Need to remove heads from 456

It can be done with the engine in...although access is poor to the rear head nuts. I've done a few in situ, although I've removed the brake booster/master for better access on the driver's side. Unbolting the engine mounts and shifting the engine side to side helps, as well. The factory/Hill tool might not work (clearance issues) on the rearmost head nuts.

Then again, you can always pull the engine and not have to deal with these issues. I guess it depends on your pain threshold and patience level. as this is a very time consuming job, no matter how you slice it.

 

I suggest that you do some additional diagnostics before just pulling heads (perhaps you already have?)

Add some BG44K to the fuel, run hard for a bit and recheck the compression and see if it improves (might be carbon build up)

- Use a bore scope and have a look in the combustion chamber...

- leak down test?

 

If head gasket, I'm thinking you would see oil in coolant or coolant in oil....

 

Not uncommon to see damaged fire rings on 456 head gaskets that have had/had a history of running hot. The piston/combustion chamber in question will be clean from the inflow of trace amounts of anti-freeze. If you have access to an exhaust gas analyzer, you'll detect HC in the cooling system. It seems that cylinders 9,10 and 11 seem to be most vulnerable.

 

Try to narrow it down before you rip the engine apart. Drain the oil out leave the drain plug off, take then intake and exhaust manifold off. Set the cylinder to TDC and do a leak down test. Should be fairly obvious where it's coming from at that point then poke around with a camera. Pulling the head with the engine in the car isn't a big deal but it's also not comfortable. I wouldn't pull the motor unless you find out the bottom end is the issue.

 

Great suggestion.

 

Hi Marc,

OK, so when you did the leak down, what was the percentage? And, could you not hear the leak path?

When you say "we" - are you working with a tech on this?

 

Marc, can you provide a little more objective data like the actual compression readings you're getting on all cylinders, as well as the leakdown readings for all?

My 550 had low compression (10% different than the others) and high leakdown (>20%) on #4, so I pulled the head(s) because 10 & 11 did too. Then I reran the leakdown on the shortblock, and #4 still failed, so when I pulled the piston, I found that the top ring was frozen/rusted and it couldn't expand to fit the bore any longer.

I attributed the frozen ring to the car having been a garage queen for most of its life before I became its caretaker, and from what I could tell, it was only driven for short jaunts.

 

Interesting thread.
Indeed most of the times with an overheating issue where all exterior things have been verified good, there is a combustion gas leak creating gas pockets, hampering circulation. Make sure the water pump is good as well as the two steam hoses.

 

Marc - with the leak of 60% on #4 - could your tech not hear where the leak was coming from? If exhaust valves, you can feel the air coming out of the exhaust....

It would also appear that "after oil" helped seat the rings?...

 

Marc with those readings you certainly have enough data to justify pulling the heads and/or the whole engine.

You can probably count on the valve guides being worn as the early 456's are known for this, and I found the same guide issues in my '99 550.

As Dan from Bradan suggested, it would be better/easier on you to isolate the problem to the top or bottom end, or if you have both head AND sticky ring issues, as I did, and if so, you may as well pull the whole engine initially.

The improved compression with oil may be a clue that you have some sticky rings, but if your techs can rig up a blowby meter on the bottom end, that will give you a better indication of stuck rings than a simple compression reading. Otherwise, you'll have to gamble that the problem is solely in the heads, then after you pull them, run a leakdown on the block and hope you don't find stuck rings.......

I found that pulling the heads in situ on my 550 was a major PITA, and pulling the whole engine initially probably would have been easier. You may have better access with your 456 than I did with the 550, but those rear outboard nuts on both heads were nearly inaccessible, and I had to use some methods to get to them that I wouldn't publicly admit to.......

 

I just posted this video in another section yesterday, carbon buildup can appear to be bad valve guides when not the case. Not saying that is your issue but I would not assume guides are bad until they are measured. (Note - this is a 355, and an early one that would be highly suspect for bad guides yet they are within specification)

[ame]http://www.youtube.com/watch?v=oY0jqb8Ld-4[/ame]

 

The trouble with early V8 and V12 guides is an engine did not necessarily get a full set of bad guides and may have only a couple mixed in with the other 38 or 46. Seems kind of funny they would both end up on the same cylinder, though. John's stuck ring theory sounds more logical since oil does help compression, but not enough to get it up to the level of the other cylinders.

 

Yep like its been steam cleaned.

 

With regard to original question, It can be done in the car. I pulled both heads off mine to do the guides at 20k. It's just parts, lots and lots of parts. Mountains of parts. You will need the hill tool and to make a tool to get the last head nut on the back of each. It's almost impossible to do the rear ones without undoing motor mounts and using a long 2x4 to lever the engine around to get some room for things. You will also need a 1/4 drive 10mm wobble socket to reach the underside exhaust header bolts. You access some of them through the wheel wells. The whole thing is a giant PITA... If drivers side, remove the booster as mentioned. Get some silicon hose bits from Dave Helms for under the manifold. You'll need to unplug the small hose nipple, it'll be full of crap. Do the motor mounts at the same time since they are all shot. Those are a special kind of joy to replace. Hope you have small hands…

I have lots of pics if you need them, I’d be happy to post
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Cool video Dave, thanks for sharing.

Hopefully not too basic of a question: what would a resolution for carbon build up be on this engine, short of pulling heads? I've often heard of "Italian Tuneup" as a way to improve this, but is this a myth?

Also, what would cause such heavy carbon build up as to cause poor leak down?

Just trying to learn a bit...

Cheers!

Ruben

 

The Italian tune up is no myth - I've increased compression in one cylinder by 20 PSI (another car) using BG44K and a couple hundred miles of hard driving.

In the specific case of the car in my video, the valves and seats also have pitting likely from condensation so regardless of any Italian tune up attempt, a rebuild was (in process) in order.

Regarding the carbon build up - I've read some information regarding the causes but I'll let others with more experience answer that question.

 

Thanks Dave - good to know that driving our precious cars as Enzo meant them to be driven is actually good for them.

Cheers!

Ruben