Webasto woes again

[David Anderson]

I've posted about this many times.  I'm in Taos skiing and my webasto has sooted up again.  It does it every time I go above sea level.  I've been told they don't work at altitude without modifications, and well I guess that is right.  I replaced the nozzle and filter and spent an hour cleaning the soot out of the burner chamber and water jacket, boy what a mess.  I fired it up and it still smokes profusely.  I adjusted the air intake for more air and it didn't change.  I'm about ready to switch to an Aqua hot 200p propane hydronic and ditch this diesel mess and webasto complexity.  I was smart enough to bring extra electric heaters this time, so we are not freezing to death.  I need to get this unit looked at and so far the only choice is to de install it and send it to Sure Marine in Seattle.  That is about $60 in freight each way.  No one around San Antonio that could look at it is there??  Anyone have any ideas for a closer look? 

I love this thing when it works, but it never works more than a few hours at best.
David

[Bill B /bus]

Check the Webasto website for dealer service. Then call and verify they know what they are doing with Webasto. The right tech can diagnose and fix quickly.
if the unit is sooting then lack of air is the cause. Fan running too slow. That means bad bearings, low voltage, corroded/poor electrical connections.
A lot of our Webasto problems were fixed when we moved the circulator pump to a different power source. The power now just energizes a relay which controls the power to the pump. Some Webasto units appear to be voltage sensitive.

Good luck,
Bill

[David Anderson]

I removed my circ pump circuit from the webasto supply long ago as a suggested fix. 

[RichardEntrekin]

David,

Rudy Legget is in Houston. Is that close enough for you?

[David Anderson]

David,

Rudy Legget is in Houston. Is that close enough for you?

200 miles.  Does he have a shop to service them?

[RichardEntrekin]

He is an independent service person for the Aquahots. He does not have a shop per se, but he is very good with them.

Contact him at  jrlegett   at

that gmail thing.

I have been thinking about what you described.   Of course improper air flow would cause black smoke and sooting. Unburned fuel would also be a cause. Since you have changed nozzles, I started thinking about low fuel pressure. That could be something as simple as a lower voltage spinning the fuel pump slower, or it could be a symptom of colder fuel, or a fuel pump not up to snuff. Check your voltage at the AH while you are in the cold. Next step would be to put the pressure gauge on the fuel pump. The AH service folks have a gauge brazed to an old nozzle that they use to check the pressure.

I have experienced a sooting problem like you describe, but it was my own fault. I replaced the coil and didn't pay attention to the grommet around the wires. It was letting out a wee bit of air. Any thing that interferes with the seal of the burner to the combustion chamber lets the air OUT, since the fan on the motor pumps air into the combustion chamber. It wouldn't hurt to really look at that interface to make sure it is sealing.

[buswarrior]

Voltage right at the unit, right now, in the moment, under the condition it is screwing up is valuable info.
Measure voltage simultaneously right at the batteries for comparison.
Small wire, old connections, resistance in the line someplace... or find it good?

low voltage leads to fuel pump running slow, leads to low fuel pressure, leads to bad burn.
Fuel pressure is mission critical on these.

What size of nozzle? Dropping a size might tip the balance into your favour, if you're burning a big one.

When you say "elevation", just how high up are you?
Has to get into serious height before it's going to care, unless you are burning it on the ragged edge down at sea level, curious as to what nozzle is in it.

You spend a lot more money in frustration changing stuff, or get what you have sorted out. Yes, damned annoying, when you are using the coach to do other things, instead of the coach being your only obsession.

I mentioned to check the voltage properly, in a religiously motivated fashion?

happy coaching!
buswarrior

[TomC]

You want reliable? Install an electric (120vac) block heater with a circulation pump (120vac) and install an Arctic Fox coolant loop in your fuel tank (only if you'll be below -20f). I had this setup on my big rig truck and I also had an Arctic Fox loop on my 75 gal water tank. In -5f weather, all stayed nice and toasty warm all night with my Onan 6.5 air cooled Emerald III running my block heater, circulation pump, electric heater for the sleeper. The cooling air from my Onan was aimed at my water tank with a simple piece of cardboard. I didn't know any truck drivers that had Webasto or AquaHot on their rigs. I still have the block heater on my truck now that I'm converting it into a motorhome. Good Luck, TomC

[Jim Blackwood]

If it isn't the original nozzle that could be a problem, I recall someone on here saying he was running a nozzle that was a size larger. Once the burner is lit it's just a matter of balance between fuel and air and soot means a rich mixture (as does problems at altitude). So either something is causing more fuel to be used or the airflow is being restricted. If the nozzle is the original size then my money's on the airflow.

Airflow doesn't stop with the inlet. The exhaust is equally important. If you have any sort of a restriction there, no matter how small it is, it will reduce the inlet airflow. That's where I'd look next.

Jim

[buswarrior]

Has this unit ever run correctly?

Jim's advice to confirm adequate intake AND exhaust is bang on.

There can be no compromises on the exhaust side, it needs big pipes and few bends.

Smooth pipe is way better for airflow than ribbed pipe.

Busnuts who are blindly "all about the coach" take note...The rest of the family quickly gets a hate-on for the coach, when it doesn't perform properly and interferes with the intended days activities.

hopefully there's a quick diagnosis for this one.

happy coaching!
buswarrior

[luvrbus]

How long is the exhaust pipe  ? Webasto's are touchy on the length 

[chessie4905]

Also, the pressure at the nozzle is going to effect the proper atomization.

[Jim Blackwood]

That's true, poor atomization would contribute to incomplete combustion and soot generation. Pressure and nozzle size has to be right. Any bur or erosion of the nozzle would also cause a problem, as would air leakage.

Jim

[David Anderson]

Richard, I think you gave me the magic bullet. I checked the grommets and the wires into it and I could feel air blowing out of it. I repositioned everything and tightened down the burner head securely with the tiedown nuts.  I fired it up and ran it for an hour and it finally cleared up. The flames sound smooth and consistent. Before it rattled and popped. I had to adjust the burner intake for more air. I am in Albuquerque now. 4300 feet so it needed more air.

Other information, voltage at fuel pump 13.3. Nozzle is original size. .035
Exhaust pipe is 1.5" slipped and clamped over the end of the heater exhaust stub. Total length is 42" with one 90 degrees bend.  I will run it a couple days and post back the results. Thanks for the help

[RichardEntrekin]

Hope that was the magic bullet. Those grommets are directional, and different depending on which side of the unit they are intalled one. There are right hand ones and left hand ones.