THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

I have a pervasive raw gas smell with no apparent origin. I see a very minor seepage on the carbs that has not changed since the smell started, there is no other leaks as far as I can tell. The hoses are all good and don't appear to be leaking either. It runs fine and starts fine so I don't know what the problem is. It is only noticeable after shutting it off and then returning. I notice nothing when driving. I have been contemplating a Webasto heater from Linden but will definetely need to get this rectified before the install...

Sure other more experienced will join in but believe it's the nature of this beast...mine does exactly the same. All minor things replaced & tuned as well

75 Pinz
What you are likely to find are worn carburetor spindle shafts and/or deteriorated seals on those shafts. Together with a leaking/slightly flooding carburetor(s) the fuel is puddling on the butterflies after shut down and then running out on the spindles to the outside. Since the engine is hot the fuel is evaporating, you therefore only smell the stink of fuel but not observing the physical evidence.
Dennis

A more mundane explaination....if your float valves are either set incorrectly or defective, some fuel will be dripping from the innards of the carburator when it should not be.

Simple test. Take off the doghouse and air filter housing. Run the truck. Shut it off. Look down the carbie throats with a flashlight. There should not be a drip, drop or dribble of fuel. If there is, suspect the float setting or the integrity of the float valves.

Also, if your fuel hose is cracked and frayed, you will have seepage. Pretty easy to check for. There is also a hose that goes between the two intake manifolds under the shroud. That also fails over time, although I can't say for sure if it will cause the symptoms you are experiencing. Either way, that hose and the vacuum hose that runs up to the brake servo are worth checking at least once early on in your Pinzgauer stewardship.

I also had a failed gasket on the fuel level float on te top of the fuel tank. The first time I filled the tank I had an impressive flood. Just as well I don't smoke or go out of my way to generate static electricity while fueling! Doesn't sound like your problem, but it never hurts to work in a few off-topic sordid tales.

Otherwise, refer back to Dennis's post. In addition to his stunning good looks, he has a son that can dump a pan of used motor oil and track it around the shop with the best!

-Evan

Gee, I thought it also the nature of the beast. More things to check. It does once again illustrate that the EFI system coming down the line is sure to be a practical way of relieving many of these "carb" difficulties and trials. I for one will be very happy to make said transition!

Are you sure it's nothing silly, like a broken fuel tank vent pipe, or a leaking/loose rubber joiner on the fuel filler pipe, etc.

what the deal is. I see no rotten hoses, I removed the doghouse, ran it and then looked in the carbs and see no drips after shutoff. Just smells like gas...If indeed the carburetors need a rebuild, what will it cost me? Particularly if the shafts are worn as Dennis indicated.

75 Pinz

What I would do first is pry off the throttle linkage at the the operating arms and then try to lift the spindles in their bases to gauge wear. If it is nominal, remove each carburator and then remove all of the linkage, spacers etc thereby exposing the casting to spindle protrusion.

You will probably see what is left of the seal, an O ring. You can pick it out with a fine screwdriver, we use a dentist's pik. Find a suitable Buna O ring from a parts store, coat the surface of the O ring with silicon grease and re-assemble the whole lot. Remember to go easy with the wrench as you can twist and distort the spindles and butterflies. (Hence the reason for lock plates on the fixing nuts.) Also make a sketch of each piece as you dismantle it, the washer/spacer arm combo can confuse if you have never done this type of work before.

Complete bases can be obtained from SAV the last time I enquired should the whole lot be worn to excess.
Best of luck
Dennis
ps don't forget to investigate possible flooding

I will mess with this this weekend. When you say nominal I assume you mean nearly no play in the bore?

75 pinz
Yes the carburetor can stand a little play on the bore but once the hole goes oval you will get response problems, like stumbling off idle.

I use O rings from an A/C repair kit that is supplied to us either by Car Quest or Napa. They have them in all sizes and thicknesses, so you should be able to find something suitable by offer up. Just remember that the spindle MUST rotate smoothly once assembled and not bind. Hence avoid the temptation to install the fastest seal you can stuff in the groove!Dennis

Dennis,
considering that I don't have any stumbling or driveability issues would you still consider this a likely culprit? I seem to have the smell all time after running in addition to being gassy smelling even on a cold morning before starting. I don't have any trouble with it starting or running strangely. It fires right up even after a good hot soak which is more than I can say for my Mog or m37.

75 Pinz.
What you state only tells me that the carburetors are not worn. Those shaft seals will allow the engine to draw air into the throats without showing any driveability symptoms and do wear or tear apart over time.

The instruments are quite good from my perspective in spite of popular condemnation on this board. Another area to look at is the choke cover and the operating spindle. Both units have propensity to leak small amounts of fuel giving you the stink.

Another sure fire way to find the source is to go to a shop that has an emissions meter. By wafting the probe around the likely sources you will find a peak in HC's as the tip passes over the source of leakage.
Dennis

I have found that the original cloth wrapped fuel hoses make for a real good wick! Fuel sitting inside while parked seeps thru. Sometimes it will not look wet. Dennis' thought is much safer(analyzer-HC) than the lit match method!
Mark

Dennis,

I have the same issue on my truck, except there is clear evidence of feul leakage on both carbs. (as much as a teaspoon at the base of each butterfly) the truck runs like a champ. it might stumble a little on a cold morning until it gets warmed up, but that isn't unusual per some of your input on intake manifold insulation.

probably my only concern at this point is the fire hazard. barring that, I'm wondering what the "break point" is for dealing with the issue. right now the truck runs so good, I'm stongly inclined to leave it alone.

Doug
In these circumstances use the fleet management maxim, "if it aint broke don't fix it" and "Let it develop". The policy works fine in most fleets including airlines.
Dennis