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Also, I read the report. Michegin Scientific. They didn't mention anything about accessories on the engine cracking, or the water pump. They did mention of course the flywheel but we all knew that. If you have another report that says water pump covers crack, I would love to read it.
If that was the only issue, maybe, maybe not. But in the larger context of your alternator and fan issues, I would flip that question back to you that you would think it's a coincidence that some of the issues were related to overheating, but others (e.g. alternator bracket) were not? Driving 10,000 miles doesn't really matter... people always opine "But yesterday it was working fine!"... that's just how many things fail - they're fine, until they aren't.
There are several reports. I'm pretty sure somewhere in this chain all of them were linked, and at one point I even quoted directly from it. Yes, the military report that I'm referring to goes through the exact failure process that both you and I have had (e.g. water pump, alternator bracket, etc.). If it wasn't in this post, it has been discussed in several others (like the one titled something like "Help! My new LMTV is blowing water pumps and breaking alternators"), which are also linked to, with the names of the reports to google, in my "Common Issues" document in my signature.
That's not really how that works. You're mixing the ideas of thermal cycling and thermal expansion. The aluminum does have a smaller (about 1/2) Coefficient of Thermal Expansion than steel in the bolts (i.e. the cover will grow more while the bolts grow less, as temp increases, so stress will increase with temperature), but the differences we're talking about here are very small (e.g. maybe a thousandth), partly because the "overheating" we're talking about is only maybe a 25-degree change from a more normal "acceptable" temp that wouldn't be expected to cause any issues. And even then, a crack is not the likely failure (cracks are usually fatigue failures). Most likely would be that you would rip out the threads in the aluminum or stretch the bolts beyond their yield point (and then it would leak after it cooled and bolts were "too long").
I don't know what "a little loose" means, like finger tight? That's bad if so. My bolts all seemed to be right, including the bolts that hold the fan clutch to the engine. Mine didn't have loc-tite either (like later became required). One thing I noticed though is a lot of the torque specs aren't really... a lot. For example, the water pump to engine bolts are ~40lb/ft. The tensioner bolts are ~35lb/ft. So with a ratchet they back off easy.
I wish my neurotic oil pressure gauge worked that way. And I forgot to pickup a new sender when I was at the cat dealer today...
I do not have first hand experience with this motor but I would be very suspicious of mixed metric and sae bolts going into the same block. Metric bolts have numerical hardness stamped on the heads and sae have line patterns on the heads. I would triple check to make sure you have the correct fastner and that the hole has not stripped or forced with the wrong bolt to save you grief down the road.
wellllll..... engine is metric.... from what have read it was somewhere early in the CAT line of being all metric...... but that being said..... all the brackets etc. are manufactured to meet the truck's needs and in design factors there may have been not much desire to try to match the engine's thread standard. Thus it is very possible attachments bolted into threaded engine holes are metric, but bracket to bracket... bracket to Aux item; like alternator, etc. could be SAE. Many have mentioned the mix of both Metric and SAE on their FMTV's
Its not that caaterpillar makes special bolts its that the sizes are close enough to be able to use both sae and metric tools. 16mm is close enough to 5/8 as is 11/16 with 17mm and 3/4 with 19mm, 7/16 and 11mm, and 13mm with 1/2.
