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Cadillac: the Northstar engines, preventing the head gasket failure

Resolved Question:

Which year did Cadillac change the head gasket on the Northstar engines, preventing the head gasket failure? All of them, like I just read is not the correct answer.
Submitted: 3 years ago.
Category: Cadillac
Expert:  John replied 3 years ago.

Hello & Welcome to JA,

 

This is the mechanical change I believe you are talking about for Cadillac.

 

 

04-06-01-032: Information on Northstar Engine Mechanical Repairs - (Oct 27, 2004)

Subject:Information on Northstar® Engine Mechanical Repairs

Models:1994-2002 Cadillac Eldorado
1994-2004 Cadillac Seville
1994-2005 Cadillac DeVille
1996-2000 Cadillac Concours
with 4.6L Northstar® Engine (VINs Y, 9 - RPOs LD8, L37)

 


Now that parts are available to correct customer concerns of oil consumption and cold start conditions on these engines, there has been some confusion on what parts are for which repairs. This bulletin has a section listing a guideline of parts required for typical engine repair. Also included is a discussion of thread repairs, when and how many Time Serts should be used during repairs. There is also a chart that shows the correct special tool numbers to use for which model years when installing Time type serts. And finally, the head bolt torque specifications when reassembling the engine are listed at the end of this bulletin.

Important: When performing Northstar® engine mechanical repairs that require removal of the oil pan, oil manifold or separation of the upper and lower crankcases, use the RTV sealant procedure in bulletin 03-06-01-027 when reassembling. The RTV sealant has a better resistance to heat and will not shrink like the current gaskets material.

Important: Light vertical scratches that are not deep enough to catch a fingernail are acceptable. If any of the cylinder bores are scored, that is not acceptable and the engine will have to be replaced.

Important: When replacing pistons or rings, the crankcase halves do not need to be separated to complete the repair. It is advised at the time of the piston/ring repairs that the original crankcase seals be removed and sealed with RTV per bulletin 03-06-01-027.

This bulletin addresses Northstar® oil economy only. The cleaning procedure in this bulletin should be done first and the oil economy evaluated. In most cases, cleaning the cylinders per bulletin 02-06-01-009C will restore the function of the rings to wipe the oil down the bore. If the oil economy after cleaning is still not satisfactory, then the revised piston rings should be installed. For an oil consumption concern, it is not necessary to replace pistons. The original pistons can be cleaned. The critical part of the cleaning process it to remove all the carbon deposits from the piston ring groves.

Important: The cylinder bore surface does not require any preparation when installing new rings. The repair would be ineffective if any honing is done to the bore surface.

Recognize that the oil consumption mileage figure of 2000 miles per quart (3200 km per 0.946 liters) in bulletin 01-06-01-011A applies to a vehicle during the warranty period. As mileage accumulates on the engine, oil economy mileage will decrease due to normal wear in the engine.

This bulletin address cold start engine knock noise. Use of top engine cleaner, or the cleaning process for oil consumption is only a temporary fix for this condition on 2000 through 2003 vehicles. Unless the driving cycle is changed, the cold knock will return in a short time. The piston listed in this bulletin is the only recommended repair to eliminate a cold start knock from reoccurring.

Important: If only a single piston(s) is installed for another type concern, this part number can be used without any balance or performance concerns. P/N 89017413 is the only service piston and it is completely interchangeable with the original pistons. If the condition is for cold knock, all 8 pistons should be replaced.

Important: A small percentage of vehicles have exhibited a subtle ticking sound when the engine is at operating temperature. The noise is usually heard through the fender wells with the hood closed. This noise is a wrist pin noise and should be considered characteristic of this engine with these pistons. There is not any mechanical damage or wear from this noise, no further repairs should be attempted.

When performing either oil consumption or cold engine noise repairs, the following is a list of commonly used parts. The recommendation in SI to replace the rod bearings was based on the assumption that the engine has over 100,000 miles (160,000 kilometers) when engine mechanical service is being performed. The rod bearing should be inspected for signs of wear and replaced, if necessary.

