'99 TCase possible leak

'99.. Z71.. 5.3L.. 4x4.. 250k

OK.. I did a stupid/lazy thing last week. Instead of doing my own oil change - outside in 10* weather - I opted for a drive thru quickie. In getting the crankshaft sensor in yesterday I noticed that the top of the transfer case appears to be wet, autotrac II level appears low and there is oil spewed all down the LEFT side of the undercarriage.

Not getting any idiot lights anywhere. Engine oil dipstick says it's OK. Haven't wanted to try to shift into 4x4 w/o sussing things out first but winter is upon us and I'm going to need it soon. Other than the soaking, w/o using the 4x4 everything seems to be running as normal.

Wondering 2 things:

Any chance that the pit crew somehow "overfilled" the case if they decided to top off?

I don't see any leakage around shaft seals, etc... Is there a usual suspect in a transfer case seal/gasket failure especially given the mileage I've got.

'99.. Z71.. 5.3L.. 4x4.. 250k

OK.. I did a stupid/lazy thing last week. Instead of doing my own oil change - outside in 10* weather - I opted for a drive thru quickie. In getting the crankshaft sensor in yesterday I noticed that the top of the transfer case appears to be wet, autotrac II level appears low and there is oil spewed all down the LEFT side of the undercarriage.

Not getting any idiot lights anywhere. Engine oil dipstick says it's OK. Haven't wanted to try to shift into 4x4 w/o sussing things out first but winter is upon us and I'm going to need it soon. Other than the soaking, w/o using the 4x4 everything seems to be running as normal.

Wondering 2 things:

Any chance that the pit crew somehow "overfilled" the case if they decided to top off?

I don't see any leakage around shaft seals, etc... Is there a usual suspect in a transfer case seal/gasket failure especially given the mileage I've got.

what are you saying ??????

luBe jocky screwed with your tranfercase ?????

YOU BEST CHECK THE FLUID LEVEL AND CONDITION !

also ,,,you cannot overfill because the fill is the top plug on the case...

also these plugs are torqued to about 12 ft lbs ..no air tools ..the transfercase metal is not steel !

lets say the fluid comes pooring out the fill hole on transfercase. it has happened a tranny seal is bad leaking into the transfercase !

Sorry, JC. That orig post was a little unclear. It's been a bit of a month around here...

No idea when the leak actually started. Could be complete coincidence. Drove fine for the week or so after the oil change and then just started vibrating on the way home 3 nights ago. Had it in the shop to replace the Crankshaft Position Sensor and they told me the entire left side was bathed and it appeared to be coming from the top of the Tcase. Crawled under and saw the mess myself. Just can't find the leak. Odd/disconcerting that it seems to only involve the LEFT side of the under carriage. And the leak starts somewhere on the engine side of the cross member.

More symptoms now that I've paid a bit more attention...

Tranny feels like it's shifting fine.

Have not tried shifting Tcase yet.

Vibe sets in hard @ approx. 40 mph.

Vibe transfers through the steering column.

Does NOT feel like it's transferring through the brakes when applied.

Vibe lessens when drive train under load. Worsens/increases when coasting and/or accelerating downhill under coast.

No codes being thrown anywhere.

More of a "hum" that, for some reason, in my head I associate with spline rotation as opposed to a "ticking" or metal on metal sound. Sounds/feels like I'm running 33" Mickey Thompson mudders all of a sudden.

Unfortunately, I don't have the time, especially so close to the holiday, to shade tree diagnose. FEELS like a possible front shaft U-joint issue but the shaft itself is tight. Most likely, throwing it in a tranny shop today in hope of getting it out of jail by Friday. Per usual, will keep you posted as possible. Thoughts/theories appreciated.

Sorry, JC. That orig post was a little unclear. It's been a bit of a month around here...

No idea when the leak actually started. Could be complete coincidence. Drove fine for the week or so after the oil change and then just started vibrating on the way home 3 nights ago. Had it in the shop to replace the Crankshaft Position Sensor and they told me the entire left side was bathed and it appeared to be coming from the top of the Tcase. Crawled under and saw the mess myself. Just can't find the leak. Odd/disconcerting that it seems to only involve the LEFT side of the under carriage. And the leak starts somewhere on the engine side of the cross member.

