I'm rebuilding the family 1970 oldsmobile 98 and I purchased a new dipstick as the old one was missing. I got it most of the way in but the dipstick is tapered about 3in from the bottom almost like there is supposed to be a seal of some kind, I tried to gently pound the dipstick in the hole past the tapers but it won't go in. Is there a seal for it im not finding or am I doing something wrong.

This picture shows the dipstick pulled out slightly so you can see the tapers

 

Those beads are what retains it in the block - there is supposed to be friction there. The problem is that every aftermarket and repro Olds dipstick tube I've ever seen has had those beads formed too large in diameter to fit into the block. The last one I got (from a very reputable Olds specialty vendor) was about 0.010" larger than the original at those beads. I carefully filed and sanded the repro part to match the diameter of the original and guess what? It tapped right in like it was supposed to. Note that this is NOT supposed to be a slip fit. You are supposed to have to tap it into place. That's what holds it there. The problem is that if the beads are too large, you end up damaging the tube when you have to pound on it.

 

Thank you! Ill give that a shot.

 

I put a small wrench right above the point circled on the dipstick. I had a piece of 3/8 steel rod bent to fit around whatever obstacles are in the way. Put the dipstick in the block, slip the wrench over the tube, position the steel rod on the wrench as close to the tube as possible, and have a helper tap on the rod with a small hammer. As long as the ridges Joe mentioned are reasonable close to the correct size it will go in fairly easily.

 

I just did this to my 350 last night. The first bead fit in the block but like Joe said, I had to file the second bead to get it to fit. I also used a small wrench on the tube and lightly tapped it in.