May on oil cap

Went to look at a car the other day, as the garage/dealer have had it over 2 months and I guessed it'd been mostly driven short trips (test drives & between the forecourt and the lockup at the back of their building) I'd have expected to find a bit of mayo.

Checked the coolant under the radiator cap - fine.

No white smoke from the exhaust.

Wiped the mayo off before the test drive which lasted around 10 miles / 40 minutes or so - long enough to clear a little bit of mayo remaining on the cap I'd have thought.

After the test drive however more mayo had returned :-/

Checked the coolant in the expansion bottle - fine.

Now then, is it possible for this to be caused by a *lot* of condensation built up over recent months of very short trips that is still making it's way out of the oil - or is it just a good sign that the headgasket is fooked?

Ideally a change of oil and a good run would've been conclusive, but dealers tend not to do anything unless it guarrantees a sale. BTW, the car was 4.5 years old, 28,000 miles and has a full dealer service history.

I know you could say I should just walk away as there's plenty others out there - unfortunately there seems to be only a handful of them up for sale in the UK on Autotrader less than 5 years old. Actually I did walk away (too much of a risk for the price, and have seen a 6 month newer car but with 23,000 more miles :( ), but would like to hear from people with better knowledge than me. I've experienced a tiny tiny bit of mayo on my own cars during damp weather and if they've only done very short journeys (not very often) - but it's always cleared after a good run. I've never experienced mayo to return to the oil cap almost immediately - as mentioned above, coolant is fine, no white smoke, could it just be more condensation making it's way to the top?

Thanks in advance.

Rubbish, I'm still waiting to now what car it is?

Or are you expecting a different response this time?

Feck. Bloody grammar checker ain't working is it :-)

Yes really, I blame everything on Tiscali >:(

Apologies for the multi-postings then, but they didn't appear for me :(

The car is a 2001 Mitsubishi FTO 24V V6 (the MIVEC engine).

My next question: If a car fails on emissions for an MOT (specifically the CO reading), what can the causes be?

Go somewhere else, buy something different.

Jap. imports are rarely a good idea - especially if the one you're looking at isn't 100%.

You replied to one of them!

Righto, it does help you see, some cars are prone to just getting a bit of mayo into the rocker cover, and on others it's a sign of coolant leakage.

Personally I don't know much about this engine, but if you'd said what car you were looking at in the first place, you would target the people that do/might know.

It's be best to get a diagnostic done, as it can be cause by almost any of the sensors on the engine. A lot can depend on how much the CO is over by too. If it's only over by a little, simple servicing could be the answer.

Otherwise, it could be a failed cat, O2 sensor, MAF/MAP sensor, TPS, temp sensor.......

Or even a suspected head gasket failure!

You would need to drive hard for an hour or two to dry out a large engine like that, take it for a 50 mile each way fast motorway or preferably fast twisty a road run, then have a look.

mrcheerful

Andy Hewitt wrote on Sun, 30 Oct 2005 23:32:27 +0000:

Surely only an _actual_ head gasket failure can cause emissions problems? Or perhaps that explains why my car keeps doing odd things -- I suspect something's wrong, so it goes wrong.

or perhaps he meant a 'suspect' head gasket ?

And remember that there is now growing evidence on the quantum level that you create what happens by your own thoughts. So perhaps it is best to always be very positive about your vehicle and not think the worst !

mrcheerful

mrcheerful wrote on Mon, 31 Oct 2005 12:34:04 GMT:

Hmm, perhaps we're all living in the Matrix.

Rich mixture. You need to have the lambda sensor checked and the air mass meter would be the next suspect.

sometimes (or most of the time), you lot are such hard work!

Perhaps we are, 'Mr' Taylor! ;-)

Ah yes, "Jap Crap" :D

Cheers, well I know that if I'd done the same journey in my car it wouldn't have accumulated any mayo. So because I'd wiped the existing gunk off I just wasn't expecting any more to return. So you're saying that it is (or could be) further condensation in the engine or oil - that's good. Well, not good, but not too bad.

Will see about getting a compression test done anyway just to be sure.

Surely this would've been obvious to the previous owner when he has to fill up with petrol twice as often as normal.

From what I know the level was around 3.6 to 6.4 when it should've been around 0.3 to 0.5 (can't remember whether the figures were for idle or fast idle).

You need a block test done, not a compression check. A block test samples the gases above the coolant and checks for combustion products, any at all mean you have a leak, probably head or gasket. The tiniest pinprick is enough to give you problems, if you checked the compression it is unlikely to show, a leak severe enough to show up on a compression test would mean it ran badly.

mrcheerful

also, if he doesn't check the headgasket, then its both fooked and not fooked at the same time ;)