Intake Manifold Bolts 2001-02 GM 8.1L VIN G Engine

[iRV4FUN]

A Jasper Tech Bulletin (11/2003) talks about the correction for high oil consumption due to oil vapor entering the intake manifold. To resolve this condition new service intake manifold bolts were developed. Jasper Tech Bull Part# 12561518 (QTY 10).

Is this a GM Part # or is it just for the Jasper rebuilds?

Did GM issue a Tech Bulletin for this issue?

Does anyone know the GM part number for new bolts?

Well, new to me

[mfire1339]

That is very interesting, My friend buys Jasper engines quite often. I'll ask if he knows more about this.

Mike

[iRV4FUN]

Looks like part#12561518 is a GM part#

I found these posts though I can’t say they're official.

Source: www.chevyavalanchefanclub.com/cafcna/index.php?topic=43119.1;wap2

The weird thing about the installation procedure is it advises; “Replace one bolt at a time in sequence to keep the intake manifold from shifting.” ================================================== ==
(Dealer service action):

High Oil Consumption (Replace Intake Manifold Bolts) #02-06-01-035 - (Oct 17, 2002)

2002 Chevrolet Avalanche

2001-2002 Chevrolet Silverado, Express, Suburban

2001-2002 GMC Sierra, Savana, Yukon XL

2001-2002 Chevrolet and GMC C6-7 Conventional Cab Medium Duty and B7 School Bus Models

With 8.1L Engine (VINs G, E -- RPO L18)
Condition

Some customers may comment about higher than expected oil consumption. Because this type of engine is used under various load conditions, the dealer should verify that the vehicle is using more than 0.946L (1 quart) of oil for every 379L (100 gallons) of fuel used.

Cause

Oil vapor pulled into combustion chamber through the intake manifold may cause this condition.

Correction

Replace all the intake manifold bolts. Replace one bolt at a time in sequence to keep the intake manifold from shifting.

Notice

Ensure the intake manifold does not shift as the intake manifold bolts are tightened in the proper sequence. Failure to follow the entire intake manifold bolt tightening sequence exactly may result in an oil leak and serious engine damage.

1. In the order shown below, remove each bolt and replace with a new bolt. Insert the new bolt and tighten to 5 N·m (44 lb in). Then move to the next bolt in sequence until all bolts have been replaced.
2. After all of the bolts have been replaced, tighten each bolt in sequence to 8 N·m (71 lb in).
3. Tighten all bolts in sequence to a final torque of 12 N·m (106 lb in).

Parts Information

Part Number Description Qty
12561518 Bolt, Intake Manifold 10
Parts are currently available from GMSPO.


(Warranty Information)

For vehicles repaired under warranty, use:

Labor Operation 0.7 hr
============================================

Another one (8.1/496):

Info - Higher Than Expected Oil Consumption (Greater Than 8500 GVW) #03-06-01-023 - (Aug 19, 2003)

2000-2004 Chevrolet Express, Silverado, Suburban

2002-2004 Chevrolet Avalanche

2000-2004 GMC Savana, Sierra, Yukon XL

2003-2004 Chevrolet Kodiak C4500-C5500 Series Models

2003-2004 GMC Topkick C4500-C5500 Series Models

2003-2004 HUMMER H2

with Gasoline Engines and Rated at 8600 GVW and above:

Information on Engine Oil Consumption Guidelines

All engines require oil to lubricate and protect the load bearing and internal moving parts from wear including cylinder walls, pistons and piston rings. When a piston moves down its cylinder, a thin film of oil is left on the cylinder wall. During the combustion process, part of this oil layer is consumed. As a result, varying rates of oil consumption are accepted as normal in all engines.

Oil Consumption

Oil usage has a direct relationship with the amount of fuel used. The harder an engine works, the more fuel and oil it will use. Therefore, oil usage as a factor of fuel usage is a more accurate indicator of acceptable oil consumption levels than vehicle mileage for vehicles at or above 8600 GVW.

The accepted rate of oil consumption for gasoline engines in vehicles at or above 8600 GVW is 0.946 liter (1 qt) within 379 liters (100 gallons) of fuel used. This rate only applies to vehicles under warranty, maintained in accordance with the appropriate maintenance schedule, driven at legal speeds and within design intent of the vehicle.

Many factors can affect an owner's concern with oil consumption. Driving habits and vehicle maintenance vary from owner to owner. Thoroughly evaluate each case before deciding whether the vehicle in question has abnormal engine oil consumption.

Gasket and External Leaks

Inspect the oil pans, engine covers, and the engine oil cooler for leakage. Inspect for oil leakage into the engine coolant.

Improper Reading of the Oil Level Indicator (Dipstick)

The vehicle must be parked on a level surface to obtain accurate oil level readings. Verify that the dipstick tube is fully seated in the block. When checking the oil level, make sure the dipstick is wiped clean before taking an oil level reading and fully depress the dipstick until the shoulder bottoms out on the dipstick tube. The dipstick should be the proper part number for the engine/vehicle that is being checked.

