flashback valve

[Mike Cardwell]

What exactly is the flashback valve, where is it located on the 1.7, where exactly are the connections to the heads made at, and is it dangerous to omit this valve (safety and performance) Thanks.

[Dave at Pelican Parts]

The "flashback valve" is a three-way hose junction with a metal screen in it. The function of the screen is, from what I read, to keep your engine from blowing up.

Actually, that's a bit of an overstatement. The screen is supposed to prevent a backfire in the intake from sending burning gases into the crankcase by way of the valve covers and pushrods. The screen is supposed to put out the flames. I think it would be a pretty darn remote possibility for a flame front to get down into the engine, or to ignite the oil/oil vapor in there if it did, but this is supposed to prevent that.

It is not needed if your car does not have the PCV (Positive Crankcase Ventilation) sytem--but I think all US-spec 914s without smog pumps do have that. Not sure on the earliest ones.

The flashback valve usually lives toward the left-front corner of the engine compartment, on top of the engine near the fan shroud. It typically bolts on to the same bracket that the spring for the engine cooling flaps does.

I don't know where exactly the hoses to the heads hook up on a 1.7 or 1.8, as I've only really paid attention to my 2.0 in that department.

--DD