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Buying a cummins

2K views 22 replies 10 participants last post by  atasirudy 
#1 ·
Hey everyone. New here to the forum.
I'll give a brief introduction.

My name is brad I'm 22 years old. I've been a diesel mechanic for around 2 years now but I've been around diesels for about 4 years now.
Im located in Orange County ca.

I've owned two 7.3 ford diesels and they have been good to me but I want to own a cummins because I hear a lot of good things about them.

I found a 98 2500 with a 5.9 cummins.

Not sure if it's the 24v or 12v what's the best way to tell and what's better?

It has a 173k miles and he is asking 8500
I think that's a little high even though the truck is immaculate. I've seen trucks for that price have 90k miles

What are some things to look at as far as power train goes? Besides the basics (engine oil tranny oil air filter leaks) etc etc

I've heard things about lift pumps and transmissions

What do you guys think of the price?

Any advice is greatly appreciated.
Thanks, brad.
 
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#2 ·
Its difficult to figure which is which. The 12v says cummins turbo diesel on the door and the 24v says Cummins 24v turbo. You're a diesel tech???
 
#4 ·
Look at the tach.

12 valve has a 3,000 rpm redline.
24 valve has a 3,200 rpm redline.

The VP44 injection pump on the 24 valve has a bad reputation. It fails often enough that some think of it as a 150k mile part. When you get a rebuilt IP they may not make it through the 1 year warranty.

The 24 valve can use a programmer. In theory it should gain mpg over the 12 valve. Press releases claimed a 5% increase in mpg. However, you have electronic junk to go bad. That could easily destroy any fuel savings in parts costs.

The best year for a cummins engine is 1997 or a 1998 built in 1997. The reason is hydroboost brakes came along in 1997. 1996 was also a good year it just has vacuum brakes instead of hydroboost. While 1994 ad 1995 were ok years they had an injection pump that was known to occasionally warp plungers requiring an injection pump rebuild.


Read this post and the entire thread.
http://www.cumminsforum.com/forum/9...g-pick-best-model-cummins-dd.html#post4699697
 
#6 ·
If it hasn't been replaced, it will likely need it shortly. Also look to make sure it isn't a "53" block. it will be stamped on the lower, driver's side front of the block, just above the oil pan.

They had thinner walls and were prone to cracking
 
#7 ·
Look at the 8th digit of the VIN. For 1998:

D = 12 valve
6 = 24 valve

Personally, I prefer the relative simplicity, robustness and subesequent reliability of the 12 valve. The VP44 injection pump of the 2nd Gen 24 valve was always too much of a crap shoot for me. If not a 12 valve, I'd just as soon skip ahead to a 3rd Gen common rail.
 
#8 ·
Some guys have gone 400k+ miles before the vp44 died. Others never got close to 100k before it needed replacing. I would not think the VP44 needs replacing although it may. The lift pump (fuel pump) however is a bad design. Many replace it with a FASS and say it is much more reliable although it costs around $600 as I recall.

A 24 valve truck should have a fuel pressure gauge installed as soon as possible. Low fuel pressure from a bad lift pump is largely blamed for many VP44 failures. The injection pump tears itself up pulling fuel when the lift pump dies. Perhaps the VP44 being lubricated by the fuel itself is why this is so bad.

Myself I would look for a 12 valve truck. What you choose is up to you.
 
#9 ·
I like the 12 valve and actually prefer the vacuum boosted brakes as they seem as strong or stronger and they have more reserve applications with the engine off.

The 12 valve is rock solid in '96 or '97.

The VP44 24valve has been around long enough now that we pretty much know how to modify the fuel supply pump and filtration system to make it live plus add a fuel gage. I'm not a big fan of electronics so I shy away from the additional electronics on the 24 valve.

The 12 valve is the last generation of any mass produced consumer vehicle that I know of that can be run and driven (with a 5 speed) with the battery removed or a total electrical failure. The shutdown solenoid linkage can be pulled up with a shoelace or ty wrap or anything and then it can be bump started in gear and driven with power brakes and power steering and zero electrical. I think that is cool.:thumbsup:
 
#10 ·
I prefer the 12 valve as well. You have to understand that you are getting a slightly biased opinion here. If you post this question and 24 valve section you will get a biased answer there as well.
Everything mentioned previously here is true, the lift pump is the true culprit behind VP44 failures. Ultimately it depends on what you prefer most. Do you like mechanical simplicity and reliability, or pushbutton power? Ppump 12 valves are capable of lots of power and towing capability so there is really no argument there.

I love my 12 valve. Just nothing like it.
 
#11 ·
It has a 173k miles and he is asking 8500
I think that's a little high even though the truck is immaculate. I've seen trucks for that price have 90k miles

What are some things to look at as far as power train goes? Besides the basics (engine oil tranny oil air filter leaks) etc etc
The steering turns to mush.

I'm not sure how much difference there is between 90K and 180...all the stuff that fails a lot is dead by 100K, and the motor should still have 200K in it.
 
#14 · (Edited)
It wasn't thin walls, it was thickness inconsistencies that caused failures. Parts of the water jacket would heat soak faster than others and cause stress fractures between the different density sections of wall.
 
#15 ·
Well I looked at it and was not impressed. Had a good size sent in bed.
Trans fluid had some black sediment in the darkish red color. Smelled a little burn as well. Had a oil leak and it was even power locks or windows.

Going to look at a 1997 12v.

Has 149k miles.

So being that I'm in California add is listed as a 97 but the door tag from photo says 96, do I need to smog this? I thought 12 v were smog exempt
 
#16 ·
94-96 was exempt, 97 had an egr.
 
#17 ·
My 98 was made 12/97 remember models always come out ahead of time and factories need lead time so just because it says built 96 does not mean its not a 97 model year.
 
#19 ·
Smog reqs will go off model year and not date of manufacture. I dont know what your commie state requires so i cant say. I dont have to test anything here in WI.
 
#23 ·
5th gear retainer backs off, there are a few different fixes, input shaft can twist or shear, get the upgraded 1 3/8 billet shaft.
 
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