'98 GMC/pu/cooling system

Old 04-07-02, 08:00 PM
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Question '98 GMC/pu/cooling system

My return line from my heater core has cracked off of the manifold, I got the piece out, but the threads are little damaged. Can I use some locktite, or is that not good enough to prevent leakage? Also, the inside was very clogged(1/16th"), with a black hard buildup of some sort, how do I get rid of it?
Old 04-07-02, 08:14 PM
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Replace the offending part. Don't do a hokey repair.

The buildup is likely from Dexcool. I do not believe in extended life coolant. I flush once a year.

Flush it out really well when you get it back together. See the GM parts counter to see if they have an approved coolant flush for this model.
Old 04-07-02, 08:23 PM
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It would also be a good idea to tap the threads before installing neww nipple.
Old 04-08-02, 07:35 PM
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Taking it off?

If you will tap it out to clean your threads. Then wrap some Teflon tape around the threads before instaltion, it will allways come out easy afterwards. That works for all fittings . Even though they mate with a flange. It protects the threads from corosion.

A verry small price to pay, for no more stuck or broken brake lines and bleeders ect. The end of the tape faces the direction away from the way you tighten not into the tightening direction or it will catch the tape and pull it up.
Old 04-09-02, 12:35 AM
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Thumbs up It's fixed

If anyone does the same thing to the threads that I did, keep in mind that there is no such pipe tap that fits the manifold. the threads are much corser than an NPT! Thanks for all your help.
Old 04-09-02, 05:33 AM
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The same thing happened to my '91 3.1L berreta work beater. And you right, that is an odd thread. I could not get the threads cleaned up enough to install a factory nipple. I just tapped it with a NPT and threaded in a 1/2 galv nipple with JBweld on the threads, cut the hard line and used a 3in long piece of 1/2 heater hose to connect the nipple and the hard line, that was 20,000 miles ago--figure it will last the rest of the usable life of the car!
Old 04-09-02, 05:47 AM
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Redneck oughta write a book on auto repair.

"How to repair your car when you don't have two nickels to rub together".

I give you credit. You are quite industrious! Lol.

You'd like the 1980 project Trans Am I got from a guy. Lol. Right up your alley! Lol.

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