Burned Exhaust Valves, Low Power & Hard Starting On
Cummins NH & NT Engines With Jacobs Brake 25B & 30

Cummins Engine Co. reported that if the following complaints are experienced in the NH and NT engines equipped with Jacobs brakes, the slave piston clearance should be checked:

A. Exhaust valve burning

B. Low engine power when at operating temperature 

C. Engine hard to start or will not start at operating temperature

A standard slave piston adjustment of .018 +/- .001 has been established.  The .018 clearance setting is a cold setting which results in zero slave piston to crosshead clearance when the engine is at operating temperature.

Should the slave piston clearance setting be less than .018, the following conditions outlined in A, B or C above may result as well as affect breaking power.

If the slave piston clearance is greater than .018 +/- .001, the following problems may occur:

1. Engine injector train component problems
2. Injector carboning
3. Bent injector push rods
4. Worn injector adjusting screws
5. Decreased camshaft life
6. Cam follower and follower shaft failure
7. Delay in breaking action

If the above problems are experienced and the engine is equipped with a Jacobs brake, the slave piston clearance should be checked with the latest Cummins specifications.

                                                                     The AERA Technical Committee

                                      Revised Injector Sleeves For
                                           Cummins Diesel Engines
           
The Cummins Engine Company has introduced a new injector sleeve design to be used when servicing N14, NT, 88NT, 86NT, L10, V28 and V903 engines.

The revised injector sleeve, which offers increased resistance to cracking, is available in both standard and oversize and should be used whenever injector sleeves are being replaced.  1990 model year NT engines used the revised sleeve in production as well.   All revised service parts will carry at least one blue Dykem stripe for easy identification.  Review the illustrations below
for placement of the identifying stripe.

                                                                      The AERA Technical Committee

                                        Cylinder Block Specifications On
                                  Cummins KT/KTA 1150 Series Engines

The Cummins Engine Company has released the following cylinder block specifications for the KT/KTA 1150 series engines. Refer to the dimensions listed below while rebuilding. 

Description Specification Illustration Mark

Cylinder block weight	925 lbs. 420 kg

Total height when tilted 23.400 A 595.00mm

Total width when tilted 18.500 B 470.00mm

Cyl. head deck surface width 13.800 E 350.00mm

Cyl. head deck surface length 47.400 F 1203.00mm

Cyl. block deck height from 16.071-16.084 H outside diameter of main bearing 408.20-408.53mm bore to deck surface

Cyl. block deck height from 18.994-19.006 J centerline of main bearing	482.45-482.75mm housing bore to deck surface

Surfacing the cylinder block may require the use of a thicker cylinder head gasket.  If less than .010 is removed use the standard head gasket, Cummins Part #3022340.  If between .010 and .020 is removed, use gasket Part #3021463.  If between .020 and .030 is removed, observe the minimum deck height of 16.051and use gasket Part #3021463. 

The block deck height parallelism from end to end should not vary more than .002 per 20 of block length. The side to side flatness should not vary by more than .001 in any 10 span. The surface finish for this block deck should be 125 micro inch or 3.18 micro meter.
                                                                      The AERA Technical Committee

                                    Thermatic Oil Control Valve Caution On
                               1986-98 DDC 11.1 & 12.7L Series 60 Engines

The AERA Technical Committee offers the following information regarding a caution on the thermatic oil control valve used on 1986-98 DDC 11.1 & 12.7L Series 60 engines. Any thermatic oil control valve-equipped engine that has been overheated must have the control valve tested before placing the engine back in service. Failure to do so may allow subsequent overheating conditions.

Detroit Diesel Corporation has revised its test procedures for the thermatic oil control valve. Thermatic oil coolers became standard equipment on all 11.1L engine in 1996 and on 12.7L premium engines in 1998. Non-premium engines use cast iron pistons. Premium engines use a steel piston. The oil cooler requires a properly functioning thermatic oil control valve to operate the system effectively and prevent engine overheating.

