Mayo in the breathing system
 

Today I decided to take a quick look at the gauze in the breather on the front of the engine and first things first the rubber boot pretty much falls apart in my hands, secondly the inside of the housing is covered in mayonnaise which tells me water!!!! however inside the oil cap on the cam cover looks fine.


Starting is always a little fun with it taking a few moments to recognize it's a 6 cylinder and not a 3 or 4 so I have a bit of a misfire just on start-up, when underway it's fine I think this weekend I will try a compression check and I am hoping I don't have a cylinder down as I know that will mean head gasket time. I have 80000 on the car from new so based on common belief that the gaskets go around 100000 miles it looks like I might be in for a long job ahead..


Not a way I wanted to start the weekend.....

If your coolant level is not going down I have found this to be from a cold start driven a few miles and shut off not to be started again for a few hours like driving a couple blocks to work then home again.Nothing more than condensation. Ahead gasket gone with any amount of coolant loss will result in milky looking oil.

Randy

Don't panic. Sometimes water vapor get trapped in certain places and creates the mayo. Water vapor is a by product of combustion and if you car is running cool for some reason the water can get trapped long enough to emulsify. I know the feeling.... The first time I opened the oil cap on the Mercedes CLK I purchased for my wife.... it had some mayo. I stole the car and figured I was beat because the car had a bad engine. Not so...it's been fine for years and uses no coolant. I often check the oil cap... sometimes there is mayo there and sometimes not. Happily I've never again had the amount of mayo I saw the first time, just a bit now and then. Do the compression test anyway just so you know for sure.

Make a ham sandwich!

Mustard goes best with ham!

I agree with the others that mayo in that area, in and of itself, is no cause for immediate alarm. It's quite common.

The misfire on start-up could be any number of things but, yes, a leaky head gasket is one of them. After a good run let the engine sit overnight and then pull the plugs. You might actually see droplets of coolant on the plugs and/or in the cylinders. I did on mine and that was obviously proof positive that I had coolant getting into the cylinders. Misfire till it burns off, of course. I drove mine for a couple months like this until I had time to replace the head gasket.

Another way to determine if a head gasket is leaking is to have a repair shop use their exhaust analyzer to 'sniff' the coolant. If you have hydrocarbons in the coolant the sniffer will pick it up. A DIY "Block Test" kit from your local auto parts store will also detect hydrocarbons in the coolant. Personally I prefer these methods if I suspect a leaky head gasket, absent visual proof as mentioned above.

Cheers
DD

Smell the exhaust
 

I have found that you can usually smell any coolant that has leaked into the cylinders if you smell the exhaust shortly after startup. Another sign is visible on cooler days, when coolant will manifest itself as a higher than normal amount of "steam" coming out of the tail pipe. Most cars will have some at startup but it will eventually dry itself out after a few miles...if you still see steam (and not coming out of most other cars), further investigation is probably in order. Keep in mind that this is a very preliminary check method and it should be followed up if suspicious.

Jim
86 XJ6

+1 on that fact that it could be entirely normal, especially if you do a lot of stop / start journeys around town with the car not always getting up to temp

You can still buy those rubber boot thingies. Not expensive either.

SNG Barratt - The Ultimate Jaguar Parts Specialist

No doubt you cleaned the little gauze capsule too ?

Thanks all, i managed to get the rubber boot etc from David at Everyday XJ...

I am not going to just whip the head off but will do a little testing once back together. The coolant level is still normal without any loss so i will keep an eye on things.