Radiator fan bolt spacing for non-clutch plastic fans? - PeachParts Mercedes-Benz Forum

Shortsguy1 · #1 04-17-2015, 11:29 PM

Hi-
Does anyone know the distance between the bolt holes on any of the plastic Mercedes fans (with 4 bolt holes)? Are these standard with other companies water pumps which use 4 bolts? Here I am specifically focusing on fans without a clutch.

For instance, my 220D has a 4-blade, 4 bolt fan 1082050906, which looks like:
https://www.google.com/search?q=1082050906&source=lnms&tbm=isch&sa=X&ei=dKoxVZCvOKPLsASv_oC4CQ&ved=0CAkQ_AUoAw&biw=1047&bih=534

Would it be interchangeable with either of the following:

1) The w123 240D has a 5-blade, 4 bolt fan (part 1152050406), which looks like this:

https://www.google.com/search?q=1152050406&source=lnms&tbm=isch&sa=X&ei=ntAxVeXsJ-S1sASAvYCAAg&ved=0CAkQ_AUoAw&biw=1047&bih=534

or

2) Toyota sells a 6-bladed, 4 bolt fan (their part 16361-60090 for mid-1970s Landcruiser) which looks like it could be compatible:
Radiator Fan 74-80 [16361-60090] - $86.72 : CruiserParts.net, Toyota Landcruiser Parts

Is there a way to know in advance if either the 240D fan or the Toyota fan would attach easily to my 220D water pump? As an aside, I am not too concerned about diameter as I can trim blades and rebalance if needed. Just looking at easy ways to get a bit better airflow. Thanks.

VT220D · #2 04-18-2015, 12:56 AM

The bolt pattern is 1 3/4" with a 5/8" arbor. This pattern is common to many American cars including Ford and Chevy. I have a Ford water pump pulley for my OM616 that fits the pattern perfectly but doesn't quite make the belt line.

You can use the 5 blade plastic fan from the W123. In fact that fan has a 115 part number since it was used on 74-76 240D's. The early fans are yellow plastic and should be avoided due to cracking around the mounting holes. Later fans are black and at 1lb. 5oz. weigh considerably less than the yellow fans. Both weigh a lot less than the fan/clutch assembly (4 lbs. 4oz.)

The reduced rotating mass and simplicity have their advantages. I've converted two 220D's to the black fan with excellent results. Mercedes took this approach too.

All you need to do is remove the studs and bolt up the fan. It can be done with the shroud in place - at least on non AC cars.

Another point worth mentioning is the pulley ratio. The 220D has a water pump to crank ratio of 0.9 to 1. This ratio was increased to 1.08 to 1 in the W115 240D when the fixed fan was first adopted. Once the W123 was introduced the W115 fan was carried over and the ratio returned to 0.9 to 1. These ratios remain the same whether the car has AC or not.

The ratio jump from 0.9 to 1 up to 1.08 to 1 was effected by increasing the crank pulley from 4.875" to 5.875". The water pump pulley remained the same. The increase in crank pulley diameter had the additional effect of increasing alternator RPM. When the OM617 was introduced in the W115 the water pump pulley diameter was increased to 6" This reduced the water pump ratio from 1.08 to 1 down to 0.98 to 1 while maintaining the alternator speed increase.

All of this is to say that Mercedes started with a 0.9 to 1 ratio and a clutch fan on the W115 220D and after several revisions ended up with a 0.9 to 1 ratio and a 5 blade fixed fan on the W123 240D. This conversion should work just fine.

Shortsguy1 · #3 04-20-2015, 09:30 AM

Thanks VT220D. That is interesting that the MB bolt pattern matches some American cars. I would never have guessed that.

Does anyone know if this bolt pattern is universal? I saw that BMW used non-clutch plastic fans in some of their cars from the 60s and 70s. And that Toyota fan I mentioned above. What are the odds that all these plastic fans have the exact same bolt pattern? Probably not high, but I am curious. I tried to search this info out on my own but failed.

VT220D · #4 04-21-2015, 12:13 AM

You're welcome. We W115 folks have to stick together!

Information on fans and clutches is hard to come by. Everything is cataloged by application rather than dimension. I can tell you that fan mounting dimensions are not universal but there are some common dimensions like certain Ford/Chevy/Mercedes. I don't know about BMW. Toyota doesn't fit. However that's only part of it. You'll need a diameter and spacing very close to stock or the shroud won't be effective.

