Dorman 6LDT Engine Overhaul

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Background

This work scope involved the full overhaul and dyno test of a client’s Dorman 6LDT Short Block Engine.

To illustrate the thorough service Bartech provide, we’d like to give you an insight as to what our standard reporting protocol for works carried out looks like, please see the following excerpts from engineers reports. Do note that there have been five separate reports sent to the customer and this is a breakdown of all five.

Following the receipt of the base engine, below is an update on progress so far:

The electrics have been disconnected from the engine and from the alternator.

The turbos and air filters were removed in order for the engine to be removed from the skid and the container. (figure 1 & 2).

Dorman 6LDT Engine

The engine was then lifted into the workshop for inspection (figure 3).

The engine spill timing was checked and engine components were marked for aiding reassembly after overhaul. The spill timing was within specification.

The following items have been removed from the engine for inspection and overhaul as required: (figure 4):

  • Water manifold
  • Air Manifold
  • Exhaust manifold
  • Water pump
  • Alternator and tensioner
  • Oil filter and cooler
  • Starter motor
  • Small bore pipework

Dorman 6LDT engine on inspection

The plan is to continue with the dismantling of the engine, carry out an inspection, clean and rebuild the engine.

During the overhaul and rebuild the following will be replaced with all new parts:

  • Piston rings
  • Gaskets
  • Small end bushes
  • Engine bearing set

The engine has been completely dismantled down to a bare crankcase.

Solution

The following components have been measured and inspected;

  • Crankcase
  • Pistons
  • Conn Rods
  • Liners (3 were found to be oval and have been rejected)
  • Camshaft
  • Crankshaft (measured and crack tested)

The crankcase has been cleaned in preparation for rebuild.

Dorman 6LDT engine crankcase work

All engine components following dismantle were sent for chemical cleaning. Upon return, some items required bead blasting before a visual inspection could be conducted to review any potential areas of concern of damage. None was evident.

In addition the following has been conducted:-

  • Inlet and exhaust valves have been cleaned and polished.
  • Exhaust pipes have been bead blasted and painted (figure 1).
  • Cleaning and painting of quantity three cylinder liners to increase anti corrosion properties (figure 2).
  • Bead blasted and painted cam follower carriers (figure 3).
  • Stripped and inspected turbo
  • Crack detected connecting rods and timing gears (figure 4).

Some heavily corroded bolts and studs sheared when removing engine components. These required machining and re-tapping (Figure 5). These included:-

  • Cylinder heads
  • Exhaust manifolds
  • Turbo housing

Dorman 6LDT work

Quantity two e bores are partially corroded and will require re-machining or suitable repair under taken.

Plan for next week:-

  • Bore repair
  • Fit liners
  • Pressure test crankshaft
  • Check end float to confirm within manufacturers tolerances
  • Fit pistons

We have repaired the damaged e bore highlighted last week using Belzona (figures 1-5). It was not necessary to repair the second e bore.

Repairing the damaged e bore highlighted last week using Belzona
e bore after honing

We have drilled out broken and damaged studs and repaired the threads on the Turbocharger (figure 6)

Drilled out the corroded and seized bolts on the exhaust elbow (figure 7)

repairing studs

Drilled out broken and damaged studs and repaired the threads on the exhaust manifold (figures 8 & 9)

repairs to exhaust manifolds

Cylinder head valves and valve seats have been cut, cleaned, lapped (figure 10) and vacuum tested (figure 11) to insure correct sealing.

valves being lapped and measured

The liners required cleaning and painting and are now ready for fitting.

The crankcase has been re-cleaned following the e bore repairs.

Pistons have been fitted to connecting rods.

The liners have been fitted and the crankcase pressure tested to 60psi for 1 hour. No leaks have been identified.

The crankshaft has been fitted.

It was not possible to check the end float of the crankshaft to confirm within manufacturers tolerances as the tab washers were damaged and require replacing. These are expected to arrive today so this activity can be completed.

We have re-fitted x2 injector tubes and core plugs on both cylinder heads and we have pressure tested to 60 psi for one hour and there were no issues of note.

The oil cooler has been disassembled, cleaned and is being rebuilt. New seals will be fitted. One of the valves will require lapping before assembly to guarantee a complete seal.

liners and plugs fitted
cylinder heads tested and oil cooler cleaned

Plan for next week:-

  • Check the end float of crankshaft to confirm within manufacturers tolerances
  • Fit camshaft
  • Fit piston and connecting rod assemblies
  • Overhaul oil cooler
  • Fit timing gears
  • Fit cylinder heads
  • Fit rocker gear

The damper and water pump will be replaced.

Outcome

Additional work carried out:

  • The speed switch was cleaned, tested and repaired as required.
  • The alternator tested.
  • The starter motor was cleaned and painted.
  • The gauge panel required cleaning and was be assembled with replacement gauges.
  • Overhaul completed and engine re-installed.

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