Coolant Leak Source

[Hamilton]

'49 Special Deluxe Club Coupe, 39K original miles.  I've owned this car for 30 years, (bought it with 32K miles) and have been a  lurking member here for a number of years.

 

Father time not to be denied, the car was leaking everything it could: coolant, oil (copious amounts), air, fuel and brake fluid, plus the clutch  and brakes were shot.  I tore into it last fall, hoping to finish up by the end of 2019 but a new job intervened and I've been on the road pretty much every week since November.  I removed everything from the engine, top and bottom, with the exception of the rotating assembly (and, unfortunately, the cylinder head) and spent a considerable amount of time cleaning, painting, re-sealing and replacing old worn out components including, of course the water pump.

 

Although I still have to install the clutch and associated parts, I finally reached the point this moring where I could test fire the engine, which started and ran immediately.  Which (finally!) brings me to the issue at hand ... leaking coolant.

 

It's percolating up from immediately behind the left side (as you're facing the engine) of the water pump, from what appears to be the extreme forward edge of the head gasket.  There's a sort of half moon-shaped opening (half of an unused bolt hole?) where the gasket protrudes from (and extends beyond) the head.  I've rebuilt engines from American V8s (a good number of those) to the one in my Porsche 930 turbo but this is my first in depth experience with a Chrysler flathead 6, so I'm hoping someone here can confirm my theory that the presence of coolant is the likely result of a failed head gasket.  There was no evidence of coolant intrusion into the oil before the tear down, something that still appears to be the case, although I've run the engine for only about five-ten minutes total.  

 

Thanks in advance for your expertise!

 

Norm

 

 

[desoto1939]

The oval hole is where the water distrubition tube is installed to provide a flow of water to the back of the engine block to keep the valves cool.. As year progress these water tube gets rotted away becasue it was made of galvanized metal.  You have to pul the entire old tube out of the hole and it can be a real pain in the butt to get all the pieces out of the tube and then install a new tube inthe same hole.

 

Then you have to replace the paper gasket on the front of the block and the backing plate to the water pump.  This entire surface onthe face of the block must be and I state must be perfectly clean of any old gaskets and or old gasket sealer material. If not the water pump will then leak at this point at the back of the WP.

Did you remove the head and was thee any damaged noted arounf the gasket or in between any of the cylinders?  When the head was off did you have it milled to insure that it was perfectly flat across the entire width and length of the bottom of the head. This should be done to make sure the surface is perfectly straight.  Then use a good cooper head gasket and can use some gasket sealer. The next step is to tighten up the head bolt in the proper sequence and the proper amt of torque.  Then run the engine to get it hot and look for leaks. After the engine comes up to temp and cools again then retorque the head blolts.

 

So please let us know in more detail what you  have or have not done with the engine as per the water tube wp gasket head gasket and torquing the head bolts.

 

Rich Hartung

[Sniper]

I think he's talking about the internal bypass, which is sounds like his head doesn't accommodate, so the head gasket protrudes there.  But I could be wrong, a pic would help.

 

Tenth post in this thread shows the differences between internal and external for the OP.  Shouldn't really matter as long as he's using the original head and block, but I think all new headgaskets these days come with the added gasket material for the internal bypass, so it would protrude in an external bypass engine.

 

 

 

Edited August 2, 2020 by Sniper
more info

[Hamilton]

Sorry about no pics - I'll try to get some soon.   Sniper is correct that I'm not talking about the water distribution tube.  I went to the tenth post in the linked thread: the image where the guy is pointing with his index and pinky fingers to corresponding holes in the block and head is,  I think, where the coolant is percolating up and out of the block.

 

_

[9 foot box]

   Did you use thread sealant on the bolts? You have to use it on most bolt going into the block.

[Hamilton]

I did, but now fear I might have gotten absent-minded and forgotten/missed one.

Edited August 3, 2020 by Hamilton
typo

[Hamilton]

Here are a couple of images.  In the first one, the port of exit for the coolant is directly above the left-most part of the hose clamp, next to the WP rear plate bolt..  In the second one it's immediately adjacent to the bolt on the lower right.

 

I do see there's water pump mounting bolt below this port.  It doesn't appear to be in perfect alignment but is certainly in the neighborhood.  Would failure to coat the threads of this bolt result in what I'm seeing?

 

 

Edited August 3, 2020 by Hamilton
typo

[Sniper]

There looks like there is a hole in the block where that half moon is, am I seeing things?  Because if that is a hole something is amiss.  As in wrong head or wrong block.  Poke a wire down there is you can.

[49D-24BusCpe]

     

    Sniper is exactly right! Notice the 'witness mark' from a previous headgasket. This engine has the wrong cylinder head and gasket installed on it.

 

    The following photo illustrates this very well;

 

 

   

 

 

 

 

[Merle Coggins]

Yup, you’ve got a head for external bypass and a block for internal bypass. You’ll need to find the proper head to match up to that block, and use the proper gasket to match them. 

The head will have a small bump at the front with a port that matches up with that port on the block. 

 

I’ve heard of some guys that have plugged the port on the block in this type of situation. It appears that you have the external bypass thermostat so you wouldn’t need the bypass in the block/head. 

Edited August 3, 2020 by Merle Coggins

[Hamilton]

Okay, I'm convinced ... mostly. 

