1F/2F smoke on steep descents?

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Aug 8, 2008
Franktown, CO
I had a great week at Cruise Moab, the old 1F generally ran pretty good (enough to pull the front wheels up on a hill climb-see picture).

However, I had 2 strange things happen of which I think I figured one out. On REALLY steep descents (like straight down) the engine would start pumping out clouds of smoke, like mosquito sprayer clouds of smoke. It would keep doing this for about 10 minutes then clear up and stop completely, at least until the next steep descent when it would repeat itself. It was so bad I had oil dripping from a seam in my muffler.

Also, once at the bottom of the hill the engine oil pressure would be zero (mechanical gauge). It would stay at zero, with the engine idling, for about 5 minutes and then pop back up to normal/40 psi at higher rpm. The oil was clean and right at the full mark. It did this numerous times.

I finally figured out it was sucking oil through the PCV valve, which on my side cover is mounted on the front of the engine. I fixed it by getting a 5' long piece of hose that fit the PCV valve. I ran the hose from the PCV to the back of the engine then back down to the carb base. This fixed the smoking since the oil couldnt go all the way up the hose towards the firewall after it got past the PCV valve.

But, the oil pressure would still drop to zero. The last time we were on a very remote trail and I had no choice but to keep driving it to get out. Eventually, after about 20 minutes of off-road driving with the gauge showing zero and some rattles starting in the engine, the pressure returned and was OK from there. PS-I know its not the gauge, I unscrewed the tube from the back of the gauge that goes straight into the engine block and no oil came out.

I figure the angle was so steep, even though the pan was full, that the oil pump pickup sucked in air. I'm not sure though why it took so long for pressure to return. Any ideas?

Are there any mods that can be made to the oil pump pickup to prevent this from happening in the future? I wasn't too worried about the current 1F motor since I have a new 2F to replace it with, but I don't want the new one to run without oil either.
Moab 2009 Kens Camera (25).jpg

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