The thermatic oil control valve operating temperature range is 220-237° F  (104-114° C) and this valve must be tested whenever engine overheating occurs. To test the valve requires heating engine oil and observing the opening and closing values of the valve using a sensitive thermometer. Previously, a mixture of antifreeze and water was recommended to use and that procedure should no longer be used.

Caution: The flashpoint of oil is approximately 430° F  (221° C), to not allow the oil used for testing to exceed 300° F  (149° C). Make sure the valve is completely dry as any moisture may cause a violent reaction with the heated oil.

The AERA Technical Committee

                       Cylinder Block Water Leakage & Counterbore Repair On
                                              All Cummins Series Engines

This bulletin provides Cummins Engine Company's guidelines for:

A.  Applying Cummins Sealant, Part No. 3801048 or equivalent
B.  Detecting cylinder block water leaks
C.  Repairing the cylinder block counterbore

A.  APPLYING CUMMINS SEALANT

Cummins Sealant No. 3801048 or equivalent is effective in preventing coolant from leaking through the joint seal between the cylinder liner and cylinder liner counterbore.  It has a pastelike consistency when initially dispensed and hardens with exposure to air at room temperature.  It is oil resistant and has a temperature resistance from -75 to 400?F continuous operation and up to 500?F for short periods.

1.  Clean the mating surface of the cylinder block and the liner using a suitable hydrocarbon solvent such as naptha, methyl ethyl ketone (MEK) or trichlorethane 1,1,1 (methyl chloroform).

CAUTION:  Naptha and methyl ethyl ketone (MEK) are flammable materials and must be used with care.  Do NOT use starting fluid as a cleaning agent.

The cylinder block and liner must be free of oil as sealant will not bond to an oily surface.

2.  Apply a small bead of sealant 3/64 to 1/16 to the liner flange or cylinder block counterbore before installing the liner (Fig. 1).  On engines using counterbore spacer rings, the sealant should be applied to both upper and lower ring surfaces.

	NOTE:  Excessive amounts of sealant should not be used as this could cause problems in the cooling system, such as plugging the corrosion resistors or cooler cores.

3.  The sealant will start curing about 10 minutes after application.  For best results, the cylinder liner should be installed as soon as possible after applying the sealant and no longer than one half hour after application to the counterbore.

4.  When the liner is installed in the block, the sealant will spread and fill voids between the counterbore and liner, creating a watertight seal.  Sealant will not affect the liner protrusion.

5.  When using sealant with liner shims, apply it as described above and place the shims on the liner before installation.  a small bead of sealant applied to the liner flange will hold the shims in position during installation of the liner.

6.  Excess sealant can be removed from the cylinder block surface by using a hydrocarbon solvent.

B.  DETECTING CYLINDER BLOCK WATER LEAKS

Sometimes cylinder liner counterbore leaks are mistaken for cylinder head gasket leaks.  The following procedure is recommended to determine the cause of the leak:

1.  Remove the cylinder heads.

2.  Clean the cylinder block deck surface.

3.  Plug all water passages.

4.  Secure the cylinder liners in the block by using liner clamps.  Space the clamps so that an even load will be applied to the liner.  Refer to the applicable engine shop manual for liner clamp part numbers and torque values.

5.  Fill the cylinder block water system and apply 5 to 10 psi pressure to the block system for 3 to 5 minutes.

6.  Check for leakage between the cylinder liner flange and the block.

7.  If no leakage is observed and the liner protrusion is within specifications, assemble the engine using the appropriate head gaskets.  Refer to the engine shop manual for correct liner protrusion specifications.

8.  If leakage is observed then:
	
a.  Measure and record the liner protrusion on all liners.

b.  Remove the plugs from the water passages and the liner clamps.

c.  Remove the cylinder liners.

d.  Check the liner upper counterbore and remove all burrs, dirt and foreign material.

9.  If the liner protrusion is not within specifications, the counterbore should be resurfaced and the proper thickness liner shims installed to retain proper liner protrusion.  Apply Cummins Sealant No. 3801048 or equivalent and assemble engine.

