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91Pioneer

Flush coolant just in engine?

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OK kind of a different question here but here goes... the coolant in my truck is easily 9+ years old (previous owner did nothing for maintenance), it's brown, it's low, it's chunky, it's nasty. The rad has a minor leak.

 

So I've got all new heater & rad hoses, and a new rad on their way to me. I'm obviously replacing those plus the coolant. My plan is to manually flush the heater core using the garden hose, flushing it out good both ways. When I put it back together I am bypassing the heater control valve and using 97-01 Cherokee heater hoses.

 

So the only thing left without a proper flush is the inside of the engine where the coolant resides. I'm just wondering is there an easy way to flush it out? Can I just remove the thermostat and spray my hose in there to flush it out? I'm aware there are coolant drain plugs in the engine but I'm thinking they could be a pain to access/remove, no?

 

If not, I will just flush the entire system before I replace any parts and call it "good enough".

 

p.s. I'm still debating about replacing the thermostat. I probably will wind up putting in a new Mopar unit.

 

p.p.s. Lucky me, I own an Uview Airlift which makes refilling stupid easy :)

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Remove thermostat, stick in hose.  There will be residual water in the block after this, so you'll need to add a slightly more concentrated blend of antifreeze.

 

If you're replacing most other cooling system parts, why would you even question changing the $10 thermostat too?  Do it.

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Prior to the flush.....drain some fluid out and pour in a gallon of vinegar (or more).....run it up to temp......this will loosen any scale and gunk in there....

 

Then drain and rinse it like you planned.....the only residual effect you will get is the urge for fish and chips for the first few miles.... :cheers:

 

And yea......Change the stat

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Ha ha. I don't know where you by OEM t-stats from, but try $30-ish, not $10.

 

Vinegar is like the best cleaner for damn near everything. Cleaning windows, anything around the house, etc. It's really awesome, too bad it smells worse than butt. OK maybe not that bad LOL

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The engine block drain is somewhat of a PITA to remove but it is definitely do-able.  If you have a sacrificial socket extension that you can grind down to fit, you can then put it on a breaker bar and pop it out.  Then you can flush away to your hearts content, back forth (thru the t-stat hole) You can use some sort of surfactant (low suds, high phosphorus, like dishwasher soap) to really get the dirt, crap and rust out of there.  I did this when I did my head with all good results and no ill effects. he

 

Once you drain the coolant there is not really a whole lot of coolant/water in there, mostly just around the bottom of the cylinders.  That is where the real sludgy crap also lives (as well as the small galleries in the head), so getting it out is important too.  Once you get the crap out, and rinse it really good, let it dry.  Put it all back together and sealed up, then flush it again with clean water...and drain it.  Hopefully you've flushed out the heater core separately, back and forth till it runs clean, clean clean...then fill the whole thing up with the 50/50 distilled water and coolant.  At tthis point you really don't need to add extra anti freeze.  A 52/48 mix is not going to make much difference.  

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You might be able to find the correct driver for the block drain plug at Princess Auto. Just a suggestion. It's an odd metric square, IIRC.

Also, a 50/50 antifreeze is only good down to around -40. I run ~2:1 just in case, and haven't had heat issues.

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I'm guessing the drain plug is the 8mm square like I had to use on my BA10?? It doesn't matter I won't be doing that.

 

OK well I bought coolant from crappy tire today, it was on sale today 25% off. I also bought prestone flush. I decided to make it easy I will just drain, flush/clean the whole system, drain, then take it all apart, flush the heater core separately and won't worry about the engine specifically. A little extra water in there, no big deal, I'll adjust the ratio 60/40 probably. I have an air hose attachment so I will blast the heater core with a small bit of air to help clear out any leftover fluid in it (I know, too much pressure can cause a leak).

 

The bottle says 50/50 is good down to -37 C. Well it got down to -34 here last February and really anything down to -40 is possible. So I think I'll do 60/40 which is good down to -50 C.

 

My rad arrived today, the Spectra CU1193. It's a beauty, looks good and with free shipping from Amazon it was a great deal. I would guess shipping on that thing would be $30+.

 

The hoses should be here next week so maybe I'll spend Xmas day working on the Jeep ha ha.

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on something that old if your changing everything ive ran CLR cleaner to clean it out. did it to this mj and it was in super bad shape looked like pure rust in the block and the radiator. i did buy a new radiator, thermostat  and water pump  

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I'm sure CLR would work, but since it's not designed for that, I decided to get the Prestone stuff that I know will work too. I used it on my 88 MJ. CLR could be to acidic, I have no idea.

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