Hey all, New to the forum...just purchased my first project truck, it is a 1950 GMC 100, 216 straight 6, three on the tree and 59,000 original miles. Little history I was given, the truck served on a cattle ranch for 40-50 years and spent the remainder of it's life as a daily driver here in southern Ohio. I purchased it this past weekend and made a 130 mile trip home with no issues at all. The next day I was headed to a local lake for some fishing when I began to have transmission issues. On the way, I noticed 3rd kept "popping" out of gear (which seemed to happen more and more as more miles passed). I also noticed that 2nd seemed to have a loud whine to it compared to 1 & 3. When I headed out to grab lunch I attempted to shift to 2nd and met a good amount of resistance, finally it went in to gear however when I released the clutch it acted as if the truck was in neutral. Attempting to shift to third only proved a terrible grinding noise. Now I'm unable to get the transmission to shift in to 2nd or 3rd at all..it appears to be completely seized up, 1st and reverse still work flawlessly. FWEEW! If anyone was actually able to read that whole schpeal and can provide any input it would be greatly appreciated. I plan on getting out this weekend and pulling the trans, taking it to a local shop if I must but would like to see if there is any experience floating around with this type of issue. thanks for your time and input.
check the linkage bushings on colum and trenny.IF OK I say the sinkromizer for 2&3 inside the tranny is bad.excuse the spelling Check fluid in tranny 90wt oil.my have to adj linkage
Thanks for the reply Dan, I did go through and disconnect the linkage and try to manually manipulate the tranny and still had no success so I'm guessing it's an internal issue. Can anyone provide the make or model number of the transmission that is in these trucks so I can try to get parts ordered? Thanks in advance
Any way I can distinguish the 216 from the 228? And yes I checked all the fluids before making the trip home, I'm planning on changing them all this week.
Yes! If GMC is stamped on the valve cover it is not a 216.
The gmc family of engines, 228, 248, 270, and 302 have 5 freeze plugs on the left side of the engine under the intake and exhaust manifolds.
If it has GMC in the Valve cover, or 5 freeze plugs, check the flat horizontal surface behind the distributor. The first 3 numbers will tell you which GMC engine is in your truck.
It is not unheard of for a GMC to have a Chevy engine swapped into it, but the gmc engines are a better design than the chevy.
I had a great running tranny and one day 3rd started popping out for no reason. It got worse over the day and I finally pulled the side cover off. I had an exploded synchro ring (see picture). Some small pieces had messed with the linkage inside the tranny. Picture of the metal pieces
Once everything was cleaned out, it still works. It needs to be taken apart and repaired but I can drive it a bit until getting fixed.
get that side cover off and make sure everything is intact. Make sure it's in neutral when you take it off and put it back together.
I just pulled the trans out of mine this morning, headed in for some breakfast then going to take the side cover off and see what I have! Hopefully don't get chunks coming at me like you did Lode. Also to swingdaddy, I went out and cleaned the flat horiztontal plate and read the number, turns out I have a 228 motor. I'll throw in a picture of that too...sorry about the oil covered mess that it my motor, next item on the list is fixing a VERY leaky valve cover gasket.
Ok need a litte more help here. Went to pull the tranny today and have hit some problems. I'm not used to working on these older trucks so maybe I'm missing a step. So far we have removed the four bolts at the rear of the trans that hold on what appears to be a "cover", and the front of the trans we removed two bolts at the top. There are still two bolts at the front (bottom) that appear to be threaded from the other side, but can't gain any access to them because of the bell housing in the way. Can anyone point me in the right direction as far as a DIY transmission removal or tips to what we're doing wrong? Thanks!
To clarify what I have posted above, here are some photo's. This is the passenger side. As you can see by the first photo we have the top bolt removed, however the bottom appears to have had the head sheared off?? Is this right or has someone F'd up the bottom end of the transmission?
they unbolt from inside the bell housing... if I remember right. Take the flywheel cover (under transmission) off and you should be able to get access to them.
As I recall, there's not enough clearance to get a box end wrench around those bolt heads on the inside. So you'll need a good quality open end. You don't want to round them off.
I ended up getting the trans out tonight! Had to drop the torque tube to get enough play for the spline gear up front to come out. But all that matters is that it's on the garage floor and headed to the transmission shop in the morning! Thanks for all the help!
I figured everyone knew it wouldn't come out with the torque tube on. Sorry for not mentioning it. Congratulations on figuring it out and gittin'er done.
"It's just a phase. He'll grow out of it." Mama, 1964
So the outlook on the tranny isn't very good. I have a buddy that has a fully rebuilt Saginaw 4 speed he'd let go for $250. So this kind of got the wheels in my head turning. Thinking about a SBC swap with the 4 speed and a new rear end. Anyone have suggestions where to start??
Seems a bit high for a transmission that doesn't have an OD.
I will never give you any more help if you put a SBC in it. In the end, it's your truck, and you have to build it in a way that suits your skill and wallet thickness. Old gmc 6 cylinders look and sound wicked in old gmc trucks. Here's a link to a 270 gmc motor that another stovebolt member owns. He and I were firing this 270 to check it's suitability for a swap.
Now doesn't that sound wicked? This is a 1957 GMC 270, which makes it a "side mount" engine. The front timing plate needs to be changed for this engine to bolt into a 1939-1955.1 GMC. Other than that, it's a virtual drop in.
You might be able to find a good torque tube 3 speed for short money. Check the swap meet section for parts for sale, and put an ad in the parts wanted section. Replacing the 3 speed with another is likely the quickest way to enjoy driving it.
Last edited by bigbadswingdaddy; 06/26/20115:29 AM.
