intake manifold gasket help?

[tooshady]

hi I have recently purchased a used 3.8L impala. drove the car with no problems for about 2 days, then 20 mins into driving the car on the third day, the car started misfiring and I heard this rattling/wierd noise sounded like from my engine, I only heard the noise when I pressed on the accelerator, took the car to a local mechanic shop, the mechanic looked at it and said both intake manifolds needed replacing, I did not ask how much because I knew it would be alot, I went and bought the gaskets, both upper and lower, and new spark plugs and wires, I dont have a garage so I have to work outside, so should I work on it myself?/ how difficult is it if you have done it? I am confused on what torques I need inches or foot, and also could this be the cause of the sound I heard?

would also like to add that I checked the oil not vanilla looking under cap, oil looked very chocolatly and was muddy and suddy looking soupy stuff, The coolant looked as though it had mud around cap, and brown stuff in it

[maxwedge]

The upper intake is the usual issue, as well as lower gaskets but they are less probable, no way for us to know your capabilities here. Google or do a site search for 3800 intake gaskets, plenty of info out there. BTW, do not drive the car in this condition.!

[HeMi101]

Weird rattling/ Misfireing sounds like a Clogged Catalytic to me...

Sound like this?

[tooshady]

yes hemi it does sound something like that, saw a video on youtube that had the sound clearer but cant seem to locate it at the moment

[tooshady]

I found the video of the sound that sounds similar to the one my car is making here it is
http://www.youtube.com/watch?v=PiEXUtUPFRY

[manicmechanix]

You may have a bad cat. I think you need to change the oil and flush and change the coolant to original Green. This will buy you some time with the intake gaskets. Also change you radiator cap to Stant 10230 or 11230. Dexcool is all right but it's not particular compatible with the silicone and nylon intake gaskets used and the cap on the radiator cooling system and all iron engine.

If you replace the gaskets with Felpro problem solvers and fix all leaks, then the Dexcool would probably work OK but you would need to make sure the radiator is compltely full at all times.

[HeMi101]

I've run dexcool with NO issues as long as you maintain your vehicle (like your kinda... Supposed to? ) but green stuff IS cheaper anyways, isn't it ? lol

other video has me wondering if its the Cat after all. when you rev up, does it die out (like in my video, couldn't go past 3900 RPM).

[manicmechanix]

Originally Posted by tooshady

I found the video of the sound that sounds similar to the one my car is making here it is
http://www.youtube.com/watch?v=PiEXUtUPFRY

I could be wrong but that kind of sounded like the timing chain. It's really hard to tell from the video, but the knock sounded constant with increasing engine speed, whereas a rod or tappet knock would normally speed up with increased RPM. It could be other things, maybe even one of the drive belt pulleys or tensioner.

[tooshady]

no car does not die at all, just makes this noise

[maxwedge]

Keep rumning with the oil/coolant mix and the world will hear your engine noise!

[tooshady]

well guys I took everything apart step by step by the book, and put it all back together again with new gaskets upper and lower and I put coolant in and the coolant ran out of the lower intake manifold I am so frustrated I dont know what I did wrong

[manicmechanix]

Sounds like maybe you didn't get one of the coolant elbows on good.

[stupidreefer]

This thread was given to me by someone here. I hope it helps you solve the issue. I have not yet started mine so I can't really help. Best of luck.

The thread is step-by-step with pic's. It's all about the 3800.

http://www.pontiacbonnevilleclub.com...hp?f=53&t=3591

[stupidreefer]

Originally Posted by tooshady

well guys I took everything apart step by step by the book, and put it all back together again with new gaskets upper and lower and I put coolant in and the coolant ran out of the lower intake manifold I am so frustrated I dont know what I did wrong

Just wondering, when you took it apart, did you check the push/oil rods to see if any were bent?? Rolling them on a true flat surface like a pane of glass. If one wobbled it would need to be replaced. Hard to tell from a video, but I heard a knock, IMO an oil or piston rod knock. I could be dead wrong though. Honestly sounded like a piston rod, when the bearing gives out. Light noise until high RPM's then louder as the bearing try's to stall.

[Fuergrissa]

doing the upper intake gasket for my 05' 3.8 tomorrow, does anyone have any pics of the burnt/melted coolant passages near the TB? I'm told this is common when it leaks from this location and means the upper plenum needs to be replaced. I'd like to make sure I know what I'm looking for, or will it be fairly obvious? I also wonder about picking up one of the 60$ plenums from ebay anyone have feedback on them? I avoid ebay parts like the plague on my Z, but I need to get the DD going as quickly and cheeply as possible.

Also will I need to remove any of the accessory drives or is that assosiated with the lower plenum removal only?

TIA,
Casey