Wrenching in The Desert; DOT 5.1 Edition

Oct 3, 2008
Earlier this month, I started doing some work on the cooling system in my Ford Explorer. To access the area where the thermostat housing sits on the 4.0L Cologne V6, I pulled the alternator off, along with the aluminum bracket (passenger side). I got big bear hands and it makes my life easier. Once the area on the cylinder head was all clean and ready for the new all-aluminum thermostat housing, I decided to paint the bracket before putting it back on, since the bare aluminum looked horrible.

There's a bracket on the driver's side, too, which houses the power steering pump, reservoir and the AC compressor. I got the PS pump/reservoir off and two of three bolts off the AC compressor, along with the one stud. The end threads of the bolts are exposed behind the aluminum bracket, and the last remaining bolt (right in front of the cylinder head) was stuck on real good and eventually rounded off. It was stuck enough to literally snap my Irwin Power-Grip bolt extractor right off my Makita impact driver! To access the bolt, I also had to get the truck on jack stands, since you need to go in from the wheel well and space is really tight.

I pulled the bracket off the cylinder head with the compressor attached to see if I can soak the threads. I tried CRC Freeze-Off, PB Blaster, Permatex Fast Break Super Penetrant, WD-40 Specialist Penetrant and Liqui Moly Multi-Function Spray/Penetrant I had on the shelf and it wouldn't budge no matter what I did. Heat, penetrating fluid, heating and tapping...nothing seemed to work. I thought the threads of the 10.9 steel bolt in the aluminum bracket were the cause of the problem.

Short of using an oxy acetylene torch, I was thinking what else I could do. Then it occurred to me; whenever I'd wash the engine, a lot of the sandy water would go down that bracket between the cylinder head and the compressor. I dry everything off real good with compressed air, but the sand tends to stay behind in some areas and it appeared extremely fine sand particles got in the threads.

Whenever I'd change brake fluid and some of it would spill on the ground, it would "dissolve" any fine sand almost instantly. I had some Liqui Moly DOT 5.1 brake fluid I used for the last brake fluid change, and using a disposable plastic eye dropper, I soaked the end threads real good and positioned the bracket so gravity would pull it right down. Secured the bracket back to the cylinder head, applied heat for a minute, got a 3/8" 10 mm Rocket Socket bolt extractor and gave it a go. I heard it "click" and move ever so slightly. Since I didn't use much effort, I thought I broke the bolt off. But it actually started to loosen with loads and loads of sand gushing out as I loosened it. Pulled the Hazet ratchet off the socket and got the Makita 3/8" on right away. The bolt came right off and so did a good bit more sand, enough to cover the tool, the control arm and the frame in dust. Amazing just how much sand was in there.

I got new bolts coming in through the mail, and they will go on with some Loctite anti-seize. Guess good old brake fluid will now be my "penetrant" of choice.


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Jun 26, 2018
This might sound counter productive, Instead of anti-seize maybe blue loctite to seal the threads and keep sand out vs anti-seize which could possibly mix with the fine sand and create a potential barrier to brake fluid.