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How to change upper and lower radiator hoses - with pics

96K views 37 replies 20 participants last post by  MaddMannDA 
#1 ·
Im shy of hitting 134,000 miles and will be doing some long trips pretty soon.
So I chose to replace my radiator hoses. (and my idler pulley).
(in the process most of the dexcool will be replaced since it needs to be drained).

I 1st purchased a pan- $5 at walmart.
Also bought 50/50 premixed dexcool. ($11 each). I used 2 bottles.
Dexcool is 150,000 mile coolant….
I chose NOT TO flush the engine… why?
Because at
47,000- my water pump was changed.
111,000 my thermostat was changed.
This means that over its life- my coolant has been mixed in with new coolant. So its not all the original factory coolant. Also—This is what my engine looked like at 111K….CLEAN.
So- I knew my engine was going to be very clean. If you’ve never changed pump or thermostat and have high mileage and the original coolant--- you may opt to flush the engine with distilled water,


So I bought ACDelco hoses. Actually theyre cheap about $40 for both.
I placed plastic on the ground to contain any spills.
Most trailblazers do not have a drain valve on the radiator. (I think 2002’s did).
Since I was going to replaced the old hoses.. I simply chose to drill a hole into the lowest part of the lower hose.
Once drilled- I placed the drill bit back into the hole to help drain…. This way you can control the draining of the coolant. Its slow—but it falls into the pan.
In this pic note the drill bit—and under the pan--- plastic to keep driveway clean. (Open the radiator cap to get airflow)


While the coolant drained-
I took a chance to photograph the new hoses. I also hooked up my laptop to the OBDII port to check for any pending CEL codes.
Comparing the old and new hoses for fit….



Once the coolant drained low enough- I took a picture of the radiators internal fins…….. 134,000- and no gunk or mineral buildup… this is the factory radiator.



I then proceeded to remove the upper hose. I used VISE grips to tighten the clamps. I think they also have a tool for these clamps at auto parts.
For some people- you may find that the rubber is really stuck on to the metal…I simply sliced the hose with a razor blade to help remove it. On the radiator—it came off easy- since it appears to be plastic.
On the engine side I did have to slice the hose and use a screwdriver to unstick it.
Here is the upper radiator hose connection at the engine block… Clean…(you can see the serpentine belt right below it)


Here is the upper hose cut at an angle.. very clean hose- looks to be in very good shape for 134,000.


You may have to fiddle with how to put the hoses and clamps back on. I found it easier to put the clamp on the radiator and inlet 1st- then slide the hoses on—as the hose slid on—then I put the clamp on the hose…
Putting the clamp on the hose—and then trying to slide it on--- wont work- the clamp only opens so far--- and it will not clear the small bumps on the inlet/rad connection points…

I then looked at how I would remove the lower hose.
The lower portion is easy.
The harder clamp to remove is the connection where the thermostat inlet is.
This is how I did it WITHOUT removing the alternator. (I left the clamp in a certain position from the thermostat change at 111K).
Disconnect battery.
I removed the battery hold down bar.
Remove the battery cover and battery.
Unbolt the Horn.
You can now access the 5 bolts that hold down the battery tray.
This leaves some working room.
This trick I used- was necessary because the vise grips wouldn’t fit with the handle open…..
Close the vise grips- turn the knob so that the grips claws are at their widest… you can then maneuver the claws on to the hose clamp- once in this position- use some pliers to slowly turn the knob- slowly compressing the clamp. Once compressed - slide the clamp toward the engine--- You can now try to remove the hose. (if this wont work for you- You may be able to access the clamp from the tire wheel well- or youll have to remove the alternator (all depends on how the clamp was left pointing from the factory).
In this picture im compressing the clamp--- the item that is in the way—is that big hose--- I believe its AC compressor related.(this also gets in the way when you do the Thermostat repair).


Remove the old hose- remove the sleeve around your old hose and put it on the new one. (almost like fishnet—most likely to help with rubbing againsts other items).
I chose to replace the one troublesome hose clamp with an old fashioned hose clamp--- the type that you tighten with a screwdriver or socket. Simple slide the hose on and tighten the hose clamp.
The inlet at the thermostat was also very clean(changed at 111K).

I then clamped the lower hose at both ends- and proceeded to put the tray, horn, battery, cover, bar back on.

I refilled the radiator- and started the engine- I left my laptop connected to monitor engine temps- and topped off the radiator.
I closed the radiator cap. And let the engine run for about 20 minutes. I also got under vehicle and checked for leaks. None found.
Later in the evening I went for a drive- Got on the highway and did a few full throttle accelerations to get the fluid moving and dislodge any trapped air pockets.
Went home and parked for the night.
The next morning- I checked the overflow bottle… sure enough- overnight as the engine cooled--- the cooling system sucked in coolant.
I topped off the overflow bottle to COLD LINE. Over the next few days Ill continue to check the level- and monitor for leaks.

Here is the coolant I drained. Nice bright red. Theres a few specks in there.. that’s the drilled rubber--- and some debris that fell in from me removing the upper hose.
I put the coolant into the dexcool bottles—and labeled them OLD- DO NOT USE…
I will take these to the next Hazardous waste roundup.
 
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