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On December 5, 2018 I posted I had finally found a coolant leak and repaired it. Two or three days after I posted success, the outside temperatures dropped into the 20's. I looked under my truck and saw a large fresh wet spot. This was a WTH moment. After a lot more searching it looked like the coolant was coming from somewhere on the top of the block, between the head and oil cooler, and running back toward the rear of the engine. I put a pan under the dripping area and saw probably 2-3 ounces of coolant daily each day.
I knew I had identified and corrected previous leaks, and there were no more coolant system connection points where a leak could occur. I decided that if the top of the block or the oil cooler's cover weren't cracked, that the leak was most likely the blue gasket under the housing. And if this was the source of the leak, coolant may be getting into the oil also. I didn't drive the truck any more, and decided to begin the engine removal and head gasket job soon, instead of waiting until spring.
On January 2nd, I began the engine removal. As soon as I took off the oil cooler and housing I saw the blue gasket had been the source of the leak. It had compressed and shrunk so much at one coolant port, that when I laid a small straight-edge on it, the gasket was flat and level with the housing. Notice the rust around that portion of the gasket where it had laid loosely against the engine block. Although the gasket appears to stand above the housing in the photos, it doesn't. When looked at from the side, and when using the straight-edge, the gasket is flat with the housing.
Yesterday I had the oil cooler and housing on the work bench for cleaning and installation of a new cooler and gaskets. After taking these photos, I removed the old gasket and laid the new blue gasket into the cooler housing channel and measured how 'proud' it stood above the housing. It measured about 0.060"-0.065".
Good observation. I guess two things I would speculate about.
With vernier calipers depth rod, is it possible that the groove varies in depth?
Second, in the brake industry we dealt with an issue called rust jacking. It affects riveted and sometimes bonded friction material to shoes or steel backs, and can screw up the runout of rotors to hubs. The formation of iron oxide is so strong that it expands and alters those dimensions. A silicone gasket would be no match. I guess this has me thinking about using the aerobic here too as a gut reaction.
I just went into the garage and looked at my cover. I pulled the gasket a year and a half ago, but there still are remnants of iron oxide transfer on that aluminum port in the center of your issue. In ten years I never had a leak there so didn't bother to look, but your time in service is longer.
When looking at the old gasket, I used the straight edge to get a cursory look at the gasket's height around the entire perimeter of the housing. There may have been 0.002" - 0.004" gasket standing proud everywhere but the front edge coolant ports. It appears the gasket material had uniformly shrunk.
In 2013 I purchased a new oil cooler/gaskets assembly from S******r D*****. I thought I purchased OEM stuff. When I pulled my purchase records a few weeks back, I had bought their "house brand". I don't know if the gaskets materials were substandard or not, but yesterday when I separated the cooler housing from the oil filter cover, the black gasket inside that area had several noticeable minor issues. Hmmm, 6 years old materials.
The oil cooler cover's gasket channeldepth had measurable differences. The front edge where the coolant ports are located were about 0.006" deeper than the rest of the channel. Yesterday I used the 12" x 2.5" stone I purchased for prepping the block, to remedy the variation in the cooler cover.
02-05-2019, 07:09 AM
