I'm very excited to say that I got my 89 k1500/LQ4 running this morning. It runs better without a MAF, and O2 sensors than my TBI 350 did on its best day LOL.

Anyways, I have just a few issues I need some help with. They are both cooling related.

I don't know whats going on with my cooling system. Both heater hoses get really hot but the upper and lower rad hoses aren't. It has a brand new thermostat (187 degree) and there aren't any leaks in the system. I thought there might be an air pocket in the system (which there still might be), but when I was filling the system, I filled it from the upper rad hose first with the throttle body line disconnected to fill up the block. Once I got a steady stream of coolant from the throttle body line I hooked it back up and filled the rad. I even jacked the front up and ran it for a little while with the cap off. Like I said the heater hoses got REALLY hot and there was some steam coming out of the rad. This leads to my next problem...

I couldn't tell how hot the system was because the temp gauge was only showing 150 degrees. I'm using a 3 wire coolant temp sensor from an F-body. I heard that the F-body CTS can give inaccurate readings (10 to 15 degrees off), but this just seems WAY off. I don't think the rad would be emitting steam if it was only 150 to 160 degrees. Maybe the earlier obs trucks (88-89) with moonie gauges just aren't compatible at all with the 3 wire CTS?

Any insight would be immensely helpful. Thanks!