Water pump and sulliniod

My son has a dodge ram 1500 and was told the water pump needs to be replaced and that the sullinoid could be the problem with the starting of the truck or the trouble with the starting of the truck. Could you please explaine to me what exactly the sullinoid does and how much would it cost to replace it in general. Not an exact price as you can’t quote that. Thanks, momstaxi

It’s spelled “solenoid.” It switches the high current power to the starter motor and pulls the starter gear into contact with the flywheel (or flexplate) gear of the motor.
Try a Google search.

The water pump and the starter solenoid are completely separate, and have absolutely no relationship to one another. I just wanted to get that out of the way.

The starter solenoid is the device that engages the starter when your son turns his key to “start.” A solenoid is just an electro-mechanical device that turns electric current into mechanical action.

In this case, the starter solenoid pushes the starter drive gear into contact with the engine flywheel, and spins the engine while the key is in the “start” position. Assuming the fuel an electrical systems are working, the engine will start.

These days it’s unusual to replace the solenoid by itself. Usually, the whole starter/solenoid is replaced.

I’d be more worried about the water pump than the starter solenoid.

Without knowing model year, or engine option, rough guesses:
water pump around $100
new starter, life warranted part, around $200. I didn’t look real hard, but didn’t see a solenoid option at my parts source.

Add mechanic’s labor. I would guess about one hour per procedure, but that is purely a guess.

On a Dodge truck, change the whole starter. Total costs can vary from $300 to about $750 to get both done. Don’t be surprised if the price goes higher. You need a new belt and maybe a tensioner.