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diesel · 08-03-2004, 12:46 AM

Silverback,

I did considerable research before I selected the Cat prefilter. Part of that research consisted of talking to my brother who works for Catapillar. He explained Cat's research and filter development. The warrentee for their new engines is based on the use of that filter. All test that I have seen have put their filter at the top.

Changing the extenal Allison filter is good preventative maintenance procedure.

I would also suggest that you change the rearend fluid. If you have been pulling your trailer, your gears should be broken in by now. Time to remove all the final lapping debris and get new fluid in there.

Janets Husband · 08-03-2004, 08:21 AM

Quote:

Originally Posted by diesel

Silverback,

I did considerable research before I selected the Cat prefilter. Part of that research consisted of talking to my brother who works for Catapillar. He explained Cat's research and filter development. The warrentee for their new engines is based on the use of that filter. All test that I have seen have put their filter at the top.

Changing the extenal Allison filter is good preventative maintenance procedure.

I would also suggest that you change the rearend fluid. If you have been pulling your trailer, your gears should be broken in by now. Time to remove all the final lapping debris and get new fluid in there.

I have also researched the Cat pre-filter and it looks the best.
One note on filters, there has been much talk about brands of filters you can do the research on the web by looking for "Oil Filter Quality".
My suggestion is to look up Baldwin filters and there are some very good deals on filter kits. ie. air, oil, fuel, trans. filters in a package. Very inexpensive compared to buying them one at a time.

Silvertwinkie · 08-03-2004, 08:22 AM

Quote:

Originally Posted by happy82301

Was talking to a salesman a couple weeks ago and he said the new duramax will have 10 more hp for 2005.

Acutally, the official GM press release said that the HP will stay the same at 310HP, torque however will go from 590ft/lbs to 610 ft/lbs. Now the question is all these engine updates and no trans update. The Allision, from what I understand was at the high limits at 590. Not sure how they got around that before upping the torque to 610.

Parts of the new release can be read on this website:

http://gm-trucks.com/home/content/view/109/1/1/2/

One last thing...when changing the Allision external filter, remember to save and reuse the magnet washer!

diesel · 08-03-2004, 11:27 AM

Janet's Husband,

I buy my Baldwin air filters and my OEM Rancor fuel filters in balk from Air Filter Service in Portland, Oregon. They ship and have excellant prices. After the air filter study conducted by a member on The Diesel Place, I bought every Duramax air filter they had when I was in town last Friday. They only had three left. They said there was a recent surge in demand for that air filter. Wonder why?

Janet's Husband,

GM achieves 610 hp by detuning the engine in first and fifth gear. A marketing numbers game. If you want more usable hp, you have to upgrade the Allison and possibly the transmission cooling system if you operate in hot climates. The engine is more than capable of producing more than 610 hp.
Since I normally run at 9000 pounds vehicle weight in high temperatures at high altitudes, I am considering the transmission cooling upgrade being developed by Mike L. on The Diesel Place.

Silvertwinkie · 08-03-2004, 12:06 PM

Quote:

Originally Posted by diesel

GM achieves 610 hp by detuning the engine in first and fifth gear. A marketing numbers game. If you want more usable hp, you have to upgrade the Allison and possibly the transmission cooling system if you operate in hot climates. The engine is more than capable of producing more than 610 hp.
Since I normally run at 9000 pounds vehicle weight in high temperatures at high altitudes, I am considering the transmission cooling upgrade being developed by Mike L. on The Diesel Place.

I was reading that thread...looks like his goal is bolt on and to drop the temps 20 degrees.

pmclemore · 08-04-2004, 11:08 AM

I just bought a 2500hd Duramax 6.6/Allison and love it. Seems to get good mileage, great pulling power - but then, I moved up from a Tahoe with the 5.7. And I think the Tow/Haul mode is magic on downhill exit ramps and on the Skyline Drive, where we took our shakedown cruise with the Safari.

Can anyone tell me what the difference is between the Duramax 6.6 and the rpo LLY?

Thanks - Pat.

