So this past week I've had some unusual cooling system issues. First let me tell you about my system. Brand new aluminum radiator (I know skib denounces the use of these but I was in a pinch and the radiator shop refuse to fix mine again), New 185 deg thermostat, and stock shroud and fan. Stock L20, weber downdraft, dogleg, maybe a mild cam. Also I'm trusting a stewert warner gauge that might be 30 years old. I've noticed lately that my car smokes quite a bit until it gets to temp, it doesn't smell like coolant though. So today by the time I get on the interstate I'm up to temp, not smoking so much, temp 190. I'm cruisin at about 3k rpm and I notice the temp is climbing, so I start to slow down to pull over and the temp comes back down. so the rest of the ride to work I keep it at 2.5k rpm and it stays at 190, droped to fourth and at 3k+ the temp starts to climb, back in 5th at 2.5k the temp comes back down.
Once I get off the interstate I notice the heater is cold and the temp is climbing. Then I have heat and temp starts going back down.
Its been doing this sorta thing for a min, and my first thought was blown head gasket, but we ran a block tester last night and the test came out alright (may have done it wrong, I'll try again this weekend). Also we did a pressure test on the cooling system and after tighening a barely loose hose clamp it would hold 15 psi. I'm also losing coolant though, but I dont know if it running hot and dumping out of the over flow is causing the loss of coolant, or its losing coolant into the engine, then running hot because of lack of coolant, then dumping out of the over flow. There are coolant stains in the engine bay but I can't replicate when it runs hot in the drive way.
What do you guys think? What should I check? Maybe a air pocket in the system?
This is my only ride and I depend on it to get me to work, I really appreciate any help.
Pierce Jones