Water Distribution Tube

Wm Steed · February 27, 2010, 11:58:26 AM

Actually many of the early inline flathead 6's/8's used the water distribution tubes... I know GM used them in the Olds & Pontiac's up through '53.
When dealing with the vehicles from the'30's/40's one should keep in mind that you are dealing with a vehicle that was just a means of transportation and in all probability the mechanics that worked on the vehicles had no formal training. An overhaul in the old days could be as simple as touching up the valves, new rings after a light hone of the cylinders, and removing some shims and/or filing the bearing caps to tighten up the rod/mains.
The overhaul did not require the removal of the engine from the vehicle.
I have seen engines that had pistons/valves removed with the oil holes in the crank plugged so the engine could be kept in service....Bill

my33ply · February 24, 2010, 03:02:26 PM

Sorry, I didn't read all the way down before I answered. It is possible they didn't put it in, but not very smart.

my33ply · February 24, 2010, 02:59:03 PM

It certainly is. Sometimes they are very difficult to get out, so they may have just bypassed this step.

CHS · February 24, 2010, 02:48:09 PM

According to my Plymouth Service manual, The water distribution tube only needs to be replaced when a complete engine overhaul is performed. Is it possible that at some point the engine was rebuilt and the rebuilder never put a new one in?

elmo · January 14, 2010, 01:39:34 AM

Plym46has given a good explanation why the tube is there, and tod is right they were there from 1935 on, not only on the plymouths, but all chrysler sourced L6 engines. as for needing them, yes they should be there , you wont notice any difference in your engine temp without one , but your valves will ultimately suffer. haveing said that i had a early fifties plym once that i used as a daily driver , it had no tube (i coudnt source one at the time ) i used it for 5 years with no problems showing up in that time . depending on when the tube was fitted makes a big difference when removing it . up to WW2 they were made of copper , but with the outbreak of war they made them from steel, as all the copper was needed for the war effort so they were then made of steel,and consequently most replacements after this would have been steel, i have no idea but assume it was a special plated steel , but they still rusted and were(are)hard to remove, if they can be rmoved copper repro,s are now available

Fr Mike · January 13, 2010, 12:01:23 PM

Thanks for the replies. The feedback confirms what I was thinking. Apparently the water distribution tubes, which likely had deteriorated by the time these engines needed serious attention, were removed when they were worked on. . . not being considered necessary as the engines seemed to have been getting along ok basically without them.

Again, thanks. I passed the info along to the shop.

plym_46 · January 12, 2010, 10:20:02 PM

The tapered shape and graduated size of slots of the tube directs coolant in consistant volumn and pressure toward the valve seat area. Life of the valves is dependent on that cooling as the only time the valves get a chance to cool is when they are in contact with the seats.

A consistant temperature of the valve seat area is critical to their operation and is the primary function of the tube. Its secondary purpose is to control the rate of flow throughout the engine. With out is it would travel to quickly through the engine, ot allowing the coolant sufficient contact time to take on heat from the engine. The tube is one of the reason's MOPAR 6 did not have the overheating issues common to their competitors.

Tubes are available from several vendors in teh 50 to 65 dollar range so it should be reinstalled. One thing you can be thankful for is that its absence saves you from the ordeal removal of the old one usually becomes.

TodFitch · January 12, 2010, 10:02:11 PM

As far as I know every Plymouth engine from 1935 up to the end of the L-6 production should have a water distribution tube in it and you are likely to have cooling issues without it. (1933 and 1934 had a different, narrower, block and did not have the full length water jacket either.)

jd2ksilver · January 12, 2010, 09:28:34 PM

Thats a new one on me. But I am not sure if they were always used or not. How is the engine running now temp wise. ?

Fr Mike · January 12, 2010, 05:48:37 PM

When my '36 P2 engine was rebuilt over the past two months, there was no sign of a water distrubution tube. This is the original engine in a car with a little over 80k on it. A '42 Plymouth engine brought to the same shop also had no sign of a water distribution tube. The Service manual gives very little prominence to a water dist. tube, and it could be easiy missed when ordering parts for an engine rebuild.

Both cars ran a long time without this part. How important is the presence of a water distribution tube to the functioning and durability of the engine and to the operation of the cooling system? (I already read where it is supposed to cool the "hot spots", especially the valves.)