Too much pressure in engine after rebuild

[velum]

Hi!

I got an engine job done on my 1973 914 2.0L FI, and since then it has been spitting oil all the way to the air filter through the head breathers and the flashback valve. The sparkplugs are dry, so there is no leak inside the combustion chambers. There seems to be a pressure problem in the heads, but I don't know why. Anyone has a clue?

The PCV valve closes and opens, but I don't know how to tell whether is is working correctly when the engine is running.

Cheers!

JF

[DutchBug]

Perhaps a too simple question but did you perhaps put to much oil in it?

[velum]

Unfortunately, this is not the problem. Th oild level is ok. I wished it would have been that simple!.

[Piledriver]

Welcome to the forums!

The 914/T4 PCV setup is fairly straightforward, but poorly understood... it can be improved upon greatly with no visible changes...

There are some excellent discussions on PCV in the forums, search for user "ray greenwood".

Ring (and valve stem) blowby are the primary culprits, and the stock setup lacks a really good oil separator out of the box, although it is amusingly easy to create an excellent one by stuffing a woven SS pot scrubber or two in your breather tower.

If it is a "new" engine a little more blow by is to be expected until the rings seat, but that should happen relatively quickly.

I will attempt to put together a unified PCV "How-to" thread and make it a stickie here this weekend. (for me, tonight is Friday..)

I run CIS on stock bus manifolding, and actually have a pretty solid case vacuum at all times... did wonders for oil leaks and consumption, the rings started sealing again.

[velum]

Is there an easy way to determine whether the culprit is the rings or the valve stems?

When you say "that should happen relatively quickly", how many miles is that? I drove around 300 miles since the rebuild. Would you drive the car hard? Someone suggested that although I thought one had to be gentle with a newly rebuilt engine.

Let me know when your PCV how-to is ready.

Many thanks!

JF

[Piledriver]

The "take it easy for the first 1000 miles" warnings indicate that the actual clearances may be on the tight side, and it is safer to wait until the engine "self clearances" a bit. This is typical of how most places build engines...

The rings should seat best under load, but won't if running very rich.

They should actually be seated the first few times you romp on it, but it depends on how the cylinders were honed.

In a perfect world, they seat on the starter, the first time you crank it.
Happens sometimes, and you have ~ zero blow by.

Did you have the heads done with new guides?
(I like viton oil seals on the intake valves... Teflon ones seem to work TOO well. I need to buy my own cutter)

[velum]

Yes, the heads were redone with new guides.

I was going to order a replacement for my PCV valve, but that part is no longer available. Is there any substitute?

[Piledriver]

Yes, the heads were redone with new guides.

I was going to order a replacement for my PCV valve, but that part is no longer available. Is there any substitute?

Yes, Ray Greenwoof recommends a 3mm restricton to manifold vacuum instead. It does work well...