65 GMC Handi Van Transmission Fluid Fill

Hey guys, long time lurker, first time poster.

Long story short: I've got a transmission fluid leak and cannot find the fluid fill spot. This is a 1965 GMC Handi-Van with an inline 6 and 3 on the tree transmission. My regular mechanic is too busy to take her in but has insisted that there's a second dipstick aside from the oil. There is not. I've dug through my manual and while it mentions filling the fluid, which makes me assume there is a fill hole, it does not show me the spot. Laying under the van I've found one square bolt towards the rear, bottom of the transmission on the passenger side and assume this is the drain. I cannot find its counter part for a fill. Any help would be greatly appreciated as I'm dying to get her back on the road sooner than later. Thanks!

Stick shift transmissions do not have dipsticks!

Somewhere on the side of the transmission about halfway up, you will find a fill plug.....Remove it carefully and if oil comes out it's already full....If not, you use your pinky as the dipstick and fill to the bottom of the hole, as needed.... That's it!... Simple!

And FYI.......All differentials fill to the bottom of the plug hole, as well......

It's been this way since the beginning of time for all gearboxes and differentials, although later model stuff may have changed this..... I guess I can safely say that no manual transmission before 1990 ever had a dipstick (somebody will correct me, I'm sure;))

Thanks for the quick response AzDon! I'll take another look. When you say plug I'm assuming it's just a pop-out and not a bolt? Thanks again!

Sorry I wasn't clear...... It'll be a 3/8 or half inch NPT plumbing plug (tapered thread) and usually has a square nose you turn with an open-end wrench, but could also have a female wrench hole in it either square that fits a 3/8 or 1/2" ratchet extension or sometimes a six-point allen hole....
It could be only a third of the way up, but obviously not at the bottom or it would be a drain plug....


The differentials almost always have the plug that takes a 3/8" extension.....

PS.....Before wrenching in an "inny" plug, be sure to clean the hole out (of any grease) for maximum penetration of your wrenching device.....otherwise the wrench could slip out and strip the hole....

Awesome! Thanks you so much for clarifying!

I finally had a chance to take another look and found the square bolt about a1/3 of the way up (as you said it would be) and took it out. Enough fluid started coming out that I figure it's full. Also stuck my pinky in there and there was enough to cover my finger. Since it seems that low transmission fluid is not my issue I was hoping you might point me in another direction.

Basically once I shift gears the engine seems slow on the uptake. It's been getting progressively worse over time and since I've always had some sort of leak I figured fluid levels were the culprit. Any idea what else this could be? I'm pretty new to diagnosing my own engine problems so forgive me if this is a no brainer. This may be unrelated but, it also used to get stuck in 2nd from time to time. I just avoid it now by carefully placing the shifter when I go in and out of 2nd.

Thanks again for the help and for any future insights!

Are you still running the distributor with points and condenser......are the points adjusted,,,,is the timing set correctly,,,,,,,are the centrifugal and vacuum advance units working,,,,do you see gas squirt down the carb when you pump the gas pedal,,,,,,see that carb throttle plate is opening all the way when gas pedal is all the way down,,,,,,so check these things out....

Thanks for the response Donivan65! Most of those checks are out of my league but, I did pop off the air filter and take a look at the carb and everything seems to be opening and closing just fine. I just took a spin around my neighborhood to try and see if I could get it to act differently in different situations. Seems to happen less when I drive really aggressively, high RPMs, faster shifting, being a jerk etc. and more so when I'm babying it and driving a little slower, shifting slowly and just cruising. It also seems to be constant across all gears making me think you are correct in that it's not the transmission. I would say that other than the slow uptake it drives extremely well.

Since checking anything else is out of my skillset I feel like I should probably just take her in. Thanks again for the input! Happy to learn a little at a time.

