Missing dowel pin

[Ironworker15]

Installed a trans in my brother's truck a few months ago and am one hundred percent certain I installed BOTH dowel pins as I had to remove them both from the old transmission. He was underneath it today re mounting the transmission dipstick tube as it loosened due to downpipe clearance. He told me henoticed a shiny spot on the bell housing and upon further inspection a dowel was missing! From the pictures it looks like it's still lined up and he hasn't had any issues. Had anyone ever heard of one of these backing out? Truck is used to hotshot tow and isn't raced or beat on. I did use some blue loctite on the engine side when I installed the dowels. All bolts were torqued to spec on flex plate and bell housing and re checked after a couple hundred miles. Is it worth pulling the trans? I was thinking about installing a new dowel through the transmission hole since they appear to be in perfect alignment. Maybe some red loctite this time? What's y'all's opinion?

 

[Chevy1925]

looks like the back side of the dowel to me

 

[Ironworker15]

Nope. The picture isn't all that clear. But it's definitely missing. The other side is about 1/4" from the face of the bell housing and you can see the chamfer on the pin. This side is 3/4" or more deep.

 

[Ironworker15]

Here's a better view

 

[Ironworker15]

I'm going to pull the starter this weekend and check converter bolts. He checked through the inspection cover on trans and couldn't see any visible cracks or anything. No vibrations or odd shifts either.

 

[Chevy1925]

i dunno but i really dont like that crack propogating from the bellhousing at the dowel area. probably why it fell out if it did. he needs to check his u-joints asap.

 

[Ironworker15]

Inspected u joints, snap rings, bell housing bolts , ect. Nothing out of the ordinary going on. I used a brass hammer to install the dowels in the back of the block on install , I must've not seated them all the way or something. They are a pretty tight fit into the transmission bell housing so I can't believe it would vibrate out like this. I know a missing dowel can cause some real carnage of anything shifts. New dowel will be here tomorrow and we'll see if it goes right in. Lucky he noticed this today or it could of been an expensive fix for sure. My engine is currently out of the truck and I just checked , both of mine are in the rear cover. Hopefully it comes back that way from the machine shop once I find one to send it to.

 

[Chevy1925]

Inspected u joints, snap rings, bell housing bolts , ect. Nothing out of the ordinary going on. I used a brass hammer to install the dowels in the back of the block on install , I must've not seated them all the way or something. They are a pretty tight fit into the transmission bell housing so I can't believe it would vibrate out like this. I know a missing dowel can cause some real carnage of anything shifts. New dowel will be here tomorrow and we'll see if it goes right in. Lucky he noticed this today or it could of been an expensive fix for sure. My engine is currently out of the truck and I just checked , both of mine are in the rear cover. Hopefully it comes back that way from the machine shop once I find one to send it to.

how did you check the u-joints?

 

[Ironworker15]

Pulled drive shaft and checked for any play. Going to go ahead and replace them and install new bushing on transfer case and new nickel plated yoke from Spicer. Got the new dowel pin in today and we were able to reinstall it through the hole in the bell housing. It was still perfectly lined up. So it doesn't appear to have moved. Pulled the starter as well and checked torque on converter bolts. All clicked at 44 ft. Lbs. No cracks or any signs of damage. I used a little bit of red loktite on the engine side of dowel. Other side is still completely seated in rear engine cover. Looks like he dodged a bullet. But I still cant understand how this happened. The only thing I can think is that the hole in the rear cover was corroded as the pins were originally pretty well stuck in the bell housing on the stock transmission when we swapped them. I also admittedly was gentle installing them in the bell housing as I didnt want to mall them even with a brass hammer.

 

[Chevy1925]

Pulled drive shaft and checked for any play. Going to go ahead and replace them and install new bushing on transfer case and new nickel plated yoke from Spicer. Got the new dowel pin in today and we were able to reinstall it through the hole in the bell housing. It was still perfectly lined up. So it doesn't appear to have moved. Pulled the starter as well and checked torque on converter bolts. All clicked at 44 ft. Lbs. No cracks or any signs of damage. I used a little bit of red loktite on the engine side of dowel. Other side is still completely seated in rear engine cover. Looks like he dodged a bullet. But I still cant understand how this happened. The only thing I can think is that the hole in the rear cover was corroded as the pins were originally pretty well stuck in the bell housing on the stock transmission when we swapped them. I also admittedly was gentle installing them in the bell housing as I didnt want to mall them even with a brass hammer.

when these joints go, they get tight before they get loose. twisting them is about the only way to find them but the shaft has to come out like you did.

id suggest drilling a hole at the end of that crack in the bellhousing i stated about earlier. stop if from propogating any farther.

 

[Ironworker15]

It wasn't a crack. It was fibers from the exhaust wrap on down pipe. Looked like a crack to me at first. But I zoomed in and could see the fibers covering part of the hole and not into it. I wiped it clean and took new pictures. No cracks visible.