Northstar

Part

Description

Front cover gasket

Install New

Rear main seal

Install New

Head bolt

Install New

Rod Bolt

Install New

Flywheel bolts

Install New

Head Gasket set -- Left

Install New

Head Gasket set -- Right

Install New

Cam Seal

Install New

Water cross over gaskets

Install New

Housing

Install New

Oil Adaptor seal

Install New

DEX-COOL

Install New

Coolant line Connector

Install New

Oil Manifold

Install New, The procedure requires outer perimeter bolts to be removed contributing to a potential leak when retightened.

Plastic Plugs (4)

Install New, These could be damaged since they are plastic. It's only splash oil behind these.

Cat Convert Gasket

Not needed. Reuse unless damaged

Rod Bearings

As needed, based on wear. Vehicles with less than 90,000 miles should not need replacement.

Front cover with seal

Not needed. Use due care and the front cover will not be damaged and can be reused.

Valve cover gaskets

Not needed. If the cover is removed carefully and the seal stays in the valve cover, you can reuse.

Valve seal

Not needed. These are very good valve seals and do not need to be replaced, especially if they are not disassembled.

Sealer

Record lot number from tube on repair order. If there are any issues with the sealer the lot can then be traced and analyzed.

Cam Lube

Not needed, Engine oil will suffice, not replacing the camshafts.

Main bolt

Not needed. Can be reused, these bolts are not stretched when installed.

Tube Seals (2)

Not needed. These are the seals on the underside of V/C these seals for the Ign. Module ground, protecting from splash oil and PCV sealing. These are reusable.

Spark Plug tube Seals (8)

Not needed. These are the seals on the underside of V/C these seals for the Spark plugs.

Pan Gasket

Should be using sealer 12378521 (in Canada 88901148) per bulletin 03-06-01-027 instead of gasket. Record lot number on repair order.

Manifold Seals (8)

Not needed. Should be reusable in most cases.

Exhaust Gaskets (2)

Not needed. These are metal composite gaskets, they should be reused

When disassembling the engine, all head bolt threads should be inspected as they are removed. If there is any section of the aluminum block thread on the bolt, that hole will need a Time Sert repair. Typically, all the cylinder head bolt holes do not need Time Serts. The recommendation is to do a thread repair on the damaged hole(s) and the adjacent holes. As the clamp load is relieved from one hole (threads pulling), the adjacent holes threads load will increase and may be damaged during reassembly.

There have been some comments about Time Serts pulling out of the block in a short time after a repair was done. The manufacture of the insert also makes a larger size insert. This larger size insert cannot be used for warranty repairs. Due to the increased O.D. of this sert, it's possible that when installing this larger sert that it will break out in the water jacket causing a coolant leak.

The most likely reason that a Time Sert pulls out after installation is that the incorrect J tools were used for the model year application. If the incorrect tool is used, installation of the sert could be either too deep in the hole or not deep enough. The table below lists which tool should be used for which model years.

Model Year:

1994-1999

TimeSert kit:

J 42385-500

Component Bolt Hole

Head

Main

Plate

301

306

Bushing

501

508

Alignment pin

502

509

Short bolt

503

510

Long bolt

--

--

Drill

504

511

Inboard stop collar

N/A

--

Tap

505

512

Driver/installer

506

513

Insert

507

514

Thread size

M11 x 1.5 x 30mm

M10 x 1.5 x 22 mm

Outboard hole depth

75 mm

32 mm

Counter bore depth

35 mm

4 mm

Thread length

35 mm

26.5 mm

Bottom

5 mm

1.5 mm

Inboard hole depth

75 mm

32 mm

Counter bore depth

35 mm

4 mm

Thread length

35 mm

26.5 mm

Bottom

5 mm

1.5 mm

Cylinder head boss height - outboard

76.0 mm

--

Cylinder head boss height - inboard

76.0 mm

--

Bolt Part Number

(NNN) NNN-NNNN(NNN) NNN-NNNN

Bolt Length (under washer)

139.9 mm

125.8 mm

Thread length

44.5 mm

23.3 mm

Model Year:

2000-2003

TimeSert kit:

