- The problem
- In the event of turbocharger compressor wheel failure, one or more of the four capscrews that hold the turbocharger together may be struck by parts of the compressor wheel, resulting in the capscrews being damaged. If these capscrews are damaged to the point that they allow the compressor back plate to dislocate from the turbocharger bearing housing, engine lubricating oil may be allowed to escape under pressure, contacting the engine exhaust manifold sections or turbocharger turbine housing.
- The fix
- Dealer will install a shield for the heads of the four capscrews, along with stronger sae 8 grade 8 capscrews, if necessary, at no cost to owner.
Vehicle safety record
1977 Mack U Problems, complaints & recalls
No owner complaints about the 1977 Mack U have been filed with NHTSA. It is covered by 8 recalls, the latest in May 1979 for the engine.
NHTSA data checked
FFar more problems than a typical U year, for its age
- Complaints
- 0
- Recalls
- 8
- Crashes
- 0
- Fires
- 0
- Injuries
- 0
- Deaths
- 0
1977 Mack U recalls 8
Recall repairs are free. Your dealer fixes them whether or not you bought the car there - check your VIN at nhtsa.gov/recalls to see if yours is done. What to do
- The problem
- An improper pinch bolt and nut may have been used in the clamping of the steering shaft to the steering gear input shaft. Due to clamping force loads applied at the bolt, the nut could yield, resulting in looseness of the input shaft yoke. Should this condition go unnoticed, spline wear could cause shaft separation.
- The fix
- Vehicles will be inspected and, if necessary, the correct fasteners will be installed at no charge to owner.
- The problem
- A casting deficiency exists in the lower section of the caps resulting in a reduction in the thickness of the material. Failure of a cap can allow the end of the rear spring to detach from the axle housing.
- The fix
- Dealer will inspect and, if necessary, replace any of the spring insulator caps found to be defective. This will be done at no cost to owner.
- The problem
- Delays of up to about 2 seconds may exist in the brake application times to the brakes on the bogie axles in the presence of certain types of wheel speed sensor signal discontinuities or distortions that may occur as a result of sensor wire failure. This constitutes a non-compliance to federal motor vehicle safety standard no. 121, "Air brake systems".
- The fix
- Dealer will install new wheel speed sensors that incorporate improved wiring and the present bogie anti-wheel lock system will be changed to an axle-to-axle system for improved reliability.
- The problem
- The tee bracket, which is mounted on the front axle of the bogie, may fail due to vibration brought on by road surface irregularities. Bracket failure would leave the tee bracket unsupported and cause broken hose connector fittings. This would result in automatic application of the spring emergency brakes.
- The fix
- The dealer will replace the defective bracket with a redesigned version.
- The problem
- A deficiency exists in the welds securing the rear spring insulator bracket to the axle housing. This is due to improper positioning of the weld, in relationship to the bracket and axle housing. Failure of the welds would cause separation of the spring insulator bracket and the axle housing, resulting in improper alignment of the affected axle.
- The fix
- Dealer will reweld the insulator spring bracket at no cost to owner.
- The problem
- The involved vehicles do not conform to federal motor vehicle safety standard no. 209, "Seatbelt assemblies". Although the seatbelts in question performed marginally with respect to the 5000 lb. Load requirement, additional testing confirmed that the anchor could fail, allowing either the anchor to slip over the hold-down nut or the anchor to separate into two pieces.
- The fix
- Dealer will inspect and, if necessary, replace seat belt assemblies without charge to owner.
- The problem
- The flex blade fans on the involved vehicles may develop cracks in the laminated stiffener as a result of fatigue during operation. If such a condition exists and the cracks go undetected, continued operation could cause pieces of the stiffener to break off.
- The fix
- Dealer will replace the original fan with a steel fixed blade fan, free of charge.
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No complaints about the 1977 Mack U yet
No owner has filed a complaint about this vehicle with NHTSA. If yours has a problem, share it here and report it to NHTSA.
Mack U: every year compared
All U yearsQuestions about the 1977 Mack U
Does the 1977 Mack U have any recalls?
Yes - NHTSA lists 8 recalls for the 1977 Mack U: engine (May 1979); steering wheel / handle bar (April 1979); multiple axle (January 1979); interconnecting assembly(wiring) (October 1978) and more. Recall repairs are free at any authorized dealer. Enter your VIN at nhtsa.gov/recalls to see whether yours has been fixed.
How many complaints has the 1977 Mack U had?
None have been filed with NHTSA so far.
Is the 1977 Mack U a reliable vehicle?
Its Safety Index is 11 out of 100 (grade F: far more problems than a typical Mack U year, for its age). The index weighs complaints, crashes, fires, injuries, deaths and recalls against how long the vehicle has been on the road, compared with the same model's other years. It is not a measure of every repair - read the complaints and owner experiences, and have any used vehicle inspected before you buy.
What should I do if my 1977 Mack U has a problem?
If it is a safety problem, stop driving it if it is unsafe and contact your dealer. Report it to NHTSA at nhtsa.gov/report-a-safety-problem - enough reports start investigations and recalls - and share your experience here so other owners know what to look for.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) complaints and recalls, checked . Complaints are owners' own reports and are not verified. How we use the data