Hey 65 ETHEL: Just to through it out there the shifter box mite be wore out? The three on the tree i had would bind up when i would down shift from second to first coming to a stop(with full synchro three speed tranny) and i would have to get out an rock the van back an fourth while pulling on the shifter lever at the same time to unjam it! So it could be in the box won't let you move out second?! I found a stock powerglide in a junk yard i replace the tranny? shifter box and radiator out of a 66 handivan! JOHN (REDVANGO)

Sorry It use's fluid to

Slow on the uptake...  I take this to mean it accelerates lazily?  But seemingly responds well/good at Wide Open Throttle (WOT)?  That's opposite to usual conditions if it was a carb or fuel delivery problem..  Usually, if a problem with fuel delivery, the symptoms/problems are more apparent at WOT and cruising is better but not always the case. an inoperative or weak accelerator pump causes the engine to bog when you push hard on the pedal but if you are using light pedal effort, might not be as big a problem.  A Weak fuel pump, partially clogged filter or gummed up fuel sock in the tank is also more of a problem at WOT.  

My somewhat educated guess based on what you said, is Spark Timing.
This absolutely needs to be set correctly.  Close is no bueno.  Timing is when the ignition fires in relation to crankshaft rotation and is expressed in degrees of advance, IE 12 degrees before the piston reaches Top Dead Center (TDC) and is set using a timing light.  That tool is basically a strobe light that will stop action the timing line on the balancer, while the engine is running, so you can see where the ignition is firing.  

There are 2 figures to be concerned with here.  Initial or low RPM timing and Total  If timing advance is set too little, the engine will run but be lazy. But at WOT, it might mask the issue a little.  I forget what the inline six numbers are but 8-10 degrees of initial and say 30 degrees total at say 2800-3000 RPM would be somewhere close to the ballpark. Additionally with point style ignition there is a setting called dwell, which is the amount of time the points stay open also measured in degrees.  Most folks just set the point gap with a feeler gauge but that is not the best way to get the best tuning.  Using a dwell meter gets you the rest of the way there and can have a noticeable effect on overall performance and engine efficiency.  Efficiency is not just a concern with fuel mileage.  The more efficient an engine operates, it usually means more power and smoother operation. For this setting, somewhere around 30 degrees of dwell will be close.  Others please feel free to weigh in with more exact figures.  

For what it's worth, I would not worry about the rest of the driveline as the cause of the problem.  If there were major problems there that were causing the engine power to be noticeably deficient whilst cruising, the problem would get much worse very quickly and there'd likely be a lot of noise to go with it.  IE if a bearing was going away/tightening up due to poor lubrication, you'd know it.  Find a local old school hot-rodder.  He'll have the tools and know how.  Your local mechanic may not.  My dwell meter is at least 35 years old...  I'd be willing to bet most shops these days don't have one.

The centrifugal advance is pretty much hidden under the points plate on a chevy six (hard to check) You can pull the vac advance hose and suck it like a straw to see if it rotates the points plate or won't hold vacuum (leaks).....
If it were my van, I'd buy a complete distributor, check the point gap is 19 thousandths, that the vac advance is working and put it in and time it.... Actually, I'd convert to an HEI distributor....
It's cheaper to just drop a new complete distributor in with all new stuff in it then to chase the different gremlins that a distributor can contain..... Often the bearings of the distributor are shot, causing the point (or star wheel) gap to not be consistent and steady.....
Also, If you are paying a mechanic, you are asking him for a book labor price to install the distributor you get from RockAuto and take with you rather than let him run the clock on a diagnostic fishing expedition.....The install includes timing it and the new distributor includes a new cap and rotor.... If you also take a new set of plug wires with you, you'd get 90% of a "tune up" for distributor replacement labor.... If you switch to HEI, you'll get a new coil as well.....If you do switch to HEI, be sure the mechanic knows to replace the resistance ignition wire with a non-resistance wire so the HEI gets full voltage....

THANK YOU EVERYONE!!! I really appreciate all the responses and the amount of insight. Just reading through these and looking in the manual has helped me make a lot more sense of my engine.

I ended up taking it in because the oil leak had gotten out of control. I explained the power issue as well and they took a look. Turns out my clutch was toast. They had a machine shop refurbish it and holy shit what a difference. I've only had the van a few years so, my guess is that I was just used to driving it with some amount of slippage and didn't really know any better until it got really bad.

Thanks again for all the input. Even if I'm taking it into a shop it's nice to have a better understanding of what might or might not be happening. Hopefully as I learn more it'll go to the shop less and into my driveway more. Thanks!

And nice post title Dave! haha