Specifically I need to know if the transmission dipstick tube can be removed or installed while the motor is in the van. Is there something holding it in place? Dog house is already off. Also what is necessary to remove the lower section of the oil dipstick tube. Does the exhaust manifold have to come off to remove the lower section?

 

Both dipstick tubes are held in place by a bolt somewhere along the length of the tube, typically closer to the open end that the dipstick goes into. The end where it mates into the transmission or engine is just held in by o-ring compression and quite possibly corrosion, especially on the engine oil dipstick tube.

They can be fun to remove when corrosion sets in. For either, I recommend spraying liberally with WD40 or other similar penetrating oil of your choice and use patience when wiggling it around.

 

I found an ad on Craigslist for used motor. Apparently this man bought a second replacement motor. The man who sold it suggested the cam be replaced as the distributor gear had worn badly. The owner hired someone to replace the cam. This mechanic guy failed to set the timing marks correctly and installed the exhaust gaskets improperly. With no luck getting the motor to run, he vanished. The owner then hired a second fella to make repairs. This guy did a fair bit to make things right by resetting the timing, however he did not install the timing chain cover and pan gasket correctly. Still not running.

All I did was flip the exhaust gaskets and plug them vacuum leaks. The second fella was trying to get a smooth running engine with vacuum lines out of place and no mass air flow meter attached. It isrunning now but leaks from the' timing cover quite a bit.
The deal I made was to get the motor running in exchange for the old motor. He was asking $150.00. So now he wants pay me to finish the repairs which includes installing the tubes and stopping the oil leak. It is a good thing the pan will come down enough to add some RTV at those pesky corners at the bottom of the timing chain cover.

I got really lucky again today at the salvage yard. The vehicle I needed for parts was only 100 feet from the door. Only bad part was it was on the ground, no rims. I was unable to see how the tubes were connected to the trans & block. Going back tomorrow with a jack.

 

the oil dipstick tubs rot into the block a lot of the times and just wont come out by just pulling on them.

cant really recall on a astro van but on fullsize vans/trucks and s10s there will be a bolt holding it to the engine. can either be one of the transmission bell housing bolts or just a random bolt on the back side of the block then it should just lift up.

also the fullsize vans have a small bolt up under the hood holding the trans and oil dipstick to the block, not sure about the astro