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> 1974 2.0l w/dual 34ICTs having blowby
justjoel
post Feb 16 2026, 09:36 AM
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Finally got my project 914 on the road and it's running really good with dual 34ICTs but I started noticing burning oil smells in the cabin. Now it does have a minor oil leak, I believe from the distributor o-ring and I will be addressing that but I realized it was blowing smoke/oil from the crankcase breather and the cylinder head vents. I installed a catch-can where I routed the crankcase breather and cylinder head vents to and have a filter on top of the catch can but it's still smoking out the filter and getting into the cabin where it proceeds to give me a nice migraine after 20-30 min drive.

I believe I should remove the top filter and run a line into the carbs for the vapors to be sucked back into the system, is that correct? Will that gum up my carbs?

Now the car sat for probably 20+ years prior to me picking it up and fixing it but it fires right up, no issues and runs "cool" and strong. Compression tests out good, valves have been adjusted to the best of my ability and there is no smoke out of the tailpipe. How concerned should I be about blowby? When I open the oil fill cap there is quite a bit of smoke and pressure coming out. I am unfamiliar with aircooled engines but I would think the piston rings are worn. Should I be thinking rebuild time? As in new pistons, cylinders, rings etc. If so, what "while you're in there" things should I start budgeting for?

Please let me know your thoughts.
Thank you.
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justjoel
post Jun 16 2026, 07:02 AM
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As an update, I pulled the engine to replace the front main seal and oil pump gasket to fix some front engine oil leaks and found that the timing marks I assumed were TDC were slightly off. I'm not sure if this was a replacement fan or what but I couldn't see the notch with it in the car. I replaced the seals (still leaks oil) but created a mark on the fan so I can see it when timing the car. I also upgraded from 34 ICTs to 40 IDFs I found on FB. Got everything dialed in, valves adjusted to "new" TDC and set the timing to 30° BTDC and it ran great with no smoke or noticeable blowby... for exactly one day. I mean it felt powerful, running and idling great.

Let it sit for a day, tried to start it.... dead. Cranks but won't start. So I started to try to figure it out. Checked spark, has it. Checked fuel, has it. Checked compression... not great but has it. #1: 80psi, #2: 105 psi, #3: 85 psi, #4: 95 psi -- definitely tired but has compression so valves are closing. I got it to fire up and it ran rough. I stupidly took it out for a quick spin in the neighborhood and it was cutting out like a dead miss or something under load. Limped it home.

Decided maybe it was ignition related so I replaced everything. New coil, distributor, cap, rotor, plugs, wires. It's all new. Went back to point ignition from electric ignition. I checked the oil, doesn't smell like fuel, thinking maybe the carbs were leaking fuel and flooding the engine.

It fired up but ran like crap. Hunting idle, wouldn't stay running...
Today. No start again.

What the heck do I do? I know it's tired and needs a rebuild but it should still start. Hesitant to throw money at a rebuild if it's something worse (or easy).

This isn't a show car and it isn't worth a ton - I pulled it out of a shed and am low buck restoring it to just drive and enjoy. I have never owned a carbureted car or an air cooled vw... so I'm trying to learn as I go but this one has me stumped and very frustrated. I don't understand what would have changed from one day to the next, running great to not running at all.

The only thing I can think of is that maybe I wiped out the camshaft having the timing off originally? Or I wiped it out with my "new" timing? Or?? I don't know where to go from here. Any input would be greatly appreciated.
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Shivers
post Jun 16 2026, 09:04 AM
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QUOTE(justjoel @ Jun 16 2026, 06:02 AM) *

As an update, I pulled the engine to replace the front main seal and oil pump gasket to fix some front engine oil leaks and found that the timing marks I assumed were TDC were slightly off. I'm not sure if this was a replacement fan or what but I couldn't see the notch with it in the car. I replaced the seals (still leaks oil) but created a mark on the fan so I can see it when timing the car. I also upgraded from 34 ICTs to 40 IDFs I found on FB. Got everything dialed in, valves adjusted to "new" TDC and set the timing to 30° BTDC and it ran great with no smoke or noticeable blowby... for exactly one day. I mean it felt powerful, running and idling great.

Let it sit for a day, tried to start it.... dead. Cranks but won't start. So I started to try to figure it out. Checked spark, has it. Checked fuel, has it. Checked compression... not great but has it. #1: 80psi, #2: 105 psi, #3: 85 psi, #4: 95 psi -- definitely tired but has compression so valves are closing. I got it to fire up and it ran rough. I stupidly took it out for a quick spin in the neighborhood and it was cutting out like a dead miss or something under load. Limped it home.

Decided maybe it was ignition related so I replaced everything. New coil, distributor, cap, rotor, plugs, wires. It's all new. Went back to point ignition from electric ignition. I checked the oil, doesn't smell like fuel, thinking maybe the carbs were leaking fuel and flooding the engine.

It fired up but ran like crap. Hunting idle, wouldn't stay running...
Today. No start again.

What the heck do I do? I know it's tired and needs a rebuild but it should still start. Hesitant to throw money at a rebuild if it's something worse (or easy).

This isn't a show car and it isn't worth a ton - I pulled it out of a shed and am low buck restoring it to just drive and enjoy. I have never owned a carbureted car or an air cooled vw... so I'm trying to learn as I go but this one has me stumped and very frustrated. I don't understand what would have changed from one day to the next, running great to not running at all.

The only thing I can think of is that maybe I wiped out the camshaft having the timing off originally? Or I wiped it out with my "new" timing? Or?? I don't know where to go from here. Any input would be greatly appreciated.


I have 40 idf’s and over the years I have become a jet cleaning expert. Try cleaning the jets high lighted in red. If this clears it up, add a good fuel filter and since you really don’t know those carbs I’d clean them. A single bristle from a wire brush works great for cleaning the jets, it doesn’t want to stay bent and springs back to straight.

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