New engine rebuild running hot, Running Hot Options

[57lincolnman]

Recently completed rebuild of 1.8L and it's running too hot. Oil temps climb to 230 with only about 10 minutes running. It doesn't matter how the engine is loaded. Items to consider: 1) case cleaned and checked for alignment; 2) LN pistons installed at 96mm with new Nickie cylinders; 3) cylinder heads (1.8L) cleaned and set for 8.25:1; 4) new connecting rods; 5) push rods check out OK; 6) car did not previously have thermostat or cooling flaps, so these were installed. Thermostat opens as it should at 180; 7) Air/fuel ratio is 12-14 and within spec; 8) engine timing within spec; 8) mild cam upgrade. 9) crankshaft and flywheel were balanced; 10) all engine tin is in place

Could it be that the engine cooling flaps are not working or reversed? All thoughts and commentary are welcome. This one has us baffled.

[mrbubblehead]

what weight engine oil? could be high oil pressure is bypassing the oil cooler.

[57lincolnman]

what weight engine oil? could be high oil pressure is bypassing the oil cooler.

Good point. I need to check with engine builder as to what he is using. I know that it is a Brad Penn racing oil that he's using to break in the engine. I'll get back to you.

[mrbubblehead]

what weight engine oil? could be high oil pressure is bypassing the oil cooler.

Good point. I need to check with engine builder as to what he is using. I know that it is a Brad Penn racing oil that he's using to break in the engine. I'll get back to you.

many believe they HAVE to run 50 wt. which all they are doing is creating heat and throwing away horsepower. you should taylor your oil weight to your psi and rpm. this is with full group 4 or group 5 (ester) synthetics. i think the bypass spring is set up for around 46 psi. racer chris or jake would know exactly. anyways when you are at high rpm, oil pressure is high esspecially with thicker oil. the engine goes into protection mode and bypasses the oil cooler to protect it. high pressure = resistance and heat. lower oil pressure = more flow. (too a point)

[worn]

what weight engine oil? could be high oil pressure is bypassing the oil cooler.

Good point. I need to check with engine builder as to what he is using. I know that it is a Brad Penn racing oil that he's using to break in the engine. I'll get back to you.

many believe they HAVE to run 50 wt. which all they are doing is creating heat and throwing away horsepower. you should taylor your oil weight to your psi and rpm. this is with full group 4 or group 5 (ester) synthetics. i think the bypass spring is set up for around 46 psi. racer chris or jake would know exactly. anyways when you are at high rpm, oil pressure is high esspecially with thicker oil. the engine goes into protection mode and bypasses the oil cooler to protect it. high pressure = resistance and heat. lower oil pressure = more flow. (too a point)

When there is too much pressure the relief valve opens, but it also closes. Shouldn't be open ever below 25 if working. For most cars once warm a single pause at idle will lower pressure enough to close the valve after warm up. Opening takes in the 40s because the area for oil to press against is smaller than the area after opening. I don't think this is overheating the car because the pressure is so low.