Cooling System Drain & Flush 2015 Jeep Grand Cherokee 5.7 V8 ?

[billt460]

Has anyone ever done this without bleeding the system? The bleed plug on my vehicle is hard to get at. (So is the radiator drain plug for that matter). I've never had to bleed a cooling system before. Simply drain, flush with distilled water until clean. Then drain and fill with 50/50 mix.

Then I then drive it until it's hot, (thermostat opens), and park it. The next morning it will suck down the overflow tank as it cools, and then I simply add more. The system, "self bleeds". After one or two heating / cooling cycles all the air is out, and the coolant level stabilizes.

Can I safely do this on my 5.7 Jeep? I'm not seeing any real difference. All engines have areas where air can get trapped. But it gets worked out after a couple of heating / cooling cycles. I drive it only long enough until the thermostat opens, then park it until it's cold.

I don't drive it for extended periods until it completes a few short trips to warm up and cool back down. Thereby working out all the air and stabilizing the coolant level in the process.

 

[Johnny248]

We have a '11 Grand 5.7 and a '11 Ram 1500 5.7, and I've always just used my "spill proof funnel" and ran it, held rpm, let it do its thing and it's always worked fine. I change the coolant every other year. 170k and 150k without issue.

 

[The Critic]

Just invest in a vacuum filler.

 

[JHZR2]

Seems like you need an answer from others that have the exact same vehicle… maybe on a jeep forum?

I have some vehicles that it works super easy, and some that will show being on the verge of overheating because air stays trapped if you just spill and fill.

 

[cptbarkey]

Has anyone ever done this without bleeding the system?

Then I then drive it until it's hot, (thermostat opens), and park it. The next morning it will suck down the overflow tank as it cools, and then I simply add more. The system, "self bleeds". After one or two heating / cooling cycles all the air is out, and the coolant level stabilizes.

done it, yup, it works.

 

[billt460]

done it, yup, it works.

Did you simply drain and fill? Do you have the 5.7 HEMI V-8?

 

[The Critic]

Instead of speculating, would it kill you to pay for a short-term subscription to factory service information and look up the correct procedure?

 

[cptbarkey]

Did you simply drain and fill? Do you have the 5.7 HEMI V-8?

two of them. traded in some time ago. what does it matter? its not special.

 

[billt460]

two of them. traded in some time ago. what does it matter? its not special.

I agree. But I've heard of people having issues with air getting trapped in the system. One guy had it done at the dealer and it overheated on him.

 

[JHZR2]

I agree. But I've heard of people having issues with air getting trapped in the system. One guy had it done at the dealer and it overheated on him.

Did it really overheat though?

On the MB 6 cyl OM603 diesels (only, I don’t encounter this on the 4 or 5 cyl in the same family), there is always an air bubble. Thus the temperature rises super fast. Hardly any makeup water is needed to get the system to full - that part was already done with the initial fill. But it takes a thermal cycle and a bit of a scare to get water in the right place so you don’t think it is overheating…

 

[billt460]

Did it really overheat though?

On the MB 6 cyl OM603 diesels (only, I don’t encounter this on the 4 or 5 cyl in the same family), there is always an air bubble. Thus the temperature rises super fast. Hardly any makeup water is needed to get the system to full - that part was already done with the initial fill. But it takes a thermal cycle and a bit of a scare to get water in the right place so you don’t think it is overheating…

I have to agree with you there. I have never heard of any engine damage because of "trapped air" in a cooling system from a drain and flush. There are always going to be air pockets until the coolant gets pumped through the system. And until all of it gets up to operating temperature.

If an engine as popular as the 5.7 HEMI V-8 had a design flaw that caused this to a large enough degree where engine damage would occur from severe overheating, you would be hearing about it everywhere. And there would be a TSB on it. There isn't.

 

[The Critic]

I have to agree with you there. I have never heard of any engine damage because of "trapped air" in a cooling system from a drain and flush. There are always going to be air pockets until the coolant gets pumped through the system. And until all of it gets up to operating temperature.

I’ve seen it cause HG failure on some older VQ35 engines.

Not sure about the HEMI platform, specifically. But I don’t take any chances.

 

[billt460]

HG ???

 

[DuckRyder]

Head gasket.

Like seriously how hard is the bleed screw to reach?

 

[SaberOne]

Thanks for reminding me that I have to do mine. I’ve been dragging my feet for quite a long time on this task.

 

[billt460]

Head gasket.

Like seriously how hard is the bleed screw to reach?

On my vehicle it's a pain. There are covers and brackets in the way. I can't even get to the drain plug on the radiator, without first removing a bunch of covers and crap. They don't make it easy, that's for sure.

On my older Ford F-150, I can reach down from the top and unscrew the drain plug. And as far as I know there are no "bleed screws" or ports because you don't need them. At least I never did.

 

[LouC]

The bleed screw on the Hemi is in the water pump housing and they often seize in place. If you just drain the radiator then it doesn’t get all the water out of the block & you can bleed out the air by using one of those radiator funnels (I have the Lisle). Now if you pull the lower hose & drain the block here’s what I’d do to avoid air pockets: replace the lower hose & fill the rad mostly full. Then remove the thermostat housing at the top of the water pump casting. Stick a funnel in that opening & fill it slowly allowing air to escape. Then reinstall the thermostat housing & fill the rad the rest of the way. That will get the block mostly full. You want coolant up against the back side of the thermostat not air. There is also a temp sensor you can remove that allows you to further bleed out air (see Motorcity Mechanic’s you tube channel for further info on this).

 

[billt460]

I saw Motor City Mechanic's video on the temp sensor. That's what I would go with. Not the Allen Head plug that often seizes up, like you mentioned. But it's still a pain on my vehicle. Just not as bad.

 

[LouC]

I’d definitely fill the engine slowly from the thermostat housing mount on the water pump it’s pretty high up and at least you know the engine is mostly full of antifreeze before starting it up.

 

[The Critic]

The bleed screw on the Hemi is in the water pump housing and they often seize in place. If you just drain the radiator then it doesn’t get all the water out of the block & you can bleed out the air by using one of those radiator funnels (I have the Lisle). Now if you pull the lower hose & drain the block here’s what I’d do to avoid air pockets: replace the lower hose & fill the rad mostly full. Then remove the thermostat housing at the top of the water pump casting. Stick a funnel in that opening & fill it slowly allowing air to escape. Then reinstall the thermostat housing & fill the rad the rest of the way. That will get the block mostly full. You want coolant up against the back side of the thermostat not air. There is also a temp sensor you can remove that allows you to further bleed out air (see Motorcity Mechanic’s you tube channel for further info on this).

My 2020 doesn’t mention a bleed screw. Just says to use a vacuum filler.