Cylinder Head Gasket failure

[gary1725]

Hi Folks, I know this one might have been done to death but here goes - my head gasket, I think slowly initially (thinking I was running the car often enough that water did not build up) and then quickly failed (car had been sat for about a month un-started) - symptoms - initial uneven idle, hesitation and white smoke (lots and I mean lots), then the smoke cleared and the idle settled ok - I figured this indicated coolant being burnt, left the car for a week and sure enough when I removed the head yesterday - water in #3 and #4.

The Head gasket I used was a 3 layer gasket - aluminum, composite sandwich material and copper gasket (no markings) but I forget where I bought it! The car has covered about 18K miles since an extensive engine rebuild and the gasket honestly looks as though it has "shrunk" at one end pulling the water holes towards the cylinder! - the rear stud hole is elongated as are the bolt holes around them (the front half lines up ok!) I had bought two of the same gasket at the time and the spare is perfect for the block so it does not look like an initial fit issue that I missed.

I have ordered a head set from Classic Sunbeam Auto parts in New York and will compare that head gasket with the spare as I don't really want to see a repeat of this issue... I also intend to have the head checked by a machine shop before refitting.

Any advice always welcome.

Gary

 

[Gordon Holsinger]

Take a steel straight edge and lay it on the block and check that the block and or the head is not warped!

 

[gary1725]

I will check the block as best I can - to be honest I was rushed a little hoping to get the head back this week (might be wishful thinking) and dropped the head off already without looking too closely - I honestly didn't really feel confident checking it myself and figured the block was less likely to have warped..

 

[alpine_64]

Ok.. Checks for the mechacials:

Check blocks surface is true and stone the surface of it to get proper bite.

Make sure head hasn't warped and is flat.

Thr factory changed the torque spec for the gaskets kate in production to address issues.. They reduced torque.

Years ago we all changed the procedure to 100, 500 and 1000 miles for retorque

As for failed around water passages.. Share a ohot of your heads face... The crescents get larger over time and people dont rebuild them up when doing the heads.. This brings them much closer to the edge of the gasket

Thr greek athena brand gaskets i am not a fan of.

 

[gary1725]

Yep - all waterways were welded and repaired when the engine was rebuilt along with replacing the thimble - the leak into the cylinder looks to be from the round water hole marked on the photo not from corrosion nor the typical crescent leaks but “movement” of the gasket.

I checked the block tonight and it looks true - the head is already with the machine shop to be checked and whatever remediation is needed.

what I don’t understand is how the gasket moved - I am going to check bolt length in case they ere bottoming out - the block was decked slightly, the head skimmed - still has good wear bars - but the head where the bolts face was also machined slightly to remove dimples from previous tightening - so perhaps all that machining adds up - I assume some leniency was allowed and seems unlikely with good wear bars - but who knows .

 

[Tim R]

Having had a couple of composite gaskets fail over the years we now use only Copper ones on all of our Alpines and as stated above torque (with an accurate and calibrated torque wrench) to 45lbs when completely cold and when you re-torque release each bolt one flat first to overcome stiction.
Tim R

 

[gary1725]

Tim - when you describe a copper gasket - are you describing the copper one side, aluminum the other sandwiching some other material? rather than a solid Copper gasket - in any case where do you source them

 

[Tim R]

Hi Gary,
This is the type of gasket I normally use, various U.K. suppliers have them.

https://www.ebay.co.uk/itm/25543752...tuYxljzQHM_uWDQCetW25JQlJLny8y2kaApWUEALw_wcB



Tim R

 

[jumpinjan]

Remember, these are vintage engines and you do what rebuilders did back then. On head gaskets you need to apply a gasket sealer like the old Permatex Aviation Form-A-Gasket or the copper head gasket spray.
Also be aware of the head bolt washers deforming into a concaved dish and deformation of aluminum boss around the headbolt hole. I always machine the head bosses flat and replace the washers.
Jan

 

[gary1725]

Hi Jan, yes - the top of the head where the bolts clamp down was machined because dimples did indeed exist and new grade 8 washers used that match the thickness of the old ones. I used copper spray on the gasket before refitting (confirmed by checking I still had it for refitting the new gasket) and the new gasket arrived yesterday and is identical to the spare I had from the build a couple of years ago. So more and more I can only suspect that I did something careless when fitting the head, the engine assembly was performed on an engine stand so I had plenty of space to work and I am pretty sure that I took my time and did not rush, but who knows - I will still check bolt lengths as I had seen reference to the possibility of them bottoming out on another thread but I would be surprised if they really had bottomed out before being tight - I just figure I would have had issues sooner, compression, water or oil getting where it's not supposed to sooner.