A couple of pictures and updates



Tank level hot, just at the seam



Tank level cold after 14 hours no more coolant loss. Note this is after about 10 hours of driving

Coolant loss is confirmed at the expansion tank overflow hose - you can see the temp catch bottle I will be using during further testing.

Removed the rad line and ran compressed air in to tank passage to confirm no blockage it is good.

Still need to remove that line and test to make sure it is clear, but there are no kink sections
.

 

Another question how reliable are the combustion gas testers on a the Disco cooling system

 

The madness continues.

Removed the coolant return line above the radiator and and blew compressed air through. Got some fine black particles like sand out not very much but some, ran the chuck end of a drill bit in the rad nippleto make sure the rad side was clear.
Put everything back in place and fired the Disco up and let it run for about 30 minutes in the driveway, while it was running I used a jar to capture the moisture out of the exhaust to make sure it was only water.

Results - no temp over 197.6 at idle
Moisture was just water as expected
Not expulsion of AF via the overflow - I have a bottle to capture fluid while testing.

I can not do the exhaust gas test until the weekend, but my suspicion is that it is a blockage somewhere, that may be intermittent. So thermostat or something else, a full flush is in the next step after the exhaust gas test.

Once complete I will document the test process it might help someone else.

 

Who knows.
Here's mine passing just fine after over 15 minutes of idling...then leaking coolant(between block and liner

s)into 3 cylinders after a complete rebuild, and with zero signs of a coolant leak or loss prior to it.

 

@Sixpack577 Two questions :

Did you get Anti-Freeze to the oil ?
Did you over heat ?

Thanks for the reply that is actually my worst fear a cracked block, but that is unlikely at this point as the system is just over pressure, and not always and the loss is via the expansion tank overflow.

 

Whenever it spits coolant out the overflow is the upper radiator hose rock hard? If you had exhaust gasses getting into the coolant and causing to much pressure (over 16LB) the first thing you’ll notice is a fuel smell from the reservoir, the second thing is rock hard coolant hoses, and the third thing is coolant pissing out the overflow.

 

No and No.
I found coolant in 3 cylinders just from cranking/priming oil with the rebuilt engine.
I pulled the engine, and then both heads.
1 cylinder on one bank, 2 on the other, and each had about a teaspoon of coolant sitting at 6 o'clock on each piston.

 

@Best4x4 thanks for your reply

Hoses are fine, soft as expected
No fuel smell at the reservoir and no AF smell at the exhaust
Temps are fine about 2 degrees higher than normal after the coolant is expelled at idle, normal at 1900+ rpms

I am due for a coolant flush and change, but figured to make sure it was not a head gasket issue 1st.

It is a little weird that it does not occur at long idle, as per my test yesterday. But rather seems to occur after driving for some time, over 40 minutes.

I have added a temp catch bottle to confirm if it occurs as I drive or after a few minutes of shutdown.

As noted after the tank reached a given level there was no further issue over 7 hours of driving.

 

Just an update, I have discovered that this may be the result of a pin hole leak in the head gasket. Basically not enough to cause significant overheating, just enough to cause over pressure as the engine cools and the thermostat closes. Now I never heard of this and it may be bad info but I should be able to test the on Sunday.

Tank holds fluid just fine overnight filled past the seam to make sure

 

Sunday update

Due to high winds and heavy rain I passed on combustion chamber test and focused on post Xmas house clean up tree down etc.

I did however top up the cooling system and run the Disco up to temp, then followed this process :

Let the Disco get to 195
Run the RPM up to 2500 for 1 minute
Drop back to 1200 normal running rpm at 30 mph for mine, for 2 minutes
Back up to 2500
Repeat twice more
Drop to idle

Results at 2500 engine temp dropped to 186 then returned 188 once I went to 1200 all three tests
I long run 2 minutes at 2500 temp returned to 188 and stayed

Left the Disco idle after the tests never broke 195, hose remained soft could press in with my thumb while wrapping my hand around the hose
So far as she cools no problems catch bottle is still empty

My only findings of a similar problem is from a BMW racing forum where the cars are also driven off track. In 2 cases both only occured on track no overheating but a over-pressure cooling system. One was a head gasket but hoses were rock hard after driving on track, the other was a partly clogged cooling system.

I will say this is as bad as trying to find and fix a random electrical fault, but I do have a known distance and route where it occurred. Worse comes to worse I will make that drive with the combustion tester and see what the result is.
The lack of overheat is baffling to me, as I have never seen that with a head gasket issue.