Hey all, got this interesting discussion where hopefully someone can lend some insight. My father has a 2005 GX470 4.7l cyl that he took to his mechanic for a “noise” (He explained it as intermittent ticking) that it was making and a check engine light (turned out to be misfires). After having the car for 3 months the shop said they couldn’t find the source of the ticking but claimed that the GX blew a Headgasket. According to them when they took the valve covers off to run the engine the oil was milky. Having little trust in them, I told my father to have them put it back together so I could look at it. I drove it around very briefly and noticed when I floored it that a large cloud of smoke came out the tailpipe. At this point I was convinced that it had a blown head gasket and started taking it apart. After getting as far as the valve covers and draining all the fluids I became less and less sure. The oil didn’t have a single drop of coolant in it and the only sign of coolant I saw was a puddle of coolant under the valve cover, which was coincidently right under the inlet for the PCV valve on the driver side. It was weirdly “unmixed” with the oil. At this point I decided I should do a leak down test and see if any of the cylinders was bubbling out the coolant hoses (since I already removed the radiator). Out of the 8 cylinders 3 of them seemed to have issues with the valves seating well, with one that built no pressure at all, all leaking out the intake valves. I turned the crank over and over and couldn’t get these cylinders to stop leaking out the intake even at tdc. At this point I’m not sure if the results I’m getting are because the engine is cold, or even if a blown head gasket could be masked by a cold leak down test.
Wondering what I should do next, wishing I had done a leak down test before taking anything apart and trying at different temperatures or even attempting a cooling system leak test. I find it highly unlikely this engine has a blown head gasket, never overheated with him and ran fine even when he was complaining about the noise. Is there some coolant lines in the intake manifold that I’m unaware of that could be leaking down into the combustion chamber and also somehow going through the pcv valve? Is my only option to put this thing back together and try testing or can I rule out a Headgasket with everything off as is. Any and all help is appreciated.
Wondering what I should do next, wishing I had done a leak down test before taking anything apart and trying at different temperatures or even attempting a cooling system leak test. I find it highly unlikely this engine has a blown head gasket, never overheated with him and ran fine even when he was complaining about the noise. Is there some coolant lines in the intake manifold that I’m unaware of that could be leaking down into the combustion chamber and also somehow going through the pcv valve? Is my only option to put this thing back together and try testing or can I rule out a Headgasket with everything off as is. Any and all help is appreciated.
