Sludge is caused by air mixing with Dexcool, often caused by a faulty rad cap as explained in the following links,
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You sound as though you need a lower intake manifold gasket again.
Apparently the first batch of GM replacements were problematic, GM also issued a revised bolt torque sequence and the use of threadlocker on the bolts.
I replaced the bolts with bolts from GM with preapplied locker, followed the revised torque sequence and used a Fel Pro Perma Dry gasket set.
That was 18 months ago at 129,000kms.
The car now has 165,000kms and all is well.
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-------------------------- Engine Oil or Coolant Leak (Install New Intake Manifold Gasket) #03-06-01-010B
Engine Oil or Coolant Leak (Install New Intake Manifold Gasket) #03-06-01-010B - (10/24/2003)
Engine Oil or Coolant Leak (Install New Intake Manifold Gasket)
2000-2003 Buick Century
2002-2003 Buick Rendezvous
1996 Chevrolet Lumina APV
1997-2003 Chevrolet Venture
1999-2001 Chevrolet Lumina
1999-2003 Chevrolet Malibu, Monte Carlo
2000-2003 Chevrolet Impala
1996-2003 Oldsmobile Silhouette
1999 Oldsmobile Cutlass
1999-2003 Oldsmobile Alero
1996-1999 Pontiac Trans Sport
1999-2003 Pontiac Grand Am, Montana
2000-2003 Pontiac Grand Prix
2001-2003 Pontiac Aztek
with 3.1L or 3.4L V-6 Engine (VINs J, E - RPOs LG8, LA1)
This bulletin is being revised to change the model Information. Please discard Corporate Bulletin Number 03-06-01-010A (Section 06 - Engine). Condition
Some owners may comment on an apparent oil or coolant leak. Additionally, the comments may range from spots on the driveway to having to add fluids. Cause
Intake manifold may be leaking allowing coolant, oil or both to leak from the engine. Correction
Install a new design intake manifold gasket. The material used in the gasket has been changed in order to improve the sealing qualities of the gasket. When replacing the gasket, the intake manifold bolts must also be replaced and torqued to a revised specification. The new bolts will come with a pre-applied threadlocker on them.
Object Number: 190523 Size: SH Click here for detailed picture of above image.
Notice
An oil leak may result if the vertical bolts are not tightened before the diagonal bolts.
Diagonal bolts may require a crows foot to tighten. Tighten
- Tighten the vertical lower intake manifold bolts (1) to 7N=B7m (62 lb in).
- Tighten the diagonal lower intake manifold bolts (2) to 7N=B7m(62 lb in).
- Tighten the vertical lower intake manifold bolts (1) to 13N=B7m(115 lb in).
- Tighten the diagonal lower intake manifold bolts (2) to 25N=B7m(18 lb ft).
Parts Information
Part Number
Description
Qty
89017279
Intake manifold Gasket
1
11588915
Intake manifold bolt - short
4
11588914
Intake manifold bolt - long
4
GM
Coolant and/or oil leaks. GM reports that many of its 1999-2003 mid- size cars and minivans with the 3.1 or 3.4L V6 (VINs J, E) are susceptible to springing oil and/or coolant leaks at the lower intake manifold gasket. The complaints you're likely to get irom customers can vary from oily spots on the driveway to continually having to top up the coolant reservoir with antifreeze. The Low Coolant light on the dash could also illuminate. A new-design intake gasket with superior sealing qualities (Part No. 89017279) is now available to eliminate both leakage issues.
GM says you must install upgraded manifold bolts with preapplied threadlocker (Part No. 11588915, short bolts; Part No. 11588914, long bolts) to get the benefits of the new gaskets sealing qualities. New torque specs and a new tightening sequence for the bolts are also on the menu (see illustration).
Here's the info you'll need to do the job: Begin by tightening the four vertical (inner) bolts to 62 in.-lbs. Follow that up by tightening the four diagonal (outer) bolts to the same 62 in.-lbs. Now go back to the vertical bolts and torque them to 115 in.-lbs. Complete the tightening sequence by torquing the diagonal bolts to 18 ft.-lbs. GM cautions that if you don't use the new torque specs in the exact sequence indicated, you could be opening yourself up to a comeback.
So after some thinking and comparing! I ended up buying a set of FelPro, Victor, and OEM gaskets and comparing them all the Victor and GM are exactly the same save for color of the rubber material. FelPro sorry are very cheap looking and don't come with the steel inserts in them. But looking at the OEM set there's this paper in there that see's to use all new bolts. And an updated torque spec 115in/lbs center 4 bolts and 18ft/lbs 4 corner bolts. I went and looked through ALLDATA and no mention of the new bolts or specs that I could see. GM guys anything to add. Parts guy we deal with did a search on the bolts, their dealership had yet to use the new bolts but the EDM wharehouse had sold appros 26,000 of each. MTL had sold 46,000 of each. Oh yeah there about $15 a bolt.
These are the parts used by GM to reseal the Lower Intake:
3.4L (E) & 3.1L (J) Engine Intake Reseal:
89017279 Intake Gasket Set
11588914 Intake Bolts {Qty: 4}
11588915 Intake Bolts {Qty: 4}
10154775 Valve Cover Gaskets {Qty: 2}
24506439 EGR Valve Gasket
10241048 EGR Valve Pipe Gasket
10189205 By-Pass Seal {Yellow}
24504709 Heater Inlet Pipe Seal {Orange}
10477565 Oil Pump Drive Seal
10108445 Distributor Base Gasket
10953472 RTV Sealant
10953031 Dex-Cool {2L}
992878 Engine Shampoo
88901247 Brake Kleen
The Lower Intake gaskets themselves are different. They incorporate rivits into the stress areas where the coolant used to leak at.