My son's 97-OBW-2.5L-135k mi suddenly started to overheat and blow coolant into the overflow. We confirmed combustion gas in the coolant using a "Head-Gasket Leak Test Instrument" (Snap-on stock #YA2000, a must tool for this work). I expect a low coolant level, cause unknown, allowed air to enter the jacket resulting in a hot spot which over heated the head. Decided to try "Bars Block Seal Head Gasket Repair", following the instructions verbatum with exception that the stat was removed to enhance circulation. Tested post treatment with water in system - no over heating or combustion gas being detected. Drained water thru the stat housing (only 3qts. of the 6.3qt coolant capacity comes out), installed the stat plus 3qts. anti-freeze. Thought I was home free, but testing resulted in over heating. The lower radiator (return) hose was cool, with significant wellowing of coolant out the radiator vent and fill neck!! Still no combustion gas was detected. Concluded that hot coolant was not reaching the stat so it remained closed, but why?? Had to be entrained air keeping hot coolant away from the stat. After 2 beers and alot of head scratching, it dawned on me that some stats have a small bleed hole in the body. Repulled the stat to check it. No hole, and this was the original stat!! With nothing to loose I drilled a 3/16" hole and re installed. Coolant was slowly added as the system came up to normal temp with a lot of air exiting the vent plug. The coolant topped out with no bubbles of any kind and the temp gage stayed in the normal range. A severe road test revieled cooling problem solved. The test will be how long the BAR'S sealent holds in place. So the lesson learned is to monitor the coolant level and should it ever get low or the system flushed, make sure the stat has a bleed hole before recharging with coolant. By the way, all this work was done with the front wheels on ramps to exaggerate the radiator neck and vent above the jacket to enhance any entrained air to seek the system high point to be expelled.
- posted
18 years ago