Engine/Transmission (1998.5 - 2002) 24 valve problems compared to 12 valve

[wrichards]

I currently have a 12 valve 1998 flat bed purchased with 50,000 miles now at 85,000 miles. Here is what i have done to it.



Rebuilt Auto Trans (previous owner may have abused)

A/C Condenser

KDP

Track Bar



Obviously a darn good reliable truck. I am looking at a 2002 3500 4wd 63k automatic chasis cab that I intend to put a utility body on. Most times will be unloaded with an occaion 2000 pound pallet of fertilizer in the bed.



Question is this. I have heard 12 valves are more reliable due to non comuter controlled "old School" "air and fuel diesel engine". Is this true? Also looking for brief explanation on how 24 valve injection system works. Sorry for so many questions but trying to decide whether I should hold out of 12 valve?

 

[wrichards]

Anyone??????

 

[blacksheepdiesel]

The 12 valve engines with the P7100 pump ARE extremely reliable. The 24 valve MAY be reliable. My 2001 has 488,xxx mi and has been very reliable. The original injection pump was replaced at the 400,xxx mi mark. The second fuel lift pump was replaced with an Airdog unit which has is still going strong after 120,xxx mi.



Differences? The 12 valve is a mechanical lift pump and mechanical injection pump - no electronics to cause issues. The downside is that any performance upgrades are "static", meaning once installed or adjusted they cannot be changed while the engine is running. The 24 valve has an electric lift pump (VERY prone to fail) and electronically controlled injection pump (prone to fail). The 24 valve can be upgraded and then adjusted on the go if desired to change levels of performance.



I have owned both and regret neither. I do enjoy being able to quickly change black sheep from fuel miser to tow monster in moments with my Smarty.



Trent

 

[BKenny]

Hey im not an expert but i give this a shot. The problem with the 24 valves fuel system is due to some poor enginering . The 24 valve electric lift pump is up by the engine and it has to pull fuel from the tank (no in tank pump) up to the engine. The lift pumps don,t like all that work and eventialy they wear out . I have 56,000 on my truck and have replaced two so far. What im getting ready to do is what a lot of poeple have all ready done Add an additional pump down by the tank . It will push fuel to the lift pump and keep it alive from then on. I like it simple my self but the one thing with haveing a computer controled engine is that you can plug and play. If you add an Edge box you can turn power up and down with a flip of a switch as you drive. Your going to be in the same boat with the auto they don,t like abuse in stock form. Im thinking if i was in you shoes id keep the 12valve you already have it and it only has 85,000 miles on it. The 98 12v is a popular rig to have . Hey if you turn the pump up to get more power i bet you would feel like you wher driveing a new truck :-laf . Thats my 2 cents. Oops i just realized some one else post wile i was typeing . Brian

 

[DieselTim]

12v / 24v

Well, from what I have had happen to my 98. 5. I found out too late that the lift pump will go south and when it dies it will take out the vp 44 injection pump. Once that happens you are going to be out a large chunk of cash and it will happen again unless you have gauges to keep an eye on the fuel pressure, even then there is no garrentee that it will not go out anyway. The cost of an injection pump from the dealer is $2300 plus install. The cost from Cummins is about $1700 plus finding someone to install or about 3 hrs labor. For what it is worth, I am planning to remove the 24v engine and replace it with a 12valve engine. I found a complete 12valve engine for $2000. So, I will have the best of both worlds 12valve engine and back doors Oo. Would I ever think of buying another 24valve truck, NO Way, unless it was just for parts at a really good deal. I have also looked into what it would take to change out the vp 44 pump to the older style. I may still do that later but for now I have an engine to replace.



Dieseltim

 

[wrichards]

Wow, was'nt expecting that thanks for the honest replies. Sound like the main problem is the lift pump and guys do have a fix for that. Are there any other inherent problems?? Oh yeah I don't plan on playing with the truck I like stock power call me crazy??

 

[blacksheepdiesel]

Oh yeah, don't buy a #53 block, they tend to crack.



Trent

 

[GEdwards]

Well, 02s do not have the 53 block. Keep an eye out when you look at older trucks. I refused to get one, just so I could sleep better at night



I think the 12 valve is better, but I think there are a few things you can do to fix the 24 valve. But I love my truck!



The biggest problem is the lift pump. Had one put in mine with like 36k. Was just barely under spec, and did not take out the VP44. I have warranty till July, but when it goes bad again, I will get FASS probably. A fuel pressure gauge is mandatory IMO.



Also, some say they have been through 3 VP44s in 50k, and as mentioned above, some say they have 200, 300, 400k on the original. Seems like luck of the draw on those. When or if mine goes out, I plan on getting the Blue Chip fedex truck style pump. Supposively have been much more reliable.



Thats about it.



I would like 12 valve, but in the newer truck(like mine) with the 6 speed, rear discs, etc.



Also, 01-02 autos have the small HY35(9cm housing) turbo which are known for high egts when bombing. Also, stock autos don't hold much more then a 60 hp box.



Manual transmission 98-02s as well as the 98. 5-00 autos still have the HX35(12 cm housing) turbo, which is better.



Keep this in mind, if you plan to bomb.

 

[wrichards]

OK sounds good the truck I am looking at is a 2002 3500 4wd does it have rear discs?

 

[Rattlin_Ram]

2001. 5 and up have rear discs...

 

[BManuel]

Mine is an 02 six speed HO, liftt pump started getting weak at 37k, :{ like a dumb A??, I ignored it. #@$%! started getting dead pedal at 50K :{ , put on the "Bully Dog" Big Fuel kit as a pusher (really just a good Holley pump with big lines and fittings), VP died at 56k :{ , replaced VP with Hod Rod VP, Could not handle the obnoxious behavior of Hot Rod VP :-{} , Now having it changed to a stock VP with a good set of injectors.



After all this, I still love my truck! I have 2 recomendations:

[FONT=Courier New[B]](1) PUT GAGES ON! so you know what's going on (fuel, egt, and boost).

(2) Put a pusher pump, or a Fass system on![/B][/FONT]

 

[Jdorfmeyer]

I have owner several 12 valves and now a 24 valve. I like the 24 value better than any of my 12 valve trucks. It is a 2001. 5 with rear disks and a manual. It is easier to drive in town because of the electronic idle controls. I did however put a new lift pump and vulcan big line kit on the 24 valve when I got it just to try and ensure that the vp44 lasts me a while. I think the 12 valve is a good truck, but I do like my newer truck the best. Just my opinion though. Joel

 

[MMoyle]

Just my 2 cents:



The injection pump on the P7100 12 valve trucks are pretty much bullet proof. They will keep running sometimes even in the worst conditions. The VP-44 is tempermental. There have been alot of people, including me, who has replaced a VP-44 and lift pump. I would like the reliablity of the P7100 in my 02 truck, but with the right care and monitoring the VP-44 can last a long time. In my opinion, the fuel system are the biggest differences between the 94-98 and 98. 5 - 02 trucks. Yes... better braking and other pluses with the 01. 5 and 02, but IMO those items can be dealt with much easier than a poorly designed fuel system. Bottom Line:



12 valve with P7100 - Bullet proof

24 valve with vp-44 - will require more monitoring and care and for a long life.

 

[Fararms]

Utility Box?

Wrichards, would you or anyone you know have use for an immaculate RK service body? 11ft?

 

[wrichards]

Maybe. What is An RK you can email me pics at -- email address removed --. Will that fit well on the short wheelbase?