TAT Express Inc

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TAT Express Inc TAT Express Inc. specializes in class 8 truck repairs and trailer repairs. Full service shop for trucks and trailers that offer DOT and FMCSA Inpections

🔧🔍 DD15 Cylinder Head Replacement Reveals Damage in Cylinder #5! 🔍🔧With the cylinder head replacement underway, our tec...
10/20/2026

🔧🔍 DD15 Cylinder Head Replacement Reveals Damage in Cylinder #5! 🔍🔧

With the cylinder head replacement underway, our technician took a closer look inside this DD15 engine. After removing the head, the technician inspected the cylinder liners and exposed internal components for evidence of mechanical damage—and found significant scoring and scuffing along the cylinder #5 liner wall. 🚛⚠️

💡 What do the cylinder liner and piston do?
The cylinder liner provides the working surface for the piston and piston rings. Together, these components help contain combustion pressure, control oil, and transfer heat as the piston moves through each stroke.

⚠️ What is cylinder liner scoring and scuffing?
Scoring refers to scratches or grooves in the liner surface. Scuffing involves surface damage caused by excessive friction and contact between moving components. Significant damage can compromise the surface the piston rings rely on to seal correctly.

🔍 A cylinder liner’s surface is designed to retain a thin film of oil while supporting piston ring sealing. Deep scratches and scuffed areas can disrupt that balance, potentially allowing combustion gases past the rings and oil into the combustion chamber.

💡 Why inspection matters:
Removing the cylinder head creates an opportunity to inspect areas that are normally hidden. Finding this damage now allows it to be addressed while the engine is already apart. Evaluating the cause is also important to help protect the replacement components.

✅ At TAT Express, we look beyond the original repair to inspect the condition of accessible engine components. A thorough inspection helps reveal additional damage and guides the work needed to get your truck back on the road.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

10/20/2026

🔧🛢️ Rear Main Seal Replacement in Progress! 🛢️🔧

A small seal with a big job! Our technician is replacing the rear main seal, which helps keep engine oil contained where the crankshaft exits the rear of the engine. Accessing this area requires significant disassembly, making careful inspection and installation essential. 🚛⚙️

💡 What does the rear main seal do?
The rear main seal seals around the rotating crankshaft at the back of the engine. It helps prevent engine oil from escaping into the flywheel housing area.

⚠️ What can cause a rear main seal to leak?
• Normal wear and aging
• Repeated heating and cooling cycles
• Excessive crankcase pressure
• Wear or damage on the crankshaft sealing surface
• Improper installation during a previous repair

👉 Common signs drivers may notice:
• Oil dripping near the engine and transmission connection
• Oil spots beneath the truck
• Oil buildup around the flywheel housing
• A gradual drop in engine oil level
• More frequent oil top-offs

🔍 Did you know?
Oil near the engine and transmission connection does not automatically mean the rear main seal is leaking. Oil from higher on the engine can travel downward and collect in the same area. Confirming the source before disassembly helps avoid an unnecessary repair.

💡 Why proper installation matters:
Replacing this seal involves more than removing the old one. The sealing surfaces must be inspected, and the replacement must be installed using the correct tools and procedures. Some seal designs require dry installation, so following the manufacturer’s instructions is especially important.

✅ At TAT Express, we focus on the details behind the repair—from checking the sealing surfaces to following the correct installation procedure. Thorough workmanship helps keep engine oil where it belongs and your truck ready for the road.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

10/20/2026

🔧🚛 Overhead Adjustment in Progress on This Volvo D13 Engine! 🚛🔧

Precision matters under the valve cover! Our technician is performing an overhead adjustment on this D13 engine, checking and setting clearances according to the engine’s specifications. These small measurements help the valvetrain operate as designed. 🔍⚙️

💡 What is an overhead adjustment?
An overhead adjustment involves checking and adjusting valve lash—the specified clearance between valvetrain components. On applicable D13 configurations, the procedure also includes checks and adjustments for the engine brake mechanism.

⚠️ Why do these clearances matter?
• Too much clearance can cause excessive valvetrain noise and impact loading.
• Too little clearance can prevent valves from fully seating as the engine heats up.
• Incorrect settings can affect engine operation and contribute to component wear.
• Proper engine brake adjustment helps support consistent braking performance.

