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Oil in Bellhousing 91 GMC Sierra


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WilliamH4
User

May 20, 2019, 1:57 PM

Post #1 of 33 (1264 views)
  post locked   Oil in Bellhousing 91 GMC Sierra  

I'm currently replacing the clutch (clutch disc, pressure plate, release bearing, etc.) in my 91 GMC Sierra 4.3 liter 5 speed manual. When I dropped the transmission, there was oil inside the bellhousing. I'm not sure if it's engine oil, gear oil or both. I decided I should replace the rear main seal (seal at the engine block and input shaft), the seal retainer gasket and oil pan gasket. What seal, if any, would I replace that might have allowed gear oil to leak into the bellhousing? I think I have everything covered that might come from the engine to the bellhousing, but I'm not sure what to replace from the gear box to the bellhousing.


Hammer Time
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May 20, 2019, 2:05 PM

Post #2 of 33 (1257 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

There is no way for gear oil to leak into the bellhousing.

It is either the rear main seal, the trans front seal or possibly the intake manifold leaking from above the bellhousing.



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Tom Greenleaf
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May 20, 2019, 2:51 PM

Post #3 of 33 (1251 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Not sure what the oil is? Rear mains do put out a drop or would burn up in smoke so easy to go nuts. Can't really do those effectively without hair pulling, engine out fix the worn crank!
It's probably as HT just said. Look up high for a leak. Simple rule, "Leaks will almost always be the highest and most forward of where it might drip." Follow the evidence UP in this - OP switch is there too I think low behind distributor plus those leak too,


T



WilliamH4
User

May 20, 2019, 3:34 PM

Post #4 of 33 (1244 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Thanks for the responses, I'm a little more at ease now. Smile


WilliamH4
User

May 21, 2019, 8:01 AM

Post #5 of 33 (1208 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Just so I'm sure, this is where the transmission front seal is, behind the bolt ring? Apparently, I did this wrong, but I think it still works if you copy and paste the address below.

http://autoforums.carjunky.com/photos/pic/470m0KPX/1475.jpg


(This post was edited by WilliamH4 on May 21, 2019, 8:04 AM)


Hammer Time
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May 21, 2019, 8:05 AM

Post #6 of 33 (1200 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Yes, that is it but if your trans fluid looks like that, you have bigger problems than a leak. Whatever that fluid is is in very poor condition.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



WilliamH4
User

May 21, 2019, 8:10 AM

Post #7 of 33 (1195 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

We replaced valve stem seals last year and the device (forgot the name) that pulls moisture from the engine (it was totally blocked). Also changed the oil a couple of times to flush out as much gunk as possible. Going to be adding new oil again as well as new oil behind this seal.


WilliamH4
User

May 21, 2019, 8:12 AM

Post #8 of 33 (1193 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

I also replaced the main rear seal, oil pan gasket and gasket behind the rear main seal retainer. Hoping all the seals being replaced will prevent this/these fluids from getting in the bellhousing again.


Hammer Time
Ultimate Carjunky / Moderator
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May 21, 2019, 8:15 AM

Post #9 of 33 (1187 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

I was more concerned about the color and condition of the fluid. That indicates other issues.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



WilliamH4
User

May 21, 2019, 8:21 AM

Post #10 of 33 (1181 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

LOL, my wife keeps asking me to get rid of this truck, but it's my truck for projects around the house. I probably don't put 1500 miles a year on this old thing. If I can make it last another few years, I'm okay with whatever else is going on. I only got in to all this to replace the clutch as it was acting up. Figured I would go ahead and address some of the issues I could easily (relatively) address. Plus, it's mostly fun to work on. If I screw it up, I'll just have it towed away and junked.


(This post was edited by WilliamH4 on May 21, 2019, 8:23 AM)


WilliamH4
User

May 21, 2019, 8:31 AM

Post #11 of 33 (1170 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Will it hurt anything if I spray a degreaser or parts cleaner up in here to help remove some of the oil/fluid?


Hammer Time
Ultimate Carjunky / Moderator
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May 21, 2019, 8:39 AM

Post #12 of 33 (1166 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

No, won't hurt anything.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



WilliamH4
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May 21, 2019, 8:40 AM

Post #13 of 33 (1161 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Thank you, HT.


WilliamH4
User

May 21, 2019, 12:03 PM

Post #14 of 33 (1144 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

HT, is the seal behind the bolt plate the same as the input shaft seal in this link (had to edit/fix the wording so anyone else reading will know what I'm talking about).

