The old head on my truck also had those cracks between the valves ~ eventually coolant became pressurized showering out of the coolant overflow tank & out the tailpipe ~ I was forced to buy a new cylinder head ~ ALSO needed to replace coolant temp sensor, O2 sensor AND remove one plugged catalytic converter ~ PLUS discovered & fixed the disconnected (at the intake manifold) vacuum hose that operated the air intake flapper valve that draws hot air from the exhaust manifold when the engine is cold ~ WELL the bi-metallic vacuum switch (valve) inside the air cleaner that operates that hot air flapper DID NOT work anymore ~ THE FIX block off vacuum where the hose connects to the flapper valve nipple (no vacuum keeps the flapper open allowing the engine to get cooler air from outside the engine bay ~ my truck was always drawing hot air and I had no clue) about it ~ I FINALLY got lucky fighting trying to discover why my truck still had a nagging intermittent miss ~ damn near everything needs to be inspected/tested to get results; especially vacuum hoses ~ LASTLY even tho a 1986 ECM is primative I (think?) my ECM took two days (16 miles total) driving to recognize my vacuum leak fix ~ I dunno
Hope this helps your decisions![]()
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