by shertex

Thanks, Dave. Wire looks good. Where's the 30A strip fuse located? I had assumed that the 16A fuse designated aux fan was the fuse.

It depends... MB did some changes on the auxiliary fan fuse location as of 1994, and I'm not positive what will be on your 1995 E300. Look for a strip fuse holder on the driver's strut mount, and also near the brake booster. If there are TWO of the 30A strip fuses, one is for the internal HVAC blower, the second is for the auxiliary fans. If you only find one... it's for HVAC.

The auxiliary fans on the 1994-95 E420 and E500 changed to using two fused relays in the relay compartment, behind the main fuse area. You need to remove the cover (six Phillips screws) to access the relays. The low speed relay has a 15A fuse, high speed has a 30A or 40A fuse. It's possible your E300 uses the fused relays. The EPC seems to indicate it may have the fused relays, not the external 30A strip fuse.

BTW - the early 124's with single fans have a 16A fuse. The mid-production M119 models with twin fans have a 30A external strip fuse. And at least the M119-engined 94-95 models switched to the fused relays. Hopefully someone can confirm if the M104/OM606 are the same way, or not. I can't imagine the twin fans running with the 16A fuse, I believe the twin fans pull >25A on high speed...

shertex · #25 07-16-2013, 01:09 PM

Thanks...I'll pose question on separate thread to find out for sure.

compu_85 · #26 07-16-2013, 03:16 PM

Interesting on the strip fuse... the dual fan W126 cars have a 16 amp fuse for the low speed, and a 40 amp fuse built into the high speed relay.

-J

shertex · #27 07-16-2013, 03:20 PM

As it turns out, I have something similar after all....16A and 30A on the realy.

gsxr · #28 07-16-2013, 04:39 PM

Quote:

Originally Posted by compu_85

Interesting on the strip fuse... the dual fan W126 cars have a 16 amp fuse for the low speed, and a 40 amp fuse built into the high speed relay.

The 1992-1993 W124 with M119 has a 30A strip fuse with a single, double-size, unfused relay. The 1994-1995 W124 with M119 has two separate, normal-size, fused relays. I'm not sure what the 1990-1995 W124's with non-M119 engines use.

Quote:

Originally Posted by shertex

As it turns out, I have something similar after all....16A and 30A on the realy.

You mentioned there was a relay next to the fused 30A that was a fused 15A, correct? This is likely the low-speed fan relay. The 16A ceramic fused may not be used, or might be for the control circuit... not sure...

Quote:

Originally Posted by shertex

Thanks...I'll pose question on separate thread to find out for sure.

Please post the URL when you start the new thread. Some of us don't browse the forum much and would never find it...

shertex · #29 07-16-2013, 05:04 PM

Quote:

Originally Posted by gsxr

Please post the URL when you start the new thread. Some of us don't browse the forum much and would never find it...

Not much of a thread....sort of answered my own question. Where is strip fuse for aux cooling fans located? 1995 E300D

DrLou · #30 07-17-2013, 12:54 PM

Shertex: Some thoughts on your aux fans question.

Mine never comes on without the AC running, even on the hottest days, running at highway speeds. It's really all about removing the very high heat buildup from the AC condenser... Mine comes on almost immediately when the AC starts running.

Advice from others here to clean out all fins in the radiator - and the condenser; which, ultimately, could block airflow to the radiator! - is excellent, and should be heeded.

Also perhaps useful: I was able to rebuild my Aux Fan myself, using inexpensive carbon brush stock I sourced from one of those hardware assortment aisles - does anybody remember the venerable old Sears?

I found the closest (over)size, and used the Dremel to size/shape them correctly. This repair could save you many hundreds of $$...

Total parts cost <$10, plus a bit of Labor of Love. Has been working great for 10+ years.

I have a feeling that, knowing our Daimler Engineering Friends, the radiator/water pump system is more than adequate to cool the engine within the full operating envelope. This assumes an unobstructed condenser, of course, on an AC-equipped car.