There really are two front main seals?

Steevo

Original poster
Member
Oct 7, 2012
194
I have a 2003 Envoy XL with a 6 cylinder engine. My front main seal is leaking.
I looked on Autozone and on Amazon, and there are apparently two front main seals for that engine? Huh?

National Crankshaft Seal 710551​

47 MM diameter​

National Crankshaft Seal 710605​

38.4 mm inner diameter​


How can there be two? What's going on here?



Amazon has two! ( a lot cheaper than autozone.)



ACDelco Gold 4762N Crankshaft Front Oil Seal, Opens in a new tab
ACDelco Gold 4762N Crankshaft Front Oil
$6.09



GM Genuine Parts 12608750 Front Crankshaft Engine Oil Seal, Opens in a new tab
GM Genuine Parts 12608750 Front Crankshaft Engine Oil Seal
$7.18
 

mrrsm

Lifetime VIP Donor
Supporting Donor
Member
Oct 22, 2015
7,639
Tampa Bay Area
Always include the Year, Make and Model & Sub-Model while investigating the purchase of OEM Gaskets, Parts and Seals at any Genuine GM On-Line Parts Distributor for ensuring Quality, Fitment and Accuracy.

Then visit RockAuto afterwards to cross-check this information using the correct GM Part Numbers to seek possible Better Pricing and Availability:

Refer to the linked GM Site Numeric Indices for their Diagrams (the Timing Cover Seal(s) are shown as Part #5) and use their List of Unique Part Numbers to ensure obtaining unequivocal accuracy... prior to making any purchases:

2002 Chevrolet Trailblazer 4.2L LL8 Motor:

Front Timing Cover Seal Part# 89017621

https://www.gmpartsdirect.com/v-2002-chevrolet-trailblazer--ls--4-2l-l6-gas/engine--engine-parts

2008 Chevrolet Trailblazer 4.2L LL8 Motor:

Front Timing Cover Seal Part# 89017622

43350772032_3f7253d0c0_c.jpg


https://www.gmpartsdirect.com/v-2008-chevrolet-trailblazer--lt--4-2l-l6-gas/engine--engine-parts

The difference between the prices of these OEM Parts vs. using ANY Off-Brands is insignificant when compared to the grief experienced if one installs the Wrong Seal(s) and must then perform any additional, corrective R&R.

Genuine GM OEM Parts... FTW!

NOTE:

Refer to THESE Links to the GMTN Threads covering the Procedures & Idiosyncrasies for performing the R&Rs of the Two Distinct Harmonic Balancers installed on the various GM 4.2L LL8 Motors:

 
Last edited:

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON

Explains the differences. Yours being a 2003, you likely have the second design.
 

Steevo

Original poster
Member
Oct 7, 2012
194
So you are saying this one
Front Timing Cover Seal Part# 89017621
is the one, but I can check for the version of the harmonic balancer to be sure, because that will tell the tale.
This engine was changed, so I am not absolutely sure of the year of the wrecking yard engine.
The seal varies depending on which harmonic balancer you have, new or old style, and if you put the new one in place of the old one you need the new version of the seal?
 
Last edited:

Steevo

Original poster
Member
Oct 7, 2012
194

Explains the differences. Yours being a 2003, you likely have the second design.
The old design harmonic balancer and seal were only used through 2002?
 
Last edited:

Steevo

Original poster
Member
Oct 7, 2012
194
This picture
Shows both new and old harmonic balancers and seals and bolts. But the bolts are different. Those bolts are available.
Crankshaft Balance Bolt
Product ID: 11609792
But the bolts in the picture are not the same. Is that an important distinction?
 

mrrsm

Lifetime VIP Donor
Supporting Donor
Member
Oct 22, 2015
7,639
Tampa Bay Area
You might find it useful to Visit, Bookmark and Download the many Images of the GM Atlas 4200 Vortec Engine Parts, Pieces, Fasteners. OEM Packing and Box End information that I memorialized over a decade ago at Photobucket and later transferred onto Flickr.com:

The Main “MRRSM” Flickr-Bucket Site that includes numerous 4.2L Engine Tear Down Images:

https://www.flickr.com/photos/126111508@N07/albums/with/72157671179967478

The Dedicated Album covering the Primary GM OEM Fasteners for the Atlas 4.2L LL8 Engines:

https://www.flickr.com/photos/126111508@N07/albums/72157715522022386

The Dedicated Album covering the Major OEM Engine Parts, Gaskets & Fasteners for the Atlas 4.2L LL8 Engines:

https://www.flickr.com/photos/126111508@N07/albums/72157671179967478

For example... to answer your Question about the Physical Appearance and Part Numbers of the *** GM OEM TTY Crankshaft Bolt (Fitted with a 'Trapped Thrust Washer' and having Factory Applied Red Thread Sealant)... have a look this image below...

43350754772_19a2c6866b_c.jpg

Then ZOOM in closely on this image to compare and match this un-wrapped Crankshaft Bolt with the one removed from your Crankshaft - Harmonic Balancer:

28529269717_e69aa41e93_c.jpg

*** Avoid trying to use this New TTY Crankshaft Bolt to try and Draw On the Harmonic Balancer, as doing so WILL strip out the Internal Threads of the Crankshaft. Instead, use the K&M Harmonic Balancer Install Tool Kit displayed among other images shown below in this Linked Album for understanding how BOTH Types of Harmonic Balancer Removal and Installation Tools function:

 
Last edited:

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I also touched on the balancer in my timing chain replacement thread:

  • Pull the harmonic balancer with a puller. Depending on which balancer you have, you may need a special Spent-Moore tool to pull. If you have an early 2002 model and your balancer looks like there is a large thick ring steel plate on the front of it like in this picture, then you will need Kent-Moore tool J 44226 to pull it. Early balancer.jpg
  • If you have a "normal" looking balancer like this one, then a 3 jaw gear puller should work. Balancer.jpg
Using RA as referral for parts.


If you have the first one pictured, it's a first early design and you will need MAHLE JV5077. If you have the second one, that is the second design and you will need MAHLE JV5039.

Why in the part number listing for the first design they say it's for 2002-2005 I don't know because I know for a fact that it was ONLY for early 2002 versions.
 

KWG2005

Member
Sep 6, 2023
41
Nashville
I measured the diameter of the "shaft" on the pulley before ordering mine. Apparently I have the older diameter. I am rebuilding my engine and I upgraded to the new oil pump/cover and oil pickup tube design. Is there any reason why the older harmonic balancer won't work with the newer oil pump/cover design?

Thanks
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
You have to change it. Because the seal was changed, so was the balancer (diameter was changed). There used to be a 1st and 2nd design available, now it just the 2nd. Seals there is both however the 2nd design does say it has a larger diameter so you have to change the balancer with the seal. Your small diameter balancer will cause a leak in the large diameter seal.
 

KWG2005

Member
Sep 6, 2023
41
Nashville
Thanks for the reply Mooseman. I ordered a GM front seal,89017621, which is for the old design harmonic balancer. The dimensions fit my old balancer, and looks to fit into the new design front timing cover/oil pump. I just thought I saw somewhere that the new front cover design requires a new harmonic balancer. From what it looks like, the new cover will take the old seal and HB, but I don't know if there's any difference in flange depth or anything like that. I did have to order the new style pickup tube for the new pump.
 

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