The Stovebolt Site Forums The Shop Area Engine Shop Newbie Needing Driveline Assistance!

Hey there folks, I just bought a '62 C10 longbed that is going to be my new rustic parts fetch'n truck. I'll post some pics tonight.

I bought it from the original owner (big back window & AC) tagged & Inspected but had not been on the freeway for 10 years. I drove it 65MPH for 80 miles to my house from his. 6 cylinder with 3 on the tree.

She didn't drip a drop of oil all night in the driveway. I decided to drive it to work after getting the oil changed. I put 10-30 in it (FYI). Once I got to work there was oil dripping from the main seal area. Not sure why this started as it didn't start until after I had the oil changed. Do I need to run a thicker oil before I look at replacing the main seal? How about the additives that make the rubber gaskets expand?

She also started chattering / vibrating pretty bad (getting worse too) when you pull away in first from a dead stop. I'm assuming this it due to oil on the flywheel / clutch due to the now leaking main seal?

I also noticed that for some reason on the way home from work (not the previous 100 miles) that she will slip out of third gear when cruising at a steady speed. Doesn't do it when accelerating or decelerating, only when cruising along at a steady speed (all speeds). I can rest my finger (VERY LITTLE pressure) on the shifter and it never slips out. I don't think this has anything to due with a worn tranny but maybe something with the linkage not locking it all the way into third. This did not start until on my way home after driving it to the office. Surely this doesn't have something to do with the oil change and leak. This is my first truck that shifts on the collum and I have been a little anxious at times with the shifting. The shifting mechanism seems a little loose and is not very uniform at all. What are your thoughts?

Thank you in advance for your input!!

I think your correct in your assessment about oil on the clutch. My suspicion is that changing the oil isn't the culprit but the long rest (10 years) had the oil pretty gummed up and the new oil just provided the detergent properties to get in all those nooks and crannies and get the leak started. You may need to change the rear seal to cure it but pulling the pan would allow you to clean it out and get rid of all the crud that has accumulated over the years. Long sleeps are often tough on engines. Sort of like an empty house that starts to fall apart.


As for the shifting it is likely all those worn parts causing the problem. At first when I read your statement about slipping out of gear I thought "ah-ha...synchronizers" but then you stated it only happens while cruising and my experience is they jump out when you let off the gas so I doubt it now. That leads me to think it's the worn shift linkage with a little vibration that they all seem to have.

Thanks Dave, she had not been on the freeway in 10 years but had been driven about once a month to and from here and there. There were no drips in the driveway from the guy I bought it from. That had me kind of going back to running this thinner oil (10/30) in it when she may have been running a thicker oil (10/40). Then again, the truck had not been driven over 50MPH for the past ten years and had probably never had a work out like the night I drove her home.

I'm going to dump this oil this weekend and go with a thicker oil and see if that stops the leaking. I'm trying to find someone here in the Dallas / Fort Worth area that can work over the shifting components as I'm sure she need a new bushing here and there. Most of the tranny shops I've called don't have much experience on this older stuff and seem to agree that it's more if a linkage issue rather than tranny problems. I'm even considering a floor shifter to work around the linkage issues of the collum shift models like mine.

I also heard that u-joints could be shot, tranny mounts could be bad, & or the carrier bearing. All the mounts are solid as a rock, u joints are tight, and maybe I am blind but I could not find a carrier bearing anywhere on the driveshaft. Hmmmm......

I thought I would see what the thoughts were of folks who deal with these trucks every day like yourselves.

Synchronizers? I didn't think these early 3 speeds has synchros. Maybe I am wrong but I thought that I heard elsewhere that they didn't. Definately NOT questioning your expertise but just want to make sure that I know what I am talking about by learning from people like yourself. Thanks!!

The difference in 10W30 and 10w40 is not that the 40 is thicker or heavier. There are good threads on this site that explain it so much better than I can I suggest you look them up in our feature found in the Search header bar above. But do look it up as you'll find that it won't solve your problem and you'll learn some things about oil.

There are sychros for 2nd and 3rd gears but none for 1st or reverse. Cruising would indicate 3rd gear on a 3 speed.

I don't know if 62's had a single piece or 2 pc. driveline so if you cannot find a carrier bearing then it obviously has a single piece.

The oil didn't make much sense to me either but it's what this old hard @ss told me today at work. I wrench on old air cooled VWs for a hobby for the past 20 years so I'm pretty savvy on oils. Just wasn't sure if there was something I was missing with his direction on running the other oil.

I don't remember there being any such thing as a easy way of replacing the main seal with out pulling either the tranny or the engine. The tranny looks easier to me and I might start there first.

Again, this is my first old Chevy truck and I have a lot to learn and a lot to tweak on her if I'm gonna run her hard 60 miles every day. I must say that it is a lot of fun to drive and get TONS of looks. You'll understand once I post some pics. I'll post them this evening when I get home. LOL

check the shift linkages at the base of the steering column. they are known wear issue. you can adjust them to a point.

as far as oil leaks, my guess dry rope seal and crud like Dave mentioned. (your original seal is rope, not rubber) pull the pan and put in a new 2-piece rubber one.

Hey Scott, so I can get to the main seal (& replace it) via the oil pan? No pulling the engine and the tranny? That's killer news if this is the case!! Please let me know!!

There are many posts about changing the whole rear main seal in the truck. Yes it is do-able. On my old 216, I couldn't get a seal to hold until I changed the main bearings because they were worn out. I don't think your seal will heal itself, it will need to be changed.

just a theory on your 3rd gear pop out but, I took the cover off of my 4 speed to find that the trans 'holds' the gear by using a ball with a spring under it that fits into one of three notches on a slider rod. This creates the 'click' when you put it in gear. My particular trans had been modified, looking like someone had lost the ball/spring/both at some time. My trans no longer clicks for 3rd or 4th gear making me think that it would be likely to let go under load.

The other fellas that commented are true veterans so take my advice with a grain of salt

Make sure you do a simple test to check the motor mounts to see if that is the reason it is jumping out of 3rd. With a "3 on the tree" the linkage goes from the cab or base of the truck to the transmission, the cab is stable and solid, the engine and trans move slightly in the mounts. Block the wheels, put on the E-brake. Have some one watch the engine for you, or watch between the hood and cab opening. Put it in gear with your foot on the brake and let the clutch out slowly. You will see if the motor "jumps' or moves off the broken mount to the side or it will look like it is twisting under the hood showing a broken motor mount, also to see the other side put the truck in reverse and repeat. You are putting the torque on the engine when you have the brake on so the engine will move if the motor mount is broken. Cruising and letting your foot off the gas at highway speeds will transfer the torque to the motor temporally and may cause the trans to slip out of gear if there is enough movement… just a thought to check and do the cheapest stuff first.

It's the main seal leaking onto the clutch assembly. I went over to the car wash yesterday and degreased the entire engine, tranny, etc. After spraying everything down with high pressure and got everything spanking clean there was very little vibration when pulling away from a dead stop. I guess the high pressure water flushed the oil out of the area and it worked great.

Later when I went for another cruise it started back slightly then got worse and worse the further I drove. Every time I took off from a red light it got a little worse & a little worse.

I'm going to change out the rear main seal as suggested. This should solve one of the problems.

As far as the 3rd gear goes, I sprayed some white lithium grease on the assembly in the engine compartment and she seemed to do much better. We rolled about 15 miles with out a problem. I'm hoping that this solved the problem but then again, having wrenched on 60's model VW for 20 years I realize that this seemed to be WAY TOO EASY OF A FIX to have solved the problem. :0)

I'll keep you updated as time rolls on...........

sent you a PM

-Leon