A Bad Case of Slobbering

Did you know that motor homes slobber, and that slobber can foul the engine just as dog drool will wreck your clean khakis? Neither did I, but I have since been enlightened.

When  I last posted, things didn’t look so good for our motor home. We purchased it from a dealer in Indiana, and drove it back to Ohio without incident. Our mechanic pronounced it sound, so we were quite surprised when it tanked on our first trip. You’re probably wondering what went wrong, how we missed it and how can YOU avoid such a fate.

A motor home is not like a big car. There are complex mechanical, electrical and hydraulic systems that govern everything from leveling the rig to monitoring the waste tank, all hiding under the comfy sofa and pretty cabinetry, just waiting to derail your trip. Issues that also contributed to the breakdown were loose wires, waste-gate actuator and turbo actuator. The actuators are what gives the motorhome it’s “oomph” to get up hills at the speed limit. A problem like this won’t surface under normal inspection, and not in a test drive situation. My friend, if you are considering a purchase of a used rig, just know that you are likely to have to spend a hunk of change on something, and be ready for it. We are once again road worthy. I bet though, you are still wondering about the whole slobbering/drooling thing.

We learned about a phenomenon called “blow by” which is a term for all the byproduct gunk that blows out of a Diesel engine in the combustion process, which is mostly oil. It is officially called (and I am not making this up) “slobber.” Because of this oily drool, Diesel engines are outfitted with “slobber tubes,” which allows the oil to “blow by”. This is a slobber tube.

A properly installed slobber tube. Not our slobber tube of course.

If the slobber doesn’t blow by (away from) the moving parts of the engine, bad things can happen. Unregulated slobbering can have an especially detrimental effect on RV radiators. Most rigs have two, and they are expensive puppies to replace. It turned out that the model year of our rig had particular issues with the location of the slobber tubes. They were located in such a spot that the fan sucked the slobber up into the radiator, instead of “blowing by” as it should. The required repair had not been done by the previous owner, so oil sprayed on both radiators for years. Dirt and dust mixed with the the oil, turning into a kind of cement. We lucked out, neither of the radiators were damaged badly, but they were so clogged that the engine was literally suffocating.

RV repair forums discuss this blow by/slobber tube issue at length. There are all kinds of home made work around solutions including a slobber collector, which attaches to the tube. This allows you to monitor the level of slobber being produced. Ben being the kind of guy he is, was very interested in the slobber so he made a collector, and here it is. Internet advice recommended a peanut butter jar but Ben determined a Kroger barbecue sauce bottle was a better fit. Sadly, the sauce was sacrificed for the proper size of container. It’s OK, we’re more the Sweet Baby Ray’s type in the sauce arena.

Exhibit A: Slobber Tube Collector.

And, here is the collector attached to the slobber tube. Note that our tube is not long as in the first picture; a design flaw.

Let the slobber collection commence!

The cotton balls supposedly help to collect and absorb the slobber, so that you can tell how the combustion process is working. Less slobber = better engine efficiency.

This installation will undergo a road test. Ben intends to drive back to Beckley with some of his mechanic type buddies (just in case) to test out the repairs and try the hills to see if he can make it slobber. If we can make it there, we can make it anywhere.

One thought on “A Bad Case of Slobbering

  1. Beth Ridedeaf

    Red Dog, you astound me with your technical know-how! Guess a dog would have some experience in the slobber department. Love your blog!


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