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I am getting fumes in my cab. It seems that it is worse when braking with the engine, ie lift foot off throttle. It also seems to be worse if I open either the fresh air vent flap or heater air flap. Exhaust is new and tight. I am thinking it is crankcase vent air.

I cannot figure out how the crankcase is vented. I see a hose from a valve cover to the oil fill pipe and another from the oil fill pipe to the plenum. Expected to see something going to the intake manifold but did not. The only vacuum hoses seem to be routed to the brake booster and the distributor.

There is a faint gas smell about the engine and I have an occasional backfire when braking extensively with the engine.

Any suggestions.

Have complaints of same issue. I had thought it might be the fill hose to the petrol tank. Just rebuilt carbs and no smell from there. I also get occasional backfire but only when starting when excessively cold as I give it more gas then by the foot pedal. Much more notable by passenger side.
Exhaust is different animal as it is always present due to soft top and sides and location of exhaust pipe.

Been wondering hoe to fix these issues for years.

krick3tt wrote:Exhaust is different animal as it is always present due to soft top and sides and location of exhaust pipe.

Morris,
You know that's why several guys have relocated the exhaust to the rear, don't you? IIRC, didn't Scott produce a small run of mufflers with a rear outlet, instead of the standard side outlet?

Yes he did and I would like to have one if I could afford it. It crosses my mind periodically as I travel. I find when I have the sides rolled up there is little smell.
I think the back area traps the fumes and just allows them to drift to the cab.
I would also reroute the pipe to go farther back and a bit higher to keep it out of a problem in water crossings.

If I could only spring the cash for all the things I want for the pinz. I am having to do it over time and as I get the cash, tying not to get the cheap China produced mods.
Those things only cause problems of their own.

Thanks Paul

Here's a picture of how I routed the tail pipe on my 710M.

viewtopic.php?f=13&t=8684&p=63986#p63986

I remember Jim saying not to place the exhaust at the rear of a M variant as the open rear flap pulls the exhaust in. I'm probably misquoting. This is not an issue on a K.

I like that location. What did you do with the shovel?

When the door window is open and the back flap is up, vacuum occurs in the cab while in motion, pulling in the fumes.
Bread box aerodynamics 101

Hey, Pinzinator, how long have you had it like that? Does
it work well with the top off, or with the top on/windows open,
etc., etc.? I would have thought that with the aerodynamics
of a flying brick, that the ideal place would be directly in front
of the wheel, but just under the rub rail like you have it. The
exhaust is one of the projects on my plate that I haven't tackled
yet and I'd love to hear how that route works for you.

Here's where I keep the shovel-



Also, this is how the exhaust pipe is held in place toward the rear-



I never have the rear canvas on, so I can't say how the exhaust smells with it in place. Without the canvas there is virtually no odor. Having the PinzSSI ignition helps out, too. This exhaust pipe was installed in 2004.

For what its worth... I don't know if it makes a difference or not. I will caution against running the exhaust pipe too close to the body of the truck to prevent hot spots inside the truck.

I've heard from some guys with the SSI installed it burns better an eliminates alot of the fumes maybe someone who has it will chime in.

It seems like I get the smell when I first let off the throttle. I am wondering if the exhaust is particularly smelly then. Maybe sucking oil past the rings or down the valve guides.