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Flush & Fill Procedure for 3.5L

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#1 · (Edited)
Engine Coolant Flush & Fill Procedure for 3.5L

So I did a flush and fill on my 2010 SE this last weekend, and between the missing/incorrect info in the Haynes/Chilton manual and my lack of experience in doing a F&F on a vehicle mfg'ed in the last 10 years, I'm surprised I got it done without screwing anything up. So I figured I better try to make good use of some of that hard-earned knowledge I gained this weekend by trying to impart it upon my fellow Challenger owners here on CT.

I realize the number of people who could actually benefit from this thread is probably pretty small since it is going to be specific to the 3.5L engine that came in the 2009 and 2010 Challenger SE/SXTs, but all I could find when I searched around before the maintenance for a 3.5L specific write-up for this, I couldn't find one. They were all specific to the Hemi's, which is a little different from the 3.5L if you haven't noticed.

And while we're on the topic of which engine this will be focused on, let me just state for the record that if your Challenger is 2011 or newer and has a V6, then this write-up is NOT for you. You have the 3.6L (aka Pentastar) that Dodge replaced the 3.5L with beginning in 2011. So if you plan on doing a F&F on yours, this write-up won't make much sense when it comes down to the details and pics and such because you have a completely different motor.

Anyway, let's get on with the show...

Since the Haynes/Chiltons manual for these model LXs already has the F&F procedures written up, I will just copy and paste them in here to save time and effort. However, as I found out the hard way, not all of the steps they list are correct, and there is some info missing in other areas about what to do or what to expect. So I will point those out and try to fill in the blanks where necessary with the manual steps, and hopefully that will give anyone reading this enough knowledge to get the job done if they choose to do it themselves.

So here's the first page in the manual that applies to us here (pg 1-27):

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That one covers the steps to drain the original coolant out of the engine, as well as flushing the system out to get rid of any remnants of that old coolant and the crap it can leave behind if left in the system too long. The drainage steps can be followed all the way up until Step #7 where it references drain plugs. You can forget about removing any drain plugs to completely drain the engine, as there are none on these last few year model 3.5L engines evidently. And even if there were, you wouldn't be able to get to them because of the exhaust manifolds. So forget about drain plugs and keep going with the next steps.


The next page from the manual is the one that details flushing the system (pg 1-28):

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As you can see there, one of its steps is to remove the thermostat and reinstall the thermostat housing before doing the flush.


The section that deals with the thermostat and thermostat housing is in section 3 (pg 3-4):

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Now that section is the one that strays the farthest from reality when it comes to what you will encounter in your Challenger's 3.5L. First of all, your thermostat is not swaged as the manual states, so you won't have to worry about any of that part if you replace the OE one with a new one from the local auto parts store (which I recommend doing since you already have it out and won't want to go through all the trouble to remove it again later to replace it when it starts to f-up on you). Also, your thermostat housing has a rubber gasket built into its base (as does the thermostat itself), so disregard any talk about replace the gasket on the housing or scraping the block clean before re-installation of new gasket and thermostat. None of that will apply to your 3.5L's thermostat, which is actually a good thing IMHO.

One other thing about the thermostat housing that the book does not say anything about is that yours has a small tube coming out of the bottom of it that goes down to the oil cooler that is integrated with your oil filter housing. And before you can get that thermostat housing loose, you will need to crawl up under your car and remove the hose clamp holding the coolant line to the bottom of that housing, and then you will need to wiggle it up and out to allow the thermostat housing to be removed completely. Removing it is a little tricky, but re-installing it is downright frustrating because of that oil cooler tube that you will have to get back into the correct position before anything will bolt up.


And one last thing I want to point out before we leave the thermostat section and go back to the fun part (pg 3-19):

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As you can see, there is the torque specs for the housing bolts for re-installation. I'm only including that so no one can accuse me of leaving information out of this thing. You won't be able to actually use it when you reinstall the housing because there is just no room to get a torque wrench down in there to torque the bolts. I suppose you could remove the power steering pump and a/c compressor and then maybe you'd have enough room to torque those bolts, but that's not even close to being worth it. They are only supposed to be 105 in/lbs, which is about 8.5 ft/lbs. So just tighten them with a wrench until they won't turn any more and you'll be fine.


Speaking of specs, here is the page from the first section which lists the fluid volumes for the car (pg 1-30):

Text Document Font Paper Menu



As you can see there, it states you will need 11.1 quarts of coolant to replace what is in there. While that might be true if you had access to those imaginary drain plugs, I'm here to tell you that you will not be able to get all of the water you use to flush the block out of the block, especially if you use their method of doing it, so you won't be pouring 11.1 quarts of coolant into the engine to refill it. At most, you will only get about 9 quarts to go back in it. And remember, you're supposed to mix the coolant with distilled water at a 50/50 ratio. So if you buy one gallon of concentrated antifreeze, then all you'll need is a gallon of distilled water you'll be good to go. Or you could buy two gallons of the premixed 50/50 stuff and just pour it all in without worrying about mixing it correctly. Either way, that's about all you'll need, not the full 11 quarts.

