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Discussion Starter #1 (Edited)
Hello all, first post. I just purchased a 1995 Suburban C2500 and started work on it. First order of business is checking and changing fluids. The overfill tank was nearly empty and after topping it off, the reservoir was full of rust water, meaning the cooling system was in trouble.

Decided to do a drain and flush based on GM TSB 99-06-02-012D. All was going well until I tried to carefully remove hoses from one of the two, 3-way heater quick-connect tees. It snapped like a crab leg. :eek:

Quickly I discovered the part was discontinued by GM based on the part number for GM trucks but the exact part continues to live for other GM products as part number
12522867 for over $10 per tee + shipping. Also, I discovered there is no aftermarket replacement and local parts houses don't carry it.

Frustrated by the lack of options and inspired by the challenge, I decided look up and cook up something better. Also I really don't like paying (over and over) for a bad design of a critical part for a critical system. :bat:

I discovered someone already made something better, so I went to work gathering parts, taking photos and constructing a better solution.

Based on info from research, I came up with a heavy duty brass fittings from SharkBite.

- Brass tee (x2) 1" X 1" X 1" UC374LF PEX Barb Core Fitting Tees for PEX Tubing Connection
- Brass reducer (x2) 3/4" X 1" UC060LF Reducing Couplings for PEX Barb Core Fittings from SharkBite

I found that both 3/4" and 5/8" fit the 1" and 3/4" snugly.

Construction - Cut two pieces of 3/4" heater hose 3 1/2" long and joined the 1" tee to the reducer (on the 1" end) with hose clamps.

Here is the end result...





Installed



Notes:
- Found these brass parts at the local Home Depot
- If the 3/4" hose joining the two brass pieces are longer than 3 1/2", the hose clamp may end up in the stacked hose support bracket; either make the joining hose longer or shorter
- The 3 1/2" hose shortened 1/4" after joining the brass parts for a total length of 3 1/4"
- When joining the tee and reducer, leave the hose clamps off until both parts are joined
- Use a flat, hard surface to help press the joining hose on
- Water or a water based personal lubricant (K&Y jelly) can help get the joining hose on each end of the brass fittings
- If using the 3 1/4" joining hose, or longer, it will be necessary to trim the 5/8" hoses that connect to the reducer
- I am not using a restriction nipple

Finished draining the cooling system, flushing the heater cores and will finish the flush tomorrow. More to come...
 

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I was wondering about the restrictor. I had the T fall apart in my 95 Caddy and while trying to come up with a replacement noticed that it had a restriction in it. What I cobbled together didn't quite work right. I don't remember what the deal was, it didn't have rear heat or anything like that. It must have been a bypass? At the time I was able to get one from GM and that solved the problem.
 

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Discussion Starter #3 (Edited)
I put the coolant system back together and successfully tested it. I had heat up front and in the rear once the engine reached operating temperature. If a problem comes up related to the OEM restriction orifice, I was thinking I could either add a restriction nipple or a check valve to limit the direction of flow.

If the restriction orifice is a mechanism for bypass, it seems that adding access to additional coolant should be a good thing. Will have to wait and see if this idea holds any water.
 

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I was just wondering if the restriction in the case of the burbs was to do with getting a balance between the front and rear cores?

In my caddy I was assuming it was to allow a path for coolant to flow with the stat closed. All engines have some sort of a bypass. Sometimes its external. Other times its internal and controlled by a stat.
 

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Discussion Starter #5 (Edited)
I can see what you are saying about allowing the coolant to flow with the thermostat closed and balancing the heater system as I was thinking along the same lines earlier. After calling a mechanic buddy of mine, he adjusted my thinking a little on a couple of points.

- The water pump circulates coolant through the heater system, before the T-stat
- There is no heater bypass valve on 7th generation GM trucks equipped with diesels before 1996 (if it had one, it would most likely be Ac Delco part no. 15-5533)
- The purpose of the heater is to provide heat; redirecting coolant into the radiator for cooling is counter productive
 

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Discussion Starter #6
The cost of the brass parts, hose & stainless hose clamps (as of July 2014)

- PEX SharkBite brass tee (x2) 1" X 1" X 1" UC374LF - $5.00 each (x2 $10.00)
- PEX SharkBite brass reducer (x2) 3/4" X 1" UC060LF - $3.15 each (x2 $6.30)
- Ideal Tridon 10 piece bag of 1/2" to 1 1/4" stainless steel hose clamps 67125 - $7.68
- 12" of 5/8" Gates heater hose 28411 - $0.60 per ft.

Total to upgrade both 3-way nylon tees - $24.58
Added bonus - all the parts are made in the USA!

:D
 

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Discussion Starter #9
Update... successfully completed the 3 hour run part of GM TSB 99-06-02-012D, because I did not know if the previous owner mixed DEX-COOL and Ethylene Glycol at any point.

No leaks and no overheating issues. Next step is drain the coolant system, refill with water, neutralize the acid, then flush the cooling system again. If the rust is gone, then replace the old thermostat & radiator hoses otherwise, it will be flushed again with acid for another 3 hours tomorrow.

