98' Caddy split intake plenum problem
From what I have read, this is a common problem of the Northstar engine as the plenum is made of plastic and is only heldb down by 6 small bolts. I problem started as a high pitch whistle coming from the passenger side of the engine. Upon inspection I noticed the bolts attaching the plenum to the engine were figure tight but when I attempted to tighten them the hole they go through all began to crack crumble and split. I couldn't even get the bolts anywhere near the torque specs as the plenum was just giving it up with each turn of the bolt. I beleive the whistling is coming from the engine pressure releif valve located behind the power steering pump as I see that other people have had that problem. So I guess I need a pressure releif valve and a new plenum. Does anyone make an aluminum plenum for the caddy? Is there anywhere to get the plenum other than the dealer? Thanks!
Mr. G
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