Ok to drive with a bit of mayonaise?

Fri Jun 03, 2005 8:50 am

After weeks of driving with this suspect cracked head problem (water seaping into combustion chamber, not the oil), i noticed this morning that it was running rough for a bit longer and the clouds of white smoke behind me lasted longer too.

Got to work and popped the bonnet to find small traces of mayonaise on the oil filler cap and a tiny bit on the dipstick.

Question is, how long is it safe to drive like this? I'm getting a replacement head next week and ordering a new cam from Germany, but i wont be ready to fit all this for about a week and a half. So should i carry on driving, or not risk it and take it off the road?

Fri Jun 03, 2005 8:55 am

Hi Pete, its not really advisable to drive it like this full stop mate,but if you did it could last an hour or a month its so hard to tell....sorry cant be more psychic (or is that psychotic!

)

Fri Jun 03, 2005 9:00 am

What you dont want is pressure building up in water system, and blowing a pipe.. or worse!!!!!

Fri Jun 03, 2005 10:50 am

Mine drove fine for a couple of weeks with just tiny traces of mayo in the oil. The water was fine.
It was only when after one journey where it got really bad where I took it off the road.

Fri Jun 03, 2005 10:56 am

If it's just a small amount you should be ok.

Mine got really, really bad before it failed nastily!

The mayo was really thick and all over the dipstick and filler cap.

But like it says above, head problems can cause pressure build up.

Fri Jun 03, 2005 11:34 am

Pete,whip off the header tank lid,this avoids any pressure build up,I've done this on REALLY shagged engines more times than I care to remember and it'll more than likely last the time you want with no problems

Fri Jun 03, 2005 11:55 am

I've run for 2 years now with a tiny bit of mayo.
no noticable loss of coolant,
still running fine.

I'm gona wait untill it gets worse before doing the gasket.

Fri Jun 03, 2005 12:06 pm

If you do alot of short journey's that can cause mayo to start to build up as any overnight moisture doesnt get a chance to evaporate as the engine doesnt warm up enough......but its normally not a huge problem as long as the car gets a good run now and again

Fri Jun 03, 2005 1:10 pm

Jesus325iTouring wrote:Pete,whip off the header tank lid,this avoids any pressure build up,I've done this on REALLY shagged engines more times than I care to remember and it'll more than likely last the time you want with no problems

Do you mean leave off the water filler cap on the expansion tank?

I'm not sure why there would be a build up of water pressure. To my knowledge, there's no oil in the water - it's leaking the other way, so if there's nothing added to the water, why would the pressure increase? I just like to understand these things.

What if i undid this cap after every journey to ensure the pressure was released, hence stopping any water being pushed through the cracks as it cooled down?

The only journey i use the car for is too and from work - 12 miles each way, mainly on dual-carrageway at "usual" motorway type speeds.

Thanks everyone for their help on this one!

Fri Jun 03, 2005 1:11 pm

Mayo is a sign of blocked up engine breathers too.

It's a common fault on GM engines. Usually enough mayo to start a Hellman's factory in the old Vauxhall 8v engines.

Fri Jun 03, 2005 1:21 pm

PeteE30Tourer wrote:
Jesus325iTouring wrote:Pete,whip off the header tank lid,this avoids any pressure build up,I've done this on REALLY shagged engines more times than I care to remember and it'll more than likely last the time you want with no problems
Do you mean leave off the water filler cap on the expansion tank?

I'm not sure why there would be a build up of water pressure. To my knowledge, there's no oil in the water - it's leaking the other way, so if there's nothing added to the water, why would the pressure increase? I just like to understand these things.

What if i undid this cap after every journey to ensure the pressure was released, hence stopping any water being pushed through the cracks as it cooled down?

The only journey i use the car for is too and from work - 12 miles each way, mainly on dual-carrageway at "usual" motorway type speeds.

Thanks everyone for their help on this one!

Pressure builds up as the water temp increases, and forces the water into places it shouldn't go.

Taking the cap off after the journey isnt a good idea! (unless you want to burn your hand) water boils at a higher temperature if under pressure, Say 120 degrees ish.
The sudden release of pressure causes the water to boil and burn your hand.

Fri Jun 03, 2005 1:30 pm

smithy318i wrote:Pressure builds up as the water temp increases, and forces the water into places it shouldn't go.

Taking the cap off after the journey isnt a good idea! (unless you want to burn your hand) water boils at a higher temperature if under pressure, Say 120 degrees ish.
The sudden release of pressure causes the water to boil and burn your hand.

Ok, i understand. Temperature still seems to be ok, i.e. not excessive, though i will keep an eye on it. I was aware about the boiling over of the header tank when hot, though it's usually more or less empty due to coolant loss!

Fri Jun 03, 2005 1:37 pm

PeteE30Tourer wrote:. though it's usually more or less empty due to coolant loss!

You need a new head gasket then!

Fri Jun 03, 2005 2:22 pm

Cheers Smithy,You've explained it better than I would have.
It was one of those things I knew worked,but couldn't really explain why very well!
Pete,good luck

Fri Jun 03, 2005 7:12 pm

The mayo's lubrication quality is far from clean motor oil, so the the cam and crank are prone to excessive wear. If the head is cracked and needs replacing, you should also change the cam and rockers while at it. In addition, if you run with inadequate lubrication, at least a piston rod bearing job is around the corner as well.