Vibration when brake stepped on at standstill, 2009 GU

[threedogs]

Do you have a fan fitted to your intercooler or an aftermarket trans cooler if an auto ??
Do you have the vacuum pump on end of alternator, mine made small noise at idle and disappeared on take off
Never lasted as long as your noise though, next I can only think the belt pulley tensioner is on its way out and letting off warning signs
just throwing all this out there at random

[happygu]

Hodge,

Have you followed up from the possible dodgy engine mounts thread?

Could they be the cause?

Mic

[Hodge]

Hey folks.
I haven't followed up on any of the stuff as I'm very short on time at the moment, and with this union vs. company s*** happening at work, I'm unsure where I stand financially or with my job for that matter so I'm a little hesitant to start booking it in, getting things looked at and/or replaced. Anyways thats another story...
@ threedogs - No intercooler fan, but speaking of fans, for a moment I though it may be the main engine fan doing "something" while engine gets hot after a bit of a power drive

@happygtu - I had a good look at the mounts my self today with a mate, and there doesn't appear to be any wear or anything, engine doesn't move much under the hood, and the stick has a tiny bit of left/right movement, but more so back and front...

@col.t - Yes! They are the worst of all problems, the ones that come and go, and this one is... well, doing my head in. Engine runs fine, idles smoothly, I have all the power there, nothing sounds out of the ordinary.

[Hodge]

OK bringing this up to top again as today I've experienced this a number of times.
I am beginning to suspect it could be the fan up the front.
I'm not 100% sure how exactly this fan assembly works. So there is a clutch in it (thermal). Once it reaches a certain temperature, it engages and in turn the fan kicks in, is that how it works ???

[Col.T]

Hodgie,
g'day again,
from what I can see, the fan has no wiring so is presumably not thermostat/electrically driven,,,,,presume!!
Therefore it is / should be a clutch operated unit (maybe), which is driven by the water pump which in turn will/may/could be driven by a thermostat .
I'd rather hope that if that is the prob. it should be in a rather loose state and a good tug on the blades would show any free movement in the unit/bearings. Don't be too aggressive though as the plastic gets brittle with age and heat.
This is possibly all rubbish but it's all I've got,
good luck
Col

[threedogs]

its driven when the fluid inside gets to a certain temp it will lock and drive the fan. I know you can replace fluid using a
bottle of Tojo therm fan fluid, but not sure on Patrol, not the cheapest tool in the shed BTW

[Col.T]

G'day Doggy,
does that mean you need to remove the fan/clutch assembly and drain/replace the fluid?
Don't want to appear even dopier than usual but I don't know how that works. That may well be because I've never had that problem. Can you go a bit further?
thanks,
Col

[Maughany]

G'day Hodge,

i know this is a bit of a thread dig and also being my first post on this forum but im trying to do a little research as im also experiencing this problem in my 08 gu st 3L auto,
i have found with mine it is very intermittent but also unlike yours speed or distance travelled seems to have no consistency it can happen immediatly at the end of the street or after a half hour drive a 110km speeds. all i can see is that on my scan gauge on braking at the decrease around 15-30km the revs will drop form the idle 750rpm to around 695-715rpm for a short period of time until i have either come to a complete stop or hit the accelerator again.

ive gone through the same symptoms you list and also expected the same problems whether it be a seizing idler pulley, tight aircon compressor, or even the stall converter in the transmission giving me grief but still havent quite been able to nutt out the problem.

If you have manage to find this or have the problem fixed i would love some feedback.

Cheers for any help or information.
Rob

[Hodge]

G'day mate. Yes I have diagnosed my vibration, although It's more of a rattle than vibration.
My one ended up being a loose exhaust system somewhere along the line. I still haven't pin pointed where. So basically when the system sees some high EGT's for a while and exhaust heats up (long run @ 100km/h), then when I stop it begins rumbling until it cools down a bit.
The reason, I originally assumed it was a vibration related to braking, is everynow and then, when I step on the brake and the car is stopped up a slight incline, the vibration stops, and then when I let go, it returns. Weird, but that's whats happening to mine anyway.

[Maughany]

ahh ok mate yeah i think mine is a little more serious than that but also alot more of an intermittent problem i notice it only really happens when the economy button is on rather than power and maybe its once a week im thinking its when its trying to get into first gear on slow down to a halt im hoping its something simple like a pulley seizing up a little and not a rooted gearbox/stall converter problem.
but cheers for the reply mate