Looking to buy a 1st gen or just bought a 1st gen? READ THIS
Ive noticed a lot of recurring posts for people that are looking to get a 1st gen or have just purchased a 1st gen, so I thought Id make this to help answer a lot of the common questions that people have and maybe give a specific thread for people to post in with questions they have about a new truck. I happen to be stuck on a long flight, so hopefully I can use this time to do something productive and help some new people out!
This post is by no means exhaustive and is just meant to be a good start. If you want more info, please use the search function, or use google to search the cumminsforum website by typing your keywords followed by: site:cumminsforum.com into the google search bar.
I find this to work much better than the search bar located on the site itself.
I’ll divide this post up into sections so it’s easier to find the info you need.
2. Things to look for in test drive
3. I have it home, what do I do to it first?
3a. general info and how-to
3b. Common modifications
I think the most common questions I see is “How much do I pay for this truck?” and to be honest, the answer completely depends on the specific area you are buying in. based on the condition of the truck, they can sell for anything from $500-$20k. The truck you’re looking at will probably fall somewhere in the middle, but again its more a matter of what YOU want to pay for it.
Don’t buy the first truck you see. Watch the market (check craigslist etc. daily), get an idea for prices, and then buy. If you do, you’ll know exactly what you should offer and what the truck is really worth.
When you do find the one, show up with CASH in hand and act quickly since these trucks are very popular.
What to look for when buying:
This area gets the second most questions since it’s a bit overwhelming to buy a 20+ year-old truck if you don’t know them well, so here are my tips:
1) the less do-dads the better. Power windows and a/c are cool, but they break. Make sure you test them all out or just avoid them all together. If the A/C doesn’t work, its probably because it needs to recharged… with R12 coolant that no longer exists. You can definitely get the AC to work again, but it will take a little doing. There are plenty of threads on that topic.
Not all of these trucks have lived pampered lives, so try to size up the owners and get a sense of the vehicle history from them and looking around carefully at the truck.
2) check the fluids. Check the oil, trans fluid, coolant, and diff fluid if possible.
You want them all to be clean, clear, and smell normal. Issues here point to poor maintenance that might not be reflected elsewhere on the truck. Make sure there is no coolant in the oil and vise-versa. If there is, run like the wind.
3) check under the truck. Don’t miss rust holes or frame cracks because you were too lazy to get dirty underneath the truck. If there is oil leaking, see where its coming from. A little is normal, a lot isn’t, and make sure its coming from somewhere minor.
These trucks can get cracks on the frame by the steering box, so check there.
Check all front end bushings and drive line components for play etc. front end issues (bushings and ball joints that are toast) are very common.
4) check for blow-by. With the truck running and warm, carefully open the oil fill tube. If haze comes out, (more than a very minimal amount) then the engine has issues and you probably want to reconsider. You can also check under the truck and watch the crank case vent tube, again a little haze is normal, but clouds are not.
5) If you live in the rust belt, check the rain gutter around the cab along with the other obvious body panels for serious cancerous rust. A lot of people on here will tell you that forking out the cash for a rust free truck is well worth it, unless you like grafting in new body panels…..
6) if the truck has an auto trans
work the transmission. Make sure all shifting is firm and purposeful. Check the function of the overdrive if the truck has a a518 (post intercooled). make sure the fluid is red and sweet smelling.
If the truck has a manual trans:
Make sure it shifts well and the clutch feels good, and keep an eye out for any odd noises. The Getrag 360 can get bearing issues if it gets beat on, so excessive growling and noise can be a sign of these. They don’t liked to be lugged though so keep it above 1500 rpm.
7) Intercooled vs non-intercooled: anything pre 1991.5 is going to be non-intercooled, and anything post 1991.5 is going to be intercooled. There is nothing wrong with the non-ic trucks. They make great power, and are rumored to get the best mileage of the bunch.
-the non IC are slightly different mechanically (aside from the obvious missing intercooler, and do have different pistons and a few other differences
-The non-ic have less electrical stuff on the engine, and are also lacking overdrive on the automatic transmissions (727 is non-ic auto). Anything post 1991.5 will have overdrive (A518) and a few more electrical components.
8) The test drive: Keep in mind these trucks were loud, slow, and had pretty sloppy steering from the factory. Check for excessively sloppy steering (ie your wheel has 15* or more of free play) but don’t freak out when it doesn’t feel new, because it isn’t. Take it on a long drive that will get you to test highway speed driving. Check for loose or wobbling front end and steering. Check for smoke that is any color other than black coming from the exhaust as white or blue smoke is not the sign of a happy diesel engine.
3. I have it home, now what?
First, do some general maintenance, CHANGE ALL THE FLUIDS AND FILTERS
then go drive it!
11qt of 15w40
'89-'15 Dodge Cummins LF16035 StrataPore Oil Filter-Geno's Garage
26 qt of green or yellow
Auto trans fluid (ATF) :
Dexron III 17 Quarts (this number is for the A518 auto with overdrive, double check this if you have a 727 without overdrive)
Manual trans fluid:
Overfill the transmission through the TOP pto bolt hole (the bolt hole for those rectangular covers on the side of the trans) with 5w30 synthetic motor oil. Don’t fill it through the normal hole as it doesn’t allow enough oil to lubricate the trans bearings properly.
