Mike,
Very good explanations about water circulation, thanks a lot. Really.
As a question I used chlorydric acid a few days, then karcher. Removed core plugs. Let dry. Use Vacuum cleaner, metal round bushes…Now is on it’s side, i’ll use again karcher. And after frozen pistons 
to remove…
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The water in the block acts as a heat sink only…there is no ingress provided to replace any water that may “expand” out of the block as the engine heats up. So, the heating and cooling cycle may replace a very small portion of the block water, but any true circulation is not possible nor provided for. The W/P circulates coolant up into the exhaust side of the head, then OVER to the intake side, then OUT to the radiator…any temp differences during warm-up and cool-down being the only mechanism providing mixture between the two “systems”, this small amount of mixture being inconsequential.
From memory, pool acid comes at 18 or 20% acid…certainly strong enough to remove rust. IF the derusting of aluminum is required, I suggest oxalic acid, as found in the “deck cleaner” I bought at Home Despot…safe for aluminum and the material I used to remove rust stains from my head(engine head, that is).
Think “lava lamp”. The density of the coolant will change with the temperature. Warmer coolant will become very slightly less dense, and this differential will cause it to be buoyant, relative to the cooler coolant above it, and it will cycle to the top, where some of it will be entrained into the dynamic fluid stream.
Yes a basic description of the standard system Lee, usefull to those posters that are unaware.of the coolant flow .
I have posted some of these allready on other threads, but obviously,
they have escaped your attention. Hopefully they will inform how it is
possible to circulate coolant through the block.
I`ve included one of the sucker fan that is fitted, rather than a blower,
these tend to restrict airflow through the rad when not in use.
If the water pump doesn’t really circulate water through the block - could this explain the tendency for these blocks to silt up and the head/block studs to corrode? Fresh coolant constantly reaching these areas ought to improve corrosion resistance, not to mention carrying away some fine silt particles. Better in the rad than block if fluid changed regularly. Easier to flush the radiator.
I should have pressure-flushed my block when I changed the fluid a couple months ago…
Dave
Peter, have you done tests to see if the flow is more or less equal, between the front and back entry points, on the block?
The entry point at the front of the block has a smaller hole than the
rear entry point Paul, pump speeds can be regulated also.
If the supply to the head is insufficient then a XJ pump will be fitted,
hence the double vee crank pulley.
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I believe your system was commented on by myself since I have also provided some measure of block flow, using all three core plugs, through a less elaborate system than yours. My concern is that the block flow remains subservient to the as-designed cross flow in the head. You do not want so much flow up the intake-side water jackets that the cross-flow is compromised/stagnated. The “big” heat from the exhaust must remain the primary coolant target.
Is the assertion that there is no communication between the water jackets on either side of the block still being entertained as true? It would seem to me that if that were the case it would be impossible to drain the block completely through the supplied drain plug which would lead to a lot of difficulties with correctly replacing old coolant, or cooling system flushes.
Yes Lee re your previous post I replied “My thoughts as yours” so why this latest post to me informing something I’m well aware of ?
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I simply got the impression that I had missed something by the phrase “escaped your attention”…I had advised previously that you would have to be careful about over-circulating the block water at the “expense” of the head water flow. After all, the block flow system you designed, as well as my own, is less convoluted (less restricted) than the stock head circulation path.
In answer to Geoff"s comments, the drain plug on the block AND the radiator drain will work together to drain the system. IF one omitted the block drain and used that hole as a water return to the W/P, say, thru the heater return port on the W/P, you WOULD have some measure of block circulation. Of course, that coolant would not pass thru the radiator so a small enough restrictor in that flow would be required.
There is communication between the two water jackets, just not through the block casting itself. The main conduit is through the head during operation but for drainage of that smaller water jacket it’s backwards through the water pump into the radiator. That rectangular opening in the block through which the coolant passes into the exhaust side from the water pump is an inch or so below the water jacket. Gravity.
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Sorry if I am seeming a bit slow but from what I can see the drainage for the exhaust side of the block is simple. Out the drain plug or back through the water pump and into the rad. It is the carb side that I can see no drainage path other than through the block itself. There is no drain plug and no communication with the water pump on that side. At the time these engines were built it was not unheard of for people to use water only as coolant and to drain the water during freezing weather. It does not seem logical for me to have an engine designed without the ability to completely drain all coolant. Am I missing something obvious?
I think the drain tap (bolt on later XK engines) on the block is on the lowest point of the inlet side and the water pump port on the lowest side of the exhaust side, draining via the radiator, so where would you not be able to drain all out? Do the XK models not have a block drain? If so, they found it necessary later on, but I assume they thought of that from the start.
A little bit of water might remain in the rear of the exhaust side, but that won’t do any damage.
Yes.
Coolant circulation through the block is largely in aid of cooling the head. The small water jacket cast into the length of the exhaust side of the block is a conduit of fast flowing coolant pumped from the rad directly into and through the head’s many smaller conduits. The head’s aluminum because it’s good at dissipating heat. That hottest coolant flows from across the head downward into the large water jacket in the block and through the intake manifold back to the top of the radiator. Limited mixing in the larger water jacket, its volume more a heat sink.
That is not quite correct. The drain tap is located on the exhaust side as is the water pump outlet. See attached diagram from the e type service manual and probably others. Sorry but I still do not understand how there can be any way to drain the intake side of the block unless there is communication between the two sides of the water jacket. Does anyone have an explanation?
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Then I have avoided an oil spill as I mistook a copper washer bolt on the intake side for the coolant drain. Of course it is in the oil gallery just like the other drillings to the mains. How stupid. Sorry for the confusion, would have been so logical.
The water jacket surrounds all of the cylinders up to about 7" from bottom of block so the drain on the block does serve to empty the block. There is a separate channel, at the top of block, which runs the length of the block on the exhaust side ONLY. This channel is about 2" deep and provides a flow path from the W/P to the exhaust side of head. The outflow from pump is pushed up to about the 1:00 position from the port, as viewed from the front, thereby supplying cool water to this channel. The intake side of the block has a water jacket about 9" deep, meaning both systems (sides) add up to 9" high.
Ok, then what you are saying is that there is one large lower water jacket that surrounds the lower part of the cylinders on both intake and exhaust sides and there is communication from side to side. In addition there is a separate water channel cast into the block high up on the exhaust side that functions to supply the exhaust valve area with the coolest temp water and then the coolant proceeds cross the head and to the water rail and back to the radiator. In addition there is communication from the head down into the water jacket on both sides of the head. Is there general agreement on this? If this is the case I could guess that there may be slow constant flow down into the lower water jacket across and up into the stream due to differences in temperature between the exhaust and intake sides.
Since there is no point of ingress for coolant into the block, other than the intake-side water jacket the W/P impelled coolant is flowing over, any expansion of block coolant is limited to just that: thermal expansion. Of course, the block is rather long so there may well be varying temperature differences around the head to block water jacket interfaces, but this would be quite localized and of not enough volume to cause any meaningful block circulation.
As I said, IF one were to suck coolant from the block drain into the W/P inlet, you would now induce a measure of circulation DOWN into the block thru the intake side as the coolant flowed over the slots…this volume bypassing the radiator.