1989 5.0, Awful squeaking/whining noise because of no PCV System?

1989FoxBro

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Apr 26, 2020
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Hey you guys, I rebuilt my mustang over high school and took me a while to get it together. Once I finally got it running I came across a bunch of problems, bad main ground, bad IAC, bad fuel tank, 2 bad thermostats from the box and just a bunch of stuff. A consistent problem I've had is a very high pitched squeaking or whining that comes from the engine only after it's warm and at operating temp. I talked to my dads friend who's a mechanic and who helped us throughout our adventure didn't know what it could be, assuming we had oil and everything. It's a manual, as I pulled away from a light and my RPMs dropped low it would go away too. I took it to my mechanic and he decided that it had something to do with my PCV system no longer being hooked up because I got after market valve covers and that pressure wasn't being released. Our solution has been to not push my dip stick all the way into the slot and you can feel hot air coming out of it and it goes away. To this day if I push it all the way in, (assuming its hot) it'll start whining again in seconds. It also effects my idle by a ton. I could never idle underneath 1000 RPM when it's pushed all the way in. Now I idle around 800 and doesn't squeak or whine when I have it pulled out.

My question is, what could be physically making that noise? I'm mostly just curious, I assume it's bad for my engine and puts a bunch of pressure on my seals and gaskets, etc, but what is whining like that? Should I just take off my valve cover and drill a hole in it and make a breather like online kinda suggests that I do for a more permanent solution? I don't have my old valve covers anymore sadly. I've been running my car like that for about 3 years with the dip stick pulled out like that.

Just wondering what you guys thought. Thanks.

Cole
 
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90sickfox

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It's the PCV system. At the back of the lower intake in the center there should be a pcv valve. Below that is the PCV screen. You probably need to change both of them. The pcv hose is supposed to go to the intake plenum. There's also a hose that should go from the valve cover to the big nipple on the throttle body.

Get a 94 dodge ram breather and put it in the oil fill hole in the valve cover. You'll need to use a combination of heater hoses to reduce the size down to the nipple on the TB. When you need to add oil just pull the breather out.

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MustangIIMatt

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Hey you guys, I rebuilt my mustang over high school and took me a while to get it together. Once I finally got it running I came across a bunch of problems, bad main ground, bad IAC, bad fuel tank, 2 bad thermostats from the box and just a bunch of stuff. A consistent problem I've had is a very high pitched squeaking or whining that comes from the engine only after it's warm and at operating temp. I talked to my dads friend who's a mechanic and who helped us throughout our adventure didn't know what it could be, assuming we had oil and everything. It's a manual, as I pulled away from a light and my RPMs dropped low it would go away too. I took it to my mechanic and he decided that it had something to do with my PCV system no longer being hooked up because I got after market valve covers and that pressure wasn't being released. Our solution has been to not push my dip stick all the way into the slot and you can feel hot air coming out of it and it goes away. To this day if I push it all the way in, (assuming its hot) it'll start whining again in seconds. It also effects my idle by a ton. I could never idle underneath 1000 RPM when it's pushed all the way in. Now I idle around 800 and doesn't squeak or whine when I have it pulled out.

My question is, what could be physically making that noise? I'm mostly just curious, I assume it's bad for my engine and puts a bunch of pressure on my seals and gaskets, etc, but what is whining like that? Should I just take off my valve cover and drill a hole in it and make a breather like online kinda suggests that I do for a more permanent solution? I don't have my old valve covers anymore sadly. I've been running my car like that for about 3 years with the dip stick pulled out like that.

Just wondering what you guys thought. Thanks.

Cole
@90sickfox and @General karthief are correct.

To elaborate, what you're hearing are the built-up blow-by gasses escaping the engine anywhere they can, causing the gasket or seal they're blowing past to vibrate like a reed being blown past, causing your noise.

This is actually incredibly common on GM's latest Ecotec 4-cylinder and some BMW engines when their PCV valve that's built into their respective valve covers fails.

@90sickfox 's solution allows you to restore factory function to your PCV system with minimal difficulty. There are other solutions, including installing the correct style of valve cover, or running an open crankcase breather (not recommended, it gets messy and isn't really legal), but his advice is going to be by far the cheapest and easiest to follow.
 
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1989FoxBro

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Great, thanks you guys for the replies and sating my curiosity. Once I get back home after my finals I'll take that problem down with what was suggested.

Cole
 

1989FoxBro

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Apr 26, 2020
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Hey you guys, I'm back with my mustang. As I was looking at it yesterday I saw that I already had the setup suggested above. My aftermarket valve covers came with basically exactly was described I should install. Yet I still got the same problem. I made sure the hose wasn't clogged. I made sure both nipples are not clogged either. When I take off the TB side (Just the VC side is plugged in) and run the car, I got a lot of suction at the end of that hose is that correct? Or should I have positive pressure blowing out air? My air filter isn't clogged or anything.

I checked the other part of the PCV system and it's there and it's new and goes into my upper manifold. Like I said, I'm just still running it with my dipstick pulled out, which also when I put my finger up to it, it has a lot of suction. What do you guys think?
 

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Sparky714

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You should have vacuum at the dipstick, not pressure. Sounds like your PCV system is all intact. Is it pulling vacuum past the dipstick O ring when it's pushed all the way in causing it to whistle maybe? Try sealing around the dipstick with tape temporally and see if it goes away.
 

1989FoxBro

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Apr 26, 2020
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Yeah I do have suction (vacuum) at my dipstick when I take it off, but that is how I'm currently relieving my crankcase pressure. If I push it in then that squeaking comes back and idles around 1100 to 1200. (No air is rushing in or leaking around my dipstick if I do push it all the way in.) So my PCV system "works" as far as I can tell but obv something is wrong with the system. Any ideas? Thanks.
 

General karthief

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Does it smoke out the tail pipes?
the crank case should not have vacuum enough to make a whistle or any noise for that matter.
I'm going out on a limb here and say you have a massive vacuum leak that is likely coming from a bad intake gasket.
 
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Cheapskate207

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The smoke machine is always a good idea. I had a strange whining noise once. It turned out to be the vacuum line from the pcv valve to the upper intake collapsing. Just a thought.
 

MustangIIMatt

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You're going to need to replace whichever gasket(s) the built up crankcase pressure blew out.
 

1989FoxBro

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Apr 26, 2020
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So I changed my oil the other day when I got back from Florida, I didn't have any water or metal chips in it. My coolant in my radiator doesn't have any oil either as far as I can tell. Once I get my smoke machine I can check my exhaust for leaks all the way up to the headers. I don't see any leaks on my rear main seal and I don't see any around my CC and water pump either. My point being, if all those things are good, (assuming exhaust is good too) where do I go from there to check gaskets/seals? I guess I can do a compression check and see if it blew my cylinder rings?