Chevrolet Cruze Forums banner

External diaphragm for intake manifold

11698 8
Many of you are aware that sometimes the diaphragm in our intake manifold decides to just up and leave willy-nilly whenever it feels like. So, today, I'm going to try to remedy this issue without buying a new intake manifold. I took my car to the dealer and they said, "there's no check engine light, so, there's nothing wrong". I'll be posting my results and a potential write up it all goes well. If not, I'll report back and say that my tests didn't go well. I will also be installing a catch can at the same time, however, this step may be omitted.

The line that runs from the intake manifold to the turbo isn't covered in corrugated plastic, it IS corrugated plastic, however, I've got a ******* solution for this and I'm sure someone will find a better one. That line on my car had gotten cracked somehow. I don't know if it was the kid that the dealership had working on my car or if it's just worn out. I'm waiting on oil-rated line to come in the mail. I know random vinyl tubing probably won't stand up to the oil forever, but, it's what was available at the time of this post. I also know that someone may have a better design or know a place to buy an in-line diaphragm. I don't, however, I do know that there is a Lowe's down the street, so, let's get started.

The generic parts list that I'm looking for at Lowe's today is this: barbed 3/8" fittings (size could change from build to build), some kind of a casing to go around the other end of these fittings to attach them so that they're positioned as "male to male", and a metal ball to go inside of here. I don't know how well this will work, but, it should be better than nothing.

On my Cruze, like I stated earlier, that PCV line had gotten damaged. So, I've got a splice of (I think transmission cooler line) going to it. I used a hacksaw and I cut off a large chunk of the line. I have a 5/8" piece of vinyl tubing on the outside of each end some fittings to take it down to 3/8" or a little bigger and hose clamps to be safe. This isn't really pretty, but, I'd rather have hose clamps than hoses that fly off. Especially since I'm tuned for ~20 psi of boost, seemingly.

The diaphragm allows air to circulate under at least vacuum and maybe even low boost between the intake manifold and the front of the turbo. Under high boost, the manifold gets sealed. That's what I'm attempting to do here. I gathered some information from this post on Sonic Owner's Forum 1.4T PCV Explained - Chevy Sonic Owners Forum . If that post is accurate (and I think it is) and the Cruze and Sonic have the same 1.4, which, I'm certain they do, then this information should apply to the Cruze. It's a good write up about our PCV system. It has a good engine dissection and nice dry-erase diagrams.

Sorry for the long post, however, I feel like this is an important step. I should note that I am currently an engineering technology student so this build isn't completely ******* engineered.
1 - 9 of 9 Posts

·
Registered
Joined
·
202 Posts
Discussion Starter · #2 ·
So, I have some photos and it works. I just need a shorter chamber or a longer bolt and a new valve cover, too. That's next on my list of things to replace and it should have been delivered today.
 

·
Registered
Joined
·
1,383 Posts
I've also read that post about PCV over on the Sonic Forum. I believe the corrugated hose is failing because of the high flow rate of gasses through it.

While you're fixing the tubing, the key point is the orange check valve inside the intake. If this is failing, or gone missing then there's excess gas always going back through the corrugated hose to the Turbo. This amount of air moving through the engine may pull oil everywhere.

I don't think the actual OEM hose is that much money. By attempting a fix where the line can take higher flows without failing is an interesting one. Preloader over on that site mentions that it may effect oil consumption.

I just posted to his tread about 2 days ago, asking him to post some pictures of looking down the large vent tube to see what we're soposed to see with a good orange check valve.

All this flow through the corrugated tube also pressures the valve cover. Sure you can fix it for the short term, but based on his theory it could rupture again.

This is the reason why some people have gone through 2-3 valve covers, and know the GM procedure is to inspect through the connection of the corrugated tube on the intake looking for check valve. Not sure exactly what can be seen with the intake on the car, but apparently it can be seen in a good intake, and without seeing the orange check valve the intake needs to be replaced.
 

·
Registered
Joined
·
202 Posts
Discussion Starter · #4 ·
My dealership's philosophy is that if there isn't a check engine light, nothing is wrong. I told my dealership to tell that to all the smoke coming out of the exhaust on the highway. So, I'm attempting to fix the missing check valve issue without replacing the whole intake. However, my valve cover is bad, too. It came in the mail earlier today, I'll be installing it tomorrow evening. The valve in the intake isn't really a valve -- it's more of a diaphragm. So, I made one and I'm going to see if that helps. I'll be updating the thread with all the information I gather.
 

·
Registered
Joined
·
15 Posts
Awesome Clausses.
Did you cut the intake manifold at the area of the diaphragm? Do you think that when it falls off, we can re-attache it somehow, or are you talking about replacing completely the valve somewhere else, outside the intake?
If you can, please post images of your build as well.
Thank you

P.S. I also had a defective intake manifold with no lights on. But the valve cover diaphragm got cracked and i had to replace it as well.
 

·
Registered
Joined
·
551 Posts
Vacuum and Pressure Adjustable Brass Relief Valves








  • Use with vacuum and air
  • Temp. Range: -15° to 250° F
Protect against excess vacuum and pressure with one valve.Adjust set vacuum and set pressure within the ranges. Body isbrass. Valves exhaust to the atmosphere; vent is on the top.Pipe connection is NPT male. Valve with 1/4 pipe size has a Type 440C stainless steel seal. Valves with 3/8 and 3/4 pipesize have a Buna-N seal.

Product Detail
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top