9/1/2002
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What’s the cause of valve seat failures with 1997-2001 Ford 2.0L VIN P Engines?
Q. What’s the cause of valve seat failures with 1997-2001 Ford 2.0L VIN P Engines?
A. According to AERA’s Technical Committee, valve seat breakage on 1997-2001 Ford 2.0L VIN P engines occurs originally at the number one cylinder intake seat. This bulletin updates information previously published as AERA Technical Bulletin 1939.
Repeat engine failure has been reported shortly after starting repaired engines that had previously failed due to valve seat breakage in this area. Subsequent engine failures have been caused by debris that was left in either the intake or exhaust manifold. The debris included particles of valve seats, pistons and rings from the original failure.
Whenever a cylinder head is serviced it is common procedure for the technician to just move the intake and exhaust manifolds back to provide just enough room to get the cylinder head off of the engine. This procedure does not allow thorough cleaning of either manifold. When a valve seat comes out of its counter-bore and shatters into many pieces, normal air turbulence may cause pieces from the valve seat to enter either the intake or exhaust manifolds. The cylinder head for this engine originally used powder metal valve seats with an approximate depth of .286˝ (7.264 mm) that, when shattered, results in many pieces/debris.
For the reasons outlined above, it is necessary to remove both manifolds from the engine compartment and clean them. Failure to clean out the intake and exhaust manifolds may cause a repeat engine failure.
One aftermarket valve seat manufacturer has changed seat materials, processes and designs in order to improve seat retention in the cylinder head and implemented an additional tempering process to eliminate the brittleness commonly found in PM valve seats. These seats also have additional seat depth and a reduced leading edge chamfer, features that provide increased seat-to-cylinder head contact area for better heat transfer. Inadequate heat transfer is thought to be a factor in OEM seat failures.
Once new seat inserts have been installed, they should be mach-ined as shown in Figures 1-2, left, at 45° with a .069˝-.091˝ (1.75-2.32 mm) width and a maximum seat run-out of .0025˝ (.064 mm).
Q. Are there new recommendations for installing cylinder heads on GM engines?
A. The AERA Technical Committee offers the following information on cylinder head installation for 1999-2002 GM 4.8L, 5.3L and 6.0L VIN V, T, Z, S, U and N engines. See Figure 3, below. This procedure should be used any time the cylinder head is installed and supercedes information found in earlier-published service manuals.
Previously published information suggested that it was acceptable to reuse the 8 mm cylinder head bolts. It is now recommended that all cylinder head bolts be replaced at the time of cylinder head installation.
1. Tighten new 11 mm bolts (1-10) in sequence to 22 ft. lbs. (30 Nm).
2. Rotate those bolts (1-10) in sequence an additional 90° turn using a torque angle meter.
3. Rotate bolts 1-8 in sequence an additional 90° using torque angle meter.
4. Rotate remaining 11 mm bolts 9 & 10 in sequence an additional 50° turn using a torque angle meter.
Finally, apply a .200˝ (5mm) bead of locking compound (GM p/n 12345382 or equivalent) to the new 8 mm bolt threads, and tighten bolts (11-15) in sequence to 22 ft.lbs (30 Nm). New 11 mm bolts come with a pre-applied sealer and lubricant and no other sealant should be used on them.
Note: Reuse of either the 8 mm or 11 mm head bolts is unacceptable. AERA is not aware of an aftermarket supplier of these bolts.
Q. Do you know of missing specifications for Chrysler VIN R housing bores?
A. The specifications shown in Figure 4 (above) for connecting rod and main bearing housing bores for 1998-2002 Chrysler 2.7L VIN R engines have been omitted from service manuals until recently. Knowing these specifications is essential to successfully rebuilding this engine.
Until recently, Chrysler was the only source of .010˝ (.25 mm) undersize rod and main bearings for this engine (rod bearings – p/n 04796548AC and main bearings – p/n 04796545AB).
Aftermarket bearing suppliers have responded to demand for additional sizes of bearings, and one manufacturer is now supplying rod and main bearings in both the .010˝ (.25 mm) and .020˝ (.50 mm) undersizes.
Q. What’s the latest on torque procedures for the Cum-mins/Chrysler diesel engines?
A. According to Cummins Service Engineers, the torque-plus-turn method of tightening capscrews results in a more uniform clampload on the Cummins/Chrysler 3.9 & 5.9L B and ISB diesel engines. The AERA Technical Committee offers the following information about revised main and rod bolt torque procedure for these engines, and the information in this bulletin should be applied to all B Series Cummins/Chrysler diesel engines.
Connecting Rod Bolts
1. Lubricate the bolt threads and underside of the connecting rod capscrew head with clean 15W-40 oil and lubricate.
2. Alternately tighten capscrews to 22 ft.lbs (30 Nm).
3. Alternately tighten capscrews to 44 ft.lbs (60 Nm).
4. Alternately turn capscrews an additional 60° turn.
5. Verify that the side clearance between the connecting rod and crankshaft is .004˝-.013˝ (.10-.33 mm). Do NOT measure the clearance between the connecting rod cap and crankshaft, as an erroneous reading may result.
Main Bearing Bolts
1. Make sure all bearing caps are positioned correctly with the numbered side toward the oil cooler side of the engine.
2. Lubricate the bolt threads and underside of the main bearing capscrew head with clean 15W-40 oil.
3. In sequence shown in Figure 5 tighten capscrews to 37 ft.lbs (50 Nm).
4. In sequence shown in Figure 5 tighten capscrews to 45 ft.lbs (60 Nm).
5. In sequence shown in Figure 5 tighten capscrews to 66 ft.lbs (90 Nm).
6. In sequence shown in Figure 5 rotate capscrews an additional 90° turn.
7. Verify that the crankshaft end play between the thrust surface at #6 main and crankshaft is .004˝-.017˝ (.102-.432 mm).