Radiator Fan Clutch Failure Modes

[Carimbo]

Hi,

What are the failure symptoms for the rad fan clutch?

I am starting to hear a definite fan whir at higher RPM's and speeds. Comes and goes intermittentely. For ex., on the freeway at constant speed, I will hear the fan whir start up, last for 10-12 seconds, then quiet again.

What controls the freewheel/lockup modes? I recall seeing a "windup clock spring" in the center of the fan clutch when I changed the waterpump last Sept. It was intact, not corroded or rusty.

[asavage]

The fan clutches I've had go bad on me (three) all failed in the same way: locked up. I don't know about one that comes & goes. I've seen a couple that failed to turn enough (leading to overheat and overpressure in A/C situations).

If the fan is changing speed at highway speed, you will notice a very definite power loss when it spins up. It's really not something you can not notice.

[glenlloyd]

Hi,

What are the failure symptoms for the rad fan clutch?

I am starting to hear a definite fan whir at higher RPM's and speeds. Comes and goes intermittentely. For ex., on the freeway at constant speed, I will hear the fan whir start up, last for 10-12 seconds, then quiet again.

What controls the freewheel/lockup modes? I recall seeing a "windup clock spring" in the center of the fan clutch when I changed the waterpump last Sept. It was intact, not corroded or rusty.

The fan engages / disengages by virtue of a thermostatic coupler. If your fan is engaging / disengaging fairly often there could be a problem, unless you're in a climate that happens to be warm right now. The fan may simply be responding properly, I don't know for sure. If your engine is at or slightly above normal operating temp it may coming on normally. If however, you're in a cold climate as I am, it shouldn't really be coming on, even if the engine is at operating temp. In Iowa engine cooling during this time of the year can be handled by the opening / closing of the thermostat.

Good luck!

SA

[TheDieseliminator]

Where would be the best place to get a NOS radiator fan clutch? Is the radiator fan and radiator fan clutch the same between the LD28 diesel and L24E gasoline? Back when I bought my car it needed a radiator fan, so what I did was go to the junkyard and buy a used fan off a Maxima gas engine. Not to say he is right, but I remember the junkyard owner saying the radiator fans were the same on the gas and diesel.

[glenlloyd]

Where would be the best place to get a NOS radiator fan clutch?

My guess is the salvage yard, but you might try Nissan too. I have access to one Mk 1 Maxima, but it's in sad shape and there isn't much that's good on it, but the engine compartment I think is intact. That is unless they've decided to crush it.

Is the radiator fan and radiator fan clutch the same between the LD28 diesel and L24E gasoline?

Al can probably find this information for you. He has the final parts book for the Mk 1 Maxima, unfortunately I do not.

Back when I bought my car it needed a radiator fan, so what I did was go to the junkyard and buy a used fan off a Maxima gas engine. Not to say he is right, but I remember the junkyard owner saying the radiator fans were the same on the gas and diesel.

If you happen to have the FSM it might indicate a difference in the fans, but that's also a little out of the realm of the FSM too. I'll look when I get home to see if it says anything, but again, Al will have a better answer on this. Did you happen to keep your old one? If so, you could always compare the part numbers on the two to see if they happen to match.

SA

[asavage]

Is the radiator fan and radiator fan clutch the same between the LD28 diesel and L24E gasoline?

Al can probably find this information for you. He has the final parts book for the Mk 1 Maxima, unfortunately I do not.

I thought that you were going to buy that one on eBay . . . it's really a handy book.

Well, the Parts Catalog says the fan clutches are different. In fact, for the L24E, the fan clutch is sold as part of the water pump (this was the case on the 280Z and some of the 720 pickups as well).

However, Beck-Arnley (via NAPA) lists the same part No. for both the L24E and LD28 fan clutches. Go figure.

[Carimbo]

Looking in my '82 FSM, p. LC-18, the Engine Cooling System general specifications table shows a functional difference between the L24e and the LD28:
Fan speed (at waterpump 4000RPM)/temp*F
L24e = 2450/149-158, less than 1100 below 122*F
LD28 = 2550/140-158

So there was originally a (minor?) difference, but I bet many cars that have had the fan clutch replaced currently have the gasser clutch.

If mine goes out I will be looking to replace the entire fan assy. w/ a thermostatically-controlled electric fan.

[asavage]

If mine goes out I will be looking to replace the entire fan assy. w/ a thermostatically-controlled electric fan.

This is undoubtedly the best idea. I have had aftermarket electric fans on most of the vehicles I've owned in the past 20 yrs -- one kit I bought in 1981, I moved to the next four cars! -- and I like them. For some reason, I haven't done that on my current stable of rigs, but I'll get around to it eventually.

[glenlloyd]

I thought that you were going to buy that one on eBay . . . it's really a handy book.

I was, but wasn't paying attention to the closing time of the auction, so it came and went, and the buyer got it for $10...I was sooooo mad at myself! D'oh!!

SA

[philip]

Hi,

What are the failure symptoms for the rad fan clutch?

I am starting to hear a definite fan whir at higher RPM's and speeds. Comes and goes intermittentely. For ex., on the freeway at constant speed, I will hear the fan whir start up, last for 10-12 seconds, then quiet again.

What controls the freewheel/lockup modes? I recall seeing a "windup clock spring" in the center of the fan clutch when I changed the waterpump last Sept. It was intact, not corroded or rusty.

Take a look at this post over in the SD22 forum:

http://nissandiesel.dyndns.org/viewtopic.php?t=172

[Carimbo]

Interesting experiment, Philip. I have been experimenting at various times this winter with radiator covers (cardboard between the grille and A/C condenser). At 40*F ambient and below I can cover 80 - 90% of the radiator and the engine temp stays near normal under various loads. Above 40*F ambient and freeway speeds will raise engine temp a bit (almost 1/8 swing higher on the gauge) higher than normal. Unless it is raining. My theory is the cardboard gets watersoaked and cools the hot rad via water evaporation off the surface.

[philip]

Interesting experiment, Philip. I have been experimenting at various times this winter with radiator covers (cardboard between the grille and A/C condenser). At 40*F ambient and below I can cover 80 - 90% of the radiator and the engine temp stays near normal under various loads. Above 40*F ambient and freeway speeds will raise engine temp a bit (almost 1/8 swing higher on the gauge) higher than normal. Unless it is raining. My theory is the cardboard gets watersoaked and cools the hot rad via water evaporation off the surface.

Carimbo: Is this just an 'experiment' you are conducting or ... is there an overcooling issue in cold weather? May I direct your attention to:

http://nissandiesel.dyndns.org/viewtopic.php?t=65

[Carimbo]

Not overcooling in normal operation. Just an effort to get to operating temp from cold start more quickly in cold weather. The route I mostly take from my house has a long downhill which significantly delays the engine reaching operating temp. Running undertemp can damage the engine also-- I am trying to minimize the time it runs undertemp.

[philip]

Not overcooling in normal operation. Just an effort to get to operating temp from cold start more quickly in cold weather. The route I mostly take from my house has a long downhill which significantly delays the engine reaching operating temp. Running undertemp can damage the engine also-- I am trying to minimize the time it runs undertemp.

I understand now. Assuming you have a thermostat that really is completely closed when the engine is cold, and knowing this engine is a diesel (little heat generated under light load or coasting), there is little you can do to hasten warm-up time with the downhill coasting you do.

Having said this, there is one thing that you may be doing which will prolong warm-up time. That is ... turning the heater to full HOT. This will do a couple of things.

1)A larger volume of coolant now has to be heated which will take longer.
2)Any air passing over the heater core (especially outside air) will further prolong warm-up.