Water pump replacement and coolant

Posted by: mclasser

Water pump replacement and coolant - 01/13/14 10:08 PM

I know these are rather novice questions but here I go--

All the coolant that flows out during a water pump replacement effectively drains coolant from the engine block, correct? So when mechanics say the coolant is replaced as well during a timing belt + water pump job, does this mean they also drain the radiator so you now have nearly 100% new coolant in the system? I've always wondered about this grin.
Posted by: bdcardinal

Re: Water pump replacement and coolant - 01/13/14 10:34 PM

Most will drain from the radiator so they avoid the mess when you pull the water pump.
Posted by: FL_Rob

Re: Water pump replacement and coolant - 01/13/14 10:41 PM

Every block is alittle different but basically it's drained at least to that level, some will remain.When you pop the hose off the WP the coolant is lost unless locking hose clamps are used and or the lost coolant is saved and returned to re-fill it.Thats pretty chintzy though.
Posted by: Jimmy9190

Re: Water pump replacement and coolant - 01/13/14 11:28 PM

When I replaced my water pump I drained the old coolant out by removing the lower radiator hose. Then coolant came pouring out of the block when I removed the pump. My engine has a block drain but I did not open it. There was not much left in the block anyway, it took right at the rated spec, I think it was about 2.5 gallons of 50/50 coolant to water to re-fill the cooling system. I used brand new coolant and water when I re-filled it.
Posted by: KB2008X

Re: Water pump replacement and coolant - 01/14/14 12:19 AM

If in fact the radiator was also drained, and not everyone does that automatically for various reasons, when the water pump was replaced then anywhere from about 60% to 80% of the coolant may have been drained.

The location of the water pump on the engine determines how much coolant is drained from the engine while changing the pump. Some engines have the water pump lower or higher on the engine than others, therefore more or less coolant is drained out of the engine and cooling system.

As for the radiator being drained, that depends upon a number of factors. One is access to the drain plug or petcock. In some vehicles it is next to impossible to get to, so the lower radiator hose is pulled instead and that is sometimes nearly as effective as draining from the drain plug. Other factors are how much time the mechanic has to do the job, how neat he is, how conscientious he is, what the shop protocol is, etc. In other words don't assume that the radiator was drained, and drained properly, in the course of replacing your water pump.

Even if the radiator was drained when the pump was changed there will still be old coolant left in the engine, and probably in the heater core and various hoses. The only way to get 100%, or even 95%, is to use a coolant change machine, which are often useless and I don't know if anyone still uses them anymore, or repeated cycles of drain, refill with water and running the engine, until the fluid drained out looks like straight water. For my cars I prefer the repeated drain and refills.

It's an arguable point as to whether or not removing 100% of the old coolant really makes a big difference. There are lots of cars on the road with way over a 100,000 miles that have had the cooling system serviced in a half...way manner that are still running fine.

If they made an honest attempt at draining the radiator and refilled with the right coolant you're probably OK.
Posted by: bvance554

Re: Water pump replacement and coolant - 01/14/14 12:30 AM

Unless you paid them for a coolant flush and refill I would assume they topped it off.
Posted by: demarpaint

Re: Water pump replacement and coolant - 01/14/14 02:28 AM

Originally Posted By: bvance554
Unless you paid them for a coolant flush and refill I would assume they topped it off.


For sure, if they did flush and refill you'd see it on their invoice and be charged for it.
Posted by: motor_oil_madman

Re: Water pump replacement and coolant - 01/14/14 07:18 AM

Originally Posted By: demarpaint
Originally Posted By: bvance554
Unless you paid them for a coolant flush and refill I would assume they topped it off.


For sure, if they did flush and refill you'd see it on their invoice and be charged for it.


Very true. In this case they probably saved the coolant in one of those 5 gallon clean yellow plastic oil change type containers and just refilled it with the original coolant.
Posted by: KrisZ

Re: Water pump replacement and coolant - 01/14/14 07:27 AM

Originally Posted By: motor_oil_madman
Originally Posted By: demarpaint
Originally Posted By: bvance554
Unless you paid them for a coolant flush and refill I would assume they topped it off.


For sure, if they did flush and refill you'd see it on their invoice and be charged for it.


Very true. In this case they probably saved the coolant in one of those 5 gallon clean yellow plastic oil change type containers and just refilled it with the original coolant.


Yup, if you did not pay for new coolant it sure as heck wasn't changed, maybe topped off. People like to assume that things just happen all on their own.
Posted by: Tegger

Re: Water pump replacement and coolant - 01/14/14 07:45 AM

Originally Posted By: mclasser
All the coolant that flows out during a water pump replacement effectively drains coolant from the engine block, correct?

Depends on the engine.

Originally Posted By: mclasser
So when mechanics say the coolant is replaced as well during a timing belt + water pump job, does this mean they also drain the radiator

They drain the rad AND THE BLOCK.

On a Honda, if you pull the water pump without draining the block, a quart of coolant will pour all over the engine in the worst possible place once the pump is loose, and make a big mess. So you drain the block as well as the rad before pulling the pump. Once the block is drained, only a small dribble will escape when the water pump is removed.

Don't let ANYBODY tell you that you can change the coolant properly without draining the block. Doing so is a "fudge" performed by home mechanics who are trying to get out of doing a proper job.