270 guts - hi res images help find the culprit!

pfarber · Post by **pfarber** » Sun Jun 18, 2006 3:57 pm

Here are some 'autopsy' photos of the 270 thats been smoking heavily.

Here is the cylinder block:

Cyl #2 seems to be the worst.. all are sooty and some appear to be 'wet'. Not sure if its from whatever problem I am having, or if its from taking the head off.

A closer look at cyl 1-3

The cylinder head itself... looks ok. There were no green pools of Anti freeze on the head.. just a little oil. Note that the first valve spring is discolored, and this was the rod that was also newer than the rest

Heres the cumbustion chamber and head gasket. All look the same.

Heres the head gasket... note that between cyl 2 and 3 there is some discoloration.

And a slight discoloration between 4 and 5

Is this all it takes to blow a head gasket? I worked on my dads station wagon (a v-6) and there was less than half an inch between cyclinders.. when a gasket went it was obvious. These marks look less than catastrauphic. But I am not a mechanic... nor do I play one on t.v.

Heres the biggest 'tell' I have to far.... underside of valve cover. Notice the brownish 'spooge'. WHen first removed this was a bright white 'spooge'. Thats the only thing pointing me to a head gasket failure.

Anyone see anything that I am missing? New gaskets will be here monday-tuesday and it should not take long to butter her back up. Only part that i am dreading is the valve readjustment. I don't have that special tool to adjust the screws on the lifter with one hand.

armydriver · Post by **armydriver** » Sun Jun 18, 2006 10:51 pm

Good luck and hang in there, this too shall pass.

Bill_Wolf · Post by **Bill_Wolf** » Sun Jun 18, 2006 11:17 pm

Make sure you check the plane of the head and the block.

Back when you did your diagnostics...

What were the compression readings on each individual cylinder?

What were the vaccum guage readings when the engine was operating?

pfarber · Post by **pfarber** » Mon Jun 19, 2006 11:29 am

Did not do a compression test, but rather the more informative leakdown test.

All cylinders had between 5-10% drop.. which is normal for older engines... no one cylinder dropped more than 10% on the leakdown guage.

No bubbles in the radiator, a little oil in the cylinder didn't make much difference either.

Bill_Wolf · Post by **Bill_Wolf** » Mon Jun 19, 2006 12:01 pm

A Leak down test is a more comprehensive test than a compression check however they are not checking the same thing in an engine. A leak down test is great to specifically determine if valves are worn and leaking or a head gasket is blown but the combination of compression, leak down, and vaccum guage on a running is real diagnostic work.

A leak down test is supposed to be performed on a compression stroke with the piston at TDC at a measured pressure of 90 PSI. It will tell what he condition of the engine is at TDC. An engine is located at TDC with valves closed in only 1% of its 4 stroke cycle. Thus Leak down misses many of the other possible causes of engine problems....including but not limited to, out of round cylinders, "bowled" cylinders, cylinder skirt issues, cylinder scratches, and so on. Most of the problems with cylinders do not occur at top dead center but occur in the middle of the cylinder (middle of the stroke).

Without complete diagnostics it is now impossible to tell exactly what is wrong with your engine. All you can do is throw parts at it. I agree that there is some evidence that there may be blow-by between 2 and 3... You may get lucky and catch that by putting a cylinder head gasket on it...then again you may not. While the head is off... I would start by checking surface plane of the head and block. Especially in the areas of the carbon. I would also get a cylinder measuring guage and measure the diameter of the cylinders to look for out of round cylinders and "bowled" cylinders.

Hopefully you can just throw on a head gasket and that will cure your problems. If not do a compression check and a Vaccum guage check prior to another disassembly.

pfarber · Post by **pfarber** » Mon Jun 19, 2006 1:06 pm

I disagree with your believe that a compression check gives more information about an engine than a leakdown test.

A compression test is a 'general health' check. A leakdown test is a diagnostic tool.

Using 100psi makes the math easier (losing 10% of 100psi means that you have 90psi 'hold' in the cylinder.

A leakdown test gives you the ability to listen for the leak.. spray some oil on the valve guides see if they bubble, look in the radiator and see if its bubbling. Squirt some oil into the cylinder to check the rings. Each step in that process tells you where the problem is. A compression check simply tells you that the compression stroke is generating X psi. Where is the lost pressure going? rings? how are you gonna tell? valves? again, how are you gonna tell?

Since the symptoms of my problem (smoke in exhaust) are generally issues with upper motor parts (valves, rings gaskets) a compression check would not narrow down the field of possible broken parts.