Originally Posted by subzali
I think conventional Land Cruiser wisdom says that the cracks in the intake manifold are due to the exhaust recirculation plate getting stuck in the closed or slightly closed position, which constantly redirects air upwards against the bottom of the intake manifold, overheating it, and cracking it. I could see that the CTE differential in the cast iron and aluminum could contribute to that though with thermal cycling. Haven't heard of a cracked intake on an engine that had a properly working exhaust recirculation plate in the exhaust manifold though.
Agreed. But how many of these 30 - 50 year old rigs have properly functioning recirculating plates?