I pulled the heads on my 406 a month ago when I decided to do a cam swap. I thought maybe I had a bent valve so I needed to get a closer look.

When I pulled the passenger side head I found three cylinders that were milky. When I pulled the drivers side head I found one cylinder that looked the same. I was really baffled with this because I had no sign of trouble. The engine had a miss which I took as a possible bad valve, but I didn't expect to find this.

I had no water in my oil, no steam out of the exhaust pipes, no bubbles in the radiator, the head gaskets looked perfect, nothing stood out as the culprit. I had changed my intake gasket about a month before I pulled the heads. The gasket looked fine and I didn't see any signs of a leak in the lifter valley.

I don't believe it could be a cracked block or head because it was on both sides. I thought maybe my intake could be warped. If it is, it looks like it would let water into the oil along with the runners.

My engine has 11-1 compression and I have been using good head gaskets. I put sealer on the head bolts and used the recommended torque. It looks like you should be able to see where this came from, but I could find no trace.

I've had a blown head gasket before on another engine and the bad cylinder was alot cleaner than the rest. These cylinders were not clean at all, more wet and nasty than anything.

Thanks for your time,

Joe

When I pulled the passenger side head I found three cylinders that were milky. When I pulled the drivers side head I found one cylinder that looked the same. I was really baffled with this because I had no sign of trouble. The engine had a miss which I took as a possible bad valve, but I didn't expect to find this.

Both sides is suspicous.

Sounds like warped intake or bad intake leak on both sides.

Got any photo's of intake and gasket.

Internal crack in the intake?

I had an intake that cracked into the exhaust crossover passage. It took me quite a while to figure out where I was loosing vacuum.

Captain Obvious here: there has to be some kind of coolat leak somewhere.

I tried to look closely at your picture and noticed that the threads on the head bolt holes look VERY shinny. What did you use for sealant on them? IF you used Permatex #2 (like a ALWAYS do) then there would be some Permatex #2 left on the threads.

I bought a complete 010 350 out of Gary's-U-Pull-It for $50 a couple of years ago. I was very clean on the outside and had new freeze plugs in it. When I pulled the intake, there was NO sealant on them which lead me to pull a head bolt which had blue RTV on them. Measured the bore and it was 4.030". Cleaned everything up, put new gaskets in, and Permatex #2 on the bolt threads. Engine had NO coolant leaks and ran like Swiss watch. Sadly, someone had spent a lot of money rebuilding a motor only to miss a minor point in rebuilding it, must have had a problem with coolant leaking, gave up on it, and sold it as junk.

Sometimes coolent doen't drain fully and some remains in the heads. When you pulled them off you opened up the cooling jackets and this coolent leaked out. I have had this happen if I don't wait long enough after draining the system. Check the heads and deck for flatness prior to reassesmbley to be sure you don't have a problem.

I used Permatex ultra grey on the threads. It has a high torque load and is made for imports. I've heard people say it's suppose to be better than the blue Permatex.

I'm going to try another intake and see what happens. I don't think the coolant leaked into the cylinders when I pulled the heads. It wouldn't have been milky if it had run into the cylinders, it would still be green.


Thanks for your time and help everyone,

Joe

How long does it typically get run for? How hot does it run? Could just be condensation build up from the last time it was run if it didn't get very warm and sat for a long time, kinda like what builds up in your valve covers. Would only happen on cylinders with an open intake valve when it was shut off, so that might explain it...

How long does it typically get run for? How hot does it run? Could just be condensation build up from the last time it was run if it didn't get very warm and sat for a long time, kinda like what builds up in your valve covers. Would only happen on cylinders with an open intake valve when it was shut off, so that might explain it...


Actually Adam it hasn't run much. I've been tinkering with it since November on and off in my garage. I'll start it up for 30-40 minutes, but I haven't drove it.

I do rememer last year seeing condensation on the inside of my valve covers. I was worried about that until I posted on here. Everyone said it was where the engine hasn't run long enough.

Could that happen in the cylinders too?

I see no reason why it couldn't? Especially if it was only run for short periods of time.