So now you have the knowledge necessary to go tackle this yourself...NOW GO DO IT!!

Seriously though, the factory pour only has a useful life of 5yrs/100K miles, so if you are over either one of those, you need to change it NOW! Take it from me, as mine was over the year limit by a full 13 months, and once I pulled my expansion tank off to clean it, I saw why it has a life span which should not be exceeded. Mine had started turning into some sort of gelatinous goo down at the bottom of the tank, very much like chocolate pudding actually. It also started to solidify into what can only be described as sand-like material. There was so much of that in my system that it clogged the filter on a funnel I was using to empty the jugs out I was using to collect the old coolant. That was very unnerving to say the least!

I took some pics during my whole process, and I'll create another post in this thread and attach them to it for visual reference on some of this stuff. Especially the crap coming out of the car that was being replaced, that stuff was nasty gross. It has to be seen to be believed.

And with that, I will wish you good luck and say, "May the Schwartz be with you!"
 
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#2 ·
Details, Details...

As promised, I am back with some of the pics I took during the maintenance event. These are going to be of some of the details you'll need to take care of before getting to the good stuff.

1st thing is getting the vehicle jacked up and leveled off. I knew I would need to get the car far enough up off the ground to be able to crawl around underneath it and maneuver my arms enough to do things like undo hose clamps and such. And I also knew that the act of flushing out the system would mean some water and antifreeze was going to end up on the ground beneath the car, so I didn't want to do this with the car in the garage. That made the driveway the only logical place to do the deed, but since it is sloped a little, I didn't feel good about trying to jack it up and put it on jack stands without an accident occurring. The solution was a set of wooden ramps I built to do things like oil changes and such...and as it turns out, coolant flush and fills:

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After backing the car up onto the ramps, I was able to use my jack to jack up the front high enough to where it was about level with the back, and then to put jack stands underneath it. Turns out that was just about perfect height.


Next detail is getting everything out of the way. Two of those things are the oil sending unit wiring harness plug and power steering pump wiring harness plug. The oil sending unit is on the front of the timing chain cover and is a bright green color, so it's pretty easy to spot. The power steering unit is on the driver's side of the engine basically on top of the power steering pump...and as it turns out, right in front of the thermostat housing.

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You need to unplug those two wiring harness plugs because their wires are run directly in front of the thermostat housing and will be all-off in the way while you're trying to remove it. So unplug them, pull their wiring harness wires up and out of the way.

One last thing: both plugs have a little red key which has to be positioned correctly to remove the plug. Basically, if you can see the red key on both sides of the plug, it is locked. Push it over to one side until it is only visible on one side, and it is then unlocked and can be pulled off the unit.


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#3 ·
Thermostat & Housing

These pics will be of the thermostat housing and thermostat since they both differ from what is in the manual.

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There you can see the housing after it is removed from the block. As you can see, it's got a section that goes straight down and that is where it connects to the oil cooler line.


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Those pictures show the housing still on the block as viewed from the driver's side fender. The red arrows are the two bolts, and if you'll look closely, the bottom arrow'ed bolt has a wrench already placed on it. That's to show you that the only way to get that bolt off is to come at with a 10mm wrench from the front of the engine. It might seem intuitive now that you're seen it, but it took me about a half-hour of messing with it from all directions to figure that out.

The yellow arrow denotes the oil cooler line extension.
 
#4 ·
Bleeders & Rubbers, Oh My!

Ran out of slots for attachments in the last post, so here's one more of the thermostat inside the housing still, which shows the built-in rubber gaskets they both have:

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So as you can see there, you don't need to worry about scraping the engine block of the old gasket or buying a new gasket, which by the way will look like this:

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BUT DON'T BUY THAT!!! Cause you won't need it.


These three pics show the location of the bleeder screw and of the plastic tubing attached to it to keep the coolant from burping out of it all over the accessory belt.

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#5 ·
Fin

In the last of my illuminating posts, I have pics of the expansion/overflow tank and the crap that you're trying to get rid of by doing this whole deal.

So when you go to refill the system, you'll want to clamp off the hose that runs from the expansion side to the overflow side of the coolant tank:

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Speaking of that tank, when/if you remove it from the vehicle to clean out, you may notice that you are getting water and cleaning fluid into the overflow tank, which doesn't appear to have any way of emptying it. But there is, as you will find a small weep hole on the side that butts up against the fender when it is mounted:

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And here you have the reason that you are doing this in the first place. For if you do not remove the old coolant, then you will have silt and sand clogging up your system and just generally making it more difficult for the cooling system to keep the engine cool:

Water
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