Maxim X Radiator Fan Switch Modification (UPDATE)

Hi,
Sorry if this is a topic that's been covered. I picked up an '85 Maxim X last weekend; for some reason the previous owner had wired in a toggle switch (taped next to the ignition key slot) to turn the radiator fan on / off. Does anyone have any idea why someone would do this? I'd like to revert it back to the stock condition, but have no idea where to begin since I don't know how the system functioned originally. I'm interested in any thoughts on the matter.

Thanks!
-steve

 

Re: Unwanted Maxim X Radiator Fan Modification

Steve,

The previous owner had one of two reasons for putting in the switch. The first would be that the Thermo Switch (located on the thermostat housing) was not switching on the fan at higher temps. The other being that they wanted to have control over when the fan came on. Typically you would turn it on manually when the engine is at a lower operating temp if you get stuck in traffic.

Does the fan work when you switch it on manually? If so, and if you wish to revert back to the stock setup, you'll have to patch up the wiring then check to see if the thermo switch operates. It should switch on the fan between the middle mark and the red line on your temp gauge.

Tony

 

Re: Unwanted Maxim X Radiator Fan Modification

Tony,

thanks for the feedback! Yes, the fan works (ingnition ON, toggle ON). For now, I'll use your guidance to switch the fan on at the right time. I'm going to try to patch up the wiring, as soon as I figure out how it's all supposed to be routed; I wish I had an example to look at. I'll look around for a service manual first.

FYI, here is a picture of the switch mod, and the bike itself (I'm pretty happy with the purchase )

-steve

 

Re: Unwanted Maxim X Radiator Fan Modification

The fan normally kicks on when the temp needle gets up into the red zone, so you could wait and see if it kicks on by itself. I was under the impression that people who made this mod wired the switch in parallel so it could be removed later.

Chacal has them, last I checked. Ask for part number HCP1145.

 

Re: Unwanted Maxim X Radiator Fan Modification

That bike looks real nice. Same color as the 85 700x I sold in June.

BTW, make sure your tires and brakes (front and rear) are safe. Even though they may look good (check the date codes on the tires) as you may have to replace some items to be sure.

On the fan issue, it's best to have a manual with a wiring diagram. That will also have a flow chart on how to check the fan operation.

 

Re: Unwanted Maxim X Radiator Fan Modification

Thanks everyone for the advice and safety tips. Going to do a top down overcheck of all systems before any serious riding (that's what's winter is for, right?). She's a good runner though, and I couldn't go wrong picking up a Maxim X with 9K miles for $1900.

This fan switch is goofy; it's wired such that when the key is on (engine running or not) you can manually switch the fan on/off. I'm inclined to agree with Tony that the thermo-switch went bad and this was a workaround - can't tell for sure though because the thermo-switch appears to have been bypassed (service manual to the rescue!). In case anyone's curious, I pulled off the front fuse panel and took another pic of the hack job. Anyone know what the top right 30A fuse is for (where the red lead is spliced in)?

 

Re: Unwanted Maxim X Radiator Fan Modification

That fuse is for the Signals and it's marked on the inside of the fuse cover. BTW, it should be a 15Amp fuse. I guess they wanted to connect up to a "Hot with the key on" point where they could splice it in.

Kinda frustrating when you discover stuff like that. Just makes you want to get started on your "Winter project" sooner so that you can sort out all the stuff that needs attention.

 

Re: Unwanted Maxim X Radiator Fan Modification (update)

UPDATE: After spending some more time researching the forums, I owe the previous owner an apology (and a big thank you for selling me his garaged, rust free, super clean XJ700XN with only 9K miles!). Turns out that adding a manual radiator fan switch to these bikes is fairly common; in fact there are several posts describing how to do it. By design, the thermo switch doesn't signal the fan to kick on until the temperature gauge is just touching the red zone; which is fine for cruising speeds, but can be disconcerting when sitting in traffic while the temperature hovers near the red line. The manual switch allows you to have more control over the engine temperature in these situations.

That being said, I didn't like having a switch taped onto the handle bars, and decided to try something I saw on the V-Max forums (apparently they suffer from the same issue): replace the stock thermo switch (Yamaha OEM part number 2EL-82560-00-00) with an aftermarket switch that signals the fan to come on at a lower temperature (about 20 degrees cooler).

First, I pulled out the manual switch installed by the previous owner, installed the proper 15 amp fuse in the upper right slot (thanks xHondaHack for noticing this), and rewired everything to the original condition. Fired it up, relaxed with a cold beverage and watched closely. Sure enough, right at the redline the fan kicked on (it's easy to see with a flashlight from behind the radiator), thus everything was working as designed. Could have stopped there but decided to take it one step further.

****Disclaimer*** read on only if you're curious...this is not a recommendation to modify a perfectly functioning bike (if it ain't broke...you get the point)...

From the V-Max forum I learned that the fan switch for the 1988 Nissan Sentra fits the Maxim X, and sends a signal at a slightly lower temperature, providing additional cooling margin. For around $20 bucks, I purchased the Wells SW537 switch. The male connector on the aftermarket switch isn’t compatible with the female one on the bike, but it was easy to modify to make it fit. In the photo, you can see the aftermarket thermo switch (after I cut off the Nissan male connector), and the flat electrical connectors that I soldered on to get it to work with the Maxim X.

After preparing the switch, next I drained the radiator, removed all the hoses from the thermostat housing, and pulled the housing (the service manual comes in handy here). With the thermostat housing sitting on the work bench, it was easy to remove the stock thermo switch and install the aftermarket one. It was also a good opportunity to remove the thermostat and check the functionality (again, according to the instructions in the service manual).