👉 What does the technician do during this service?
• Positions the engine at the correct points in its rotation
• Measures clearances with precision tools
• Adjusts components to the specifications for that engine
• Secures adjustment hardware to the required torque
• Rechecks measurements to verify the settings

🔍 Valve lash is measured in fractions of a millimeter! A setting that looks almost identical to the eye can still be outside specification. Correct engine positioning and accurate measurements are essential throughout the procedure.

💡 Why maintenance matters:
Wear and normal operation can change valvetrain clearances over time. Checking them at the manufacturer’s recommended intervals helps identify adjustment needs and gives the technician an opportunity to inspect accessible components for abnormal wear.

✅ At TAT Express, attention to detail matters—from identifying the correct engine specifications to verifying each adjustment. Precision maintenance helps keep your truck performing mile after mile.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

10/20/2026

🛢️🔍 Active Cam Housing Oil Leak Found on a DD15 Engine! 🔍🛢️

During another oil leak inspection, our technician identified an active leak at the cam housing on this DD15 engine. Finding the source is an important step—oil can travel down the engine and collect on other components, making the leak appear to originate somewhere else. 🚛⚠️

💡 What does the cam housing do?
The cam housing supports the camshafts, which help control intake and exhaust valve operation. Its sealing surfaces help keep engine oil contained while internal components receive lubrication.

⚠️ What can cause oil leaks around the cam housing?
• Aging or deteriorated seals
• Compromised sealing surfaces
• Repeated heating and cooling cycles
• Improper sealant application during previous repairs
• Incorrect installation or tightening procedures
• Excessive crankcase pressure that contributes to oil leakage

👉 Common signs drivers may notice:
• Fresh oil around the upper engine
• Oil streaks running down the engine
• Dirt buildup sticking to oily surfaces
• Oil spots beneath the truck
• More frequent oil top-offs
• A burning oil smell if oil reaches hot surfaces

🔍 An oily engine does not always reveal the exact source of a leak. Residue from an older leak can remain after a repair, while fresh oil can spread with gravity and airflow. Cleaning the affected area and checking for fresh leakage helps distinguish an active leak from leftover residue.

💡 Why inspection matters:
An ongoing oil leak can lower the engine’s oil level over time and coat surrounding components. Identifying the source early helps guide the repair, prevent unnecessary parts replacement, and reduce the chance of the leak going unnoticed until oil loss becomes more significant.

✅ At TAT Express, we inspect beyond the visible oil buildup to help locate the source. Accurate diagnosis is the first step toward a proper repair and keeping your truck ready for the road.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

10/20/2026

🧪 **Bubbles Don't Always Mean a Blown Head Gasket!**

Seeing bubbles during a cooling-system test doesn't automatically confirm combustion gases are entering your engine coolant.

For the Cummins combustion-gas test discussed in this video, the test fluid starts blue. A change toward green or yellow is the indication we're looking for.

⚠️ Even with a positive result, the source still needs to be identified.

🎥 **WATCH THE FULL VIDEO:**
https://youtu.be/Bujp88z61XM

🔧 **Need help diagnosing coolant loss or excessive cooling-system pressure? Contact TAT Express.**

📍 TAT Express Inc.
4140 Langdon Rd, Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com
📍 Google Maps: https://maps.app.goo.gl/DogmNLGpfpYtoU9j7

⛽🔧 Lift Fuel Pump Resealed on This Cummins X15! 🔧⛽During fuel system repair on this Cummins X15, our technician resealed...
10/19/2026

⛽🔧 Lift Fuel Pump Resealed on This Cummins X15! 🔧⛽

During fuel system repair on this Cummins X15, our technician resealed the lift fuel pump to correct leakage and restore proper sealing around the pump assembly. Even a small fuel leak in this area should be addressed quickly because it can create mess, fuel loss, air-entry concerns, and possible drivability issues if the condition worsens. 🚛⚠️

💡 What does the lift fuel pump do?
The lift pump helps move fuel from the tank toward the engine’s high-pressure fuel system. It plays an important role in maintaining a steady fuel supply so the engine can start, idle, and operate properly under load.

