Leaking inlet manifold gaskets = mayo?
 

Can leaking lower inlet manifold gaskets on the KV6 cause large amounts of mayo in the rocker covers?
If so please can someone explain to me how, as I can’t see it myself.
In my mind any coolant leaking internally will be burnt in the combustion chambers and perhaps cause steam out the exhaust.

I am trying to establish the cause of coolant loss and mayo build up on my V6.

Hello Ashley,

Do you have mayonnaise in the expansion tank and/or on the dipstick as well?

Has the engine recently overheated?

Is the car receiving little use at the moment?

Simon

No mayo in expansion tank or on dipstick.
In fact when I removed the rocker covers there was no mayo below the rocker gaskets, only above the gaskets.

Gets driven 40-50 miles per day (2x 20 mile dual carriage way 60-70mph trips).

Have just cleaned mesh gauze filters, cleaned out as much mayo as I could, fitted new thermostat and inlet gaskets. After a couple of weeks and 4-500 miles I can see through the oil filler hole that mayo is building up again. Been topping up with coolant still every 2-3 days.

I’m puzzled as there doesn’t appear to be mayo in the oil at all.

I did notice some pitting on the inlet manifold to head mating surfaces, but any leak here would not explain the mayo, would it?

Have you investigated the possibility of an oil cooler failure?

As the V6 cam cover gasket is sheet metal are you saying that there is no contamination of the camshafts and valve gear, only the underside of the cam cover and top of the gasket?

If so, I was going to suggest checking that the coolant is reaching a proper temperature but you've said that you've renewed the thermostat. Did you follow the official bleeding procedure (raising the expansion tank etc.)?

How much coolant are you adding after 2-3 days? Can you see the 'MAX' marker when looking into the tank through the filler neck?

Simon

New oil cooler fitted from DMGRS. I guess it could be faulty but I doubt it.

That is correct. No mayo underneath the rocker gaskets, only above on the top face of the gaskets and in rocker covers. I cleaned it all out, replaced the mesh filters with some clean ones from a spare engine, and ensured the breather holes were clear. Checked all the breather pipes were not clogged.

Yeah, changed the thermostat as it had a small leak from one of the O rings.
Have driven it in diagnostic mode, can’t remember exact figures now, but I think temp was in the 90’s when driving, creeping up to around 100 in traffic and fan cuts in. I’ll double check it on drive home this eve.

Sometimes when I check the expansion tank there’s no coolant in there, probably only takes a cup full to reach max mark. Other times I check and I can see coolant in the tank. Seems random.

The mayo is a puzzle. How could moisture enter the area above the cam cover gasket but nowhere else? But your engine temperature is fine. :shrug:
When you replaced the thermostat did you use the cylinder block drain tap as well as the bottom radiator hose?
When refilling, did you follow the MGR procedure exactly?
Is the coolant level staying above the 'MIN' marker?

Simon

It is indeed! Well it could get mayo in the breather system if there was a blockage or broken breather pipe etc - but I’ve checked everything and rectified anything that wasn’t right.


Coolant drain / refill procedure was followed, but I can’t see how this is relevant to the mayo issue?


So, do you know if leaking inlet manifold gaskets could cause mayo? Someone told me it could and I’ve read a comment or two in other threads suggesting inlet gaskets when someone has had a mayo problem, but I can’t see how this would be related.
If someone is able to confidently say yes, and give an explanation how leaking inlet manifold gaskets can cause mayo build up then I will take the inlet manifolds off again and re-investigate, as the faces were not perfect. But if it’s not a possibility then I’ll save myself the time.

On drive home this afternoon temp ranged from 88-93 cruising at approx 70, but seemed mostly to be around 90. This is with AC on.