Putting everything back together was fairly smooth, except that the new switch sticks out a little bit further than the stock one, so it took awhile to find the perfect angle to fit the thermostat housing back into the frame.

I flushed the radiator, refilled with coolant, crossed my fingers and fired it up. I'm pretty satisfied with the results; the fan now switches on when the temperature indicated on the gauge is at the 12 oclock position. When cruising, the bike runs at the same temperature as before, but stays away from the red zone when idling in traffic.

 

Re: Unwanted Maxim X Radiator Fan Modification

here's a photo of the position of the temperature gauge just before the fan kicks on with the lower temperature thermo switch installed. It ultimately goes a bit higher than this, but stays well away from the red zone.

 

Re: Unwanted Maxim X Radiator Fan Modification (UPDATE)

Hey Pick......nice job there. Contact Len Chacal at XJ4Ever, and make sure he sees this procedure. Looks like you may have a winner there for a good write-up for his site and/or for the xjcd, too.

Dave Fox

 

Re: Unwanted Maxim X Radiator Fan Modification (UPDATE)

Nice setup with the new switch. Now you won't have to worry about switching the fan on manually.

 

Re: Unwanted Maxim X Radiator Fan Modification (UPDATE)

sent a PM to Mr. Chacal. And yes, it will come in handy, especially during our blast furnace summers here in the eastern washington desert

 

Re: Unwanted Maxim X Radiator Fan Modification (UPDATE)

This is a great mod for the X thanks for doing the leg work, it's something I think I'll try. Do you have any pics of the swith mounted?

 

Re: Unwanted Maxim X Radiator Fan Modification (UPDATE)

X2 - add a few more pics and you'll be golden!

good work!

 

Re: Unwanted Maxim X Radiator Fan Modification (UPDATE)

I've had this concern with my bike since I've owned it. The whole waiting for the fan to kick on so late while in traffic is stressful. I'm gonna have to do this one

 

Re: Unwanted Maxim X Radiator Fan Modification (UPDATE)

Sorry for not taking more pics during the job. You can get the basic idea from the Parts List (see picture below). The thermo switch (part 13) threads into the thermostat housing (you have to pull the thermostat housing to get to the switch).

The original yamaha stock switch has two male connectors that plug into the two female connections on socket cord assembly (part 15) which is part of the bikes electrical system. The aftermarket Nissan switch has a large plastic connector that I cut off and then replaced with some fittings that were close in shape and size to the male connectors on the stock switch. The modified Nissan switch will now plug directly into the bike's socket cord assembly.

The good thing about this approach is that you do not have to modify any of the OEM parts in any way; that way, if you need to, you can put it back the way it was (you did read my disclaimer, right?)

 

Re: Unwanted Maxim X Radiator Fan Switch Modification (UPDATE)

That makes it a lot clearer and esier to understand.
Great work!

 

Re: Unwanted Maxim X Radiator Fan Switch Modification (UPDAT

Thanks for this. I have been considering the manual switch for some time, but didn't want to add a cheezy switch. This will provide the safety margin desired in a non-obvious way.

 

Re: Unwanted Maxim X Radiator Fan Switch Modification (UPDAT

Thanks for the pictures and description on the how to. Looks to be a simple enough mod and I think I'll be doing it as well.

 

Re: Unwanted Maxim X Radiator Fan Switch Modification (UPDAT

Since folks are going to try this, I want to make clear that I’m no mechanic, so please be thorough and cautious - modify at your own risk!!. Along these lines, some thoughts for discussion:
1) you can plug the thermo switch in two ways. From my limited knowledge of electronics, based on where it is in the circuit, I don't think it should matter which way the thermo switch gets plugged into the socket cord assembly. I only tried it one way, and it worked. The fan should draw air through the radiator toward the engine; that is spin counterclockwise when looking at the fan from behind the radiator.
2) Why did Yamaha design it this way in the first place? There is surely an optimum operating temperature for the engine. From what I've seen, the lower temperature switch mod doesn't change the temperature when cruising, which kind of makes sense because a lot of air is being pushed through the radiator with or without the fan running. With the switch mod, the engine temperature is maintained at the cruising speed value ALSO when idling; which I perceive as being a good thing. I feel better looking at that temperature gauge and seeing it hold steady at 12 oclock high.
There is also this piece of information from the XJ700XN Owners Manual: "Engine Temperature Gauge: This gauge indicates the coolant temperature when the main switch is ON. The engine operating temperature will vary with changes in weather and engine load. If the needle points to the red zone or higher, stop your motorcycle and let the engine cool. Caution: When the engine is overheated, do not continue riding"
3) I used the o-ring provided with the aftermarket Wells switch; I'm not sure if it is the same as the one originally supplied with the bike. I used a LITTLE bit of high temp RTV around the seal and threads just in case. I don't know if that was good or bad, but there are no leaks; so at least that's good.
4) pay attention to how you remove the thermostat housing from the frame, it's a tight fit and the orientation is key. You'll reverse the procedure to get it back in. Also move all the radiator hoses well out of the way, you'll need the room.
5) the blue electrical connectors I used were slightly larger than the gauge wire used on the Wells switch. I pinched them on with needle nose pliers and then soldered the wires in, so it was good and secure. Perhaps you can find similar connectors with a slightly smaller diameter to fit the wire better.
6) if anyone tries this and finds a better / easier way, please share.