Not Waiting Long Enough After Running Engine to Check Oil Level

The vehicle should be allowed to sit for at least 15 minutes, after the engine has been shut off, before taking an oil level reading to assure the oil has had enough time to drain back into the crankcase. In order to ensure accurate results, the temperature of the oil should be close to the same temperature as the last time the oil level was checked.

Improper Oil Fill After an Oil Change

Following an oil change, verify that the proper amount and type of oil was put in the engine and that the oil level on the dipstick is not above the full mark or below the add marks. Refer to the Owner's Manual or Service Manual for information on recommended oil quantity, viscosity, and quality.

High Speed or High RPM Driving

Continuous driving at high speeds/high RPMs may increase oil consumption. Because this may not always be an everyday occurrence, it is hard to determine exactly how much the oil economy will be affected.

Towing or Heavy Usage

Towing a trailer or hauling additional weight will increase oil consumption. Large frontal area trailers will further increase the work required from the engine, especially at highway speeds, and thus increases the rate of oil consumption.

PTO Operation

Operation of a PTO will increase fuel and oil usage, as the PTO driven accessory uses engine power to operate.

Crankcase Ventilation System

Verify that the positive crankcase ventilation (PCV) system is operating properly. Blockages, restrictions or damage to the PCV system can result in increased oil use.

Oil Dilution from Condensation

On vehicles that are usually driven short distances, less than 8 km (5 mi), especially in colder weather, condensation generated from cold engine operation may not get hot enough to evaporate out of the oil. When this occurs, the dipstick may indicate that the oil level is over-full. Subsequent driving on a trip of sufficient length to enable normal engine operating temperature for 30 minutes or more, in order to vaporize excess moisture, may give the customer the impression of excessive oil consumption.

Engine Temperature

If an engine is run at overheated temperatures (see Owner's Manual or Service Manual) for more than brief periods, oil will oxidize at a faster than normal rate. In addition, gaskets may distort, piston rings may stick, and excessive wear may result. Verify that all cooling system components are in proper working order.

Engine Wear

Piston scuffing, excessive piston-to-wall clearance, tapered or out of round cylinders, worn, damaged or improperly installed valve guides, seals and piston rings will all cause an increase in oil consumption.

Measurement of Oil Consumption

Engines require a period of time to BREAK IN so that moving parts are properly seated. Therefore, oil economy should not be tested until the vehicle has accumulated at least 8000 km (5000 mi) and the oil has been changed for the first time. During initial engine break-in periods before the first oil change, oil consumption may exceed 1.9 liters (2 quarts) or more per 379 liters (100 gallons) of fuel used.

1. Verify that the engine has no external leaks. Repair as necessary.
2. Begin oil consumption test after next regularly scheduled oil and filter change. Oil changes should not be performed during the test.
3. Verify that the engine is at normal operating temperature (see Owner's Manual or Service Manual).
4. Park the vehicle on a level surface.
5. Wait at least 15 minutes, after the engine is shut off, before checking the oil level to make sure that most of the oil has had time to drain back into the crankcase.
6. Verify that the oil level is at, but not above, the full mark on the dipstick and that the proper viscosity and quality oil are being used as recommended in the Owner's Manual.
7. Dealer should record the vehicle mileage, date and engine hours at the start of the test on the form included in this bulletin.
8. Ask the customer to verify and record the date, odometer, oil level, fuel added, and engine hours, each time the vehicle is fueled, following steps 3-5 and return the vehicle to the dealership if the oil level is found at or below the add mark, 0.946 liter (1 qt) low, if possible. The dealer will add oil to return the oil level to full. If the oil level remains above the add mark, the customer should continue to operate the vehicle and verify the engine oil level until either the oil level drops to or below the add mark or at least 4800 km (3000 mi) has accumulated since the test began before returning to the dealership for a final evaluation.
9. If the final evaluation shows that the engine uses more than 0.946 liter (1 qt) in 379 liters (100 gallons) of fuel used, follow the published symptom diagnostics as described in the appropriate Service Manual. If the oil consumption test shows that the engine uses less than 0.946 liter (1 qt) in 379 liters (100 gallons) of fuel used, explain to the customer that their engine meets the guidelines for oil consumption.

---
================================================== ====

Many 8.1L owners claim the bolt change didn't fix their oil consumption problem. …and then in January 2005 GM came out with a new intake manifold gasket – hum?

So why not change the gasket & the bolts at the same time?

[DriVer]

Originally Posted by iRV4FUN

So why not change the gasket & the bolts at the same time?

That's what I'm talking about ...

[Full-Timers]

But still it says 1 qt oil to every 100 gal of fuel. That is still excessive in my book.

[iRV4FUN]

Originally Posted by Full-Timers

But still it says 1 qt oil to every 100 gal of fuel.

What "still says 1 qt every 100 gal of fuel"?

• Your MH with a new gasket & bolts?
• The WHCC bulliten that says 1gt per 100 gal.

I'm sorry I'm confused, but, what "still says 1 gt..."?