What are you trying to achieve?

t walgamuth · #5 04-21-2015, 06:04 AM

I'm pretty sure I have a spare black five blade I'll sell reasonably.

Shortsguy1 · #6 04-21-2015, 06:25 PM

Quote:

Originally Posted by t walgamuth

I'm pretty sure I have a spare black five blade I'll sell reasonably.

Hi Tom. Thanks for the offer. The fans are very cheap via the dealer, so if I decide to use the 240D fan, I will probably just buy new. MSRP is $31 and you can find it for low $20s from those online MB dealer websites.

VT220D, thanks again for the help. My 220d runs very hot at high load. I know that the general consensus is that at freeway speeds, the fan doesn't do much. But I switched from a broken clutch/metal fan to the 220d fixed 4-blade fan, and it really helps with cooling, even when going 45 mph up a steep hill. So I just want to see what my options are to improve things even more. The fan I am using if from the junkyard, so I want to buy a new one to ensure it doesn't break.

I know I have mentioned this before, but it is odd that the very earliest 220Ds came with a clutch and metal fan, but all of the later 220D or 240Ds went to rigid plastic fans. Clearly plastic weighs less, so that is an improvement. But not having a fan clutch has to be a detriment on such a low power vehicle.

t walgamuth · #7 04-21-2015, 07:31 PM

When you are moving down the highway the fan essentially is freewheeling.

VT220D · #8 04-21-2015, 10:06 PM

[QUOTE=I know I have mentioned this before, but it is odd that the very earliest 220Ds came with a clutch and metal fan, but all of the later 220D or 240Ds went to rigid plastic fans. Clearly plastic weighs less, so that is an improvement. But not having a fan clutch has to be a detriment on such a low power vehicle.[/QUOTE]

I don't know why Mercedes abandoned the clutch fan. They had a name for it like "fuel saver" which implies its obvious advantage on a 60hp engine! On my first 220D (71) I replaced the clutch fan with a 5 blade and noticed no loss of power. I went with the 5 blade after a fruitless search for a good used clutch. New ones are expensive!

I agree with buying a new fan. They are cheap and the older ones are often cracked at the mounting holes.

I remember your cooling thread and I was surprised by how hot your engine runs. Before changing the thermostat configuration my 220d ran cold even on 90+ degree days. In traffic my temp would drop to 160 degrees. Only under load could I hold 180 degrees. Cruise temps would drop to 160. Opening the heater valve would drop the temp another 40 degrees for a short while. I tried and tested several thermostats. Basically my engine cooled too much just on the thermostat bypass flow. All of this was verified with a Fluke IR thermometer. The solution was a conversion to the W123 3 stage thermostat. Now I can attain thermostatic temperature at any load.

I can go above thermostatic temp but only by climbing a long grade at high speed. For instance while traveling at 80 mph through Oklahoma in August with three people and luggage I hit maybe 200 degrees for a short time. In fact my avatar picture is from that trip.

I know you've done several flushes etc. However, I wonder about the condition of your water pump impeller and housing. Also, is your water pump bypass tube plugged? This tube purges air from the pump housing and can clog easily. Your pump may have a large air pocket that prevents it from coping with heavy loads. Another item that comes to mind is a rubber flow restrictor that goes between the thermostat housing and the head. I've never seen one in the wild but I have seen it in the factory manual. If this item was later discontinued a 1968 car would be most likely to have it.

noahlambert · #9 02-27-2016, 02:52 AM

The above photo is from a 1968 optional accessories catalog.

More period Mercedes literature here: www.oudemercedesbrochures.nl

Is it possible the early cars with fan clutches were simply optioned that way?

leathermang · #10 02-27-2016, 12:13 PM

' Flushes' will not get the gunk accumulation you almost certainly have at the lower back of the coolant passage in your block...
To possibly get that out you will need some kind of physical aggravation... think ' roto rooter' ... WHILE flushing or better yet Vacuuming ... a shop vac for safety of course..
' Stuff' precipitates out where the flow is least and turns back towards the pump... it just falls to the bottom of that cavity and hardens up..
This is why in the old days.... rebuilds involved ' Vatting' the block... everything was taken off including the core plugs ( freeze plugs ) and it was lowered into a hot caustic solution... then cleaned up and the machining done to it....
You almost never see that happening to these engines.....but that does not mean that gunk is not slowly building up over the decades....
Harbor Freight has a roto rooter for cheap... might need to alter the end... and lots of patience and repetition is needed if you need to address the potential overheating cause...