U S Marine

Doh! I'll check it out, with sound during lunch. Sorry!

edzdallas79

sleeper took the words right out of my mouth. haha

yeah, the video shows the vacuum gauge at idle. the knocking sound, to me at least, is very faint and the only time i can hear it is at idle when the hood is up. there's no noticeable blowby, so i don't think it's an issue with rings. i was thinking about pulling the head and doing a valve job, but the machine shop suggested not doing that unless i work on the block also. i think the first step is swapping the vacuum hoses out for silicone to see if that's what's causing the issue. i may do that in the next week or so. i've also been told to put a quart of ATF in the crankcase and that will clean up the lifters if they are dirty.

U S Marine

Well, it's not jerky/rapid so that pretty much rules out a stuck valve or collapsed lifter. Stuck valves/bad lifter usually will be rapid and pronounced, like a windshield wiper. I can't really hear the knock, but then again, my wife says I can't hear her either! (There is a reason for that) ANYWAY, it looks like you just might have a worn out seats in the head. An air leak shouldn't cause surging vacuum readings. It has to be something changing the direction of air flow. Just an outside shot here, but have you checked the one way valve/check valve on the brake booster? Might be worth a shot. Forgive me here, but I can't remember if you stated whether you had good oil pressure or not(?). A low idle knock can be worn rod bearings.

U S Marine

Your machine shop guy is probably correct. If you seal up the head really good, then the compression will go right back through the rings, causing crankcase pressure and you'll be venting oil where you don't want to vent oil. Make sense? I've heard of the ATF trick, but I can't verify. Never done it that way. There are a lot of crankcase cleaners out there. I've used a qt of kerosene and IDLE the engine for 10 minutes or so, then drain. What I can verify is this: I've done this on 2 cars so I KNOW THIS WORKS. After you clean your crankcase, use a good oil, I use Motorcraft oil and install a BOSCH oil filter. Change it after 1000 miles, then replace the oil and filter with the same stuff and change the oil in another 1000 miles. Then go 2000 miles doing the same thing, then 2500, then 3000, which is the recommended interval. My current 'stang has 130K on it and I could take a picture of the oil, on a white cloth, that has been in the engine for 2200 miles, and it IS STILL CLEAN!!! Sorry for the long post.