By the way, they don't offer the heavy duty acid flush kit anymore but I was able to get a list of the ingredients and make my own. The original flush kit was offered by GM and Prestone and consisted of two parts; an acid part and an acid neutralizer part.
- GM Heavy Duty Cooling System Cleaner - part number 12346500 (discontinued)
- Prestone Heavy Duty Cooling System Cleaner - part number AS100 (discontinued)

The info on the ingredients is here.

These compounds can be easily gathered from multiple sources.

- The acid part of the kit is Oxalic acid in 99% pure crystalline form
- When using the acid, the GM kit consisted of 9 oz (dry)
- The neutralizer part of the kit is soda ash in 99% pure crystalline form
- Not verified yet, but the neutralizer should also be about 9 oz (dry)
- There are 5 other ingredients listed but account for less than 10% of the kit
- I believe these other ingredients were conditioners for the cooling system and are replaced with better compounds found in modern coolants and quality coolant additives such as Red Line Water Wetter

Acid Notes:
- Oxalic acid is an acid and should be respected :duh:
- It should be treated like oven cleaner (lye)
- Oxalic acid is eco-friendly, but the stuff it removes may not be
- Use gloves and goggles while handling the acid
- Don't breath hot steam from the coolant system as the acid can irritate your respiratory system
- Make sure to mix the acid crystals with hot or warm water to completely dissolve the crystals BEFORE adding it to the engine
- Wipe any spills immediately on glass as it can leave a mark; some people say it etches glass
- Remove all air in the cooling system using the bleed-valve; Air pockets in the engine will react with the acid and heat, causing accelerated rust production in these areas
- Getting the engine to full operating temperature is key as heat acts as the catalyst necessary for full removal of the rust in the engine
- After running the specified period of time, allow the engine to cool and avoid chemical and heat burns, then drain the cooling system
- Collect the waste as the acid is active and can bleach the surface under your truck
- If you have stains on the driveway from working on your truck, Oxalic acid is wonderful for getting impossible stains out
- If you have stains on your wood deck (from working on you truck?!? :uhoh2: :cookoo:), Oxalic acid is great at renewing weathered wood as it is also known as Wood Bleach
- Oxalic acid can be used to remove orange rust commonly found on houses, buildings, sidewalks and toilets caused by hard water stains in well water systems

Neutralizer Notes:
- Neutralizer part of the original GM\Prestone kit was Sodium Carbonate (Soda Ash) and is used in water purification, disinfectants and soft drinks
- Soda Ash is a strong base and should also be respected :duh:
- Large (and high purity) concentrations can cause chemical burns
- Soda ash is also eco-friendly and has multiple uses at home
- Use gloves and goggles while handling because the crystals are concentrated
- Make sure to mix the neutralizer with hot or warm water to completely dissolve the crystals BEFORE adding it to the engine
- Remove all air in the cooling system using the bleed-valve; Air pockets in the engine will react with the neutralizer and heat, causing pitting of aluminum!
- Getting the engine to full operating temperature is key again, as heat acts as the catalyst necessary for full neutralization of the acid
-DO NOT ALLOW NEUTRALIZER TO SAY IN THE COOLING SYSTEM FOR MORE THAN 10 MINUTES AFTER THE ENGINE HAS REACHED OPERATING TEMPERATURE AS IT WILL PIT\EAT ANY ALUMINUM IN THE COOLING SYSTEM
- Check the cooling system for green on copper and brass after flushing the neutralizer. A little is ok, a lot requires more rinsing cycles or another cycle of acid flushing
- Make sure to flush the cooling system thoroughly to remove all neutralizer
- Soda ash can be used in many areas of the house for cleaning and for laundry, removing grease effortlessly (my work shirts after a day under the Suburban) :D
- An alternate to using the Soda Ash (Sodium Carbonate) neutralizer like provided in the GM\Prestone kit, is Baking Soda (Sodium Bicarbonate)

Hope this helps keep your ride going! :thumb: :saluteusa:
 

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Discussion Starter #10 (Edited)
The discontinued GM\Prestone heavy duty flush kit contained 2 dry ounces of Soda Ash neutralizer according to some old-timers.

Also you can see the effects of Oxalic acid on rusted metal here, so it can be used outside of the engine for removing rust from other things too!
 

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without the rubber in the middle, the tees are available online, or through an actual plumbing supply company...

 

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without the rubber in the middle, the tees are available online, or through an actual plumbing supply company...

Available at Home Depot
 

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Not 1/1/3-4
 

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Available at Home Depot
Just to be sure, I went and checked Home Depot stock. They do carry a 1/1/3-4 which would place the 3/4 joint in the middle. But a 1/3-4/1 tee is not in their inventory. Not here in nc anyway...
 

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I meant the parts. You have to do some soldering (easy) to get the exact replacement for one of the tees.
 

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Discussion Starter #18
The setup I did as described does not have a restriction end like the OEM part. This does not seem to affect the flow of coolant in the truck at all. Tested the heater on the coldest days of winter and there was plenty of heat. Inversely, the lack of restriction also did not seem to affect time for the engine to reach operating temperature on cold days. I don't count this part of the test done as it never went below freezing this winter in central Florida.

When we visit family next winter, will be able to test in freezing and subzero weather.
 
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