Overpressured cooling system 1HZ

[troopa]

Hey all,
noticed a leak from top tank on my 6mth old radiator yesty (75s 1HZ), unhappily pulled it out to be fixed and noticed top tank is bowed and distorted. Also when i was under it noticed the old girl is leaking coolant from almost every hose (which were all new 6mths ago aswell). Was about to whip the head of it but decided to put the fixed radiator back in it this morning to do a bit of investigating first. Took it for a long drive and when i got home i noticed the bottom of the radiator was cold and the top hot. Could a crook thermostat cause overpressure? It also is only 6mths old along with the cap. Thinking of getting a comp test done to rule out H/Gasket. Any info or ideas appreciated,
Leigh.

[loosecanon]

from my experiance, which is min, start easy, take out the thermo, make sure it's in good working order, i would leave it out get it up to running temp and see if the bottom hose gets warm, it sounds like you have a blockage, is the car getting hot?

[troopa]

Na it doesnt overheat, but the guage will go down on the back side of hills. just tried to book it in for a comp test but they cant do it til next week. AARRHH!

[old ed]

I would suggest you ckeck for faulty or incorrect radiator cap. I had similar issues and that was my problem.

[brissle]

Na it doesnt overheat, but the guage will go down on the back side of hills. just tried to book it in for a comp test but they cant do it til next week. AARRHH!

Had a camry that did this just after the missus cooked it and stuffed the head gasket

[thrashlux]

has it got a turbo??

1hz's love to crack heads once turboed

does teh pressure build before the truck warms up?
if so its combustion gasses, not steam and yoiu have a cracked head or blown gasket

jonathan

[Hilux_Ryan]

Undo the radiator cap (when cold otherwise you'll spray yourself with hot coolant) and then start it up and leave it idling.

If you get bubbles out the radiator its a fairly good indicator that you have a cracked head.

Also when the engine is proper cold first thing in the morning or something, there should be no release of pressure when you remove the radiator cap. If there is it usually means there is extra air being forced into the cooling system, again, often a cracked head.

[troopa]

Cheers for the ideas guys, i replaced the rad cap and thermostat but seems i still have the problem. I Just drove it for a hour and it wont overheat, but Its still overpressuring (leaking from top and bottom hoses) and cold at the bottom hose and bottom radiator tank. Obviously i dont wanna get straight into doing a head or gasket, as it seems to me like maybe some other gremlin in it. Water pump maybe?

[troopa]

Also I dunno why it pushes water past new hoses and hose clamps but not past the cap into the bottle, which stays at the same level.

[old ed]

From the symptoms you have listed my money is still on the radiator cap.I know you replaced it but it is the only component in the system that can regulate the pressure.If the head or gasket was the problem you would begetting overheating and water going everywhere. Unless you have very rough water fittings and just can't get a seal so that the hoses leak before the system comes up to pressure, I still say cap. Take it to someone who can properly pressure test the system and the cap and double check that the cap is correct for the radiator neck. A long cap in a short neck will not release at the correct pressure, if at all.

[RAY185]

Doesn't explain why the bottom tank is cold while the top is hot. If this is happening after an hour of driving then it has to be a dud thermostat or a radiator blockage - but then none of that makes any sense if the temp isn't going up. Very weird. There has to be more to this.

What is your temp guage reading when you have done an hour of driving and your bottom tank is cold and top tank is hot? How much water are you having to top up each time? Are you finding your expansion/overflow tank full? Have you done as suggested above - cap off, run engine to operating temp and watch for a regular flow of bubbles in the rad filler (start with a full system). Overpressuring sure sounds like a cyl head drama in any case.