Greg,
If you have 20K miles on the fluid you should be changing it about every
12k Miles. I have switch to the Mobil 1 fluid and you can mix it also
without problems. Without being able to hear the noise I wouldn't say
for sure what it is. But the suggestion that it could be the fan clutch
is valid. If your note running the Hayden 2797 servere duty fan clutch
the lesser clutches have a tendency to fail. Look in your fan schroud
for oil spray. If it is a real heavy oil coating (silcone) the Fan
clutch is leaking. That what mine did when it failed.
J.R. Wright
GMC GreatLaker
77 Eleganza II
Michigan
>
> Hello all... Spinning off on this thread a little if you don't mind:
> I'm currently in Vail CO, in the midst of crossing the Rockies on I-70, and
> though my GMC usually has a decent amount of power for climbing hills, the
> 8,500-11,000 ft elevation areas were very difficult.... (also, i'm a little
> more loaded down than usual, but not towing anything). So, even while
> running the 85 octane that's recommended up here in place of 87, sometimes we
> were in the breakdown lane going 8 mph, and nursing it over the pass! Now
> i'm down at a modest 7,000 ft and acceleration is almost back to normal, but
> i am noticing a bit of noise upon acceleration that might be transmission
> noise. it happens when in park as well, but not as loud as when in gear.
> sounds almost like a muffled belt noise, but its really hard to tell the
> origin, even with the doghouse lifted while driving. however, the
> transmission still seems to be shifting normal, and though the fluid is about
> a pint or 2 on the low side, it doesn't smell burnt. I'd like to add some
> fluid to get me home, but i don't know what type was in there when i bought
> the coach 20,000 miles / 8 months ago, though it looked like it was freshly
> changed at that time. Is it OK to mix fluids? all i can say is that its a
> dark pink in color (is synthetic a different color?) The manual calls for
> Dexon II, though somebody gave me some Dexon III saying its no problem....
> I'll do a complete fluid and filter change when i get home, since i just
> noticed that the service manual recommends changing the fluid every 12,000
> miles! But what should i do for now?
> Secondly, wondering if altitude causes as much trouble with the
> vacuum/modulator as it does with the carb air mixture? In which case maybe
> this noise will just go away when i get down to sea level.
> OK, thanks in advance for any ideas.
> Greg
> '78 Eleganza II
If you have 20K miles on the fluid you should be changing it about every
12k Miles. I have switch to the Mobil 1 fluid and you can mix it also
without problems. Without being able to hear the noise I wouldn't say
for sure what it is. But the suggestion that it could be the fan clutch
is valid. If your note running the Hayden 2797 servere duty fan clutch
the lesser clutches have a tendency to fail. Look in your fan schroud
for oil spray. If it is a real heavy oil coating (silcone) the Fan
clutch is leaking. That what mine did when it failed.
J.R. Wright
GMC GreatLaker
77 Eleganza II
Michigan
>
> Hello all... Spinning off on this thread a little if you don't mind:
> I'm currently in Vail CO, in the midst of crossing the Rockies on I-70, and
> though my GMC usually has a decent amount of power for climbing hills, the
> 8,500-11,000 ft elevation areas were very difficult.... (also, i'm a little
> more loaded down than usual, but not towing anything). So, even while
> running the 85 octane that's recommended up here in place of 87, sometimes we
> were in the breakdown lane going 8 mph, and nursing it over the pass! Now
> i'm down at a modest 7,000 ft and acceleration is almost back to normal, but
> i am noticing a bit of noise upon acceleration that might be transmission
> noise. it happens when in park as well, but not as loud as when in gear.
> sounds almost like a muffled belt noise, but its really hard to tell the
> origin, even with the doghouse lifted while driving. however, the
> transmission still seems to be shifting normal, and though the fluid is about
> a pint or 2 on the low side, it doesn't smell burnt. I'd like to add some
> fluid to get me home, but i don't know what type was in there when i bought
> the coach 20,000 miles / 8 months ago, though it looked like it was freshly
> changed at that time. Is it OK to mix fluids? all i can say is that its a
> dark pink in color (is synthetic a different color?) The manual calls for
> Dexon II, though somebody gave me some Dexon III saying its no problem....
> I'll do a complete fluid and filter change when i get home, since i just
> noticed that the service manual recommends changing the fluid every 12,000
> miles! But what should i do for now?
> Secondly, wondering if altitude causes as much trouble with the
> vacuum/modulator as it does with the carb air mixture? In which case maybe
> this noise will just go away when i get down to sea level.
> OK, thanks in advance for any ideas.
> Greg
> '78 Eleganza II
