2007½–2010 CHEVY SILVERADO / GMC SIERRA HD · 6.6L DURAMAX LMM
LMM Duramax repair in Tucson: weak points & fixes.
The LMM was the first Duramax with a DPF, but it kept the tough CP3 fuel pump. Most of its problems come from emissions parts and soot, not the engine itself. Here’s what we see on these trucks and how we fix it at your location.
- 365 hp660 lb-ft stock
- DPF + EGRBosch CP3 pump
- Allison 10006-speed automatic
- We come to youTucson & nearby
Jump to a system
KNOW YOUR TRUCK
Is it an LMM? It changes the parts.
In 2007 GM sold both the old “Classic” body with the LBZ and the new body with the LMM. The 8th digit of your VIN tells us which one you have.
LBZ (VIN 8th digit “D”)
- 360 hp / 650 lb-ft
- No DPF
- Older body style
- See the LLY & LBZ guide →
LMM (VIN 8th digit “6”)
- 365 hp / 660 lb-ft
- First Duramax with a DPF
- Larger EGR cooler
- Allison 1000 6-speed
- New body style (GMT900)
POWER THROUGH THE YEARS
Where the LMM Duramax fits in Duramax history.
Peak factory pickup ratings by generation, horsepower and torque. Yours is highlighted. Tap any bar to see that generation.
- Horsepower
- Torque (lb-ft)
WEAK POINTS, SYSTEM BY SYSTEM
What fails on the LMM Duramax, and how we fix it.
Tap a system to see what fails, what you’ll notice and how we fix it. Common = we see it often. Towing / tuned = shows up with heavy loads or added power. High miles = age and wear items.
DPF & emissions
Clogged DPF and frequent regensCommon
You’ll notice: a regen that runs often, poor fuel mileage, low power, a DPF light.
Why: Short trips and idling don’t give the DPF time to burn off soot, and extra regens can thin the oil with fuel.
Our fix: We check sensors and soot load, run a service regen and clean or replace the DPF when needed, all emissions-legal.
EGR cooler and valveCommonHigh miles
You’ll notice: coolant loss with no leak, white smoke, surging, EGR codes.
Why: The EGR cooler can plug with soot or crack and leak coolant; the valve sticks with carbon.
Our fix: We pressure-test the cooler and clean or replace the valve and cooler.
Exhaust and DPF sensorsHigh miles
You’ll notice: check engine light, derate, failed regens.
Why: Pressure and temperature sensors in the exhaust fail with heat and age.
Our fix: We test each sensor and replace the failed one.
Turbo
Sticking turbo vanesHigh miles
You’ll notice: slow spool, low or high boost codes, a weak exhaust brake.
Why: Soot builds up on the variable turbo’s vanes over time.
Our fix: We diagnose the turbo and clean, repair or replace it.
Fuel system
Low rail pressureTowing / tuned
You’ll notice: power loss in hot weather, a check engine light, limp mode.
Why: A leaking fuel pressure relief valve, air in the fuel or a tired CP3 drops pressure.
Our fix: We test each part and replace what’s failed; a FASS lift pump helps the CP3.
Air in the fuel (filter head)Common
You’ll notice: hard starts, stumbling, loss of power.
Why: The O-rings in the fuel filter head harden and let air in.
Our fix: We reseal or replace the filter head and bleed the system.
Cooling & leaks
Leaking transmission cooler linesCommon
You’ll notice: red fluid under the front of the truck, low transmission fluid.
Why: The factory cooler lines and their crimped fittings leak with age.
Our fix: We replace the lines with quality parts and top off the Allison.
Water pump leaksHigh miles
You’ll notice: coolant drips at the front of the engine, running hot.
Why: The pump seal and bearing wear out with age.
Our fix: We replace the pump and check the fan clutch and belt.
Allison 1000 automatic
Slipping or limp modeTowing / tuned
You’ll notice: flare between gears, harsh shifts, limp mode.
Why: Old fluid, heat and added power wear out the Allison’s clutches.
Our fix: We service it, diagnose the codes and rebuild with heavy-duty parts when needed.
Front end & steering
Loose steeringCommonHigh miles
You’ll notice: wandering, play in the wheel, uneven tire wear.
Why: The independent front end wears out idler arms, pitman arms, tie rods and ball joints on these heavy trucks.
