Mayo in the oil filler cap

Guapito · 26th April 2007, 17:57

Just spotted some of the dreaded mayo-like substance in the oil cap of my ZT 160. I usually associate this with poss head gasket problems but the car has 85k and is running fine. Could there be another reason why this gunk is in my oil cap or I'm I looking at a near future head-gasket failure/replacemnt?

JohnDotCom · 26th April 2007, 18:16

Head Gasket is normal for that sympton or water getting in there and mixing with the Oil.
Being more on Diesels myself someone with more knowledge on these things will be along to help shortly.

tony g · 26th April 2007, 18:20

Quote:

Originally Posted by Guapito

Just spotted some of the dreaded mayo-like substance in the oil cap of my ZT 160. I usually associate this with poss head gasket problems but the car has 85k and is running fine. Could there be another reason why this gunk is in my oil cap or I'm I looking at a near future head-gasket failure/replacemnt?

It could be just condensation that builds up with doing a lot of short runs ? giving it a good run out can sort it ( and an oil change ) are you loosing coolant ?

driverjgp · 26th April 2007, 20:07

Quote:

Originally Posted by Guapito

Just spotted some of the dreaded mayo-like substance in the oil cap of my ZT 160. I usually associate this with poss head gasket problems but the car has 85k and is running fine. Could there be another reason why this gunk is in my oil cap or I'm I looking at a near future head-gasket failure/replacemnt?

Check the vacuum hoses under the engine cover, use a 8mm socket and lift the cover off then you will see a network off small vacuum pipes, what normally happens is were they all meet at the junction in the middle it just simply breaks up then it sucks in moisture from the air and converts into mayo, its quite harmless but never the less it will need sorting, short term you can blow them though then you can tape them all back up and put them back until you get the parts, mine have been tapped since December but they will be replaced when I go for my MOT on 8th May, while the engine cover is off get a good torch and shine it into the V area of the engine and check the thermostat and temp switch is not leaking as this things are known on the KV6 which if left could cause HGF, are you losing any water?

hth

Jason

Guapito · 27th April 2007, 13:36

No, no loss of water. I've cleaned the stuff out of the cap and will leave it for a little while and chck it again. Like someone has mentioned, it could be a small build up of condensation. But I will do the checks you've advised.
Thanks

driverjgp · 27th April 2007, 17:01

Quote:

Originally Posted by Guapito

No, no loss of water. I've cleaned the stuff out of the cap and will leave it for a little while and chck it again. Like someone has mentioned, it could be a small build up of condensation. But I will do the checks you've advised.
Thanks

If there is no loss of water then I'd put my money on the breather pipes as described in my previous post.

Keep us informed.

Guapito · 29th August 2007, 16:27

You were right. I took the cover off and found that the joint, where the 3 vacuum pipes join, had rotted away. I've just ordered a new set from SMC in Slough for £16.
Thanx

MikeHurley · 17th November 2007, 14:59

Interesting as I have a 2.5l also. Noticed a slight amount of what you could call dark mayo on the underside of the Oil Filler Cap and following the comments above just nipped out and removed the engine cover to view the junction of the 3 vacuum pipes.

One of the pipes came away from the 3 way join very easily and like to underside of the oil filler cap there was evidence of the same kind dark coloured Mayo. The car has been on relatively short journeys over the last couple of weeks in this colder weather.

So I think I'll tap the vacuum pipes together tomorrow and observe is the moisture being pulled in from the air is the cause of this mayo.

Members views and comments welcome as usual.

26th April 2007, 17:57	#1
Guapito Regular poster MG ZT CDTi 135 + Join Date: Mar 2007 Location: Bracknell Posts: 62 Thanks: 10 Thanked 0 Times in 0 Posts	Mayo in the oil filler cap Just spotted some of the dreaded mayo-like substance in the oil cap of my ZT 160. I usually associate this with poss head gasket problems but the car has 85k and is running fine. Could there be another reason why this gunk is in my oil cap or I'm I looking at a near future head-gasket failure/replacemnt?

29th August 2007, 16:27	#7
Guapito Regular poster MG ZT CDTi 135 + Join Date: Mar 2007 Location: Bracknell Posts: 62 Thanks: 10 Thanked 0 Times in 0 Posts	Mayo You were right. I took the cover off and found that the joint, where the 3 vacuum pipes join, had rotted away. I've just ordered a new set from SMC in Slough for £16. Thanx

26th April 2007, 18:16	#2
JohnDotCom * Rover 75 FaceLift Tourer CDTi 170BHP Auto ConnSE 2005 Model Starlight Silver Join Date: Nov 2006 Location: Abergele Posts: 28,735 Thanks: 0 Thanked 6 Times in 5 Posts	Head Gasket is normal for that sympton or water getting in there and mixing with the Oil. Being more on Diesels myself someone with more knowledge on these things will be along to help shortly.

27th April 2007, 13:36	#5
Guapito Regular poster MG ZT CDTi 135 + Join Date: Mar 2007 Location: Bracknell Posts: 62 Thanks: 10 Thanked 0 Times in 0 Posts	No, no loss of water. I've cleaned the stuff out of the cap and will leave it for a little while and chck it again. Like someone has mentioned, it could be a small build up of condensation. But I will do the checks you've advised. Thanks

17th November 2007, 14:59	#8
MikeHurley Gets stuck in Rover 75 Saloon 2.5 V6 Join Date: Sep 2007 Location: London Posts: 659 Thanks: 129 Thanked 26 Times in 24 Posts	Interesting as I have a 2.5l also. Noticed a slight amount of what you could call dark mayo on the underside of the Oil Filler Cap and following the comments above just nipped out and removed the engine cover to view the junction of the 3 vacuum pipes. One of the pipes came away from the 3 way join very easily and like to underside of the oil filler cap there was evidence of the same kind dark coloured Mayo. The car has been on relatively short journeys over the last couple of weeks in this colder weather. So I think I'll tap the vacuum pipes together tomorrow and observe is the moisture being pulled in from the air is the cause of this mayo. Members views and comments welcome as usual.