Robert Posted September 16, 2010 Share Posted September 16, 2010 I recently overhauled my engine. Metal head gasket, flat cyl head. But when Im driving, and especially under boost, the coolant overflows into the overflow tank! Is there any "typical" reason for this, except the obvious head gasket or cyl head? L24E T4 Turbo 23PSI boost HKS head gasket HKS SR20det high flow 63C thermostat No overheating, except when the water goes low (takes about 30miles with some fun road driving) Any good ideas? This was one of the reasons I overhauled, the cyl head is swapped for one that I know works, and Its straight. Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted September 16, 2010 Share Posted September 16, 2010 Sounds like air is getting in to your cooling system. Leak down test? Quote Link to comment Share on other sites More sharing options...
Robert Posted September 17, 2010 Author Share Posted September 17, 2010 I did test it without finding leaks before I stripped the engine, but shure, I could try again, hard to believe its the head gasket or cyl head.. Quote Link to comment Share on other sites More sharing options...
TimZ Posted September 18, 2010 Share Posted September 18, 2010 Does it do this every time you run the engine or just every now and then? I had an issue where the secondary seal on the pressure cap had a slight leak - the system is supposed to be able to allow some fluid to escape to the overflow tank as the coolant expands and the pressure cap regulates the pressure. When the system cools it's also supposed to suck the overflow fluid back in as the coolant in the system contacts. The secondary seal leak was allowing the fluid to escape just fine, but made it impossible for it to get sucked back in. So eventually my coolant level would go low and the tank would overflow. A bit of hylomar around the outer sealing surface for the pressure cap solved this problem. Quote Link to comment Share on other sites More sharing options...
softopz Posted September 18, 2010 Share Posted September 18, 2010 I just removed the radiator and put new coolant in and it is spitting out the rad neck filler ( I dont have a overflow hooked up ) just need to let it run for awhile and bleed out. I think this is normal and there is air in the system Quote Link to comment Share on other sites More sharing options...
Robert Posted September 18, 2010 Author Share Posted September 18, 2010 Id say its every time, and gets worse the harder my driving is. Thats why Im afraid its cylinder pressure... Changing radiator caps did not help Quote Link to comment Share on other sites More sharing options...
zxtman Posted September 23, 2010 Share Posted September 23, 2010 (edited) deleted post Edited September 23, 2010 by zxtman Quote Link to comment Share on other sites More sharing options...
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