Engine Block Drain Bolts Stuck

[dgbull3]

I drained all water from the block due to some cold temps coming up and am now back replacing everything to do the oil change & complete winterization. Problem is I can't get the engine block bolts back in. They go in about one thread then won't turn more without risking cross threading. I'm thinking there's some tiny bits of stuff that got between the threads when it drained and now jamming the bolt. Anyone run into this before? Quick remedies?

[DOCDRS]

You could use a tooth brush to clean the threads and try , or re tap the block hole with the appropriate tap.....I have had to do this the one time I left the bolts out over the winter

[dgbull3]

You could use a tooth brush to clean the threads and try , or re tap the block hole with the appropriate tap.....I have had to do this the one time I left the bolts out over the winter

Tried the toothbrush, no luck. What size tap / threads is it?

[dgbull3]

Never mind it's NPT thread. That was throwing me for a loop!

[lee]

1/4" npt....