allison transmisson noise

[Janandoug]

I just purchased a 2003 Dolphin LX by National. Has a workhorse 8.1 and Allison 1000 transmission w/ 18400 miles. I recently drove it home from Florida to Iowa (1300 miles). There is a very strange noise (I believe a transmission noise) between 30 and 50 mph and appears to be only in third and fourth gears. It is a whine, howl, harmonic, kind of sound. If you accelerate rapidly or decelerate rapidly through the shifts it is hardly noticable but normal driving in those speed ranges the sound is very pronounced. It seems to be louderer with hot oil. Fluid level is correct and fluid is original as I recieved it. Shift up and down shift sequence and timing seem to be normal. Noise is always the same sound but volume varies from time to time. noise does not always start or stop at the same MPH, engine RPM doesn't seam to affect it much.
Any thoughts on this noise, has anyone ever experienced the same sound with the WKHorse/Allison setup. Thanks DH

[DAN L]

JANANDOUG:
WELCOME TO OUR FORUM.
i recently installed AMSOIL synthetic tes295 torque drive transmission fluid in my moho. (9k miles). some folks use transyd synthetic. i used amsoil because of their guarantee. it reduced the 2nd and 3rd gear "whine" considerable. i never noticed a 1st, 4th or 5th gear "whine".
get an allison filter pn 29539579, not a substitute. check the irv2 forum for reasons why. OEMY on irv2 has this filter available. there is a circular magnet that looks like a washer in a recess on top of the old filter. be sure to check it for metal, etc, clean it and install it on the new filter. i cut my old filter apart to check for debris and found none.
i found that a new allison 1000 transmission holds 14.1 qts. fluid on the allison website.
i let my moho set unused for about 3 weeks and drained 13 qts from it. the filter holds about .5 qt. if you drain it hot, only about 10 qts will drain. the torque converter will not drain. some folks change the fluid twice to get a nearly complete change. the fluid runs about $40 a gallon. kinda expensive to do it twice.
do not over fill the transmission.
i installed a SCAN GUAUGE II from MILEAGE PROS website because it has an "x gauge" readout for the allison fluid temperature. my fluid ran between 137-142 degrees on the freeway before i changed the fluid. i haven't had it on the freeway yet since i changed the fluid.
don't forget the rule: "i before e except after c."

[Janandoug]

Thanks for all your helpful thoughts. I just greased all the u joints and checked the carrier bearings. All appears tight and in good shape however I cannot really speak to the carrier bearings. They are a new arrangment for me, they appear to be mounted in a rubber flexable ring that will let the shaft move slightly. Seems good and tight and in good condition. I also greased all front steering links and joints. I will look at grill possibilities but not sure how to pursue this. Keep the cards and letters coming I am interested in all comments I am going to change the tranny oil (replace with syn) and filter, check both for metal and if all is well continue to drive and wonder. Thanks DH