Dead in the water.

Changed my transmission pan, filter, and fluid yesterday and everything seemed fine.

Then on the way home from running errands tonight I heard a faint ticking noise while driving followed by a slightly louder pop when I revved it in Neutral. After that pop I lost all drive gears. The trans holds in park, but when shifting into any gear reverse or drive all I get is neutral. No drive lines hanging or spinning at all. No funky noises at all and nothing else out of the ordinary.

I'm thinking the chain in my transfer case finally went out. Is there anyway I can check things out without opening anything?

Did you accidentally put the TC in neutral? Did you try to shift the TC into four wheel?

I did make sure it was in 2H. Also while waiting for my tow rig I put her in 4wd with the front hubs locked hoping to get something (like if I had broke a rear drive line) but that didn't change anything either.

edit: When shifting the transfer case it did seem to go into the different gears. But it also seemed to go into gears rather easily as compared to the last time I used 4wd.

You verified the correct fluid level.

I reckon the filter fell out... You'll have to drop the pan again.

Rusty Nail said:

You verified the correct fluid level.

I reckon the filter fell out... You'll have to drop the pan again.

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Yep fluid level was correct.
I was also wondering if the filter fell but I was not too sure what the truck would do if that were to happen. That is a great idea though, and I'll start there. Thanks!

Good luck!

700R4? You pulled the old separate seal out? New filters have a grommet built on the neck so if you don’t pull the old seal out, they won’t seal right.

1987 GMC Jimmy said:

700R4? You pulled the old separate seal out? New filters have a grommet built on the neck so if you don’t pull the old seal out, they won’t seal right.

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Yep, got the old seal out. before I put the new filter in, and made sure there wasent another one sitting in there. While installing the new filter I was thinking to myself that it didn't quite seem right. But I was unable to get it in any further I tried this same online brand before and ended up pulling it and replacing it with a napa bought wix filter due to other problems I was seeing at the time. So I would not be surprised if its just a junk filter.

Also this new pan I put on is a derale cooling pan so it has an additional 2qt or so of fluid but still uses the OEM filter. I do believe there would be more then enough room for that filter to fall out a ways. Tonight after work I plan on pulling my trans inspection cover to check the bolts to the converter, then drain and drop the pan to inspect the filter and shift linkage. Then If I still am not finding anything I'll pull my np208 fill plug and see if I can feel/see my chain through the hole or not, might end up draining that and seeing the condition of the fluid or any chunks of used to be important things.

Alright everyone..

Just got done rolling around under the truck in the dark, rain and mud with my flashlight and tools. I pulled the inspection cover as well as drained the trans and pulled the pan. Everything is looking as it should. filter is up and in in place. converter is securely bolted up. gear selector inside as well as outside of the trans is hooked up and working.

I did read somewhere that if you check the trans fluid level with the truck off, then start it and find no difference in the fluid level then your pump inside of the trans is bad somehow. Before I drained it I tried this and I did not see any difference in fluid level. Does this sound accurate? or what else can I check out without splitting the trans and t-case apart?

If that’s what you suspect, and that makes sense, I’d check the trans pressures. I guess since it’s not doing anything, you can only get the idle reading, but that would tell you what your pump is doing.

ok, so If my thinking is correct. I could put it all back together, fill it, pull one of the cooler lines (poor man pressure test) and see if its moving fluid through the lines. Kinda thinking its time for a paid pro to take a look see.

That would show you if the pump is completely dead, but it could be moving some fluid and not building enough pressure. There’s a 1/8” NPT test port on the transmission for you to screw in a fitting for a pressure tester. Should be fairly accessible. You can borrow a pressure tester, and it should be a pretty legit diagnostic. Here’s a stock image showing it. I might try the cooler line test first just to see what happens, but if something does happen, I’d like to attach a numerical value to what it’s doing pressure wise.

1987 GMC Jimmy said:

That would show you if the pump is completely dead, but it could be moving some fluid and not building enough pressure. There’s a 1/8” NPT test port on the transmission for you to screw in a fitting for a pressure tester. Should be fairly accessible. You can borrow a pressure tester, and it should be a pretty legit diagnostic. Here’s a stock image showing it. I might try the cooler line test first just to see what happens, but if something does happen, I’d like to attach a numerical value to what it’s doing pressure wise.

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That makes good sense. I'll give a call to a shop tomorrow to see what kind of time frame I am looking at for them to be able to look at is. I am guessing it wont be until mid next week. While I wait I'll go ahead and do this test myself just so I know that I'm not being taken for a ride by the shop. My temp sending unit is currently in that port so its super easy to do.

Thanks all! I'll be sure to post back up my findings.

If the transfer case were broke in a way that would keep the truck from moving under it's own power, then the truck would be able to roll while in park.