More symptoms now that I've paid a bit more attention...

Tranny feels like it's shifting fine.

Have not tried shifting Tcase yet.

Vibe sets in hard @ approx. 40 mph.

Vibe transfers through the steering column.

Does NOT feel like it's transferring through the brakes when applied.

Vibe lessens when drive train under load. Worsens/increases when coasting and/or accelerating downhill under coast.

No codes being thrown anywhere.

More of a "hum" that, for some reason, in my head I associate with spline rotation as opposed to a "ticking" or metal on metal sound. Sounds/feels like I'm running 33" Mickey Thompson mudders all of a sudden.

Unfortunately, I don't have the time, especially so close to the holiday, to shade tree diagnose. FEELS like a possible front shaft U-joint issue but the shaft itself is tight. Most likely, throwing it in a tranny shop today in hope of getting it out of jail by Friday. Per usual, will keep you posted as possible. Thoughts/theories appreciated.

could be the wheel weight feel off...check for lost weights.

on leaks the top of case is a vent. make sure hoses secure. also check that the case is not cracked,,,this is common !

Going to check the Tcase fluid level and hunt around for missing weights this afternoon.

Spoke with a local shop. Unfortunately, they can't get to it until Monday. They DID say that it's not uncommon for the 99 era tcases to leak from the top. I tripped over a video (http://www.youtube.com/watch?v=Nj5ZS8wOmNk) that got into one possibility last night. Shop says that the cases can be heliarced if necessary but, again assuming that I'm dealing with the video problem, they've been having good luck with simply epoxying the hole if it's small enough and replacing the offending OEM part(s) with aftermarket.

Unfortunately, I just don't have the space/time to tackle a tcase diagnosis/repair which frustrates the hell out of me but....:banghead:

Going to check the Tcase fluid level and hunt around for missing weights this afternoon.

Spoke with a local shop. Unfortunately, they can't get to it until Monday. They DID say that it's not uncommon for the 99 era tcases to leak from the top. I tripped over a video (http://www.youtube.com/watch?v=Nj5ZS8wOmNk) that got into one possibility last night. Shop says that the cases can be heliarced if necessary but, again assuming that I'm dealing with the video problem, they've been having good luck with simply epoxying the hole if it's small enough and replacing the offending OEM part(s) with aftermarket.

Unfortunately, I just don't have the space/time to tackle a tcase diagnosis/repair which frustrates the hell out of me but....:banghead:


gm recommends epoxy for hole repairs in this metal.

I have not tried the aluminum brazing rods yet. these have flux built into them . at about 700deg f the rod melts . used in the boating world with great results. only need a small propane torch.

welding on these cases is super high heat. but is possible..

you think the crank sensor replacement had something to do with this oil leak ? crank sensor under the starter motor passengerside ..

Doubt the crank sensor replacement had anything to do with the leak but I'll make sure that everything gets documented. I'll be a new client at the tranny shop. I got the impression on the phone that they go by the book so we'll see what they come up with. They were already well aware of the aftermarket replacement parts and tcase issues so we'll see.

With the snow flying today I had no ambition to crawl on the ground but after 250k orig miles I'm going to guess that the shop will find a hole in the case. Like or not, after 9 years/250k miles of no major 4x4 or tranny issues I have nothing to complain about.

About all that's left at this point is to say "Ho Ho Holee crap - what's next?"

I hate to see people dump 2,ooo to repair a vehicle thats only worth 2,ooo....

250,ooomi what's next...this vehicle is at the top limit !

Oh I don't disagree, JC. I've always been a big proponent of spending money right the first time as well. Unfortunately, it's the lesser of evils at the moment. FWIW, another piece of shrapnel is that I've got a line on a bone yard tcase for $500. Hasn't been processed yet so no word on the mileage.

NOW the questions become:

"Do I fix the tcase I have with the 250k on it?"

"Do I throw the "new" tcase in as is?"

"Do I do the aftermarket fix on the "new" tcase before throwing it in ensuring that I at least won't have to worry about the known wear through issue?"

