2 questions (75 CJ5)

[BC CJ]

Awesome guys! I think we are getting to the bottom of this. I'll have to hunt around tomorrow for my PCV valve and figure out what hoses go where. If connected the mystery hose would bring fumes back to the top of the engine... then maybe there is a line to get those fumes back above the carb. It just might be the answer to the propane smell as well.

Or maybe it is just an old drain hose for a turbo...

I'll let you know what I find. Bed time now for the kids and me!

 

[BC CJ]

OK, there are a lot of hoses in there! But many of them are vacuum hoses operating things like the brake booster and the propane cutoff thingy.

The PCV valve is at the back of the intake manifold near the firewall and runs to the carb - just like the original gas setup.

There are 2 hoses (.5" and 1" approx) from the mixer to the carb. One obviously delivers fuel to the carb... the other? maybe recirculates what isn't pulled into the engine?

So the options with this mystery hose are:
-hook it up to the hose to the oil filler and close the system. Tarry, you mentioned a "closed crankcase ventelation system"

-Or use the oil filler hose as a vent (with gas this would go to the air cleaner for recirculating fumes?) and plug the mystery hose. If it was a drain hose for a turbo that should be fine.

Another thought. At the top of the oil pan where this hose comes out - would it be submerged in engine oil? If so would it be able to pass any propane fumes back up for recirculation?

 

[tarry99]

BC/CJ
First of all.......I would think the system is supposed to be a closed system,most are. Second I would either talk to someone that is into that Propane conversion business or maybe a competent smog guy or check out the internet and see if you can find a drawing.
Now is not the time to guess where they all go.
On the hose in the top of the Pan no oil should be that high up.
Question: Did you just purchase this Jeep?

 

[BC CJ]

I've had the jeep for 2-3 weeks. I havn't been driving it, just firing it up every few days. Always seems to run perfectly except for that propane smell. I wont be hitting the road with it for a couple months yet I'll get some solid answers on the hose and propane system first.

 

[BC CJ]

OK, I talked to some knowledgeable people and they all say there is no need for a vent off the oil pan. The hose must be left over from a turbo system or possibly some kind of external oil filter. So I'll plug it.

As for the upper hose, the one that usually runs to the air cleaner. I always thought it was a vent but maybe it recirculates vapours to the carb intake. Everything seems to work fine with it open to the air but maybe it adds to the propane smell when the engine is running. I still think the main culprit is the exhaust, there is a major leak at the connection of pipe to manifold on one side. Either way, I'm hoping a tune-up will help the engine burn more of its' fuel which in my mind should be the initial cause of the propane smell.

10 points to CJ, looks like you were right. And thanks for your help Tarry; I spotted your Jeep in another thread and I love it! Even the modifications have that classic look to them. Very cool.