The HG can go for quite a long time if it's just weeping near a water passage like mine & luckys. If it actually breaks or blows out then that's a different story. A cracked block would leak internally and produce misfires on the cracked cylinder. External leak can be HG, valley gasket leak @ front then drains down the back. A cracked block would cause overheat episodes too. You would certainly know if the block were compromised. These Rover blocks are poorly manufactured but still more robust than people give them credit for. Mine was running hot when I bought it then overheated pretty good 2-3 times when components started failing and it survived just fine, or so it appeared when I had it torn down. With all things being equal, I presume that you have to put this engine through a ringer to crack it or have a liner come loose but then again, it could all come down to quality control and it is just hit or miss. The sooner you get coolant operating temp to 180, the better off you will be; any kind of external coolant leak, would chalk it up to poor rebuild, subpar gasket, cutting corners and so on.

 

Well, I would love for this to be true, but I have a hard time believing both of these guys could be wrong when they each didn't think it was true initially and are very experienced with these trucks.

So, if the block is cracked there is no way it could crack in such a way to aloow these symptoms and still run with these temps?

And how do I test this conclusively? Would a pressure test just tell me there is a leak, but that leak could be the block or HGs? I have recently found a grayish ring around the top of the expansion tank. I guess that is carbon buldup from exhaust gasses entering the coolant?

 

you can do a search on cracked blocks, there are about 3 different forums/websites full of them. a cracked block cracks on the inside between the cylinders where the aluminum material is super thin, or it will crack from the bolt taps outward to the cylinder. Then the coolant seeps through the crack, behind the cylinder sleeve and goes over the top and in. People test for cracked blocks all of the time but if you are going to go through that trouble you end up putting the updated flanged cylinder sleeves in at the same time. The only true way to test for a cracked block is to pull the engine, tear it down to bare block, heat it up, remove all of the sleeves then put the pressure to it. In the past they would test for cracks with block still in the vehicle, but without the sleeves removed you will almost certainly get a false reading that the block hold pressure but once the engine is running and heats up, the block expands, sleeves loosen and the coolant seeps from the crack. on a cold block the sleeve holds tight and the coolant won't seep past in most cases. Its a hell of a thing from what I've read, can't say I experienced it first hand but I've read plenty of first-hand accounts on these forums.
If your engine cracked to the outside which is nearly impossible, it would be the first I have heard of, but there are members who have dealt with more compromised blocks than anyone so it would be worth getting their opinion. The guy that jumps to mind is on discoweb, I can get his username for you if you are interested and he will confirm if nobody else comments on this subject and can back up your claim.
I don't have enough experience to comment on the residue within your overflow tank. If you have time run through a search on this forum and maybe a couple others and get some other accounts. Did the techs who ran the pressure test give you a visual on the location of the coolant leak?

 

Well if you had a cracked block, you theroretically should loose a lot more coolant, run hot a lot and depending on where the crack was, you should have a milky texture to your engine oil. If you oil is fine, then it could be a external crack but it should leak more than what you say and expand when the engine is running and leak worse especially since you are in Maine and I'm sure it cold cold cold up there. I would still say it's probably a head gasket based off of what the symptoms are but that's not looking at it. If you look at chubbs888 head gasket job, he had coolant on top of one of his pistons. You can pull the spark plugs and shine a light down the hole and look to see if you see carbon build up on the piston, no leak near that cylinder but if it's shiny, it's been steam cleaned and u got a leak somewhere around that cylinder but you wouldn't be able to tell for sure if it was a cracked block or a gasket until you got the heads off. It's not that bad of a job to do just time consuming. But do the pressure test and if you can't find the leak externally, pull the spark plugs and look down that way.

 

You got to it quicker than me Joe. I was typing when you replied. I wouldn't think it's a cracked block personally. I don't think they could test it or spot it. I think they were basing off of an assumption but I would say it's bad head gasket job.

 

It's almost impossible to say 100% it's cracked.

A leak down test will get you 90% sure of the fate.

Another way is to put a camera down the spark plug hole, if the piston is steam cleaned more than likely it a cracked block, especially if it's the center cylinders(3,5 & 4&6).

Also, you should have stiff coolant hoses as exhaust gases are getting into your coolant passages, although the coolant leak(which I believe to be your head gasket) could be allowing this pressure to escape.

I had a customer with 230 degree temps and rock hard coolant hoses.

Did a leak down test but it did not show a crack in the block. Put a camera in and found coolant in cylinder 5. The reason the leak down test showed no crack is by the time the test was done the bock had cooled and the crack sealed up. That's why pressure testing a block is not always conclusive as it's impossible to get the block to operating temps while testing.

in the end I put on a 180 t stat and he daily drives the thing. Every few weeks he gets some air bubbles in the system and bleeds it but temps never get over 200.

 

And if all else fails, call trailhead 4x4 and go with the chevy ls engine swap

 

just got off the phone with them and they start at around 10k and that's everything done and installed but they have to do it. They also said that lucky8 will start doing them also sometime around April but they will also be done in house. No diy kit. Looks like I'll have to make a long drive at some point

 

Thank you guys for your help and info.

Probably hard / impossible to see / tell, but this is where it is leaking from.

 

I can't see it but mine head gasket was leaking right on top of there and ended up causing my solenoid on my starter to go out