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Cat Bridge Engine?

78K views 22 replies 12 participants last post by  justdoug 
#1 ·
From what I have been in 2004 Cat made what was referred to as bridge engine and noone has any nice words to say about them. Were all 2004 trucks equiped with these engines? What was wrong with them and is there anyway of correcting them and making them worth having? I seem to come across a lot of clean 2004 trucks for sale but I always walk away if not run. So look forward to your responses. Thanks.
 
#2 ·
The truck I used to have had a 525 bridge engine in it. In stock form not a very good engine. Didn't pull any better then a 475 and the EGT's ran at 1200 to 1300 degrees. Then I put a 100 ohm resister on the fuel sensor and a 10 ohm resister on the air sensor and I also put code 6999 on the injectors. What a difference that made. Gained 10 - 12 km/h on the hills and the EGT's cooled down to 1000 - 1100 degrees. It even idled a lot smoother.
 
#7 · (Edited)
I have one. Stock it was sucky. I put a nonwastegated borg warner turbo on it, and flashed it to some older 6NZ files, plus a fuel temp wire now it's a great motor. Putting 6NZ injectors and camshaft, or PDI injectors with 800hp marine cam would make mine better but it does good now. On the rollers stock form MBN 475 flash it put 421hp down we estimated it almost puts 500 down now. Pulls like a champ. Egt's never over 900* now. In stock form would go to 1200* easily or higher. I have about $2500 in ecm flash, turbo upgrade, and fuel temp wire to make it right. I would not hesitate to buy a well maintained stock MBN but would definitely do some tweaking to it to make it good. When negotiating price on an MBN truck use the fact that bridge motors are not so great from the research you have done to get the selling price down even lower. Tell them you have been looking at a similar '02 6NZ truck or something along those lines. Get a W900 or 379 with an MBN so you wont have any cooling issues. I have a T600 and right now dont have any problems but I belive I'm at the limit of how high I can go performacewise without first putting a 4 core radiator in.
 
#9 ·
Get a W900 or 379 with an MBN so you wont have any cooling issues.
No coolant temp issues with the MBN and the W9. :D Tony put a fresh set of injectors in for me last month. No more haze at idle in the summer and running pretty good. :D Mileage is back up closer to where it used to be. Up from the 4.7-4.9 range to 5-5.3, and gonna get the fuel temp wire back on. Pick up .3-.4mpg with that and more power. Has the 525hp uprate, but we didn't take the time to see what the other ECM settings it might have done to it as well. Pulls hard and don't get passed very often. :D Stays in the ol' Monfort lane pretty good. :woot:
 
#8 ·
PDI will tell you to put at least a stage 1 turbo and tune with there manifold on to make it run good. To really make them a horse you need injectors and a cam then you pretty much have a 6nz. We have 3 of them in our fleet and they are all right. I will tell you they are better then are isx cummins.
 
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#10 ·
The turbo I have is the same turbo PDI calls a stage 1 they sell them for $2400 I paid $1683 for mine from turbo exchange. The cheapest way to fix an MBN is to flash it 6NZ then disable the stock turbo's wastegate. That'll give you a 550 motor that will run better than most every newer 500+ truck on the road. Since I've done my upgrades I havent run across a truck yet that can hang with mine. I'd like to have a radiator, cam, and injector upgrade with a 7CZ flash though. Right now I'm averaging 5.9mpg
 
#13 ·
Right now I'm averaging 5.9mpg
What do you pull?

My numbers are when pulling the bullrack. On the rare occassion I'm pulling a hopper, I get 7-7.5mpg. :D
 
#11 ·
If I owned the truck, there's no way it'd still be as stock as it is. :D Tune the ECM, cam and turbo upgrade at minimum.
 
