Community Forums

Janandoug · 03-26-2009, 11:04 AM

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

Marty too · 03-26-2009, 12:19 PM

Me think I'd look more at U-Joints or center carrier bearing if you have one. It'd be unusual for that Allison transmission to be giving out noise like you have tried to express. However, maybe a trip to a Allison transmission shop might be in order.

Just my thoughts here.

Marty

Gary RVRoamer · 03-26-2009, 05:53 PM

I had a 2002 Dolphin LX and it made a whining sound too. Turned out it was generated by wind rushing through the grill and National slipped some rubber moldings along the edges of the grill bars to dampen the vibration. Perhaps a former National RV dealer might still have some around?

However, quite a few people report a whining noise on the Workhorse chassis. What you are hearing may be normal transmission noise that happens to be at a frequency level you are sensitive too.

David K · 03-26-2009, 08:05 PM

I would go with the suggestion to look at the U-joints -- sounds very familiar to a noise that I had last Spring -- turned out to be a bad U-joint.

Bob (WA0MQE) · 03-27-2009, 04:52 AM

When I took the moho into Brazel's Shop to check it out on their Dynometer we all noticed a high pitched squeal type of noise that sounded like it was coming from the rear running gear area. It hasn't caused any problems as yet, but it's definitely there. While driving I never notice this noise at all. I guess there's too much other noise, plus the drivers seat is so far away from the rear.

Problem is, what to look for. Just investigating it, could cost as much or more in labor then fixing it, if and when it ever gives up the ghost.

speed racer · 03-27-2009, 11:18 AM

I had a noise like this and it turned out to be the grill. I hade to mount the grill in rubber isolators to stop the noise. I also have a noisy power stering pump .

tessi · 03-27-2009, 12:38 PM

same problem on our 04 and now on our 07. different makes so i don't think its grill noise. has to be another workhorse problem.
dave

Janandoug · 03-27-2009, 04:44 PM

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 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

DAN L · 03-28-2009, 01:42 AM

Quote:

Originally Posted by speed racer

I had a noise like this and it turned out to be the grill. I hade to mount the grill in rubber isolators to stop the noise. I also have a noisy power stering pump .

AMSOIL PSF universal synthetic power steering fluid quieted my power steering pump considerably.

tessi · 03-28-2009, 02:11 PM

dan l, iv'e suspected the p/s pump for some time. did you drain it? if so, how?
thanks dave

DAN L · 03-28-2009, 05:34 PM

Quote:

Originally Posted by tessi

dan l, iv'e suspected the p/s pump for some time. did you drain it? if so, how?
thanks dave

on my moho, there is a long blue hose running from the bottom of the power steering reservoir to the brake master cylinder (for boost).
i disconnected this hose and drained the reservoir through it, almost 2 pints. it took about 30 minutes to quit draining.

before i reconnected the hose to the master cylinder, i had enough hose

so i cut about 3/4 inch off of the hose to give it a new "end". i used a new worm gear type hose clamp.
after refilling the reservoir with AMSOIL PSF, i ran the engine and checked for leaks.

i turned the steering wheel back and forth and applied the brakes several times. then i topped off the reservoir.