Bleeding S6 rad in a Cerbera

[mulsanne]

Hi fellas,
not been on this part of the forum before as my '99 S6 Cerb has never had an engine issue in 7 years of ownership, (now there's tempting providence........!), so I usually use the Cerb forum for electric/running gear issues.

I have done the usual searches for an answer to my current problem but it seems that the V8 boys have different arrangement of their cars' cooling systems to mine. I have recently been experiencing very high coolant temps from my usual, with 95 -100 degrees on the gauge, it's usually 80ish and if it climbs in traffic, will always drop down when fans kick in.

I now find that the temp rises even on a steady run and the fans, although working correctly, are not dropping the temp. Took the engine panels off tonight and found that when the thermostat opens, the top hose and the RHS side of the rad get hot, but LHS and bottom hose stays cold. I suspect air in the system, but can only find a single bleed plug on the LHS top of the rad. Got a little air out but still can't get the rad to work. Hot in, cold out. I dare not let it get over 100, as it's never usually anywhere near that.

The V8 guys talk about an extra 2 bleed valves with wing nuts in various other places, do we have any on our S6s that I've just overlooked? I've followed advice about raising the nose of the car when bleeding, but can't make a difference through the single bleed plug on the rad.

Any advice on the peculiarities of S6 cerbs would be really welcome right now, as I've got to that well known stage where I'm just going in circles!

Thanks in anticipation

Mark

[Buffoon]

I don't believe for one second it is air. Drained and refilled mine 3 times in last couple of weeks without issue. You do get some residual air in it after bleeding at the rad, but the water pump soon clears that on a run. My first port of call would be the thermostat. May not be opening properly.

[mindstar]

I'm by no means an expert on this but, is that not what the rad should do?? Hot in , cold (or less hot) out.

Have you checked the rad for damage from stones?

Do you have a coolant pressure gauge?

[mulsanne]

Thanks for your replies. I think it's sorted now. There must have been SOME air going round as when bleeding there was always a little amount of bubbles coming out, but certainly not enough for an airlock.

The thing that confused me most was the top hose became very hot when the thermostat opened and yet this didn't make the opposite side of the rad warm up. (Stone cold). When the fans came on, (the sensor is in the cylinder head) meant the engine was ready to maintain it's temp, but cold air was felt from the back of the rad. The temp gauge kept going up as the rad was not dissapating the heat and the fans stayed on. Clearly the 'stat WAS opening, but maybe not enough for the coolant to circulate fully.

I took the thermostat out, resealed the cooling system and ran the engine. Of course it took longer to reach normal temp, but when it did, the fans reduced temp, then switched off as it was reduced. I let it cycle through this a few times and concluded that the themostat had failed in a closed/very slightly open state.

A replacement is now on order and hopefully I'll fit it tomorrow. This just shows that we (or is it just me?) seem to to become conditioned to expect the worst from our cars when most times it is usually quite simple.

I make this post as testament to my own naivity and just maybe as a hope to future sufferers that things sometimes aren't as bad as they seem at first!
Rgards

Mark

[G20RG B]

Glad you got it sorted, but out of interest where is the thermostat on a SP6 Cerb in case I ever have to go there!!.

[mulsanne]

Hi G20RGB
Location of Thermostat housing is in the centre of this pic (assuming it uploads as I've not done this before!) You can see the thick hose leading forward from it to the top of the radiator and the 2 hex-headed bolts at the top and bottom of the housing.

http://thumb2.webshots.net/t/83/183/3/26/16/210232...

As far as cerberas go, it's a doddle to remove and replace, but here's hoping you never have to do it.

all the best,
Mark
ps having seen your profile pic of your shiny engine, I almost hope my pic DOESN'T upload! I am embarrased to notice my cerb's engine is not as shiny as yours...

[G20RG B]

Thanks Mark,

At least I know where it is now, if I have to go there, I did replace the water hoses and pipe which attach from the radiator to the thermostat just never new thats what it was. I learning as I go along!!.