Wondering if anyone has a shop manual for a 3.8L (2008 here) that could advise on proper procedure for coolant drain and flush procedure.

Lots of pots and you tube clips on, even some from coolant manufactures:

-cool motor, drain fill with water.
-run motor to operating temp, then turn off allow to cool
-drain and fill with water
-run motor to operating temp, then turn off allow to cool.
-fill with 50/50 coolant as per manual spec.

Ok. But the process of fill drain a few times with water is good to flush, and some information I see suggest a chemical to flush as well. To me this leaves plain tap water (x amount) still nicely primed in the water jackets and areas you can't drain.

Would that not throw off your 50/50 mix ratio when you fill for the final time?

How do you drain the block? Is it even necessary? Do most just drain fill with 50/50 coolant not worry about a flush and just move on with your day? LOL.

Thanks

 

CLEANING/REVERSE FLUSHING

CAUTION: The cooling system normally operates at 14 -16 psi pressure. Exceeding this pressure may damage the radiator or hoses.

Reverse flushing of the cooling system is the forcing of water through the cooling system. This is done using air pressure in the opposite direction of normal coolant flow. It is usually only necessary with very dirty systems with evidence of partial plugging.

CHEMICAL CLEANING

If visual inspection indicates the formation of sludge or scaly deposits, use a radiator cleaner, Mopar® Radiator Kleen or equivalent, before flushing. This will soften scale and other deposits and aid the flushing operation.
CAUTION: Be sure instructions on the container are followed.

REVERSE FLUSHING RADIATOR

Disconnect the radiator hoses from the radiator fittings. Attach a section of radiator hose to the radiator bottom outlet fitting and insert the flushing gun. Connect a water supply hose and air supply hose to the flushing gun.
CAUTION: The cooling system normally operates at 14 - 16 psi pressure. Exceeding this pressure may damage the radiator or hoses.

Allow the radiator to fill with water. When radiator is filled, apply air in short blasts allowing radiator to refill between blasts. Continue this reverse flushing until clean water flows out through rear of radiator cooling tube passages. For more information, refer to operating instructions supplied with flushing equipment. Have radiator cleaned more extensively by a radiator repair shop.

REVERSE FLUSHING ENGINE

Drain the cooling system, then continue with reverse flushing procedure.

DRAINING COOLING SYSTEM


WARNING: Do not remove the cylinder block drain plugs or loosen the radiator drain**** with system hot and under pressure. Serious burns from coolant can occur.
NOTE: Radiator drain**** is located on the right/lower side of radiator, as viewed from behind the radiator.


1. Remove radiator pressure cap from radiator or coolant recovery container as necessary.
2. Raise and support vehicle.
3. Attach one end of a hose to the drain****. Put the other end into a clean container. Open drain**** and drain coolant from radiator.
4. If necessary, siphon coolant from coolant recovery container. (Diesel engine)

Remove the thermostat housing and thermostat. Install the thermostat housing. Disconnect the radiator upper hose from the radiator and attach the flushing gun to the hose. Disconnect the radiator lower hose from the water pump. Attach a lead away hose to the water pump inlet fitting.

CAUTION: Be sure that the heater control valve is closed (heat off). This is done to prevent coolant flow with scale and other deposits from entering the heater core.
Connect the water supply hose and air supply hose to the flushing gun. Allow the engine to fill with water. When the engine is filled, apply air in short blasts, allowing the system to fill between air blasts. Continue until clean water flows through the lead away hose. For more information, refer to operating instructions supplied with flushing equipment.
Remove the lead away hose, flushing gun, water supply hose and air supply hose. Remove the thermostat housing. Install the thermostat and housing with a replacement gasket. Connect the radiator hoses. Refill the cooling system with the correct antifreeze/water mixture.

I see this site doesn't like the perfectly legitimate word "drain****".

So, let's try another legitimate name for it: pet****

Oh well.

 

Thank you Ron, I was hoping you'd see my post.

At this point i think the Chemical flush is best suited for my Jeep.

Very interesting read on the drain procedure! With the T-Sat removed, flush gun on top rad hose, and hose on water pump removed, run water until clear. Makes sense.

I'm reading between the lines here...in this above set up once water is running clean, allow to drain...then use short burst of just 'AIR" to fully purge any remaining water left in the block. Does that sound right? If so, then then you really do start with a empty block, rad ect....and this should not effect your 50 / 50 mix ratio.

To me that sounds like a very good and complete flush and drain.

Looks like I need to finally break down and purchase a small air compressor for my garage, and a flush gun of some sort (purchased or manufactured)

I'm sure the dealer charges a pretty penny for this, so that helps the purchase of tools.

I will change the T-SAT while I'm there, coolant sending unit (it freaks out from time to time) rad cap is only 8 months old...started to leak. Only think I debate in my head is leave the water pump alone, or change it?? No signs of any leaks, weeps, nosie ect....187,000KM original (knock on wood)

All hoses look good, no cracks, bulges, splits....still seem soft when inspected with a warm motor.

Thanks again Sir.

 

Spigot. LOL.

 

The dealer charges $180 to do the flush and fill. To the point of the chemical flush, I don't know that it's changed but the 10 states not to use any generic flush (prestone) as it is not "good" for the system.

I did my own flush/ fill at 100k per the manual but did fills with distilled water. Tilting the jeep up on the driver's side helped to get more coolant out of the radiator. Lifting it up on the passenger side helped to burp they bubbles.

Be careful with your petc0ck, it's only 1/4 twist (IIRC) and it should pull out. The radiator and "pet" are both plastic in that area so be careful not to break either. I purchased a spare "pet" in case the o-ring tore on my removal/ installation. Jeep runs just as cool now after the change as it ever did and the fluid checks out for proper protection level.


Tips... clean that drain hole thoroughly before your final fill. Failure to do so will leave you with random leaks at operating temps, randomly. I had to pull it all back apart, clean the hole, and try again. Also, clean out your overflow by removing it from the jeep and get the casting sand out of the bottom of it. It's not easy but it does come out.

 

In the above procedure, the air is used in short bursts while the engine is full of water. Allow the water to refill the block between air blasts. (I've never used air, though. Seems just flushing with water has been fine.)

Any water remaining in the block won't affect the ratio since it can be adjusted easily after running by removing some of the mix, and adding water or straight antifreeze as needed.

 

^ thanks again Ron... Will be tackling this work next weekend