This still sounds like a flow issue - especially if it heats up quickly. I know it's been mentioned before, but it is possible to install the head gaskets in the wrong direction. They are usually labeled "FRONT -->". If they are installed backwards then a water port is blocked. This would cause the flow issue. When you ran it with the cap off, could you tell when the thermostat opened (it started flowing)? You can test your thermostat by putting it in a pot of water on the stove - turn the fire on and see if it ever opens.
The cap is no more than 6 months old at the most, and it is a fresh rebuild with about 100 miles on it now. It was not bored over, just honed with stock pistons.
What is the timing set at? I had one do that cause someone read the timing mark wrong when timing it. Set it way to advanced and it would heat up in the blink of an eye. I would check that before tearing off the heads -Matt
We have played with the timing as well. It is currently advanced about 10 degrees, but we had it at about 14 and it liked it more there. I just got done taking the thermostat out and i drove it without it, and it took a long time to heat up, as I expected. This means that my water pump is good and there is no blockage, right? Once it cools down, I am going to stick the other thermostat in and see what happens.
A little trick a friend taught me was to take a dremil tool and cut out the center section of the thermostat so your left with an basicly a "flat-washer". I installed the "washer" and during the summer the car ran with no cooling problems. The reduction of the ID at the housing was still slowing down the flow enough so the water still had time to cool in the radiator without runnig to fast thus recirculating hot water back through. I have to put a regular t-stat in during the winter so my heater blows hotter. Just somthing that has worked for me.
So with out the T-stat it still got hot???I would think no T-stat cruiseing at 55/65 mph it wouldnt get much over 170 deg 180 on a hot day.I too feel that you have a flow problem.Are you under driving the water pump???Are your pulleys stock for your application???We are back to a bad pump(I know its new)The impeller may be spinning on the shaft(I have seen this with re-mans)Loose fan belt/blockage in the rad or block/heads or head gaskets installed improperly.How many miles on the re-build.they do run a bit hot but it shouldnt be uncontrollably hot on a fresh re-build.Or you have an inaccurate temp guage/sensor.
I didn't actually drive it out on the road, just down my little street and back. Sorry for the misunderstanding. Tomorrow I am going to drive it a little around town w/o the stat and see what happens. I didn't have time to drive it around today because I had to go to work. Tomorrow should be a good test, too, because it is going to be in the 90's again. And
And to answer your other questions, I have stock pulleys and around 125 miles since the rebuild. I too have questioned my gauge because it tends to stick at times, then all of a sudden it jumps up to the actual reading. I guess I should loook at getting a different one for comparison.
Get a good one(temp guage) It sounds like your existing one is definitely questionable.Its a simple variable to eliminate.Cheaper than head gaskets thats for sure.Good luck tomorrow.
Sorry for the late update, I have been real busy with work and today was the first chanc I got to drive the car at all. Without the thermostat, it took a few miles and a couple stoplights to get it up to about 180, but since I was going steady at about 50 mph, it hovered around 183-185. It heated up once I got onto my little gravel road and was at 195 when I turned it off.
