Ping: Mike Romain

Mike, my daughter and her "new" Nissan truck are causing me problems of a
type you can probably diagnose.

The thing is a V-6, 4x4 PT, 5-spd manual. She came in the other day
worried about a slipping clutch. Under light load on a level road doing
seventy five (or more - I know her) she says that the engine suddenly
accelerated. No change in speed, no surge. She says that she was getting
the same engine noise on the way over to the house, but only when the
engine was warmed up good. I took it out and drove the dog p$$$ out of it
- jackrabbit starts, full throttle with a lugged engine uphill, and such
and I can tell you that that is one good clutch <g>.

Anyway, we head off down the open highway and she points out what she was
hearing. With no other sympthoms, the engine noise would increase, then
fall off a bit. The engine noise sounded too loud to me so I checked - the
fan clutch was tighter than a Scotsman when the outside temp was in the
low 30's (F). Even cold, I could basically slip the belt trying to turn
the fan. My guess is a clutch locking up and the fan running at
high speeds making the noise. Doesn't the fan clutch sense the temp of
the airflow rather than engine temp? Otherwise, why is it such a power
saver at highway speeds?

I'm ready to just swap the fan clutch but thought I'd get your take first
- they sure are proud of those things for a Nissan! Oh, and have you ever
heard of a reverse rotation fan? Looking at the parts catalogs, I see
about half specifically call out "standard rotation". Never saw that on
anything beside the water pump before.

On Fri, 17 Nov 2006 22:59:47 -0500, Will Honea >
wrote:

>Mike, my daughter and her "new" Nissan truck are causing me problems of a
>type you can probably diagnose.
>
>The thing is a V-6, 4x4 PT, 5-spd manual. She came in the other day
>worried about a slipping clutch. Under light load on a level road doing
>seventy five (or more - I know her) she says that the engine suddenly
>accelerated. No change in speed, no surge. She says that she was getting
>the same engine noise on the way over to the house, but only when the
>engine was warmed up good. I took it out and drove the dog p$$$ out of it
>- jackrabbit starts, full throttle with a lugged engine uphill, and such
>and I can tell you that that is one good clutch <g>.
>
>Anyway, we head off down the open highway and she points out what she was
>hearing. With no other sympthoms, the engine noise would increase, then
>fall off a bit. The engine noise sounded too loud to me so I checked - the
>fan clutch was tighter than a Scotsman when the outside temp was in the
>low 30's (F). Even cold, I could basically slip the belt trying to turn
>the fan. My guess is a clutch locking up and the fan running at
>high speeds making the noise. Doesn't the fan clutch sense the temp of
>the airflow rather than engine temp? Otherwise, why is it such a power
>saver at highway speeds?
>
>I'm ready to just swap the fan clutch but thought I'd get your take first
>- they sure are proud of those things for a Nissan! Oh, and have you ever
>heard of a reverse rotation fan? Looking at the parts catalogs, I see
>about half specifically call out "standard rotation". Never saw that on
>anything beside the water pump before.

If it is the fan clutch, then it probably is working as intended....
(IMHO, YMMV however).

How long did she have the truck? Was there a time when this didn't
happen? I knwo that some people tend to (especially when the vehicle
is 'new' to them) amplify and agnoize every little sound! <bg>

That does sound like a bad clutch. When the fan is locked spinning it
makes an amazing roar compared to the working clutch. I have a fixed
fan in my CJ7 and a clutch in my Cherokee so can easily hear the
difference.

I do not know if her engine is a reverse rotation one or not. I know on
the Jeep engines, the serpentine belt versions are reverse rotation and
the V-belt version is a normal rotation system.

I don't know what differentiates between the Nissan systems.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Will Honea wrote:
>
> Mike, my daughter and her "new" Nissan truck are causing me problems of a
> type you can probably diagnose.
>
> The thing is a V-6, 4x4 PT, 5-spd manual. She came in the other day
> worried about a slipping clutch. Under light load on a level road doing
> seventy five (or more - I know her) she says that the engine suddenly
> accelerated. No change in speed, no surge. She says that she was getting
> the same engine noise on the way over to the house, but only when the
> engine was warmed up good. I took it out and drove the dog p$$$ out of it
> - jackrabbit starts, full throttle with a lugged engine uphill, and such
> and I can tell you that that is one good clutch <g>.
>
> Anyway, we head off down the open highway and she points out what she was
> hearing. With no other sympthoms, the engine noise would increase, then
> fall off a bit. The engine noise sounded too loud to me so I checked - the
> fan clutch was tighter than a Scotsman when the outside temp was in the
> low 30's (F). Even cold, I could basically slip the belt trying to turn
> the fan. My guess is a clutch locking up and the fan running at
> high speeds making the noise. Doesn't the fan clutch sense the temp of
> the airflow rather than engine temp? Otherwise, why is it such a power
> saver at highway speeds?
>
> I'm ready to just swap the fan clutch but thought I'd get your take first
> - they sure are proud of those things for a Nissan! Oh, and have you ever
> heard of a reverse rotation fan? Looking at the parts catalogs, I see
> about half specifically call out "standard rotation". Never saw that on
> anything beside the water pump before.