98 vt v6

[dazzalenko]

hi all
after some feed back things driving me crazy
keeps blowing hoses
to much pressure in the cooling system
done all the bleeding etc
need to no why there is excessive pressure build up
put a gauge on it and the twin fans don't work till it reaches 90 kpa
tested cap also
could it be the temp sensor ?

doing my head in

all help is much appreciated

[RK5TAR]

I have the same model car and a similar problem.
It hasnt blown any hoses yet, but blew the radiator (was blocked) and the water pump went.
Had the pump fixed a couple of weeks ago and there is a lot of pressure in the hoses. It hasnt blown anything, overheated or leaked again yet.
Mechanic suspects head gasket is about to go. But it's behaving itself for now touch wood.
I asked here a little while back and the guys suggested to check/change radiator cap, radiator, thermostat etc. All of which have been changed in mine.
Also I think DanLucas mentioned to check the temp sensor.
Ive been checking my temp periodically witht he mode switch and its ok.
Good luck with it. Im in the dark on this one too, but I dont have it blowing anything as yet.

[Killr6]

your fans should kick in at about 104 degrees so check in your system that they are working.

also, have you changed your thermostat? it could be stuck. building up pressure.

[dazzalenko]

yea thanks heaps
done the thermostat and water pump just recently radiator 2 yrs ago still looks brand new
fans kick in at about 95 kpa
pressurised the system and there was no leaking in the system
also tested the cap fine also
only leaves me to try the temp sensor
can i change the sensor to make it run cooler or even the thermostat
gauge sits inbetween 1/4 and 1/2 but when i blow a hose the gauge still doesnt move
just wnat the fans kicking in earlier to reduce some of the pressure

cheers

[Killr6]

changing the sensor wont make it run cooler, i dont think its your temp sensor because your car is not overheating and its not sending fauty readings to your dash.

you could have a blocked radiator.

and also which hoses is it blowing?

[dazzalenko]

which ever hose is the weakest link

[Killr6]

well you gota be more specific, is the same hose? or hoses all over the engine?

[dazzalenko]

it varies
had bootom hose blow of pump yesterday
month earlier heater hose went
month earlier top hose

[vx_commodore]

Commodore V6's have extreme pressure as is, So any more pressure than normal things begin to fail..
Haave you made sure everything is on nice and tight? all hose clamps ect?
Had a car in work not to long ago doing the same thing as urs... We pressure tested it and that all came up fine but it continued to blow things out... ended up being the inlet manafol gasket was dodgey... it would go fine for 2 days then just blow water out of everywhere then behave again for a further 2 days ect...
Maby something to look at if you cand find anything else...
Good luck!

[dazzalenko]

thanks guys for all ur input
going to flush and re do all hoses this weekend
cheers

[pieces]

thanks guys for all ur input
going to flush and re do all hoses this weekend
cheers

Good move do all the hoses at the same time . Also be careful removing hoses from plastic. I carefully cut a slit along the hose for easy removal .

[dazzalenko]

hi all
drove home from work tonight
bit hot out side
stop starting
when i got home and turned the car of i noticed that the overflow bottle was making a bubbling noise
tending to think it could be a inlet manifold gasket.
how much is the valley cover gasket
is it a simple job


any ideas

cheers

[vx_commodore]

Yeh id say its ur inlet manafold gasket if its blowing out your overflow bottle, Pretty easy job to do, Just have to take note where everything goes, Maby get some masking tape to wrap around everything you un-hook so u can write where they go,(or something to that affect)

Id also suggest doing it now rather than later because if its blowing out the overflow that means there is some pretty high pressure's goen on there and could cause further damage.

Also while your doing the inlet gasket, might be worth getting a VRS kit and doing the head gaskets along with the rest while your there, Once you have the inlet manafold off, there is only a few more bolts and the heads are off so might as well. Get new head bolts if you end up taking them off!
And once heads are off you can give everything a real good clean! there is a lot of build up on the piston's and heads. makes everything run better when thats all cleaned up.
VRS kit is around $199 for ACL, comes with all top end gaskets. from the heads upward.

[Monster-VZ]

sound like gasket

[tumut123]

The inlet manifold doesn't contain any pressure, unless its supercharged. Within the mainfold the air pressure is negative , ie vacuum.
If the gasket was dodgy, it would be pulling fluid into the cylinders and blowing white smoke out the exhaust.
The only way for an build up of pressure to occur, assuming no blokages in hoses or radiator amd water pump is working correctly, and considering it is only a slow/minor build up of pressue venting through the 15PSI relief valve of the radiator into the overflow bottle, is that one cylinder is leaking through the head gasket/ cracked head/ cracked cylinder. A normal reading in a cylinder when conducting a compression test is approx 120PSI
Therefore what we have is a pressure differential 120 beats 15 everytime.