I believe I have finally located the exhaust heat up valve thingy you guys are referring to. It's at the bottom of the exhaust manifold, right? It was partially hidden by the heat shield but I saw a spring and lever type contraption back behind it. I need to replace the manifold gasket anyway, and this give me an even better reason to take it off. I'm going out of town for the weekend but will report back after I've completed the wrenching. Any gotchas you guys can think to warn me of before hand?
Yesterday I pulled the manifolds off to replace the gasket and get at that butterfly device in the exhaust manifold. Before tearing it apart I took the heat shield off and played with the weight on the end of the butterfly. I could move it by hand but found it would not move on its own no matter how hot the engine got.
After getting the manifolds separated I took the spring assembly off the butterfly and shimmed it in the open (exhaust going out the manifold rather than up to the intake) position permanently. I also bought a sheet of 22 guage metal and toyed with the idea of creating a plate to block that passage off completely, but ended up not doing so, thinking it'd throw off the alignment of the manifolds and I wouldn't be able to get them bolted back onto the head.
I did some other small stuff, like buying plugs for the EGR tube (since the valve has long been non functional) and removing old vacuum lines for the extinct smog pump, EGR, A/C, etc.
Got it all buttoned up and went for a test drive last night. It never got hot or bucked / jerked / hesitated, but there is still excess pressure in the system and it again blew the PCV valve out of the valvecover. I put a vacuum guage on it today and came up with the following readings. At idle it jumps between 17 and 18 inches. Blipping the throttle it would drop to 4-6 inches, up to 22, then back down to 17-18. Holding it steady at 3k RPM, it raised up to about 20, then when I let off it peaked at 22 then settled back down to 17-18. I don't know what "excessive" needle fluctuation mentioned above equates to, but other than the jumpy needle my readings seem pretty decent. The jumpy needle did happen across the board, and would fluctuate 1 or 2 inches. Is this indicative of a bad head gasket? I need to do a pressure / leakdown test to see what the rings say, but I foresee more wrenching in my future regardless. As usual any and all input is greatly appreciated.
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