Silvertwinkie · 08-04-2004, 11:36 AM

Quote:

Originally Posted by pmclemore

I just bought a 2500hd Duramax 6.6/Allison and love it. Seems to get good mileage, great pulling power - but then, I moved up from a Tahoe with the 5.7. And I think the Tow/Haul mode is magic on downhill exit ramps and on the Skyline Drive, where we took our shakedown cruise with the Safari.

Can anyone tell me what the difference is between the Duramax 6.6 and the rpo LLY?

Thanks - Pat.

Prior to the first quarter of 2004 GM had the Duramax engine, build code LB7. This engine I believe did not have a common fuel rail. Injectors on the LB7 engines seemed to have more issues than the LLY engines. GM has also extended the warranty on the injectors on LB7 powered vehicles due to the many issues that were happening.

First quarter(ish) 2004 GM made mods to the Duramax boosting torque (and possibly HP as well). They updated the injectors and also made it eaiser to replace the injectors and I think a common fuel rail was introduced, but don't quote me on that part.

The LLY also received and EGR (exhaust gas recirculation) valve, catalytic converter, head redesign (I think) and a variable vein turbo charger.

For 2005, the LLY has at the very least been given a torque increase (which was noted earlier). There could be other mods (particularly in the cooling areas, but nothing that has been confirmed yet).

Both engines however are 6.6L.

So far, most folks (not all) seem to feel that the LB7 engine (that was produced before 1st quarter 2004) got better fuel economy. It really depends on who you talk with about it. I do not own one (yet) as I am on the fence still. Here is a forum that gets more into the LB7 and LLY engines:

http://dieselplace.com/forum/

Happy reading.

diesel · 08-04-2004, 11:57 AM

Actually both the LB7 and the LLY have the Bosh Common Rail Fuel System.

Go to the following web site to read the changes made to the Duramax engine now designated as the LLY:

http://www.thedieselpage.com/duramax/lly2004.htm

RivetED · 08-04-2004, 04:28 PM

Quote:

Originally Posted by diesel

...I bought every Duramax air filter they had when I was in town last Friday. They only had three left. They said there was a recent surge in demand for that air filter. Wonder why?

Are the air filters you bought GM originals, oil-bath (ie:K&N), or something else???

diesel · 08-04-2004, 05:38 PM

Ed & Debbie,

They are Baldwin's replacement for the AC Delco paper filter.

After the study done on air filters as reported at The Diesel Place, I removed the K&N in my wife's Tahoe and the Amsoil Dual Stage in my Duramax. Both K&N and Amsoil filters were oiled foam. Both rigs now have OEM or equivalent paper filters.

RivetED · 08-04-2004, 06:40 PM

Quote:

Originally Posted by diesel

Ed & Debbie,

They are Baldwin's replacement for the AC Delco paper filter.

After the study done on air filters as reported at The Diesel Place, I removed the K&N in my wife's Tahoe and the Amsoil Dual Stage in my Duramax. Both K&N and Amsoil filters were oiled foam. Both rigs now have OEM or equivalent paper filters.

Diesel,

Thanks. I've used K&N's in my last 2 pick-ups but have recently 'heard' the incerased air flow comes with increased contamination=turbo+injector probs.

. I have 25K on my current diesel (yeah it's a Ford-sorry!) & the air filter needs to be replaced. I'll check into the Baldwins, if available for the 7.3L PSD.

Not being a GM/Duramax owner I'm on the 'dieselstop' forum instead. Again thanks for the input.

Pick · 08-04-2004, 07:01 PM

I have put 22,000 miles on my Duramax LB7 since September. It has been trouble free. My best tank has been 22.7 mpg so far. Most of the time it runs around 20.5 mpg on freeway trips and 18 mpg country cruising. Towing varies from 12.5 to 15.5 mpg, depending on weather and terrain.

I have added a Caterpillar fuel filter between the fuel tank and the OEM filter. The OEM was changed out at 18K and looked like it could have gone to 50K. I highly recommend the additional fuel filter. You never know what kind of crap your getting from some of these fuel stops. My regular fuel stop has filters on their pumps.

dscluchfc · 08-04-2004, 11:04 PM

I buy Fram air filters and spray them with K&N Air Filter Oil.
Seems to work fine on the air filter side of things.

