1974 2.0l w/dual 34ICTs having blowby Options

[justjoel]

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.

[Ninja]

Most likely oil is leaking on the exhaust/heat exchangers.

They are bad about the pushrod tube O-rings.

Makes for nasty smells!

I wouldn't run that. Lots of "got it running after XX year threads" end up with a dropped valve/broken spring which equals a complete rebuild.

I have a 75 with 31K that hibernated for 33 years (1988 inspection sticker).

It also runs OK.

I will not run it again before removing the engine, replacing ALL of the rubber seals and replacing the valve springs.

Some (at least two) of the valve springs sat open (compressed) for decades. These are the springs I worry about.

The parts are not seriously expensive until you drop a valve.

I know my advice sucks but $300-$500 today could save 3000+ two months from now.

This is not 914 specific. Valve springs SHOULD be replaced every 20-30 years on anything.

[930cabman]

(IMG:style_emoticons/default/welcome.png)

Great start to the fun of 914's and welcome aboard

If the compression checks out and there is little/no smoke from the tailpipe, I would say the rings are ok

After a 20 years sleep (IMG:style_emoticons/default/beer.gif)

[justjoel]

Thanks for the input. I feared it'd be a rebuild. I was hoping to enjoy the car this spring and summer before tearing further into it. It's already spent 6 months on jackstands getting the hell hole fixed up. But you're probably right. Delaying the inevitable engine rebuild.

[justjoel]

Most likely oil is leaking on the exhaust/heat exchangers.

They are bad about the pushrod tube O-rings.

Makes for nasty smells!

I wouldn't run that. Lots of "got it running after XX year threads" end up with a dropped valve/broken spring which equals a complete rebuild.

I have a 75 with 31K that hibernated for 33 years (1988 inspection sticker).

It also runs OK.

I will not run it again before removing the engine, replacing ALL of the rubber seals and replacing the valve springs.

Some (at least two) of the valve springs sat open (compressed) for decades. These are the springs I worry about.

The parts are not seriously expensive until you drop a valve.

I know my advice sucks but $300-$500 today could save 3000+ two months from now.

This is not 914 specific. Valve springs SHOULD be replaced every 20-30 years on anything.

Well I was thinking it was oil getting on my exhaust but I already replaced all the pushrod seals, the oil cooler seals, rear main seal... it's got a slow leak from above the oil filter area so I was thinking it was distributor shaft seal leaking. I have one sitting in the garage ready for replacement before I realized the blowby was happening. I watched Han's Garage on Youtube replace the springs with the heads on and it didn't seem too terrible. I'll have to add it to the list. If I'm going to replace the pistons, rings and cylinders I'll definitely replace the valve springs and guides while I'm in there. It's just time and money right....

[930cabman]

just time and money, how far and fast do you want to go?

stick with it, I was a 356 and 911 guy for many many years, got bit by the 914 bug in 2020, sold the 356 and now have 5 914's

they are a blast, especially if you can fit one with a /6

[justjoel]

just time and money, how far and fast do you want to go?

stick with it, I was a 356 and 911 guy for many many years, got bit by the 914 bug in 2020, sold the 356 and now have 5 914's

they are a blast, especially if you can fit one with a /6

That's awesome. I am envious because I'd love to own a 356 or a 911! I can ONLY afford the 914 haha. Well I have another entry level Porsche, the Boxster as well. But! I really love driving the 914 and the sense of accomplishment from resurrecting this thing from the dead. It really should have been a parts car but I refused to let it die, even though it feels like it wants to die sometimes.

How does the 914 compare to driving a 356 or a 911?

I think I will try ducting the crankcase vent into the carb and see if that alleviates the headaches when I drive it. It's not the right fix but maybe the fix I can afford for now haha.

Thanks for the response!

[914sgofast2]

Excessive blowby on an engine that has sat for a long period of time often indicates that the oil control rings have gotten gummed up. Change the oil more frequently and drive it .