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Discussion Starter · #1 · (Edited)
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Hello! I smoke tested my Cougar trying to find a vacuum leak. Three areas have smoke coming out: Intake manifold lines, the throttle body where the springs lead to for the pulley, and the EGR holes (which was replaced a few years ago).

My Cougar still idles lean when you put it in drive or reverse on a cold start. Once it warms up the idle is normal.
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Does anyone know what these lines do? Did the circle inserts wear out? I push down on them to make sure they are snug but they still leak with the test.
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I honestly do not know what to do next. Should I look for these parts to replace or come up with a temporary fix, like a sealant?
I would appreciate any help, regards.
 

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1999 mercury cougar v6 5 speed
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Get some rtv sealant for thr intake hoses but not the egr valve it may be the gasket but also could be slightly defective with loss of vaccum through the diaphragm. The throttle body it much harder to fix. A new throttle body would be best. You can get one on ebay new or used for about 50 to 100
 

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Discussion Starter · #3 · (Edited)
Thank you 1999mercv6! That is a great idea for the intake hoses. I will buy some RTV sealant. As for the throttle body and gasket I'll see if I can get a better view of why there is a leak, but I'm definitely pricing them out online now.
 

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1999 mercury cougar v6 5 speed
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Discussion Starter · #9 · (Edited)
Status update: I gently pulled out the P444C line by pushing it up and down and it came off without breaking anything. I can confirm after reading this forum: vacuum clips on upper vac lines, going into UIM?
That it is held in by a black plastic piece that's surrounded by a gold or brass cover. You can slightly pull out the plastic piece with your finger nail and try to apply RTV sealant. I just need to find a tooth pick to spread the sealant and it's supposed to take 24 hours to cure. I will try it again soon.

Anyways, this vacuum leak also explains why this engine becomes easily heat soaked since it's sucking hot air directly from the top of the engine bay. The intake manifold valves open at 4000K+ rpm and that's exactly when it struggles to accelerate on 90+ degree days. Once this issue is fixed I'm hoping this Cougar will perform better.
 

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Throttle body spring leak seems to be normal on older cars because a lack of seal between the spring and the Throttle body.
Actually its the throttle shaft bushings that wear out and he air goes out the side of the TB. The spring side bushing near the return spring wears out first because more load.

Status update: I gently pulled out the P444C line by pushing it up and down and it came off without breaking anything. I can confirm after reading this forum: vacuum clips on upper vac lines, going into UIM?
That it is held in by a black plastic piece that's surrounded by a gold or brass cover. You can slightly pull out the plastic piece with your finger nail and try to apply RTV sealant. I just need to find a tooth pick to spread the sealant and it's supposed to take 24 hours to cure. I will try it again soon.

Anyways, this vacuum leak also explains why this engine becomes easily heat soaked since it's sucking hot air directly from the top of the engine bay. The intake manifold valves open at 4000K+ rpm and that's exactly when it struggles to accelerate on 90+ degree days. Once this issue is fixed I'm hoping this Cougar will perform better.
I bought bushings from darkcat, he might have more. Also in the bottom of the brass "sleeve" is an o-ring. Replace that if the rtv fails.
 

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IIRC, the throttle shaft has an o-ring that can be replaced. You have to take the whole thing apart, including probably destroying the throttle plate screws and replacing them, but it can be done. just get new screws and an O-ring from the local hardware store. Repair is probably a $5 job but it will take a couple hours if you aren't experienced.

An impact screwdriver works great on throttle plate screws. One of the ones you hit with a hammer, not a powered one.

This old how-to might help you:
 

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Discussion Starter · #12 ·
Thank you guys for the help! I decided to order a throttle body from a lower mileage donor Cougar with a new gasket. I want to have a second one I can take a chance with that could work fine and to understand what it looks like inside with its O-ring and bushing before restoring the first one.
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Also I finally understand the O ring on the UIM line ports that keep it sealed, which means I should apply RTV sealant to the bottom inside circumference.

Quick question: How do I remove that brass sleeve?

I think I'll fiddle around with it carefully to see if it comes out for better access to apply sealant.
 

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Please note with the throttle body - there are 2 different styles, one for the manual trans car and one for the automatic.

You CAN use either one, but both of the attached cables are also different between the two, so if you use a different style, you have to replace the throttle body, throttle cable and cruise control cable.

PERSONAL OPINION: the automatic throttle body is an improvement for a manual trans Cougar as far as throttle response is concerned, but you don't really want to put a manual throttle body on an automatic trans Cougar because it will make everything super mushy and unresponsive.
 
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Discussion Starter · #14 ·
Thank you B3NN3TT, I was able to order the automatic throttle body for my AT Cougar. I also ordered a used manifold intake that includes two vacuum clips/brass sleeves that could work better than my current ones, and so I can also have an extra pair that I can restore with RTV sealant since it's not sold anywhere anymore.
 

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Discussion Starter · #17 · (Edited)
I used this "Automotive EVAP Smoke Machine Diagnostic Vacuum Leak Detection Tester" from eBay:
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I stuck it into the throttle body opening and I held the throttle pulley back to open the valve. I did have to take off the air filter box to access that.

Also I'm glad there are still ways to improvise. I hope all of our Cougars stay alive over this century. :)
 

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Discussion Starter · #19 ·
Okay, I will do that 👍. I remember AutoZone has those angled picks, I will pick that up too. Thanks, I wasn't sure if it was possible.

Also hello SpaceCatsAz! Vibrant white is a great color with its albedo effect.
 
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