10.  If the liner protrusion is correct and there are no visible major cracks, measurable erosion etc., apply sealant as above and assemble the engine.

DETERMINING WHEN BLOCK REQUIRES SALVAGE

The following information should be used to determine whether or not a block requires repair or salvage.  Blocks with counterbore cracks can be used without repair or salvage operations when:

1.  Circumferential cracks do not extend to a cylinder head capscrew hole or a water jacket hole.  See Fig. 2.
2.  Circumferential cracks do not extend beyond one half the width of the counterbore ledge from the radius. (Fig. 2).

3.  The counterbore runout and depth are within specification limits to obtain proper liner protrusion by installing liner shims or oversize spacer rings where applicable. 

C.  CYLINDER LINER COUNTERBORE SALVAGE

The cylinder liner counterbore requires salvage when:

1.  The counterbore runout or depth is not within specifications.  Begin by removing material from the upper counterbore ledge per standard procedure as outlined in the applicable engine shop manual.  For K/KTA engine series refer to Service/Parts Topic 80T 22-6.  Remove material from the counterbore ledge using the proper tool until the runout or worn condition has been removed.  The cutting depth should not exceed the worn limit counterbore depth listed in the applicable engine shop manual.

Install the proper thickness liner shims to obtain liner protrusion.  On some KT/KTA-1150 configurations and on all KT/KTA-2300 and KTA-3067 engines it is possible to vary liner protrusion by the use of oversize counterbore rings.  Any combination of oversize rings and shims can be used to obtain correct protrusion.  Shims must be installed between liner and counterbore ring.  Apply Cummins Sealant No. 3801048 or equivalent and assemble engine.

2.  The cylinder liner counterbore must be enlarged and either a counterbore salvage sleeve or oversize liner (on models with oversize liners) installed when:

a.  The cracks extend more than one half the width of the counterbore ledge surface from the radius to the sealing edge (Fig. 3).

b.  Radial cracks are present in the counterbore and/or extend to one or more capscrew holes.

NOTE:  Cracks extending into a capscrew hole can be repaired using the capscrew thread salvage tool kit, Part No. 3375195 or equivalent.

3.  The cylinder block should be replaced when:

a.  Radial cracks in the counterbore extend to the water jacket.

b.  Radial cracks extend to lubricating oil or water passages.

c.  Any counterbore cracks in Section C that extend beyond the maximum cutting depth for sleeving.

                                                                            The AERA Technical Committee

                Cylinder Block Specifications On
                  Cummins V-555 Series Engines


The Cummins Engine company has released the following cylinder
block specifications for the V-555 series engines.


                                               Illustration
Description                 Specification          Mark

Cylinder block weight          403 lbs
                               183 kg

Total height when tilted       18.300               A
                              465.00mm

Total width when tilted        18.300               B
                              465.00mm

Nominal cyl. block width       6.650                C
from main bearing bore center 169.00mm
to pan rail

Nominal cyl. block deck height 11.650               D
from main bearing bore center 296.00mm

Cyl. head deck surface width   9.200                E
                              234.00mm

Cyl. head deck surface length  26.300               F
                              668.00mm

Degree of V                90o +/- 15'             G

Cyl. block deck height from 9.766-9.777             H
outside diameter of main bearing248.06-248.34mm
bore to deck surface

Cyl. block deck height from11.642-11.653            J
centerline of main bearing 295.71-295.99mm
housing bore to deck surface

Surfacing the cylinder block may require the use of a thicker
cylinder head gasket.  If less than .005 is removed use the
standard head gasket Cummins Part #3017062.  If between .006 and
.0015 is removed use gasket #AR62074.  If between .016 and
.020 is removed use gasket #AR62075.  When surfacing the
cylinder block, do not exceed a deck height variance of .0004
(.01mm) from one bank to the other.



                                     The AERA Technical Committee


April 1991 - TB 764

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