Hey guys. I've got a questions for you.

I had noticed my 4runner was starting to run pretty rough. So I instinctively check the oil, or should I say chocolate milk. Sound familiar yet?

I had been trying to pull the timing cover, but the harmonic balancer was giving me trouble. I managed to strip the bolt, so I broke out a cut off wheel and went to town. Got that off, pulled the timing cover, and inspected. I found minor signs of wear, and a "lightly abused" driver's signs timing chain guide. No holes, or channels ground into the soft aluminum cover.

Next up is the head, that came off relatively easy. I say relatively, because the coolant hose mount in the back of the motor is one of the most stupid ideas implemented to date. I inspect seating surfaces, and old gaskets for signs of a blow out: none present. I grab my Engineer's Ruler, and check the head for warping: none. I check the block (never know): nothing. I even go over a few more times looking for cracks and see nothing.

How common it is for the timing cover to be the culprit, but show no obvious signs on failure? Any more advice to offer?

 

Oh yea, I forgot to mention I just ordered; a full set of gaskets, new timing cover, chain, metal chain guides, oil pump and water pump, and harmonic balancer bolt... so I think I am hitting all the bases nicely.

 

Nothing? Awesome.

 

Well, if you have oil and coolant mixing and the cover is in good shape you probably had a leaking head gasket. How did the head gasket look when you pulled the head off?

 

Gasket looked so good I was tempted to use it again.