456 Headgastet

Symptom
Bubbles in the water tank when engine runs. (Higher rpm = more bubbles)
Tank will pressurize and then coolant escapes via the pressure relief.
No white mousse in oil yet.


The assumption is the head gasket.
(Would you believe that the two non-official ferrari garages don't have a gas tester)


So, is it possible to change the head gastets with the engine in place ?

 

Try to determine the cause and which of the head is affected, usually it will only be one side.

Inspect the spark plugs, they could have some indication - usually water present in combustion will make your spark plugs and combustion chamber very clean.

A gas tester to check for CO/CO2 is good, but not necessarily and should only be used in conjunction with other tests: Easy way to check:

Put pressurized air in cylinder via the spark plug hole, and listen/check for air bubbles at the expansion tank - this way you will also know exactly where the problem is.

*NOTE: Obviously make sure that both valves are closed (compression stroke) when you apply the pressurized air.

CO/CO2 tester is just to another "check", but not definite.

Post pictures!

 

Angus, to your question about pulling the heads - yes they "can" come off with the engine still in the car. It's no fun, and it'll require a special wrench t/b fabricated to reach the two rear outboard nuts, but it can be done. To get access to all the rest of the head nuts will require the 15mm Hill Engineering head nut wrench (looks similar to a small flogging spanner) and a length of 1/2" or 3/4" galvanised pipe, or similar, for a "cheater".

 

Hello John,

what needs to be done the to the wrench? Do you need Hill head nut wrench AND a modified wrench?

Thank you

 

Is this the required wrench?
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Yes, that's the Hill wrench for the head nuts.

Leave the Hill wrench stock. Unfortunately with the engine in the car, it can't access the rear outboard nuts, so the "trick" that David Feinberg (FluentinFerrari) came up with was to cut a 15mm combination wrench in half, and weld a socket onto the cut end, in order to make a crowsfoot type wrench. This, plus an extension enables you to break the nut loose.

Be very careful with these nuts as I found them to be rather soft, and if you round their hexes off, you're then into the project for far more fun than you counted on

 

Do you have a pictures of the combination wrench trick?

 

Here are the ones I made after David shared his solution with me (he was pulling the heads on a 456 at the same time I was pulling my 550's heads.)

I tried making both a ratcheting version as well as a regular one, but could only get the regular one to fit in there. Those last two nuts are real bears.
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Many thanks to all for this info.

So it seems doable - but a ball ache.
But still better than taking the whole engine out - i guess.

 

Angus, in my case, and with benefit of 20/20 hindsight, I should have just pulled the engine to begin with. After wrestling the heads off, I ran a leakdown on the bottom end and still had >18% leakage in three cylinders, so the rest of the engine had to come out.

After pulling the pistons, for 2/3 of the cylinders with high leakage, I discovered the top compression rings were stuck - and not just "stuck" from carbon, but WELDED, where you couldn't visually detect where the end gaps had been.

Hope this doesn't happen to you!

p.s. Further to 360Modena2003's suggestions for diagnosing the BHG, I'd also consider running a leakdown test of the block/cooling system, and if you still want further confirmation before pulling the heads, I'd purchase one of these combustion leak testers and test for combustion gas in your coolant expansion tank (although from your description it's pretty obvious that's what's causing your bubbles & pressurisation there): Amazon.com: combustion leak tester

 

Thank you John - why doesn't a regular crows foot wrench work?
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Couple of reasons:

1. You really need a true box end (not a partial box), and a 12 point box at that because of the lack of "swing angle". Also it should be a tight fitting quality box due to its propensity to slip and round off the hexes (AMHIK - I had a close call with one of those nuts due to using a worn Hill wrench that had developed some "slop" in its fitting)

2. The studs/nuts are buried in a "pocket" in the head, so the wrench needs a lateral extension (the shank) to get it "out" of the pocket.

Even with the Hill wrench, if you try to loosen those rear nuts with a mallet and/or a cheater, there's just not enough swing room, hence the socket fitting to get access from the top.

BTW, Hill sells an extension for the wrench, and I have it, however I found it to be ineffective for those last two nuts, however it should work better for retorquing the heads.

 

You need the engine mounts and trans mounts fixings off, shuffle the drivetrain forward then the hill tool works fine. I'm in the middle of valve guides on an MGTA at the moment...
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Interesting Eddie - for my 550 it looked like if you tried to pull the drivetrain forward any more than 1/2" or so, the front of the bell housing would foul the rear of the cross member. I figured the 456 would be the same?

 

Update

So I got the gas tester kit off Amazon - 4days to HK - very fast.
It apparently it goes yellow for petrol and green for diesel.

Process...

1. Started engine - let it start to warm
After a few mins little revs of throttle.
Must have pumped the tested 20 times - still purple.


2. As the engine warmed...
The water was expanding and overflowing from the water tank.
Eventually stopping and leaving enough air at top of tank to put tester tight into mouth.