⚠️ What can cause a lift pump to leak?
• Worn or hardened seals
• Damaged O-rings
• Heat and vibration
• High mileage
• Loose mounting or fittings
• Contaminated sealing surfaces
• Previous improper installation
• Normal seal deterioration over time

👉 Common signs drivers or technicians may notice:
• Diesel smell around the engine
• Wetness around the lift pump
• Fuel residue on nearby components
• Hard starting
• Extended cranking
• Air entering the fuel system
• Low fuel supply concerns

🔍 Did you know?
A leaking lift pump does not always mean the entire pump has failed. If the pump is functioning properly and the leak is coming from the sealing area, resealing it may correct the problem without unnecessary component replacement.

💡 Why proper resealing matters:
The mating surfaces must be clean, the correct seals must be installed properly, and the system should be inspected again after the repair. A poor sealing surface or incorrectly installed O-ring can cause the leak to return.

✅ At TAT Express, we identify exactly where a fuel leak is coming from before replacing major components. Accurate diagnosis and proper sealing help reduce unnecessary repairs and keep the fuel system operating reliably.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

🛞🔧 Front Shock Absorbers Replaced — Restoring Better Ride Control & Stability! 🔧🛞The front shock absorbers were replaced...
10/19/2026

🛞🔧 Front Shock Absorbers Replaced — Restoring Better Ride Control & Stability! 🔧🛞

The front shock absorbers were replaced after inspection showed they were no longer providing the proper damping needed to control suspension movement. On a heavy-duty truck, shocks play a major role in keeping the front end stable, improving tire contact with the road, and reducing excessive bouncing. 🚛⚠️

💡 What do front shock absorbers do?
Shock absorbers help control the movement of the suspension after the truck hits bumps, dips, or uneven road surfaces. Without proper damping, the front end can continue bouncing instead of settling quickly.

⚠️ What can cause front shocks to wear out?
• High mileage
• Rough road conditions
• Heavy loads
• Internal seal wear
• Fluid leakage
• Worn internal valving
• Constant vibration and heat
• Age-related deterioration

👉 Common signs of worn front shocks:
• Excessive bouncing after hitting bumps
• Front-end instability
• Increased body movement
• Uneven or cupped tire wear
• Poor ride quality
• Nose dive during braking
• Visible oil leakage from the shock
• Reduced steering confidence

🔍 A worn shock absorber does more than make the ride uncomfortable. If the tire is bouncing excessively, it can reduce consistent contact with the road, which may affect steering response, braking stability, and tire wear.

💡 Why replacement matters:
New shock absorbers help control suspension movement and keep the front tires more consistently planted on the road. That can improve ride quality, steering stability, braking control, and overall suspension performance.

✅ At TAT Express, we inspect shocks, bushings, mounts, leaf springs, steering components, and tires together because one worn suspension component can often affect several others.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

10/19/2026

🛞🔍 Loose Suspension Leaf Spring Components Found During Inspection! 🔍🛞

During suspension inspection, our technician found loose components in the leaf spring assembly. This is an important finding because the leaf spring system helps support the weight of the truck, control axle movement, and maintain stability while driving. 🚛⚠️

💡 What does the leaf spring suspension do?
Leaf springs help carry the vehicle’s load while allowing the suspension to move over bumps and uneven road surfaces. They also help keep the axle positioned correctly under the truck.

⚠️ What can cause leaf spring components to become loose?
• Worn bushings
• Loose or stretched hardware
• Worn spring pins or hangers
• High mileage
• Heavy loads
• Constant road vibration
• Corrosion or damaged mounting points
• Previous improper installation or repair

👉 Common signs drivers may notice:
• Clunking or knocking noises
• Excessive suspension movement
• Uneven ride height
• Steering or handling concerns
• Vehicle pulling or feeling unstable
• Uneven tire wear
• Movement around the spring or hanger area

🔍 Loose suspension hardware can sometimes look minor while the truck is sitting still, but under braking, turning, or carrying a heavy load, that movement can become much more noticeable and place extra stress on surrounding components.

💡 Why inspection matters:
A loose leaf spring component can affect axle alignment, ride quality, tire wear, and overall vehicle stability. Catching it early also helps prevent additional damage to bushings, brackets, hangers, and other suspension parts.