Silvertwinkie · 08-05-2004, 08:13 AM

Quote:

Originally Posted by dscluchfc

I buy Fram air filters and spray them with K&N Air Filter Oil.
Seems to work fine on the air filter side of things.

I'd be fairly wary of anything with the Fram name on it. Several folks in various car clubs have had issues with some type of Fram filters at some point. Fram does not make the quality they once did.

There was a study done on thedieselplace on air filters specifically though.

jasper2222 · 08-09-2004, 06:39 PM

[QUOTE=diesel]Silverback,

I just recently purchased a 2003 duramax with 55,000 miles. I want to replace the rear end, transmission fluids and brake fluids. I have the duramax owner manual but see no quantities listed for fluid changes. I understand the requirements are for synthetic rear end fluid and I will probably use synthetic for the transmission also. Are the GM filters (transmission, fuel and air) the recommended way to go? I usually work on my on vehicals.

What about this caterpillar fuel filters. Is that something that most people do themselves or take it to a dealer. What is the best location, and approx. cost. Also where is a good place to buy one.

For the mileage people, I have gotten between 19-20 on 2 tanks and that was a combination of local and highway, no towing.

Any thoughts would be appreciated.

Silvertwinkie · 08-09-2004, 09:15 PM

I've read that the front takes 2 quarts and the rear 4 quarts. Unsure if the G80 rear needs limited slip additive or not.

Front axle can use conventional oils, however there is a TSB out on the front diff stating that customers that are in cold climates (-12F or colder) should use synthetic 80w90.

Rear axle 75w90 synthetic (no mention of additive in the book).

As for filters, GM has a good following. Their air filter is suppose to block most dirt. Trans, I have no idea, but with the Allison, it's a breeze unless you want to drop the pan too and change out that filter as well.

Now I am unsure what oil filter the Duramax takes, but I will say first hand that if it is a AC Delco PF series filter, there may be a UPF for it. For example the 5.7L LT1 takes a PF-52. AC Delco also make a UPF-52. Better flow and lower micron filtering....it's called an Ultraguard. It's all I use FWIW.

davidz71 · 08-09-2004, 09:41 PM

Go to www.pickuptruck.com and ask them capacities. I run Amsoil series 2000 75W-90 synthetic gear lube in the rear differential of my 2500hd which is an 11.5 inch rear end. This is the same rear end you have. I could not give you a capacity because I have the Mag-Hytec rear end cover which adds an additional 1.5 qts. to the system. The G80 locker does not require an additive.
Royal Purple, Mobile One and Red Line all offer synthetic gear lube.

Careful on your selection of synthetic for the Allison transmission if that is what you have. According to Amsoil Action News, "The only oil on the market that is formally identified by Allison as a TES 295 product replacement is TranSynd Synthetic Automatic Transmission Fluid which happens to be sold by Allison in partnership with Castrol. Amsoil developed a replacement product called Torque-Drive which is a premium synthetic transmission fluid based on the same chemical technology as TranSynd."

You might check to see what users on the pickuptruck forum have been using. I am due for a trans oil change at 35,000 miles and I plan on using the Torque-Drive. Also, don't forget to take off the round magnet that sits on top of the Allison trans filter, clean it and place it back on your new filter.

I want to add that Allison has replacement transmission filters that you can buy cheaper at a heavy duty truck center that services Allison transmissions rather than a Chevy dealer. When you buy a replacement filter it will be a blue GM filter rather than the original orange/red filter. Check out Allison dealers on the internet.

Pick · 08-10-2004, 04:45 AM

Ken, I have added the Caterpillar fuel filter to my Duramax. It is the same as the Nictane, I just parted it out myself. Get a Nicktane.com filter kit. That Cat filter is 100 times better than the OEM. My OEM was clean as a whistle at almost 19,000 miles. Cat has been installed since 2600 miles.