Of course, all of this may well hinge on the mileage of the "new" tcase as well. Devils known v. unknown. My kingdom for a heated garage...

[quote=MikeD266;6851519]Oh I don't disagree, JC. I've always been a big proponent of spending money right the first time as well. Unfortunately, it's the lesser of evils at the moment. FWIW, another piece of shrapnel is that I've got a line on a bone yard tcase for $500. Hasn't been processed yet so no word on the mileage.

NOW the questions become:

"Do I fix the tcase I have with the 250k on it?"

"Do I throw the "new" tcase in as is?"


[quote]

"Do I do the aftermarket fix on the "new" tcase before throwing it in ensuring that I at least won't have to worry about the known wear through issue?"

open the transfercase up see the condition. if worn rebuild before install. this would be the cheapest way to go for this not to be an issue again. do the clip fix to prevent this from wearing the hole thru the case again.

then with the vehicle running you can sell for another lower mile newer vehicle.

oil prices rising with gas going over 4.oo a gallon soon ,these vehicles will be cheap.

oil 100.oo a barrel

]

Well... Confirmed that it was a pin hole leak in the tcase today. Having it pulled and cracked open to see what it looks like inside. Will have an idea of the condition of the "new" bone yard tcase hopefully tomorrow or Wed. Storm may have messed up the timing of things unfortunately....

OK... Well, now that I've recovered a bit from the minor infarction induced by the bill.... :runaround:

Turned out that the case DID have a pin hole worn into it. Fortunately, it was caught soon enough that nothing roasted.

For those with the ability to spend a day or two to do this mod on their own I would HIGHLY recommend it. Retail shop cost came in at $1002.29 - to essentially install a $52.38 aftermarket "case saver" pump housing to solve GM's design flaw. Parts, all told, came to $198.47 once you factor in the new input and output seals, gaskets, epoxy, fluid, bushing etc. May be able to knock an additional $35.00 off of that as well as I also needed new case bolts as mine had corroded significantly.

Turns out that these cases (at least mine) are magnesium, as opposed to aluminum, which makes them lighter but also "softer" and therefore more prone to wear. There is also the potential for a chemical reaction between the magnesium and other metals if/when contacted long term, hence the need for the correct bolts.

Did some reading in my down time and tripped over this "wear" issue happening as early as 80k miles if I remember correctly.

Had I been properly set up to tackle this myself, i.e. a relatively warm (something above 30*), dry floor and a decent jack I certainly would have given this a shot myself. Once the case itself was out it was only 17 bolts, a couple of seals and gaskets and a pump housing - what could go wrong? :cwm27:

OK... Well, now that I've recovered a bit from the minor infarction induced by the bill.... :runaround:

Turned out that the case DID have a pin hole worn into it. Fortunately, it was caught soon enough that nothing roasted.

For those with the ability to spend a day or two to do this mod on their own I would HIGHLY recommend it. Retail shop cost came in at $1002.29 - to essentially install a $52.38 aftermarket "case saver" pump housing to solve GM's design flaw. Parts, all told, came to $198.47 once you factor in the new input and output seals, gaskets, epoxy, fluid, bushing etc. May be able to knock an additional $35.00 off of that as well as I also needed new case bolts as mine had corroded significantly.

Turns out that these cases (at least mine) are magnesium, as opposed to aluminum, which makes them lighter but also "softer" and therefore more prone to wear. There is also the potential for a chemical reaction between the magnesium and other metals if/when contacted long term, hence the need for the correct bolts.

Did some reading in my down time and tripped over this "wear" issue happening as early as 80k miles if I remember correctly.

Had I been properly set up to tackle this myself, i.e. a relatively warm (something above 30*), dry floor and a decent jack I certainly would have given this a shot myself. Once the case itself was out it was only 17 bolts, a couple of seals and gaskets and a pump housing - what could go wrong? :cwm27:

your hole due to the pump housing wear into the magnesium metal case is variable in failure ..depends on how this pump assembly was finished and the clip position on it. another recall GM got away with !

another reason it is now G overment M otors !

I saw a you tube showing this job being done . not too hard..

magnesium is a very tricky metal..use the wrong drain plug or bolts it is a total mess.