block drain threads are rusted

[bear_69cuda]

Hey gang,

My 2000 7.4 Gi PEFS SN:4012007343 has two 9/16" brass nut with NPT threads (I don't know size threads?) used for drain plugs under each knock sensor. I removed them to drain the block last fall... Over the winter the threads in the block have corroded, I'm having issues when I try and thread the brass plugs back into the block. Any tips? Small round metal wire brush? Chase threads with a tap? I'm stumped and don't wanna strip the plugs threads... here are pics of the block drain holes... Man I wish I would have cleaned them better, or left the plugs in after draining... Oh well...

Thanks for any advice in advance!

 

[Don S]

Re: block drain threads are rusted

Use a 1/4" NPT pipe tap to clean the thread, don't go more than JUST enough to clean the threads (1/4 turn approx). Then put some gasket sealer on the pipe plug, not so much to keep it from leaking, but to prevent corrosion. Then, in the winter when you drain the engine. Put the plug back in. Then it can't rust.

 

[superpop]

Re: block drain threads are rusted

If you have a dremel, I would go to HD and get the little wire wheel and clean up the threads that way first, less chance of jacking up the threads with a brass wire wheel. On my 305 I purchased 2 3" pipes and ball valves and threaded the pipe into the freeze plug to extend it out from the block then I installed a ball valve on each pipe. I did the same with an elbow and valve on my manifolds. I can drain my block and manifolds in about 30 seconds and with the ball valve open you can still stick a wire in the passage to check for sand or other debris that would block proper drainage. I typically drain my whole motor after most outings while I am doing a post run check of the motor. Extending the pipe by a few inches also keeps the starter from getting any water on it when I drain the block.

 

[bear_69cuda]

Re: block drain threads are rusted

Hey Don thanks as always! Worked great!

Brutha Superpop...

That's a great idea, I'll be checking that out!

Thanks again both of you!