View Full Version : '90 SC use 1 or 2 PCV Valves?

07-21-2003, 05:37 PM
I am in the process of replacing all 6 of my fuel injectors. Upon disassembly of some of the parts on the upper end, I noticed that:

A) there was no PCV Valve on the drivers side. Only and elbow to a hose which connects to the middle of the long tube between the MAFS and the Throttle Body (TB). Shouldn't there be a PCV Valve here? All that oil blow by going into my TB, Yuck! There is one on the passenger side going to the Inlet Plenum, but not one on the drivers side. I read in the non-tech forum that they are SC specific to keep from leaking boost, so would this not have an effect upon the engine with no pcv valve in the drivers side?

B) There was no gasket, nor sealer between the TB and the Inlet Plenum. Ford makes and shows a gasket for it. Maybe a big problem I was having eh? I have ordered a gasket, but has anyone every gone without?

Thanks all!

'90 SC, 5 Speed, SCP Exhaust, SCP Air Induction Kit, mostly stock but worked on by the local Ford idiots.

07-21-2003, 05:58 PM
There can only be one PCV in a car. The routing is as air enters the car through the MAF a small amount of air enters the tube that runs to the drivers side of the engine and runs through the crankcase and out the PCV into the inlet plenum where it ends up going through the SC, Tubes IC and finally into the cylinders where it is burned with the fuel and air.

Does that explain it?


07-21-2003, 10:30 PM
Thanks Jeff,
That makes perfect sense. Kind of like a fan in the window pulls air into the house, but really pulls it if another door or window is open. And here I was going to show those stupid Ford Mechanics that they forgot one! Ha!

Just seemed so oily and dirty in the throttle body. Then again I wonder if it has ever been off or cleaned.

Thanks again Jeff!

Randy N Connie
07-21-2003, 10:40 PM
When you put it back together .I t would be a good idea to put hose
clamps or plastic ties on every vacumm line end that you can.


07-22-2003, 01:15 AM
You should see the IC it's probably full of oil. It's a good idea to take the IC apart and clean out the tubes and IC with mineral spirits. Oil in the combustion process leads to detonation, and you really don't need that. Using hose clamps and wire ties are a very good thing to do.


Use a gasket under the TB or blue RTV I prefer the gasket.

07-22-2003, 07:07 PM
I did clean out the IC and tubes, and By Pass Valve on TB, and TB, and the acuator on the plenum. Man was that stuff filthy! Looks great now.

I have been replacing the vac lines and heater hoses as I go with new rubber and using good quality clamps on the big stuff and strong quality zip ties on the small ones. I figure I may not want to pull this apart for a while for something as stupid as a $1 heater hose or clamp.

I also ordered a gasket for the TB. It was only $2.44. Cheap price to pay to have no vac leaks.

Thanks to all for tips.;)

07-22-2003, 07:21 PM
I understand your question! I have also read that there is two PCV valves on the 90 SC.
I thought that it was strange at the time. I know mine only has one.