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major cooling system issues (not overheating tho) help plz

2518 Views 10 Replies 5 Participants Last post by  Marty626T
hey guys, searched the forum, couldnt find anything like whats happenning to BOTH my mx6 turbos! (91 and 89 models)

both cars do not overheat, both run on 1/4 temp the whole time, perfect.

when i turn the cars off, all the hoses puff up really tight, and any less than perfect hose joins squirt coolant from the tiniest leak.

in other words, the systems pressurise REALLY badly.

I have tried 4 different types of radiator caps, and NONE of them will let the pressure out into the overflow bottle OR suck the coolant in the bottle back in when low. the owners manual says to top up the coolant from the overflow bottle so I get the idea its supposed to flow in and out of the bottle freely?

this problem has caused my 91 model's water pump to fail, blew the head gasket, burst the radiator cap off, burst the bypass hose, caused the top hose to expand dangerously AND made the top tank on the radiator leak, all on SEPERATE OCCASIONS

and no, it is NOT the head gaskets. all the compression is fine, there is no coolant in oil/oil i coolant, they run wonderfully and dont lose coolant or oil, plus the 91 still did it after the head gasket was replaced.

any knowledge on this would be greatly appreciated! i dont want to go through all this with my 89 as well!

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have your coolant checked for exhaust gases, and IIWY, if everything checks out fine, get a radiator cap with the manual relief valve and run your cars with that up, or get a 7psi radiator cap.
mmmkay cheers man. havnt heard of a manual cap before...

souds like it may do the trick
they have lever on the top, usually it's a red lever.

Like these
aight man i will look for some. thanx heaps eh
does anyone know how to burp the cooling system as well?

only ever heard of this on the net, never seen or heard anyone do it.

does having air in the system present problems?
Have u try replacing your thermostat?
yeah just did. car not running atm so will test this once its on the road
First thing I would do is buy a pressure tester. Remove the cap and install the rad pressure tester. Warm the car up at idle and measure the pressure until car reaches normal temp.

Record this pressure. Turn off the car and see what the pressure rises to once the car is turned off.

I suspect you may have a clogged radiator. Also your temp sensor could be out of wack and is not reading the correct temp. SO you think you are not running hot but really are.

Pressure when running should be around 14lbs.

Burping is done to remove air. Get the car hot and park it uphill. Wait a few hrs and remove the cap when cool. If air is in the system it will rise to the highest point which will be the front of the car as you parked up hill. Jacking up the front will do the same if you can't find a hill. Add coolant and repeat.

i have a funnel that chucks right on to the radiator in place of the cap(i got it off the matco truck, it has adapters to fit all makes/models), the correct way to "bleed" air from the cooling system is to fill to full then run to operating temp. once at op. temp. YOU MUST RUN THE HEATER ON HIGH, run "high idle"~2,000 rpm and you i can watch the air escaping up into the funnel, you can also achieve this by taking off the radiator cap and depressing the spring then holding the spring depressed with a steel clip then put the radiator cap back on to the radiator, this will keep the spring open and "complete" the cycle into the overflow, then fill the overflow fo full and somehow hang it up from the hood, depending on how clear your overflow bottle is you can see the air bubbles escaping and being replaced by coolant, this is the quickest/easiest way to bleed air from the cooling system

air in cooling system will most likely be heard as a gurgling noise behind the dash (air trapped in heater core)
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wow ok thanx guys.

guess i will pull the radiators off and test if there blocked.

will burp my system this arvo

lol neither of my cars have a heater tho, they both have leaking heater coils, so i disconnected them. probably helps.

cheers for the help, if anyone else has any ideas please add.
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