02 discovery having several issues with coolant. First a little history. Has has an external head gasket leak on both heads that was recently reapaired using oem parts. After the coolant expansion tank literally cracked in multiple locations. After replacing the tank I also replaced the thermostat. The truck was driven or a day or so and my wife noticed a small leak. I saw the radiator was now leaking. Replaced the radiator. Now after head gaskets,t stat,radiator,and a second expansion tank I just noticed the expansion tank once again is leaking at the seam! I'm
Lost now. I've run the truck with my coolant pressure gauge and at operating temp the gauge never goes above 12psi. Yet for some reason this tank keeps cracking? I paid 250 bucks for this tank t the dealer and don't want to keep replacing it. Adding to the repairs I forgot the water pump was done in January for a leak issue which in hind sight was the heads leaking all
Along. Please help. ! This truck is testing all my experience and abilities ! If anyone has any ideas is truly appreciate them.

 

First off dont buy parts from the dealer. If you can take that tank back and say it is defective as it very well may be. I bought mine on ebay from Miami Rovers for $65.00 and free shipping. Do you know what the engine temp is? Its a long shot but it may just be a faulty tank. Do you have an Ultra Gauge or any way of checking the coolant temp? Im in the south and mine runs between 199 and 207 F.

 

well I don't know what would be causing that kind of pressure... maybe time for a new coolant cap? but just so you don't spend another 250 on the tank, atlanticbritish has the tank for 69.95 for 1999-2002 DII's

 

Scott is right a new cap may be the fix. Again do not buy from the dealer...

 

Thank u! The temp was checked at 210 max. And the idiot gauge never goes above the middle. Btw it has a new cap as well. Bought it with the tank. Thank you for the info on parts. This tank is tank number 2. That's why I'm at a loss? To my knowledge head gaskets leaking compression usually cause this kind of thing. However with new gaskets I can't see cracking tanks and not blowing a hose or something ? Does anyone know if the new t stat coukd cause a back pressure issue if it doesn't open? Although it's aweek old I'm not 100% it's correct . To me it takes way too long to open and like most vehicles the radiator never truly gets hot at all four corners. The drivers side gets really hot (near the upper hose) the passenger side I can touch and not get scolded. Could the clutch fan be that efficient? Or am I just chassing a wild goose here out of frustration?

 

did you put the tstat in correctly?

 

This is always the possibilty that the head gasket job did not take or you have a cracked head or block.

 

make sure you routed the fan belt correctly so that the coolant is flowing properly.

Get a coolant tank from eBay.

If you have the waterfall sound from your heater core - when you start off from stop lights = then your system is not bleed correctly.

If you can't bleed the system, then you may have combustion pressure
and gasses entering the cooling system and causing the tank to blow.

I think that the dealer tank was very weak.

First things first - bleed the system and see if it will hold a bleed and not get air back into it.

 

Yes, even though I see a directional arrow the hose configuration only allows the install one way. It's external.

 

Cracked head,, that's my fear. But would I see the pressure raise in the coolant system once it's at oper temp? I'm using a pressure tester.