gas heater smells a little gassy

[Derek May]

I think that the answer may be that the heater outlet is slightly undersized, compared to the flexible stainless pipe it goes into -- there is some gap, its not a perfect seal, which would permit inflow of fresh air as the exhaust flows, probably similar to your household hot water heater example. With the configuration, it would be difficult for the exhaust to leak out, unless there is restriction farther down the pipe.

[Derek May]

More on the gassy smell -- for anyone actually following the thread.

I replaced the exhaust pipe, the old one was rather rusty. I'll skip the details. I noticed that the BA6 outlet pipe has a gap that permits fresh air to get sucked in to the exhaust stream, to finish the burn, or cool it? Not sure. Mine was in working order.

Noticed a residue on bottom of BA6 unit, smelled like gas, but is sticky.

Exhaust is proper now, but still smells gassy.

Next step is to follow up on earlier suggestion to check fuel pump for proper delivery. Rich mix could explain the residue.

[ray greenwood]

A couple of inportant things to look at. There may be leakage from several areas: check the o-ring around the blower unit, also the tightness of the clamp. Check the gas tightnes of the thermocouple probe. It goes through the air chamber to reach the flame chamber. If the union nut is rusted or leaking, it will put vapors into the chamber and leak down. Check glow plug gap on the points. If the spark is not enough...it takes too long to warm up and may puddle in the unit...leaking at seal. One bad thing that I hope is not wrong....with the blower out...carefully inpect the asbestos and wire flame mantle. Its that circular cloth looking thing right inside the blower. It can get ripped...leaking vapors at the chamber seam right behind it. I don't really know how to fix that. I had that problem Rust could be a problem...but rarely. I would check the fuel pump output...but usually this will show-up as a dirty glowplug first...and also as a heater that tends to be hard to control at the thermostat (runs hot). Check the location of where the exhaust dumps out by the body. At the same time...try to keep track of wether you only smell gas when you are sitting still or moving. If it is only when you are sitting at a light...it is probably running a little rich...and the exhaust is drifting back up into the engine intake and being recirculated. This is more of a problem when using the factory stock right hand exit muffler...if the heater exhaust exits right above it. The rising engine exhaust vapors help to lift it upward to the air intakes. Replace the fuel line evn if it looks good....I never trust them. I replaced mine with 3/16" steel tube. I had to clearance the fuel spigot a little and the brass union...but it works great. Ray

[Derek May]

Thanks Ray.
I'll check all that out. This is the BA6 I'm playing with -- not a BN4. They work on pretty much the same principles, but mine of course is under the Van, integral to the heating system rather than in the engine bay. The muffler is now quite good -- I repaired it, its the kind that vents out to the driver's side of the Van, just in front of the rear tire. Turns out the first two sections of pipe were good, so the repair was fairly simply done with sections of pipe from the autosupply and a few muffler clamps.

What I noticed when repairing the muffler was a bit of residue on the underside of the Unit. It almost felt like pancake syrop, but smelled gassy. I had the heater blower off it last year, and the thing seemed quite sound all around. I don't think I'm getting exhaust into the system -- it smells just as gassy standing still as driving. Somehow, I think I'm getting gas into the part of the system that the fresh air is supposed to go through, so checking seals etc for leaks is the next thing to do. When I had the exhaust pipe off -- I checked the outlet, and it wasn't too sooty nor did it have residue -- so there's no indication there that its running too rich, I'll test the fuel pump output while at it. I think the residue is the clue -- so I suppose I've got Saturday planned. I was hoping I woudn't have to pull the thing off the Van, but looks like that's gotta be done before ski season.

[Derek May]

oh -- fuel line to the BA6? I replaced all fuel lines (from gas tank to engine and back again, vaccuum and air hoses, summer 2000, with proper stock metric VW hoses, so I know how old each of them are, and each is proper size and strength. You are absolutely correct -- I tell anyone who will listen "if you don't KNOW how old the line is -- replace it". The lines are fine, although the clamp to the injector in the BA6 is worth checking again.

[ray greenwood]

Hee hee...Talk about a jinx...I just had to replace my fuel line last night in the cold. I reccommend installing a piece of steel fuel line from the top down to just past the blower motor. I used a 3/16" brass sae pressure union...with the nut and collet resized a few thousandths to slip ocer the inlet nipple at the top. This remains leak free...and gets potential leaks down past the hot area. The fuel lines on the heater tend to last a very short time...like a little more than a year in areas with hot summers. This I would suspect, is because the fuel evaporates out of the top end of the line with a day or two when the heater is not in use. Gasoline is an excellent solvent. Once it opens the pores in the rubber...it needs to be there to keep it from oxidising. I replaced the lower hose last winter with correct German metric cloth braided fuel line...its stiff already, and cracked. This was a 10 minute change since all the top line is steel. Ray

[Derek May]

Problem solved.

Thanks for your input, Ray.

Turns out when I examined the heater, the gas line to it hadn't been changed over -- was one of those "meant to do" things. And turns out it was the gas line that was the problem. It was a little short, so it had been stressed going the 90 degrees to the fitting, and that's where it cracked and leaked -- ergo the gassy smell. The line leaked, the gas would drip and pool on the top of the heater, and make it into the fresh air part of the unit.

All fixed. Problem was the fuel line.