'90 gti 8v, oil in water bottle problem

[Scooterist007]

Hi, just thought I would see what you folks would say about this, I have just been to look at a 1990 gti 8v on a H plate, the guy wants ?1000 for it, well the car is very nice, body you cant fault it, but the engine, well! I got the guy to start it up, and while at the back of the car, looking for blue smoke, everything was ok, but when I took the oil filler cap off, while the engine was runnning, it nearly stalled, and the engine revs were rising and droping until i put the cap back on, also when the cap was off, there wasnt much pressure coming from the hole. Also, in the water bottle, there is some white gungy mayoniasing, and also the red warning light is flashing, but the car didnt overheat when i took it out for a test drive, the temp guage went up and didnt go above 1/4 way, also the car drove really well, so if it is a head gasket problem, surly it would run like a tractor! so this one has stumped me, the guy selling the car is getting fed up and i said i wouldnt over him no more than ?500 for it. thanks for any advise.

[Blue MK2]

with the oil filler cap causing the engine to rev high/low. Sounds like a digifant engine which is the later 8v engines.

any mayo on the dipstic?

the red warning light could be the water level light indicating that it is low.
for the mayo under the cap. most older cars get this on cold days/starts. how does it look with the engine up to temp?

[Scooterist007]

well what is the problem thats causing the revs to rise and lower?

no there is no mayo on the dipstick.

The water level was ok, up to the level marks on the water bottle, and the mayo isnt just under the cap, its floating on top of the water level and when you put your finger in it, it covers your finger with quite a lot of mayo, and it is still there when the enging is up to temp.

thanks fo your responce.

[Alexg40]

Either it has been stood for a while and condensation has caused the gunk OR the headgasket is gone or going OR the oil cooler could be at fault.  The car can run fine with a knackered Head Gasket it all depends on where it has blown.

[...joe]

mayo on the dipstick or filler cap normally means head gasket, but never seen it in the expansion tank like that. it would seem to be some kind of cross contamination. my head gasket went a short while ago and right before i noticed, i was hoofing along thinking 'my god, my cars running like a dream!!' then poof lots of white smoke and mayo in the oil filler cap. you can get a simple test done by a garage on the coolant that will tell you if there's oil in it or pay the aa for an inspection for peace of mind.
sounds a bit suspect to me.

[free]

sounds like head gasket to me, as for the revs going up n down, (hunting, or trotting, as its otherwise knowen,) its prob the idel v, its that round metel thing with wires 2 it on. on top of the cam cover.

[Scooterist007]

Right thanks for all of your answers, it has stumped me because there isnt any mayo going on in the dipstick or the oil filler cap, but what does confuse me (which doesnt take a lot!) is, im not getting mayo on the cap and dipstick so where is the oil coming from in the water bottle? it has got to come from somwhere, i also dont think it couold be the oil cooler as alesg40 said, cos i didnt think the water circuit had anything to do with the oil cooler, maybe im wrong! well the guy has accepted my offer of 500 pounds for it, it has 12 months mot and taxed til the end of the year, it is very good condition with 89,000 miles on the clock, I am toying with idea of buying it! Cheers

[wellfan]

I had the same problem with my last 8 valver. It was the oil cooler at the base of the oil filter, water circulates through this cooler and if it is knackered oil can force its way into the coolant. My car ran perfectly well, however, I did change the cooler, get it from euro carparts. As for the erratic idle with the oil cap removed, my last 3 cars have all done the same, you are causing a pressure drop when you remove the cap.

[Gambit]

for ?500 buy it

i agree on the Oil Cooler leaking and the pressure drop when the oil cap is removed

but id get a compression test done just to make sure the head gasket is ok

all easily fixed for buttons

[rubjonny]

If you take the oil filler cap off it will create a vacuum leak so I recon that isn't a worry, and I agree that oil in the water is most likely the oil cooler. Since the oil pressure is higher than the water pressure any leaks will result in oil being forced into the water I would have thought.

Doesn't cost too much to buy new either...