3. After some mins gave it revs of throttle.
Must have pumped the tested 20 times - still purple.


4. Continued,
engine now at 90-95
water radiator = hot
fans kick in

5. More and more pumping on tester - probably nearly 5-10 mins running test
Colour has slightly changed to a purpleish-GREEN
( yes green - i must have a v12 diesel )
( i had to keep the nose of the tester up a little so i could avoid the rising water - so perhaps it was sucking free air)


NOW THE REALLY WEIRD THING......

6. Just was we turn the engine off,
Suddenly a massive gush of water out of the water tank
the peak must have cleared the mouth of the tank by a few inches.
and it was a LOT of water. in the order of 1L to 2L


So would this indicate... thermostat or water pump or have aliens invaded the engine ?


A.

 

Subscribed, as my sons Mazda 3 does the same thing ... sometimes.
Pete

 

Angus, confirm the gas tester actually indicates correctly by sticking it in the tailpipe. Perhaps it was shipped with fluid that was past its shelf life......

 

checked using my breath.

4 sucks = green
8 sucks = yellow

 

Hi,

I have had the exactly same thing on my 1972 V12 E-type. The engine is original, untouched and has now 86.000km on it, but the last 16.000km I have driven have not changed it one bit.

Jaguar has as standard service procedure the Bar's Leaks treatment. Now I'm not saying you should do it for the 456GT, but someone with more knowledge or experience could chime in?

As I have understood it, that treatment fills micro cracks etc in the cooling system and lubricates the water pump spindle.

But that particular V12 remained the same, if I just switch it off after a spirited drive, it may gut out ca 1-2 liters of coolant. I think part of the problem is that there is air in the system which will allow coolant to boil in the heads after the engine had been switched off and the water pump stops as does the flow of coolant.

A small amount of coolant can really expand with tremendeous power when it boils, think of the power of steam engines!

But I have no solution really, if there is no air, it will not boil, but also in my case it seems some air will develope or enter the system from some combustion chamber and then the coolant can boil. Then again it has been like this for three years and 16.000km. If I remember to allow the fans to be switched on for a couple of minutes after the engine has been switched off and then run the engine for a minute or two, the coolant will stay in.

Lets see how these things develope and if we can find any more info or useable solutions to get rid of the problems.

Cheers,

Pekka T.
Fin.

 

I have found the litmus fluid tests to be so inconsistent that they are useless.

A leak down test done with a pressure gauge on the radiator is a very good test. So is sniffing the cooling system with a good exhaust analyzer. If doing the leak down test way, just be sure to be careful with the pressure. You don't want to blow up a good radiator.

Not a huge obstacle getting the heads off. Unbolt motor mounts and move motor around a little.


I would be concerned why it blew a head gasket. While not unheard of it isn't common. I hear of so many of these running hot or outright overheating. They have a very good cooling system and in my opinion if it is running hot, there is a problem. People just want to shrug it off as a marginal cooling system and that is not my experience nor is it the experience of most of the good shops that work on these, even in very hot climates.

 

As Rifledriver says, these "gas tests" are very marginal, very hard to get consistent readings of a gas that is passed (and filtered) through water, coolant, rubber hoses, cylinder walls, etc.


Try doing the test with putting compressed air in each cylinder and looking for air bubbles/pressure build at the expansion tank.

Also, remove all spark plugs and inspect, post pictures of all, maybe we can help you see an anomaly.

Will be easy see if any of the plugs differ from each other (make sure to mark each spark plug so you know from which cylinder it was removed)

 

Blackstone Labs
will test for coolant in the oil and a side benefit is you can then properly determine your oil change interval for your driving conditions.

 

The litmus tests are testing for gasses the car builders are trying very hard to eliminate from the combustion cycle. They were all the rage in 1958 and should have been abandoned about the same time.

When trying to confirm a head gasket problem I see no value in looking for problems where none need to exist. It is a distraction. Many cars with bad head gaskets have perfect plugs. I would suggest keeping eyes on the ball until then.

 

Given the comparatively little effort it takes, remove the spark plugs and take a look.

While the plugs are out, turn the engine until you are on the "power stroke" (both valves closed) and then put compressed air in and check at the expansion tank.

 

Update
Just for the record the car is stuck at the GF's car park and not at the workshop - so there in lies the difficulty.


1. Pressurised each cylinder = no bubbles.
2. No water in oil etc..
3. Plugs look totally normal.
4. Bearing/belt squeal from front of engine - not hugely loud but definitely there.
5. Thermotstat
Changed the thermostat = no difference.
Removed thermostat = so i could see the water flow.....


Symptoms
(Now I admit this was at cranking speed)

1. The rate of flow of water out the thermostat outlet could not be described as a torrent.
More like someone had barely turned on the tap.

What sort of flow should I be seeing ?