'89-'93 Dodge Cummins FS1232 Fuel Filter-Geno's Garage
1) unplug the wire to the sensor on the bottom of the filter.
2) Drain filter by using the water separator.
3) Unscrew old filter, making sure to get the little o-ring with it.
4) screw the water separator back on, and Fill the new filter with fresh fuel
5) Apply a thin coat of oil to the seals
6) screw filter on, and and plug the wires back in to the filter.
You may have to release the air in the filter. On the line that comes out the front of the filter housing is a fitting with a 10MM headed bolt. This is the bleeder screw.Loosen the bleeder a turn or two. Then grab the lever on the side of the lift pump. Pump it till you get clear fuel out with no bubbles. Close the bleeder screw. Then pump the lever a couple of times till you feel resistance. Then be sure to lock the lever back into the up position. You’re done!
If your truck does not start, then you have air in the system, and you need to bleed the injectors. Crack them loose just slightly, crank the truck and watch diesel spray everywhere and on everything, then tighten them back up and youll be good to go, after cleaning up that diesel that’s now on everything.
Gates FleetRunner K080830HD
NAPA Belt 080830
Tensioner Cummins 3935819
Tensioner Dayco 89219
Check your brakes and pads (checking the rear drums is a pain, but there is a how to for that below):
FIX your KDP (killer dowel pin):
you can read about this at the link provided, but in short, this little dowel pin has the ability to total your engine if not addressed. It doesn’t happen to everyone, and is actually relatively rare, but a lot of people just don’t want to roll the dice on it.
Ram Diesel KDP retainer
general info, Read these Tech articles:
If there is anything else you want to know, need to fix, or have issue with, these links are a FANTASTIC resource. There is a how to for practically everything you can do on these trucks:
89-93 Tech Articles - Dodge Cummins Diesel Forum
FAQ/Knowledge base "How do I...?" Look here first! A.K.A. "The Sticky" - Dodge Diesel - Diesel Truck Resource Forums
Engine: 5.9-Liter, OHV, Diesel Six-Cylinder
Type & Description: Six cylinder, in line, liquid cooled, turbocharged, intercooled
Displacement: 359 cu. in. (5.9 L)
Bore x Stroke: 4.02 x 4.72 (102.1 x 119.9)
Firing Order: 1-5-3-6-2-4
Engine Rotation as viewed from engine front: Clockwise
Valve System: OHV, 12 valves, solid sliding tappet lifter/followers
Valve Adjustment (engine cold)
Intake = 0.010" Exhaust = 0.020"
Adjustment interval - 24,000 miles
Fuel Injection: Bosch VE High-pressure direct injection, mechanical
Fuel Pressure: 18-24psi at idle, 28-36 at 2000 rpm with no load.
Max Fuel Pressure drop accross filter: 5 psi
Max allowable fuel return line restriction : 20.4" Hg
Maximum Inlet Restriction to fuel transfer pump: 4" Hg
Construction: Cast iron block & head
Oil Capacity: 11 qt. (9.5 L) with filter
Minimum Oil Pressure @ Idle: 10 psi
Minimum Oil Pressure @ Rated: 30 psi
Regulated Oil Pressure: 65 psi
Oil Filter Bypass Diff. Pressure: 20 psi
x Coolant Capacity: 24 qt. (22.7 L)
Battery: Maintenance-free, 1100 CCA
Max boost from stock turbo with stock pump= 15-19 psi
275º max auto trans temp
max egt: 1200º ( you can hit that here and there, but don’t sit on it at 1200)
1)drill some holes in the front of the stock air box. It is very restrictive.
2)Get a new exhaust, ditch your muffler, or get a straight through muffler. The cheapest 4in kit exhaust I know of is made by diamond eye and is available through a couple of different websites for about $250-$270
3)Get gauges! These old trucks need to be watched, so before engine mods go any further, get gauges! Exhaust temp and trans temp (for autos) are a must, and fuel pressure, boost pressure, oil pressure, and coolant temp are recommended.
4)the next common modification is done via the VE fuel pump and allows you to get some free HP and TQ with just a few turns of a screw driver. This however is a whole topic of its own, so you can read about it here:
However I feel the need to add, please don’t tune your pump to dump smoke. Its not good for your engine and even worse for the diesel community. Don’t make us look bad or we will make you get a gasser, and that’s no fun.
Hopefully that helps to give everyone a good bit of information to start with. Also to all you 1st gen gurus, if there is anything I need to fix or add, let me know and I will add it. I know there are a lot of you that know far more about these trucks than I ever will, so feel free to chime in. (I'm sure I missed plenty of stuff)
If you have any further questions about the price of a truck, or need opinions on one you are looking at, please post them in this thread instead of in a new one. It will help to reduce clutter on the site. Thanks for reading and enjoy your 1gens!