 

The "mostly" part is because, albeit only very occasionally, I've been driving this car since 1989 and never had, until last two years or so, any coolant loss and no problems with overheating.  Given the explanations and photo evidence provided here, it would seem the issue should've been present from day one.

 

_

[Sniper]

Crazy, I reread your initial post and I believe you said you did NOT remove the head?  Only thing I can think of is some crud was blocking that hole and it got dislodged?

 

I suppose you could pull the head, tap the hole and use a shallow pipe plug well sealed to close it up.  Just make sure it sits below the deck so teh head will set down properly.

 

Might be an opportunity to mill the head some for a boost in compression, trying to find a silver lining for you here.

[Hamilton]

Correct, Sniper, I left the head and rotating assembly in place, figuring I'll do a full rebuild after I retire in a few years.   Seemed to make sense: I'd still be able to get the car out from time to time, sans all (well, mostly all) the leaks without the additional time and hassle of a complete rebuild. 

 

Glad you brought up simply blocking it off, as I was going to ask about a counter-sunk pipe plug. 

 

_

[JBNeal]

14 hours ago, Hamilton said:

...replacing old worn out components including, of course the water pump...

 

One thing I subtly pointed out is that for many years there were 2 different replacement water pumps available dependent on year of the motor...water pump castings were different for external and internal water pumps, and backing plates differed by the presence of a hole as shown in the 1st pic I posted.  The new replacement pumps available marketed by Gates out of china are a redesign that adds a tapped port for a cabin heater but more importantly accommodates both the external bypass thermostat design with a tapped flange and the internal bypass design with the extra hole in the casting + backing plate.  Possibly an easier fix for your predicament is to remove the backing plate from your water pump and weld or braze the hole shut then grind or machine flush so the water pump gasket can seal adequately...this will foul up the plate's zinc plating but if that can be sealed over or re-plated then it's not a problem...at any rate, modifying the pump eliminates the leak source, though plugging that port in the engine block would also be advised...if the backing plate is sealed over, then a splat of black RTV in that engine block hole oughta keep any moisture or debris out 

[Jerry Roberts]

So did you ever stick a wire into that spot to see if in fact there is a hole there ? There was a thread with pictures on this forum a couple of years back where someone had plugged that hole in the block . You might be able to find the thread with a search . 

[Hamilton]

Apparently, JB, subtly is lost on me.  I was kinda rushing through things last night, and in doing so I opened the pics in that thread but didn't read the captions.  Probably should have, as it would have explained things.  I still have the old water pump, the backing plate of which is blocked-off, like the one on the left of the pic in the linked thread.  I wonder if it might effectively be swapped over.

 

As to Jerry's question about sticking a wire into the opening: here's a pic (and one of the back of the old pump) ...

 

 

 

 

 

Edited August 3, 2020 by Hamilton
typo

[JBNeal]

There ya go, them plates should be interchangeable, though you need to use your judgment on if there is acceptable erosion on that plate for the pump impeller to work effectively...FYI if ya look at your old water pump gasket, you can see it has the internal bypass hole...the first flathead gasket set I ever bought had the external bypass gasket without that extra hole...later flathead gasket sets all had the water pump gaskets with the extra hole...as long as there's no hole in that backing plate and there's no water passage in the head, there's no way coolant can leak from that extra passage in the engine block unless there's a crack in the block, but that's not a common mode of failure in that area

Edited August 3, 2020 by JBNeal
added efficiency info

[49D-24BusCpe]

Hamilton,

 

    Don't mess with the engine block!

 

   Put the plug in the replacement cylinder head (with the boss out front).

 

   This works! The engine in my picture is now running an external bypass, AND an Edgy head with a un-drilled out boss - thus plugging the head.

 

Walt

[Hamilton]

Pulled the new pump and, as expected, the port for an internal bypass is open.  I also removed the back plate from my old pump since the internal bypass port has been plugged, and will be swapping it over to the new pump. 

 

Does anyone know of a source for a one-off purchase of the back plate gasket alone?  Best supplies one with their full engine kit but I don't see it as being available separately.  Likewise, I didn't find one listed on Felpro's website.

 

I've made my own gaskets many times over the years but would prefer a well-manufactured one if I can get my hands on one pretty quickly.

 

Thanks to all for your insight and advice!

 

 

[Andydodge]

I'd just get some gasket paper and make a gasket.............make sure ALL bolts going into the water pump and those attaching the pump to the block etc have some sort of pipe thread sealer and a light smear of gasket goo on both sides of the gasket......at least thats what I'd do.......andyd 

[Hamilton]

Yup, picked up some gasket material today that's better suited for water/coolant than what I already had.  Heading out of town but figure to have things buttoned up again by Saturday morning.

[Young Ed]

Check a fel pro 4267

[Hamilton]

Thanks, Ed, but the 4267 is the standard water-pump-to-block gasket.  I was looking for the back plate gasket.

[Young Ed]

9 hours ago, Hamilton said:

Thanks, Ed, but the 4267 is the standard water-pump-to-block gasket.  I was looking for the back plate gasket.

Oh gotcha ya I doubt you'd find that unless part of an old water pump rebuild kit. 

[desoto1939]

try contacting art gould waterpump rebuilder in Mass, 1-508-210-0891 they might have a wp body gasket.

 the Mopar gasket number would be 637439 taken from my 39 Desoto parts manual

or McCord gasket number 38315  newer mopar number 1326324

Rich Hartung

Desoto1939@aol.com