Flushing cooling system and water pump installation (1 Viewer)

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Dec 10, 2007
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I'm doing a cooling system flush and water pump RR on my 96 80. While doing the oil pump and crank seal replacements I noticed that my water pump squeaked when rotated by hand and had a very slight amount of play, so decided to RR that while everything was apart. Glad I did as once I had the old pump off it was easier to feel the play in the axle shaft.

I've read through a bunch of previous flushing threads but in my case the water pump, fan, and belts are already out so no chance to run the engine. After draining the coolant with the heater valve fully open I flushed the system using a garden hose stuck into the radiator top where the pressure cap sits with the old water pump and radiator drain plug out. I did it a few more times until all the water coming out of the radiator was clear with no smell of coolant.

Edit: I found an interesting block drain plug with a mini-drain pipe attached; it's a 14mm steel pipe plug with external threads that screws into the block with an internally threaded hole to accept a 10mm brass bolt in the center (see photos below). It looked like it had never been opened before. I cleaned it up with an acid product meant for removing rust from clothes and was surprised how strong that stuff was, only took about a minute to remove the corrosion. What all the other threads say about opening the block drain are correct. After flushing via the radiator a few times with the water pump removed and the radiator drain out and no water in the system, when I opened the block drain I still got at least two more quarts of undiluted coolant. To reach the block drain I got on my creeper and positioned myself head first facing the front of the vehicle and reached up with my right arm and unscrewed it (had loosened it earlier via the wheel well).

Next time I drain the block I'll hold the main plug with a 14mm wrench while turning the brass bolt with a 10mm wrench. Probably also will put a section of rubber hose on that little drain pipe to better direct the coolant into a pan.
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80ways

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I believe I had to remove the block plug entirely. To put it back I used an extension and socket and started by hand. IIRC, the plug on my 97 was brass and has no drain pipe.
 
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Here's a couple more photos showing the coolant I drained and looking down into the radiator, it was very clean considering it's at least four years old. Only got a small amount of light grey sludge in the overflow tank and a tiny bit more when I flushed the radiator, and when I dumped the used coolant I noticed a small amount of red "sand" at the bottom of the pan. Guess using the Toyota Red is good for the system.
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It's super easy to get to the block drain with the DS wheel off. You have a direct line of sight. You just need the socket and about 2' of extensions.
 

94SRUNNER

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What MKTSC said on the block drain.

Nice write up Kernal. You mentioned that you didnt see a whole lot of gray sludge. In the picture showing the location the water pump bolts to, it looks to be, from the picture, a good deal of gray sludge that settled out? Or is the lighting?
 
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I was able to get underneath the truck to screw the block drain in and came back up to tighten it with a 14mm socket. BTW, your bolt looks different (appears to have some type of washer).
 
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94SRunner: No sludge, just the light and the wet metal. The sludge was on the bottom of the overfill tank; forgot to get a photo of it; there was a small "island" of sludge at the bottom of the tank maybe 3x1 inches by a couple of millimeters high. Here's a direct shot of the pump area, those bumps may have looked like sludge in the photo above.

harrydunn and mktsc: no problem getting to the drain plug, my concern was whether there was a trick to reach it to get it back in without removing the wheel.
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Here's a few photos of the bolts and studs that hold the water pump on. They all had some corrosion and old thread locker/sealant on them (top photo) which I cleaned up using a brass brush, a 8mmx1.25 die, and solvent (middle photo). I noticed however that the die removed some of the cad plating off the threads so next time I'll probably stick with just the brass brush. Also noticed that the shortest bolt had a different head marking (6) where the other bolts had the two opposing dashes (- -) which is a 6T. Not sure why, maybe someone lost the original bolt and used this one in it's place?? On the other hand, the FSM lists 15ftlbs for the torque spec on the water pump nuts and bolts which matches up with a 6T 8mmx1.25 flange bolt (up to 16ftlb). FWIW.
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Block drain is pretty straight foward. When removing the plug take a look and notice the plugs head does not sit flush like a regular bolt does. I though mine was cross threaded because I could not get it to sit flush and it was really tight.

My radiator was pretty sludged up, so I ran prestone cleaner in it. I reccommend using the set up in the FAQ with the PVC couplers and water hose with pressure gauge. Especially if your radiator is gunky. I fitted mine so I can flush the system either way especially to backflush the radiator. Just make sure to take you T-stat out.

If anyone is in the bay area they are welcome to borrow my setup.
I also have a 5 gallon bucked pre measured in 2qt increments and hose for the transmission fluid exchange.
 
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RWhat; My system as shown in the photos was clean and gunk free probably due to using the proper amount of Toyota Red (and nothing else).

Edit: the block drain I discovered is a tapered pipe type thread, like the plug used for the steering knuckles (different size however); it doesn't go all the way in because of the tapered threads. Read somewhere that tapered pipe threads seal better without the use of thread sealants or tape due to the design alone; apparently there is no gap between the pipe threads once it's snug unlike regular straight thread types.
 