JNNN-NN-NNNN/p>

Component Bolt Hole

Head

Head

Main

Plate

301

301

306

Bushing

302

2022

307

Alignment pin

303

303

308

Short bolt

503

503

510

Long bolt

604

604

--

Drill

2006

2006

511

Inboard stop collar

2017

2017

--

Tap

2007

2007

512

Driver/installer

2008

2008

513

Insert

507

507

514

Thread size

M11 x 1.5 x 30 mm

M11 x 1.5 x 30 mm

M10 x 1.5 x 22 mm

Outboard hole depth

96.5 mm

89.5 mm

32 mm

Counter bore depth

51.5 mm

45.5 mm

4 mm

Thread length

38 mm

38 mm

26.5 mm

Bottom

7 mm

6 mm

1.5 mm

Inboard hole depth

80 mm

73 mm

32 mm

Counter bore depth

35 mm

29 mm

4 mm

Thread length

38 mm

38 mm

26.5 mm

Bottom

7 mm

6 mm

1.5 mm

Cylinder head boss height - outboard

76.0 mm

76.0 mm

--

Cylinder head boss height - inboard

92.5 mm

92.5 mm

--

Bolt Part Number

12557775

12557775

(NNN) NNN-NNNN

Bolt Length (under washer)

157.2 mm

157.2 mm

125.8 mm

Thread length

45.3 mm

45.3 mm

23.3 mm

Important: Late in MY2002, cylinder head bolt holes in block were revised. Thread start height was raised by 7 mm, block bolt hole depth was reduced by 7 mm.

Model Year:

2004-2005

TimeSert kit:

 

JNNN-NN-NNNNHead

JNNN-NN-NNNNMain

Component Bolt Hole

Head

Main

Plate

301

306

Bushing

302

307

Alignment pin

303

308

Short bolt

2035

510

Long bolt

2036

--

Drill

2031

511

Inboard stop collar

2034

--

Tap

2032

512

Driver/installer

2033

513

Insert

108

514

Thread size

M11 x 2.0 x 30 mm

M10 x 1.5 x 22 mm

Outboard hole depth

89.5 mm

32 mm

Counter bore depth

45.5 mm

4 mm

Thread length

38 mm

26.5 mm

Bottom

6 mm

1.5 mm

Inboard hole depth

73 mm

32 mm

Counter bore depth

29 mm

4 mm

Thread length

38 mm

26.5 mm

Bottom

6 mm

1.5 mm

Cylinder head boss height - outboard

76.0 mm

--

Cylinder head boss height - inboard

92.5 mm

--

Bolt Part Number

11589058

(NNN) NNN-NNNN/p>

Bolt Length (under washer)

157.2 mm

125.8 mm

Thread length

64.8 mm

23.3 mm

 

1993-1999 Head Bolt Torque

First Pass 40N·m(30 lb ft)

Second Pass -- 70 Degrees

Third Pass -- 60 Degrees

Fourth Pass -- 60 Degrees (190 Degrees total)

 

2000-2003 Head Bolt Torque:

First Pass 40N·m(30 lb ft)

Second Pass -- 70 Degrees

Third Pass -- 60 Degrees

Fourth Pass -- 45 Degrees (175 Degrees total)

Customer: replied 3 years ago.
Cadillac supposedly changed the gasket material and bolts during sometime in the 2000's so that people did not need the fix outlined above. I have been looking at buying a 2001 or newer Cadi, and I know not all had the problems but I don't want to buy a car that is going to need it's engine replaced. So, is 2004 the answer??
Expert:  John replied 3 years ago.

Yes, it officially reads 2004 & newer , but I suggest you go to 2005 & newer.

I worked for Cadillac & the above repair was a normal daily thing , for what seemed like 24 hrs a day for years.

 

Models:1994-2002 Cadillac Eldorado
1994-2004 Cadillac Seville
1994-2005 Cadillac DeVille
1996-2000 Cadillac Concours
with 4.6L Northstar® Engine (VINs Y, 9 - RPOs LD8, L37)

John, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 9176
Experience: ASE CERTIFICATIONS A1-A8 & L1 / 40 YEARS AUTOMOTIVE EXPERIENCE
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