IMHO if a person throws a new set of bolts on an old gasket they might make their problem worse. The intake manifold gaskets are not reusable. What was GM thinking when they came out with the swap bolts only bulletin.

Has anybody had any luck with a new intake manifold gasket (post Jan 2005) & bolts.

[DriVer]

Originally Posted by iRV4FUN

Has anybody had any luck with a new intake manifold gasket (post Jan 2005) & bolts

iRV4FUN, 2 other critical components are the front an rear rubber seals that seal the manifold to the engine block. If I'm reading the text correctly - it's these pieces that need to be installed absolutely perfectly using the torquing strategy. The instructions advise to look over the seals at every opportunity and between torque increases. There are 4 torque rotation tables I believe.

[pkmesser]

As some of you may be aware, I am heading toward retorqueing the bolts on mine, I saw the bulletin, and saw that removing the bolts, one at a time, was a way to clean the bolts and boltholes w/o totally loosening the manifold. Perhaps this was the thinking in the bulletin also. ??

[dieselclacker]

Originally Posted by pkmesser

As some of you may be aware, I am heading toward retorqueing the bolts on mine, I saw the bulletin, and saw that removing the bolts, one at a time, was a way to clean the bolts and boltholes w/o totally loosening the manifold. Perhaps this was the thinking in the bulletin also. ??

What are you hoping to accomplish by cleaning and re-torqueing or replacing the intake manifold bolts? Are you having an oil consumption problem? As I read the bulletin, this is the purpose of the retorque/bolt replacement.

Dieselclacker

[Full-Timers]

Originally Posted by iRV4FUN

What "still says 1 qt every 100 gal of fuel"?

• Your MH with a new gasket & bolts?
• The WHCC bulliten that says 1gt per 100 gal.

I'm sorry I'm confused, but, what "still says 1 gt..."?

The last part of the bulletin you referred to says:
9. If the final evaluation shows that the engine uses more than 0.946 liter (1 qt) in 379 liters (100 gallons) of fuel used, follow the published symptom diagnostics as described in the appropriate Service Manual. If the oil consumption test shows that the engine uses less than 0.946 liter (1 qt) in 379 liters (100 gallons) of fuel used, explain to the customer that their engine meets the guidelines for oil consumption.

At 7 mpg that’s 1 qt every 700 miles (Less than 2 tanks of fuel). Or about 4 qts between oil changes. At that rate there is no need to ever change your oil.

I say BS! 1 qt in 100 gallons does not meet my guidlines for oil consumption. Mine uses 1/2 qt in about 430 gallons (3000 miles).

[DriVer]

Originally Posted by Full-Timers

I say BS! 1 qt in 100 gallons does not meet my guidlines for oil consumption. Mine uses 1/2 qt in about 430 gallons (3000 miles).

FT, I would say that it does not meet with anyone's guideline other than GM. You oil consumption appears to be better than mine. I will burn a qt in about 1,200 miles. (from home to FL and back) I'm not going to loose any sleep over this - I'm just going to put in the oil.

[pkmesser]

Originally Posted by dieselclacker

What are you hoping to accomplish by cleaning and re-torqueing or replacing the intake manifold bolts? Are you having an oil consumption problem? As I read the bulletin, this is the purpose of the retorque/bolt replacement.

Dieselclacker

I am checking torque. If I get any bolt movement, with applied torque, I will take the bolts down to rated torque. I will then remove them, one at a time, clean, apply threadlock, and reinstall.

There have been engine failures due to supposed air leakage at the intake manifold. If the original torque was not correct, or if there has been bolt stretch due to thermal cycling, my steps may prevent the same thing happening to my engine. (I don't consider my oil consumption to be excessive, and I am not installing new bolts.) No one has explained why the air leakage developed on those engines, this is my "take" on why it may have occurred.

It's taking a little longer to get this done than I had planned, due to getting a torque wrench with a proper range. Autozone is supposed to have one in today.

[DriVer]

Originally Posted by pkmesser

I am checking torque. If I get any bolt movement, with applied torque, I will take the bolts down to rated torque. I will then remove them, one at a time, clean, apply threadlock, and reinstall. There have been engine failures due to supposed air leakage at the intake manifold. If the original torque was not correct, or if there has been bolt stretch due to thermal cycling, my steps may prevent the same thing happening to my engine..

pkmesser, If this is indeed the case and you are going through the effort of doing it the right way, you need to discard the old fasteners and buy new ones. The reason for this is that if there have been any thermal dynamics applied to the bolt where it may have changed the OE dimension, those bolts need to be replaced.

In for the penny in for the pound.

[Full-Timers]

Originally Posted by DriVer

pkmesser, If this is indeed the case and you are going through the effort of doing it the right way, you need to discard the old fasteners and buy new ones. The reason for this is that if there have been any thermal dynamics applied to the bolt where it may have changed the OE dimension, those bolts need to be replaced.

In for the penny in for the pound.

I got to agree with you 100% on this one DriVer.
Best bet is to leave well enough alone unless you are replacing them.