✅ At TAT Express, we inspect suspension components closely for looseness, wear, cracking, and abnormal movement. Proper suspension maintenance helps keep the truck stable, predictable, and safe on the road.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

10/19/2026

🛢️🔍 Checking for Oil Leaks Around the Cam Housing Area on This DD15! 🔍🛢️

During engine inspection on this Detroit DD15, our technician is carefully checking the cam housing area for signs of oil leakage. Because oil can travel across the top and sides of the engine, identifying the exact source is important before replacing seals, gaskets, or other components. 🚛⚠️

💡 Why is the cam housing area important?
This area surrounds critical valvetrain and camshaft components and relies on proper sealing to keep engine oil contained. When a seal or mating surface begins to leak, oil can spread onto nearby components and make the source harder to identify.

⚠️ What can cause oil leaks in this area?
• Worn or deteriorated seals
• Gasket or sealing surface failure
• Loose or improperly torqued fasteners
• Heat and vibration over time
• Previous improper installation
• Cracks or damaged mating surfaces
• Excessive crankcase pressure

👉 Common signs drivers or technicians may notice:
• Oil wetness around the upper engine
• Oil running down the side of the block
• Burning oil smell
• Oil collecting on nearby components
• Gradual engine oil loss
• Dirt and grime sticking to oily areas

🔍 Oil seen around the cam housing does not always mean the cam housing itself is the source. Oil can travel from a higher sealing point, which is why cleaning the area and watching for fresh oil is one of the best ways to pinpoint the leak.

💡 Why proper leak tracing matters:
Replacing the wrong gasket or seal wastes time and may leave the original leak untouched. A careful inspection helps determine exactly where the oil begins before any repair is performed.

✅ At TAT Express, we trace oil leaks back to the true source before replacing components. Accurate diagnosis helps prevent unnecessary repairs and gives the engine the best chance of staying clean, dry, and properly lubricated.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

10/19/2026

🌡️🔍 Intermittent Fan Clutch Concern — Checking Engagement by Hand! 🔍🌡️

During cooling system diagnostics, our technician performed a hands-on check of the cooling fan and fan clutch. As shown in the video, when the technician attempts to rotate the fan by hand, the fan resists movement, indicating that the clutch is engaged at the time of this inspection. 🚛⚙️

The important part? This truck has an intermittent fan clutch concern. The fan clutch works correctly at times, but then randomly stops responding as it should, which makes reproducing the failure an important part of the diagnostic process.

💡 What does the fan clutch do?
The fan clutch controls when the engine cooling fan engages. When additional cooling is needed, the clutch locks the fan in so it can pull more air through the radiator and charge-air cooler. When that extra airflow is not needed, the clutch can disengage to reduce unnecessary drag on the engine.

⚠️ What can cause intermittent fan clutch operation?
• Internal fan clutch wear
• Air supply or control concerns
• Solenoid or control valve problems
• Electrical connection or wiring issues
• Sensor or ECM command concerns
• Contamination or mechanical binding
• A failure that only appears once components heat up

👉 What symptoms can drivers notice?
• Engine temperature rising unexpectedly
• Fan not engaging when temperature increases
• Fan working normally one moment and not the next
• A/C performance changing at idle
• Fan-related fault codes
• Overheating under load or during low-speed operation

🔎 Finding the fan clutch engaged during one inspection does not automatically prove the clutch is good. Intermittent failures can pass a test when the problem is not occurring, which is why technicians often need to monitor the system under different temperatures and operating conditions.

💡 Why this hands-on check matters:
The resistance seen in the video confirms that the clutch can engage mechanically at that moment. From there, further testing can focus on determining why operation becomes inconsistent and whether the problem is in the clutch itself, its control system, air supply, or electrical command.

✅ At TAT Express, we don’t replace a fan clutch simply because the complaint is intermittent. We reproduce the concern, verify engagement, and check the complete control system to identify what is causing the fan to stop responding correctly.

📍 TAT Express – Dallas, TX
4140 Langdon Rd
Dallas, TX 75241
📞 972-225-3017
🌐 https://tatexpressinc.com/
✅Semi-Truck, Trailer & RV Repair Specialists
✅Built on Integrity. Striving for Excellence

Address

4140 Langdon Road
Dallas, TX
75241

Opening Hours

Monday 8am - 6pm
Tuesday 8am - 6pm
Wednesday 8am - 6pm
Thursday 8am - 6pm
Friday 8am - 6pm

Telephone

+19722253017

Website

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