Bad Experience with Cooling System Flush?

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bleech1

NAXJA Forum User

Location

Albany, NY

• Oct 30, 2003

• #1

I plan to convert my closed cooling system on my '90 4.0 to open in the next few days and was thinking of first flushing the system with a chemical flush such as Prestone and then backflush. Has anyone had a problem doing this on an older vehicle with high miles? Im concerned with clogging the water passages in my block or pump with the crap that has inevitably built up. Should I just swap out the radiator, or do the flush first?

 

Eagle

Lifetime NAXJA Member

NAXJA Member

Location

Terra Firma

• Oct 30, 2003

• #2

Flush first. Passages in the block are big enough not to be a problem. Radiator passages are small and could be clogged. You might wish to by-pass the heater core when doing the forward flush just for that reason. Make up some garden hose adapters and flush the heater core separately.

Craig H has a write-up on that at his "Swiss Army Jeep" web site:

http://www.olypen.com/craigh/

 

RichP

NAXJA Forum User

Location

Effort, Pa

• Oct 31, 2003

• #3

Those 15 minute fast flushes break some pretty big pieces loose. The 7 hour type flush does more dissolving of the build up. It does kind of a reverse plating effect vs the quick flush which is like blasting it with the shotgun.
If you have never replaced the heater hoses before don't try to pull them off, slice them lengthwise with a razor knife. If you do the lower hose make sure the replacement hose either has a spring inside to prevent it from collapsing or move your old one into the new one if it will fit.

 

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Mich88XJ

NAXJA Forum User

Location

Houghton, Michigan

• Oct 31, 2003

• #4

My only problem with this was draining the block. On my 88 it uses a male pipe plug socket (I forget the size) to pull the drain plug. For one it is hard to get at, and second off the thing was so rusted that it just rounded out the hole. I ended up just pulling the coolant temperature sensor at the front of the engine. I don't know what anyone else will say, but I would say just do this first, unless you think you could get it with the pipe plug socket.

 

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pancake

NAXJA Forum User

Location

Seattle, WA

• Nov 1, 2003

• #5

I am about ready to drain my 7 hour flush...we'll see.

 

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bleech1

NAXJA Forum User

Location

Albany, NY

• Nov 3, 2003

• #6

Does is matter if the prestone back flush is performed through the upper or lower radiator hose? What is the prefered method?

 

RichP

NAXJA Forum User

Location

Effort, Pa

• Nov 3, 2003

• #7

You want the heater inlet hose that is the hose that comes off the thermostat houseing area.

 

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bleech1

NAXJA Forum User

Location

Albany, NY

• Nov 3, 2003

• #8

RichP said:

You want the heater inlet hose that is the hose that comes off the thermostat houseing area.

Click to expand...

Thanks Rich, I've got that in place, but I was wondering if I should flush OUT of the lower or upper hose.

 

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mudhound32

NAXJA Forum User

Location

Long Island NY

• Nov 3, 2003

• #9

If I remember correctly the lower heater hose is the inlet. So if your going to backflush you should go with hooking up the water hose to the top thus giving you the backflush. I just finished this procedure last week and I now have heat!

 

RichP

NAXJA Forum User

Location

Effort, Pa

• Nov 4, 2003

• #10

If you stick that J shaped adapter in the radiator cap bung the water will come out of it. For neatness go buy about 4 or 5 feet of heater hose and stick it on the end of that adapter with a hose clamp so you can direct the flow better than just dumping it on your front bumper and grill.

 

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bleech1

NAXJA Forum User

Location

Albany, NY

• Nov 4, 2003

• #11

Thanks Rich, but I have a CLOSED system. No radiator cap.