Our fix: We rebuild the front end with heavy-duty parts and set the alignment.
RELIABILITY UPGRADES
Bulletproof it in the right order.
If you plan to keep your LMM, these are the upgrades we recommend, in the order that protects it best.
- Lift pumpA FASS lift pump protects the CP3 and the injectors.Call nowRequest a quote
- Healthy DPF habitsRegular highway runs and the right oil keep regens short and soot low.Call nowRequest a quote
- Transmission cooler linesFresh lines stop the most common LMM leak before it hurts the Allison.Call nowRequest a quote
- Cooling refreshRadiator, water pump and fan clutch keep it cool through Tucson summers.Call nowRequest a quote
- Transmission coolingA PPE deep pan adds fluid and cooling for the Allison.Call nowRequest a quote
MAINTENANCE SCHEDULE
LMM Duramax service intervals.
These are GM’s factory intervals from the owner’s manual schedule. The factory “severe” column covers towing, dusty roads, short trips and long idling, which describes most working trucks in Southern Arizona. Our recommendation follows the severe schedule, with oil every 5,000 miles and fuel filters every 10,000.
| Service | Factory, normal use | Factory, severe use | Our recommendation |
|---|---|---|---|
| Engine oil & filter | 10,000 mi / 12 months or oil life monitor (maximum) | Sooner when towing or idling | Every 5,000 mi |
| Fuel filter & water separator | 15,000 mi | Not listed separately | Every 10,000 mi |
| Engine air filter | 45,000 mi | Check at every oil change | Check at every oil change |
| Coolant | 150,000 mi first service, then 50,000 mi | Same | 150,000 mi first service, then 50,000 mi |
| Allison 6-speed fluid & filters | 50,000 mi | 25,000 mi | 25,000 mi |
| Transfer case fluid | 50,000 mi | Same | 50,000 mi |
| Front & rear axle fluid | Not set by the factory | Not set by the factory | No factory interval; we inspect it at every service |
Always go by your owner’s manual for your exact truck. Factory figures are maximums, and the dash service reminder comes first when it shows sooner.
WANT MORE POWER?
LMM Duramax performance upgrades.
Staged builds, lift pumps, transmission, exhaust and suspension upgrades for the LMM Duramax.
BUYING A LMM DURAMAX?
Get it inspected before you buy.
Our Diesel Pre-Purchase Inspection checks the engine, fuel system, transmission and front end, and looks for signs of past problems. We meet you at the seller.
How mobile service worksTell us your truck and where it is, we diagnose on site, you approve a written estimate, and we fix it where it sits.
See how it works →PLAIN-ENGLISH GLOSSARY
LMM Duramax terms, explained.
- LMM
- The 6.6L Duramax used from mid-2007 through 2010.
- DPF
- Diesel particulate filter. Traps soot in the exhaust.
- Regen
- When the truck burns the soot out of the DPF with extra heat.
- EGR
- Exhaust gas recirculation. Sends some exhaust back into the intake to cut emissions.
- VGT
- Variable-geometry turbo. Moving vanes change boost at different speeds.
- CP3
- The high-pressure fuel pump on the LMM.
- FPRV
- Fuel pressure relief valve. Lets extra rail pressure out; it can leak.
Name-brand partsWe install proven brands like Banks, FASS, Mishimoto, Edge, PPE and Bilstein.
See all the brands we install →OWNER QUESTIONS
LMM Duramax questions, answered.
Is the LMM Duramax a good engine?
Yes. It kept the CP3 pump and a strong bottom end. Most problems are emissions parts and leaks, which we fix without deleting anything.
My truck keeps regenerating. What’s wrong?
It can be short trips, a bad sensor, an EGR problem or a loaded DPF. Call us and we’ll find the cause.
Do you delete DPFs?
No. We repair and clean emissions systems so your truck stays legal.
Why don’t you list prices for these repairs?
Every truck is different by now. Mileage, past repairs and how it’s used all change the parts and labor. Call us at 520-990-1033 and we’ll give you a straight quote.
What warranty do repairs have?
Repair labor is backed for 1 year or 12,000 miles, and new parts carry their manufacturer’s warranty. Warranty details →
LET’S TALK ABOUT YOUR TRUCK
Call, text or request a quote.
Tell us your year, mileage and what you want done. We’ll recommend the right repair, quote it and come to you.