Engine/Transmission (1994 - 1998) Buying My First!

[Mr. Cummins]

I am about to purchase this weekend a 1998 12 valve 3500 4x4 quad cad sport with 52,000 miles on it. I am a mechanic so I know my way around cars but not to technically familiar with the cummins. Wondering what if anything major I should be checking on and looking for powertrain/drivetrain wise with this truck. I have a snap-on scanner that will be going on the trip with me, so I can look for certain readouts if anyone knows of guidelines for these motors. Its a 6 hour trip for me to get it so Im gonna be spending alot of time making sure the truck is right and if so will be taking it home. Any assistance/feedback is greatly appreciated. IM EXCITED!!!

 

[DavidGardner]

If you need to know if the fuel plate has been changed from stock just lok at the injector pump and toward the rear is what they call ther AFC. This would be the rear most portion of the top of the injector pump. Now carefully look at the 4 bolts and screws on this part of the pump. The top right will be a regular screw looking bolt (takes a flat blade scre driver to remove) The two bottom bolts take an 8 mm socket to remove. The top left (closest to the front of the engine) will look smooth. If this top left screw or bolt looks any different than this then the AFC has been removed and the fuel plate has been diddled with or replaced. Botttom line is this truck is not stock. Some times this is a good deal and some times it means the truck has been rode hard and put to bed wet.



Buyer beware.



just my . 0002 cents worth.



Your friend Dave Gardner

 

[Deezul1]

Good advice. The AFC housing has a ALLEN wrench plug in the top of it and the tamper proof screw is the top left one, closest to the engine towards the front. It is a break off screw. Look at the paint on that area also for chips to indicate someone wrenching on it. This is not all bad as long as it was done by someone with knowledge. If the break off screw has been replaced with something else and there is no sign of gauges then be wary. Check the exhaust manifold just before the turbo for a place that has been drilled and tapped for a EGT gauge.

Good luck

John

 

[Blakers]

I don't think your scanner will tell you much as these engines are not computer controlled. I believe the computer only controls the grid heater, the alternator, and the transmission (if it's an automatic). I don't think it does a thing for the engine.



I would check for normal signs of abuse. Look for blowby, uneducated tampering, and especially leaks up around the front timing cover. Look at the general appearance of the whole truck and see if it looks like it was maintained.



Good luck.



Blake

 

[Deezul1]

Thats correct, the 12 valve trucks have no computer controls for the engine.

 

[JoeBioDiesel]

Hello, and Welcome

The 12V doesn't have computer controls, but you'll still see a data stream. You can monitor RPM, TPS, Intake air temp, Desired Charge Voltage, Actual Charge Voltage, Gov Pressure, OD Solenoid, TCC Solenoid, among quite a few others. It will have a 16 pin connector under the dash. Obviously missing wll be O2 Sensors, Boost Pressure and Coolant Temp.

You can control a few outputs, but not any fuel related stuff.

Good luck with your new truck.

Joe

 

[WadePatton]

Welcome and Good Luck!



Any more than a wisp of black smoke under hard, pre-boost acceleration will indicate AFC tampering. Which, like has been said, doesn't mean much. I'd just be double wary if it pumps much smoke and doesn't have an EGT gauge or evidence of one.



Where is the truck?--maybe a TDR BOMBer can help you out on the spot! I certainly would.



Also I'd pull the air intake to the turbo and make sure the blades are clean and it spins freely. If it is straight piped, just stand by the exhaust and have somebody else shut it down--listen for nice long spin down.



These engines are really tough, but can be fouled up by the real idiots (but you've probably seen that before) and then very $$$ to fix. Let us know what you find.