# Symptoms for blown Valve cover gasket VS blown head gasket



## samach (Jun 19, 2014)

Can somebody please elaborate the difference in symptoms between a blown head gasket and/or a blown valve cover gasket. Or may be it's not possible to differentiate?

I have the following symptoms and I am baffled:

1) I have to top up the coolant every month by half a litre. The cars does 1000-1500 km's on average per month.
2) When I rev the engine, i see moderate smoke and water sprayed out of the tail pipe. It also smells gasoline.
3) No coolant deposit on the dipstick (looks normal).
4) Engine oil cap looks like this:



















I figure this might be because of the moisture in air?!?!?

5) When engine is hot, it idles rough


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## rstolz (Jun 16, 2009)

that's a head gasket failure.

valve covers allow oil to either leak out, or into the cylinders via the plug openings.

head gaskets kill compression, allow oil and coolant to get into the cylinders and into each others' reservoirs.

that white foamy stuff is tell-tale head gasket. If you did a compression test I 'd bet you've got at least one cylinder down as well.


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## groggory (Apr 21, 2003)

rstolz said:


> that's a head gasket failure.
> 
> valve covers allow oil to either leak out, or into the cylinders via the plug openings.
> 
> ...


yup


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## samach (Jun 19, 2014)

roger that ..... but coming back to my original question (for general knowledge), are there any concrete symptoms that differentiate between a blown head or valve gasket?

For instance, if your head gasket is bad you will see white smoke from the tail pipe which cannot happen if the valve gasket is blown...

According to this article http://www.offroaders.com/tech/milky-stuff-under-oil-cap.htm its not always the blown head gasket that can deposit mayonnaise on your oil cap.


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## 87vr6 (Jan 17, 2002)

*FV-QR*

A valve cover gasket will just leak some oil in various places in your engine bay, like I dunno, around where the valve cover and head meet... A head gasket and valve cover gasket have by no means the same symptoms, causes, or results. They are not interchangeable.


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## rstolz (Jun 16, 2009)

rstolz said:


> that's a head gasket failure.
> 
> valve covers allow oil to either leak out, or into the cylinders via the plug openings.
> 
> ...





samach said:


> roger that ..... but coming back to my original question (for general knowledge), are there any concrete symptoms that differentiate between a blown head or valve gasket?
> 
> For instance, if your head gasket is bad you will see white smoke from the tail pipe which cannot happen if the valve gasket is blown...
> 
> According to this article http://www.offroaders.com/tech/milky-stuff-under-oil-cap.htm its not always the blown head gasket that can deposit mayonnaise on your oil cap.


you asked for symptoms, there they are. Are they concrete, yup. Can other things cause the same issues, yup. That's why, when you get one symptom, you look for another relating symptom. IE, frothy coolant? is it the head gasket? check contamination at the oil reservoir, in the coolant reservoir, check the exhaust for burning coolant/oil, and run a compression test. A blown head gasket will have all of the symptoms.

Blown rings will cause bad compression and a bit of oil burning, but no coolant contamination. White frothy oil could be from a bad PCV breather assembly, but won't come with coolant contamination...


Read and follow the symptoms, test and check various things to rule out various issues that may have some overlapping symptoms. This is old-school diagnostics 101... stuff that most modern mechanics have forgotten how to do, now that cars have computers and scanners. You're on the right track, just have to keep plugging away. 

Once the car is warmed up, note the color of the exhaust, and check against thishttp://www.freeasestudyguides.com/exhaust-color.html
then draw some coolant out of the reservoir and check it for oil contamination; pour a fresh sample into a container, and a sample from your reservoir into another container. look at the color and feel the texture.


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