OVER HEATING VR6 AND BLACK SPARK PLUGS

[nickeboy 0]

hi, im new to this site, and corrados, previously from a long history of mk1 golfs,

the problem i am having is that the car keeps overheating, either in traffic or if i go more the about 80 mph it gets hot, it tends to run at around 110 in traffic then if i dont turn the engine of or get moving it will bubble over, if i drive at around 40 - 50 it keeps at around 100 witch seems fine, i have flushed it with g12 changed the expantion cap, thryed to changer the thermostat but one of the bolt has a treaded haed so i have just bought a bolt extactor, to give that a go, however the bottom hose seems to get hot enough, not as hot as the top one but i guess the rad is colling it, i have been planning to change the water pump but again it seems ok, at idle there is a trickle of water from the little hose in the expantion tank that turns into a gently stream when reved,

 

the only other thing to mention was that 2 of the spark plugs became so black and messy that it started to miss fire, front left and front right as i remember, i have cleaned them and replaced them a couple of times and it happens maybe a couple of mounths later, is that a fueling thing or a oil thing? maybe a knakered injector or sensor?, other than that it seems to run well, i am thinking a vag com may be in order, where is best to get that done, in west london, how much would i cost?, i read a few kind ofers on this site from people with one! if anyone could help it would be fab definatly a few beers for the trouble,

 

any help welcome, i am sure there is simple solution,

 

many thanks

 

nick

[dr_mat 0]

One: sounds like your thermostat is stuck closed, easy fix.

 

Two: the oily plugs is likely bad news though mate .. That usually means cylinder head work or a full rebore, depending on which end the oil is getting into the cylinders from .. How much oil is it using between services? :(

[nickeboy 0]

hopefully the thremostat is at fault, although it does get hot at the time it should open?

 

hard to say how much oil, i top it up as and when, i guess i may put half a littre in each month if i have been using it a fair bit, there is know smoke from the exhuast though, could it not be to much fuel in those cylinders?

[nickeboy 0]

any other thoughts??

[Supercharged 2]

If it gets to 110 in traffic then the rad fan thermoswitch is probably knackered and only working at 1 stage.

 

Is the electric water pump working?

[Kevin Bacon 5]

On the running temps, I'd be tempted to replace the stat, the stat housing, and main water pump and a thorough flush using G12+, without getting any air locks in there!

 

An inspection of the cooling fan system would be a good idea...try the search as it's been covered many times.

 

On the plug fouling, it's oil. half a litre a month isn't enough to produce plumes of smoke from the exhaust under normal driving, but it is enough to gradually coat the plug electrodes. It's more than likely bore wear on 1 and 6, which is common on the 2.9.

[nickeboy 0]

the fan seems to be working at 1 and 2 i will have to check 3 again,

 

if it is bore ware causing the plugs to get messed up how and how much might that cost, and is there any way of checking it?

 

nick

[dr_mat 0]

Compression test and leak-down test will give you *hints* to bore wear, but the only real way to find out is to whip the head off and look ..

Price of a rebore is high. Many people are currently thinking that a replacement engine is cheaper and better in the long term ..