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Shake, Rattle, and Roll

scottystills

scottystills

1/2 ton status
Joined
Jun 7, 2009
Posts
376
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34
Location
Calgary, AB
So got myself a little problem. A few weeks ago had to make a trip to Winnipeg from Calgary (for those Americans in the audience, we're talking 1300km, or around 800 miles). Being that the trails 20 minutes from my house opened May 1, and my buddy in Winnipeg loves to wheel, I thought it would be a great idea to take the Blazer with me and get some warmup in the mud after months of winter wheeling in Alberta.

Little background... 88 K5, 6.2L diesel, Banks sidewinder, 700r4, NP208, corp 10s, 33x12.5x15 FCIIs.

Anyhow, truck drove the first stretch like a champ. I'd never taken it on the hwy that far before (and seriously should have reconsidered taking the back off before I left in 0 degree rain). Drove the entire week in Winnipeg with no problems. Unfortunately got no wheeling in in Manitoba. The day after I got there a fire ban was called on account of the dry weather out there, so all trails were closed and I'm not the type to go around the law. Hell, being in Manitoba, driving a big a$$ diesel Blazer with AB plate on the back and a 12k winch on the front, people were already looking at me cross eyed.

To the point: On the way back passed through Regina, not quite half way back, hit the gas to merge onto the hwy and got a shudder going in the truck. Figured I must have clipped a shoulder and got some mud, but pulled over to check. No problems. Got rolling, shudder continues. Wasn't losing power, no major problems, but stopped 20 or so times to look the thing over since I couldn't figure out what in the world was causing it (and we all know our "healthy" shudders as opposed to "unhealthy" shudders in our trucks). Got all the way back to Calgary, parked the truck, and while I was unloading my gear I notice ATF POURING out the bottom of the thing. Finish unloading and find not only ATF but oil/gear oil mixed in there as well. Checked my engine fluids and no problems, oil was still up, PSF still up, trans mission dip totally dry (at idle of course). So I'm guessing that I've dumped the tranny (obviously) and possibly the transfer case. Although the tcase is supposed to be ATF not gear oil... FYI I bought the truck from a buddy (and mechanic) a year or so ago and haven't changed the tcase oil yet, that was on tap for this spring.

A detail: The shudder would not come under 30km/h whether I was on the skinny pedal or not. Over 30km/h, the shudder only happens when I'm on the power, and not necessarily hard.

It's sat for a week or so (and drained completely I'll assume) but finally have time to get under it this weekend. I went out today, soaked the underside in degreaser, hosed it down so it's clean. I figure I'll dump ATF back into it and bring it to idle, see where the fluid's leaking from.

It's weird though! Still drove (probably not now with no ATF) and only dumped after I'd parked, not while it was under pressure for nearly 800km! Not sure why I'd drain both the tranny and tcase either. Everything looks kosher from a glance anyway.

Any ideas? Thought better to ask now then go in there unfocused on the weekend. As much as I've nearly rebuilt that engine, I haven't done any transmission work before in any way. Quick side question too, should the tranny be totally empty, what's the best way to refill it? I've heard that it's not so straight forward...
 
My guess is the seal between the trans and tc lost it and you filled the tc up with your tranny fluid.

I'm not entirely sure why it would have shuddered like that, but I imagine it had to do with the gears in the tc cavitating from being overfull maybe. Unfortunately you're going to have to at least pull the tc to fix this, but it's possible that you now will have trans issues from it being low. I assume it's a 700r4?

As far as filling it, just dump it down the dipstick tube like normal. I doubt you drained the torque converter too. I think the pan holds ~5-6quarts iirc.
 
That's what I'm hoping. Fingers crossed. The alternative thought was that if I cracked the tranny casing it would have drained and been vibrating if it was loose. I would think that if that were the case though, no way it would've driven that far before dying out on me.
 
You wouldn't think so, but I've seen crazier things. I suppose on that note you could have chucked a torque converter bolt/multiple and that would be your shimmy, which in turn caused the tranny to blow a seal and fill the tc.... I'd say now that you degreased it you're just gonna have to inspect it real good and go from there. The shimmy part is the only odd thing that has me concerned it might be worse than just the seal between the two. I hope it's just that though:waytogo:
 
38377k5 said:
There shouldn't be gear oil in your tranny or t-case, if there is, there could be issues.
Click to expand...

I was thinking the same thing, but doing some google-ing, it seems like the early 208s were gear oil and the later moved to ATF. Doesn't sound right though...

Either way, I'm just glad the engine's still got fluids and is still running well. I can deal with a tranny/tcase replacement if it comes down to it. Not that I'd be overly impressed, but the lesser of two evils.

Any time you see those colours dumping out the bottom of the truck though, you get this sick feeling in your stomache. Especially when the trails have just opened and you CAN'T GET OUT TO THEM!!!! :chainsaw2:
 
scottystills said:
I was thinking the same thing, but doing some google-ing, it seems like the early 208s were gear oil and the later moved to ATF. Doesn't sound right though...
Click to expand...

NP208's NEVER had gear oil spec'd for them, most NP205's were spec'd for gear oil while the later ones were ATF.
 
My 700R4 was shuddering and then started grinding before it caught fire, just saying. Hoping its something that goes away with something cheap and simple though, good luck
 
Look at the 4 bolts holding the adapter to the trans, i bet your trans is seperated from it.

This happenns when you pull the threads out of the bolt holes in the trans. If the trans is still alright then just helicoil the holes and your good.

But who knows if the trans is good
 
So I'm going to do some more investigating today, but it looks like I've blown the seal between the transmission and tcase. Nothing immediately evident why though.

The transmission itself seemed to be shifting fairly well (when it had fluid) but now I'm thinking to myself about the torque converter. The thing would only shake after 30km/h or so, and only on the gas, so I'm wondering if it would be shaking when the TC's locked up? So that leads me to two questions:

1. How do you actually test if a torque converter's shot?
2. Any idea what the stall speed is on the 6.2L 700R4 torque converter?
 
Well, finally gotten around to playing at this. Figured out a couple more things. ATF is only leaking when the tranny's shifted into reverse, and it's not leaking, it's spraying out at high pressure at the top of the tranny/tcase adapter seal. I'm going to go pull the tcase once I get off the laptop to make sure it's the seal and not a cracked case, but I still shouldn't be getting that much fluid there.

Tranny output shaft seal, or something worse?
 
Well, I'm more confused. Pull the tcase, and the seal looks fine, and there was no ATF in between it and the tranny. The seal around the tcase input doesn't look great, but the output from the tranny looks fine. Losing fluid from both though, and no idea why it would be hitting pressures like that...

tcase input
IMG-20120604-00173.jpg


tranny output
IMG-20120604-00174.jpg

IMG-20120604-00175.jpg


Sorry, the tranny ones are a little blurry...
 
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