Blocked Radiator..

[nighthawk]

Got a radiator question...would a blocked radiator(blocked cores) pressurise the system? like top radiator hose. Dont think its anything else, after i re installed the radiator i filled it up with the green stuff ran it till the therostat opened(new one) put cap back on. never worried about it for a while cause car still not registered yet, temp does not go over half.after I run it for a while, the next day I go to check the water and the system is still got pressure in it while cold. Got a new 13psi cap.I know the radiator is F...ed and the cores where blocked cause last owner cooked engine.its got no bubbles comming up and no leaks......yet.

[geeves]

If the engine was at normal temp them allowed to go cold there should be a slight vacuum in the system not pressure. Are you takeing pressure by a hiss when you take the cap off (poss normal) or hard radiator hoses(bad)
Best way to check for bubbles is to get a foot or 2 of clear hose to be a tight fit in the filler on the radiator. Connect this to the radiator when cold and fill to the top. Start the engine and run till operating temp. The system runs below 100c normaly so this is fairly safe. It will overflow a bit while warming up. Bubbles will be obvious.
It is common on the 4jb1 for air to be trapped behind the thermostat after changing the water. These can take a few cycles of operating temp t get rid of. Dont let it overheat till this ha cleared. This may also cause bubbles in your case but they should clear.

[nighthawk]

Hey geeves, will try clear tube, yep my radiator hose goes hardish. first time i took cap off when cold, bit of water went everywhere now i take it off slowly to releif pressure first which goes into the overflow bottle, but its not adding extra water,just air. had simular prob with my 2000 pajero only to find out you got to bleed those cooling systems. Hope its just an airpocket

[geeves]

When I burst the top heater hose on my truck resulting in 1 of only 2 tows home in 14 years it fizzed furiously for half an hour after the hose was replaced but I cant remember it pressurising the system It had me panicking a little as I had driven 20km since smelling steam. (very cold night and you cant buy heater hose at 11pm in Wellington). It settled ok and has done 5 years since
hope you have good luck with this one

[nighthawk]

ran it hot with cap off got all air out of the system, it bubbled quite a bit with me thinking oh no not the headgasket, put cap back on and left it, checked hose just before when i got home and its fine....for now. hope it stays this way

[geeves]

Good luck
Radiator specialists have a device for detecting combustion products in radiator water. the only way they get in there is from a blown head gasket.

[nighthawk]

Problem solved. when i put engine back together I prob didn't torque bolts down tight enough with half turn here 3/4 turn there like it said in manual. cranked her down quite a bit more and all good now. HAPPY thanks Geeves for input

[geeves]

I would seriously consider changing that gasket again. It might be ok but the water could of caused all sorts of nasty things to start happening. It might be ok but there are only 2 ways to tell. One is now the other will be when it chooses.