Link deleted ............ not allowed


(This post was edited by Hammer Time on May 21, 2019, 12:19 PM)


Hammer Time
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May 21, 2019, 12:08 PM

Post #15 of 33 (1136 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Yes, that's the right seal and I just realized that for some reason I was thinking this was an automatic but being a manual, yes, that can be gear oil. I know you said you were changing a clutch but that went right over my head.

Make sure you check the level in the trans when you are finished.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



WilliamH4
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May 21, 2019, 12:14 PM

Post #16 of 33 (1131 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Thanks again, HT. I really appreciate all your input.


WilliamH4
User

May 22, 2019, 10:35 PM

Post #17 of 33 (1091 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

There was enough break in the weather this afternoon for me to work. I got the bushing, clutch disk and pressure plate installed. Had time to clean the bellhousing a little and remove the bearing retainer to replace the input shaft seat. How do I separate the 2 parts of this bearing retainer so I can install the new seal. Do I tap the horn part (for a lack of a better description) down through the base? The seal is sandwiched between the 2 pieces. I assume it can be separated without damage.

BTW, I could see where oil was leaking from around the bearing retainer. I'm guessing most of that mess in the bellhousing was gear oil.


http://autoforums.carjunky.com/photos/pic/470m0KPX/1477.jpg

http://autoforums.carjunky.com/photos/pic/470m0KPX/1478.jpg


(This post was edited by WilliamH4 on May 22, 2019, 10:38 PM)


Hammer Time
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May 23, 2019, 3:55 AM

Post #18 of 33 (1075 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

That seal has to be pried out from the back. Be very careful installing the new one not to bend or dent it. Find something flat and about the same size as the seal to pound it in evenly without damaging it. Make sure you install it facing the right direction. Look at the old one before removing it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



WilliamH4
User

May 29, 2019, 8:07 AM

Post #19 of 33 (997 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Only just now getting around to reinstalling the bearing retainer with the new seal. As I look at this bearing at the back of the bellhousing, I would think gear oil could get in from around the bearing? Is there a seal on the other side of this bearing too? Wanted to be sure to address any other potential issue(s) before putting everything back together.

http://autoforums.carjunky.com/photos/pic/470m0KPX/1485.jpg


Hammer Time
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Hammer Time profile image

May 29, 2019, 8:35 AM

Post #20 of 33 (987 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

The bearing is supposed to get oil to lubricate it. The seal should be only on the outside of it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



WilliamH4
User

May 30, 2019, 6:09 AM

Post #21 of 33 (962 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Of course, that makes sense. Thank you, HT.


WilliamH4
User

May 31, 2019, 1:57 PM

Post #22 of 33 (937 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Is there supposed to be a small nut or something on the clutch fork pivot ball? It's threaded as if there's supposed to be a nut, but I don't recall there being a nut. The nut would have to be quite small.

Looks similar to this
http://autoforums.carjunky.com/photos/pic/470m0KPX/1487.jpg


Maybe that's not threaded, but ribbed?


(This post was edited by WilliamH4 on May 31, 2019, 2:03 PM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 1, 2019, 6:25 AM

Post #23 of 33 (872 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

That's a strange looking pivot. The allen hole would indicate that it threads in but it would have to be inserted from the outside for that to work it appears.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



WilliamH4
User

Jun 1, 2019, 11:51 AM

Post #24 of 33 (859 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

Thank you, HT. I hope this is the last question, LOL. I'm mating the transmission and the engine. I have perhaps another 1/2 to go and can't seem to get it to go. Should I hand crank the engine to aid in alignment? I used the clutch alignment tool, so I know I'm good there. Something is just slightly off, I think. I can keep moving the transmission from side to side and keep trying though.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 1, 2019, 11:59 AM

Post #25 of 33 (851 views)
  post locked   Re: Oil in Bellhousing 91 GMC Sierra  

It's the pilot bearing that hasn't mated yet. You're going to have to rock the transmission around while applying pressure in. You could have been not completely straight with the pilot tool and be off just a little on the alignment. Just the weight of the clutch disc can do that.

If all else fails, sometimes I put the bolts in and without applying pressure, bring them all down snug to hold the transmission straight and then use something like a prybar to engage the clutch arm enough to release the clutch disc and let it center itself. It will sometimes drop right in when you do that.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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