#4 Cylinder intake valve stuck open Options

[gnomefabtech]

So I'm trying to resurrect this 76 (or is it a 75?) that I just bought and it doesn't have compression on the #4 (rear right) cylinder. After some tests with compressed air it's clear that the intake valve isn't closing. I pulled the valve cover and the rockers move OK but that valve does not close all the way. Everything else looks good.

I have a lift but was wondering if I could pull that head without dropping the engine. It looks like there is room but I'm not sure about the engine tin etc. Seems like either the valve is bent or somehow stuck and maybe I can just fix the one thing there.

Anyone pull heads while the engine is still in the car?

[Superhawk996]

Drop the engine.

First - because that is the proper way to work on a 914 engine. Mid engine cars don’t lend themselves to doing work on the engine as installed. This is true of almost any mid-engine car.

Second - almost all of these cars have been used and abused over the last 50 years. Gaskets and seals have dried out. Oil and gunk has clogged the oil coolers. Mice and rodents have been inside the engine cooling tin and have set up house or have left debris inside the tin.

The reason that engines drop valves and valve seats is from being overheated. This can be due to build up of gunk on oil coolers and cooling blockages or engines that were run in a poor state of tune (lean and/or timing too advanced). The proper way to prevent this is to start by pulling the engine and making sure the cooling system is up to snuff.

2 of the 3 engines engines I’ve torn down had issues that would have led to serious overheating had they been run 1st before teardown & cleanup.

Are you sure this isn’t your engine?

Mouse house


Blocked oil cooler - gunk and oil


Blocked oil cooler on 911 engine


Another very common issue on these engines is the number of people that have pulled the cooling flaps. Urban legend of the 80s was that removing the flaps would help prevent overheating. In fact, flap removal creates overheating because you loose the airflow through the oil cooler. These engines are not only air cooled, they are oil cooled. A bypassed oil cooler greatly increases the chance of overheating the engine.

So drop the engine. It’ll be easier to work on and while it’s out you can properly inspect and clean it to ensure it cools properly.