Problems driving in heavy rain


RV: 2003 Southwind 32V Workhorse 8100 Vortec Allison

When driving in rain for a length of time (as little as 20 minutes) the engine will start to miss and buck when the cruise pulls on the power. Like going over a freeway overpass.

First time this happened I was in a bad rainstorm for several hours last fall and I didn't think I would make it to help. I stopped along the road and called the 800 number for Workhorse. They finally put me in touch with a service garage in Birmingham, Alabama, (four hours away). By this time the "Service engine soon" light was on.

Called the garage on the phone and described the situation. He said something to the effect that the engine had sucked enough water into the intake that the air filter was wet. And the engine computer was getting all confused when the need for power was required. He said if I could get to his place, he could take me in.

As I drove on down the road, the rain had quit and the further I went, the less the engine missed and bucked. By the time (four hours later) that I got to Birmingham, it was running fine, although the "Service..." light was still on. I decided to head on home to Texas and called the garage and told him thanks. The RV dealer back home said the compter had a mass air flow sensor code in it, about what I would expect.

Since then, I have had two other situations where I had to drive in heavy rain and the same thing happened, although not as severely as the first.

The air intake on my MH is a large round bell-shaped opening covered by a screen, facing forward, high in the area behind the grill and hood. It is positioned EXACTLY where any water would feed directly into it! It looks like a terrible design, but apparently is the standard Workhorse configuration.

I was in Raper RV last summer and was asking them about the problem. They referred me to the local GM dealer that did Workhorse service. The service folks there added a large flap of rubber, a piece of a mud flap, pop-riveted to the sheet metal above the air intake. It hangs down in front and is intended to deflect the incoming water, I suppose. Since I had this "fix", I have not had the "opportunity" to drive the RV in any heavy rain.

Has anybody heard of this kind of problem before? Any experinces with solving it?


Bill Lee
Problems driving in heavy rain

Not familiar with your problems, just ensure the rubber flap will not cover the opening under way and with suction applied by the air horn. Also, some times when sufficient moisture is exposed to the plug wires/coil etc it will cause a misfire under slight load and will dry out when the moisture is removed. A light coating of WD-40 will manytimes correct this. Good Luck
Problems driving in heavy rain

Ford had a very similar problem with the '99 & '00 V-10's and it was solved with a tech bulletin that changed the air intake. It was taking in water with no place to go except the engine. Basically, a hole was put into the rear of the air intake so water could pass thru/drain out before getting to the engine. No further problems after the fix.
Problems driving in heavy rain

The NEWMAR's have this problem everytime they are driven in the rain an it doesn't have to be a heavy rain storm. I own a 03 KS on W-22 chassie. I have come up with a fix for the problem. If you go to and look up "workhorse power downs RAIN WATER" on Newmar site you will see your not the only one having this problem. also on the Workhorse post look for "its happening again" I think this will help anyone with this problem. "007"
Problems driving in heavy rain

Hi Guys,
Sounds like all the people designing these air intakes, believe that we only camp and travel in dry sun shine weather or either they are trying to supplement water for fuel to increase mileage.