I had my 65 Coupe about four years with no problems. Last year lost a head gasket and recently (after over six mos sitting dismantled) replaced the gaskets. Did fine for a while, but I am now getting oil on the plug in the same cylinder where originally was coolant (due to blown gasket). Is there an easy was to diagnose gasket failure vs cylinder ring vs valve guide. There is no coolant in my oil. Engine last rebuilt in 1972.

 

did you have the head resurfaced before you installed the new gasket and have you ever done a valve job to the head.

 

The quick answers are no and no.

I tried the cheaper route initially, but obviously it didn't pay off.
I have been putting away money since that time and am considering having a rebuild. But, if I could tell for sure I was heads only I could have the heads worked and spend the money on something else. ( there is always something else )

 

do a leakdown test! 1. pull the sparkplug. 2. force compressed air into the cylinder. 3. listen to the dipstick tube. if air is coming out its the rings. if air is coming out the intake or exhaust its the valves.

 

Yes and yes. You can perform a vacumn test that will tell you if the problem is the valves, rings, or head gasket. Basically, you need a vacumn tester and you hook it up to the sparkplug hole of a cylinder near the problem. As the engine turns over, the level and eradidication of the vacumn will tell you what the problem is. HOWEVER, this is not needed in any case. If it is the head gasket, you will need to take off the head and replace the gasket. If it is the rings, you will be taking the engine out and apart anyway. So, what I would do is take the head off and carefully see if you can determine if the gasket was leaking into the cylinder. You can check the rings when the head is off as well as the valve seats. You will then know what the problem is. If it is the same head that you replaced the gasket on, I am betting it is just the gasket. If the head got hot, it must be resurfaced. If you are going to get it surfaced, then take BOTH heads off and have them both resurfaced and gone through.

 

Thanks for the reply. How can I test rings for compression after taking the heads off? Serious question.

 

the easiest route is what silverblue describes, but you'll need compressed air for that ...

 

You cannot test the rings for compression after you take the heads off. However, the point is that if the car is leaking oil past the rings, you will see that fact clearly on the cylinder wall. You will also see it on the surface of the piston top near where the ring blow by is occuring. When oil leaks past the rings into the cylnder, the car will smoke (some) and when that cylinder fires, the oil leaves a black burnt area at the point of blow by. Go ahead and do what silverblue suggests and check compression before you remove the head. If it is a head gasket, depending on where on the gasket it is leaking, you will either lose compression into the water port or you will have water in your oil. More than likely, the oil is coming through a valve seat or valve sleeve.

Do a compression test. Drain the oil and look for any water (radiator fluid). Pull the head carefully and see if you can determine the condition of the gasket and if you can see any sign of blow by. Finnaly, pull the piston down to the bottom of the cylinder and check the walls for blow by marks...as well as the top of the pistion.

Good luck.