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#18 ·
The 1LW is basicaly the same engine as a 6NZ internally. The big difference is the electronics between them. The 1LW uses the same camshaft. The pistons are the same compression ratio and same part number on the crown for the last of the 1LW and all of the 6NZ. The injectors are the same reman number for the first 6NZ and last of the1LW, 0R-9257. I don't know if the turbo's are different but they'd be very close in air flow for the 550 hp engines. The big difference in the actual structure of these engines is the block. The 6NZ is called a sculptured block and weighs less than the 1LW block, its also stronger. The reason for this is the casting is much more controlled during with the manufacturing of the 6NZ block and steel is only used where its need the most. Also the 6NZ seals the front and rear structures differently for less oil leaks as the engine gets older. The oil pan and valve covers also seal differently for less chance of leaks and to keep the corners of the oil pan from breaking.

The stock CAT flash files for the 1LW are better if you can find a per LOW NOX file(I have them) than the stock CAT files for the 6NZ. With the programs that PDI has out now.........the 6NZ no longer has a disadvantage in this area any longer.
 
#15 ·
40 pin to a 70 pin and people say that the 6nz was the best ever built cat engine.
 
#19 · (Edited)
get your ecm flashed by kurt to a 6NZ or 7CZ file, 5232 or 6999 trims, get rid of the mufflers, get a pdi manifold, bw 175963 non waste gate turbo, fuel temp wire,4 row 320 dimpled tube rad 16 fins sq. inch w/180 t. stats & put a smile on your face & MONEY BACK IN YOUR POCKET!!!!!:peelout. I went from 4.8 - 5.1 to 6.1 - 6.5 mpg per tank of fuel!!:woohoo watch out for any MBN w/ 600k + miles cuz the head gaskets tend to let go. (doing mine right now @675k).:wtf since im goin down that far i'm gonna rebuild it to 6NZ w/ 800hp cam, 958 injectors! :toytruckCA CHING CA CHING!!!!!!
 
#20 · (Edited)
bmoeller - I pull a 53' dry van gvw of 75-80K every load 3500 miles a week. I can see you getting the mileage you report with the short runs you do. I'd be skeptical if you were otr unless you drove like my grandmother everywhere.

t800kwhopper - With the blown head gasket I wonder if the difference between a 6NZ and 7CZ flash on a basically stock MBN is too much. Knock on wood, I havent had any problems and my motor runs great 6NZ'd. Let me know how the cam and injector upgrades go. I wish I had the money to do that. I can't really justify it on this truck if I can ever get the glider I want I will though.

Btw, I saw where you posted you'd like to upgrade to an 18 speed. I think you'd benefit from a 3:70 gear swap too. You can run 75mph, plenty of top end IMO, and no-one can hang with you pulling hills. The perfect setup I love it.
 
#21 ·
bmoeller - I pull a 53' dry van gvw of 75-80K every load 3500 miles a week. I can see you getting the mileage you report with the short runs you do. I'd be skeptical if you were otr unless you drove like my grandmother everywhere.
That's pretty good. I actually get worse mileage pulling a van vs the bullrack. Run far lighter loads with the van, too. Grossing 60-80k delivering seed to farms and dock-to-dock for a seed company in the spring. Figure that one out. LOL My truck likes a good load on its back. :thumbsup



And, I agree on the 3.70 gears for T8.
 
#22 ·
I did something really impressive this week. I kept the speed around 67-70 mph with a light 12,000 lbs load up i-81 to NJ from TN. Got 7.48mpg going up and 6.2 on the way back down with a 17,000 lbs load. Was really dissappointed with the numbers on the backhaul but 6.7 mpg on 1608 miles round trip I can't complain about that. I need to keep my foot out of it on the heavy loads and see what she'll do. Heavy loads with a heavy foot are killing me but I cant complain much for how I drive it. I'm always slow and easy to build up but when I get her wound up look out!
 
#23 ·
Guaranteed you were runnin faster on the way back-just couldn't get outta Jersey fast enuf! Really though,that mileage with the kinda power you got is awesome. That particular run with the lite loads is where your 3.70's w/22.5's is not helping you. Good set-up though if you're usually at the limit.
 
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