rioncrsn
Well-Known Member
ok I got a 1986 359 pete with a 400 low flow cummins engine. It has a new water pump, thermostats, hoses, and all system cleaned, also radiator rebuilt. It will idle and never heat up, if you drive it down road it will hear up in a couple miles. I took the plug out of top of water manifold with engine running, seemed like it was not much if any flow, then I took radiator cap off and started flowing and pushing water out of hole, put cap back on and cut flow off. Just trying to figure out what would cause radiator cap to make system pull vacuum and almost immediately with taking cap on and off. Thanks