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Reinstalled a new metal gasket and water pump. The gasket can only go one way but FWIW the high side of the dimple goes toward the engine. First I put the studs into the holes which are at about the 1 and 7 o'clock positions using Permatex insensitive Blue thread locker on the engine side threads, it has a higher breaking torque than regular Blue but not as high as Red. Then hung the metal gasket on the studs and the water pump over that. I used Blue medium strength thread locker on all the bolts and the nut ends of the studs before running the nuts down. The blue color in the photo is thread locker that got squeezed out, not silicone. The shortest bolt goes in the 9 o'clock position, the two long bolts go at about 3 and 5, and the middle length bolt goes at 10 o'clock, FWIW. The middle and bottom photos shows the casting numbers for the old and new water pumps; the new pump appears to have a better quality casting.
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RWhat; My system as shown in the photos was clean and gunk free probably due to using the proper amount of Toyota Red (and nothing else).

I wish my radiator was as clean as yours. I'm gonna replace my radiator in the future. My temps seem good. We shall see how it is in the summer loaded up headed to the sierras.

Also, i had toyota red in the system. It had Lexus service until the last 25k. For some reason the coolant did not seem diluted correctly. It was really concentrated.
 
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Fan clutch casting numbers and hub

Cleaned up the back side of the fan clutch mounting hub with some flat files and emery cloth. It had multiple gouges and rolled up metal high spots from some previous mechanic using a pry bar or chisel to separate it from the water pump pulley, which also had multiple dings. So many that they didn't fit completely flush together. When I took the hub off the water pump pulley I used a brass drift and hammer to tap it a few times and it loosened right up without any carnage. The other photo is of the casting numbers from what appears to be an original fan clutch (95).
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Cleaned up the back side of the fan clutch mounting hub with some flat files and emery cloth. It had multiple gouges and rolled up metal high spots from some previous mechanic using a pry bar or chisel to separate it from the water pump pulley, which also had multiple dings. So many that they didn't fit completely flush together. When I took the hub off the water pump pulley I used was a plastic hammer to tap it a few times and it loosened right up. The other photo is of the casting numbers from what appears to be an original fan clutch (95).
Is that the Eaton clutch? You doing the fluid in there also?
 
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The fan clutch appears to be the original Eaton, I added a photo of the front side uncleaned as it came off the engine. It seems to work fine so no plans on breaking it open just yet. FWIW the green rear seal/bearing in the photo in an NTN brand # 6205LUA1.
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I'm doing a cooling system flush and water pump RR on my 96 80. While doing the oil pump and crank seal replacements I noticed that my water pump squeaked when rotated by hand and had a very slight amount of play, so decided to RR that while everything was apart. Glad I did as once I had the old pump off it was easier to feel the play in the axle shaft.

I've read through a bunch of previous flushing threads but in my case the water pump, fan, and belts are already out so no chance to run the engine. After draining the coolant with the heater valve fully open I flushed the system using a garden hose stuck into the radiator top where the pressure cap sits with the old water pump and radiator drain plug out. I did it a few more times until all the water coming out of the radiator was clear with no smell of coolant.

Edit: I found an interesting block drain plug with a mini-drain pipe attached; it's a 14mm steel pipe plug with external tapered threads that screws into the block with an internally threaded hole to accept a 10mm brass bolt in the center (see photos below). It looked like it had never been opened before. I cleaned it up with an acid product meant for removing rust from clothes and was surprised how strong that stuff was, only took about a minute to remove the corrosion. What all the other threads say about opening the block drain are correct. After flushing via the radiator a few times with the water pump removed and the radiator drain out and no water in the system, when I opened the block drain I still got at least two more quarts of undiluted coolant. To reach it I got on my creeper and positioned myself head first facing the front of the vehicle and reached up with my right arm and unscrewed it (had loosened it earlier via the wheel well); also got another sweet smelling coolant bath.

Next time when I drain the block I'll hold the main plug with a 14mm wrench while turning the brass bolt with a 10mm wrench. Probably also will put a section of rubber hose on that little drain pipe to better direct the coolant into a pan.

My block drain is just a bolt. Is that aftermarket?
 
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The block drain plug appears to be original (it still had some cad plating on the threads before I cleaned it), but don't know for sure. Any parts gurus out there?? This drain plug concept could be modified/replaced so that the drain pipe points down and is a bit longer, that way you could easily slide a rubber hose over the pipe before you loosen the center bolt which in turn would allow draining the block coolant directly into a pan. From looking at the plug it has threads which seem to be very close but maybe not exactly the same profile (wider groove?) as the threads of the knuckle plug (?5/8 BSPT - 19TPI, an older British Standard Pipe Thread Tapered); the block drain plug is about 1/2" across. The photos compare a steering knuckle inspection port plug with the engine drain plug that came out of my 96 80.
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My drain plug seemed to be made out of brass. That's why I was worried about over torque when it went in. Has anyone elses plug not fully seat?

Kernal, seems like since you have everything out doing the clutch might be a good idea. It was actually easy. The hardest part was finding the fluid. I ended up mixing 2 different weights to get the weight I wanted.
 
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Rwat: the point I was making with the knuckle plug is that it doesn't screw all the way either because it also is a tapered pipe plug, they only screw in about 1/2 the length of the threaded length. It doesn't show up well in the photos but if you look closely both plugs are wider at the top of the threaded portion than at the bottom, they get narrower as you move toward the tip. So it follows that the engine drain plug will not screw all the way in because it's also a tapered pipe plug. When it gets tight that's it; the nature of the threads will seal it off, no need to go further.
 
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