Made In Michigan

Water distribution tube

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Does my 1937 218 motor need a water distribution tube? When I stripped down my motor two weeks ago, I found that it did not have one and was wondering if it is supposed to. Did it come from the factory with one in it? Or is a distribution tube a aftermarket thing? Thanks, Frank

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The water distribution tube provides a vital function in cooling your engine. It directs cooling water directly form the water pump to the upper block and valve area. Generally it is removed for inspection when an engine is overhauled, and replaced as required. However, in my experience, many production rebuilders do not perform this repair because the tube is rusted in place and difficult to remove. Failure to replace a rusted out water distribution tube will certainly lead to hot spots in the block and future problems. 

Water_Dist._Tube_Original_thumb.jpgReplacement water distribution tubes are readily available from many NOS suppliers, manufactured in either steel or brass. Be sure you order a tube for a your engine block. Two versions are used, one for 23” and the other for 25” blocks. Access the tube by removing your water pump. If you are doing a rebuild, access is straightforward. If you are trying to do this in the car you will need to drain the coolant, remove the radiator, fan and water pump. Looking at the block face, it is the "D" shaped opening on the left, almost in line with the valves. Using a hook formed from 1/2 inch steel rod, insert the hook and catch one of the slots cut into the upper edge of the tube. This is not an easy repair to do with the engine block in the car. If you are really lucky, a sharp pull should break it loose and the tube will slide out. I you are like the most of us, it won come out. Next step is to liberally apply a lubricant like Liquid Wrench or motor oil along the edges of the tube. I flip the engine block upright, and this allows the lubricant to run down the sides of the rusted tube. Let it soak for a while and give the hook another try. If you are having trouble getting the hook to stay set in the tube hole, try squeezing the edges of the tube together with a pair of vise grips. You can generally collapse the tube sides inward 2  3 inches and this provides a firm grip for the vice grips. A small slide hammer can be hooked on to the vise grips and a couple swings on the slide hammer pops the tube out. Still no go? Take a piece of 1/2 wide flat bar stock and gently drive it into the block between the thin straight side of the tube wall and the block. Again, use plenty of lubricant like Liquid Wrench or motor oil. You are trying to break loose the rusted tube wall from the block. Usually the tube collapses inward a bit, making it easier to remove. Drive the bar stock in 6-8 inches, then try the vice grips and slide hammer. If this doesn’t work, try driving the bar stock in a little deeper until you can finally remove the old tube. I have used this technique on four different blocks with success. If it is not moving, be patient and let the oil soak overnight. Give it a chance to loosen up the rust bond between the tube wall and block. Another trick is to remove the manifold and manifold studs. Penetrating oil can be applied through the holes directly onto the sides of the rusty distribution tube for the entire length of the tube.

 

 
If you are really unlucky, the tube will break and only a section will come out. I have not had this happen, but have seen it mentioned in the service manual. Slightly sharpen the edge of the bar stock so you can catch and lift the remaining tube pieces away from the block side and again lubricate well. I think you will need a stronger hook to catch the remaining tube pieces. In my experience it was very easy to pull the hook out of the 1/4 inch rod stock when trying to pull the tube. A heat formed hook would be the way to go. If you are doing a rebuild, cleanup is easy. When they hot tank the block it will remove the lubricant from the water jacket. It the block is in the car, rinse well with a soap solution, then flush the water jacket until the water runs clear.

 

 

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Installation of the new distribution tube is straightforward. Inspect the block to make sure the water jacket is clean. If not flush and clean. The new water distribution tube is slid into the opening and then the front D shaped edge gently peened over to hold it in place. Reinstall the components you removed and refill with appropriate coolant.

 




 

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Sure enough, the water tube is rotted away and half of what's left is in the block! Another thing I noticed is there was no thermostat . Is the thermostat a common size? Or is this most likely going to be hard to find? I've never seen one on Ebay or anywhere else. I'm going to have a bitch of a time getting that tube out!   Frank

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Sure enough, the water tube is rotted away and half of what's left is in the block! Another thing I noticed is there was no thermostat . Is the thermostat a common size? Or is this most likely going to be hard to find? I've never seen one on Ebay or anywhere else. I'm going to have a bitch of a time getting that tube out!   Frank

Thermostats should be available at your local auto supply store. The newer replacement thermostats for the bypass style application look different from the original but should work fine.

 

For 160° I think you are looking at something like http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Thermostat-Regular/_/R-THM55_0183567381

 

There should also be a 180° version.

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which way do the holes in the tube face? Up or down?

My car was built before they started using the water distribution tube, but I believe the holes in the tube face up as they are intended to direct coolant flow to the underside of the valve seat areas.

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Cost and info to purchase.

Thanks

Dave

Hi Dave,

$50 plus shipping from Bloomington, CA.

  Regards,

  Gary

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My car was built before they started using the water distribution tube, but I believe the holes in the tube face up as they are intended to direct coolant flow to the underside of the valve seat areas.

 

Correct ;)

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I thought the distribution tubes were "D" shaped and could only go in one way with the taper toward the top.

Edited by keiser31 (see edit history)

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John

Didn't you look at my post #3?

Yes. I was replying to "Made In Michigan's" post #7.

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On 1/22/2016 at 8:45 AM, dpcdfan said:

I have new water distribution tubes available in both sizes.


I just joined this forum, I haven’t even introduce myself yet in the new members section, But I just bought my son a 1953 Dodge pilot house pick up and I was wondering if these water distribution tubes are still available?

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53 minutes ago, Fritz L said:


I just joined this forum, I haven’t even introduce myself yet in the new members section, But I just bought my son a 1953 Dodge pilot house pick up and I was wondering if these water distribution tubes are still available?

Do you have the 23 in or 25 in engine?  I have the 23in tubes.

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11 hours ago, Fritz L said:


I just joined this forum, I haven’t even introduce myself yet in the new members section, But I just bought my son a 1953 Dodge pilot house pick up and I was wondering if these water distribution tubes are still available?

I have both the 23" and 25" water distribution tubes

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22 hours ago, countrytravler said:

Do you have the 23 in or 25 in engine?  I have the 23in tubes.


I believe I have the 23 inch 

I pulled off the water pump today and the thermostat and everything with plugged with scale, so I am sure that injecting tube is probably clogged as well

 

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2 hours ago, Fritz L said:


I believe I have the 23 inch 

I pulled off the water pump today and the thermostat and everything with plugged with scale, so I am sure that injecting tube is probably clogged as well

 

Given how much stuff you are seeing at the top of the head/block there is like to be much more lower in the block. You may want to consider pulling the freeze/core/welch/expansion plugs along the side of the engine and then flush the block while using a stiff wire probing to remove the sediment and sludge that usually accumulates in there over the decades.

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