cracked head gaskets

[ajs76]

Thanks for adding me to your group. I have been working on a 51 Jupiter for a couple years now and I am having an issue with cracked head gaskets. I replaced the gaskets last fall because the gasket cracked and leaked water into the left side cylinders. All went well and the car has been driven regularly since besides being stored for the winter. Out of storage I replaced the generator and regulator due to it not charging and the car was driven a couple hundred miles until the head gasket cracked again. I will attach a photo of the gasket. What did I do wrong?

[Srenner]

That's the #4 stud with the rubber seal in the head. There is a supporting liner locating plate and tube that slips over the stud. One style was a steel tube and plate; there was also a cast alloy version. My guess is that this is not the original set-up and the replacement tube is the wrong length. Does the area seem more or less compressed than the other areas?

[ajs76]

That's the #4 stud with the rubber seal in the head. There is a supporting liner locating plate and tube that slips over the stud. One style was a steel tube and plate; there was also a cast alloy version. My guess is that this is not the original set-up and the replacement tube is the wrong length. Does the area seem more or less compressed than the other areas?

This is the steel tube and plate style. When i replaced the gaskets I made sure the steel tube had the same protrusion as the cylinder liners. I can check to see if anything changed there. Ive read about the NZ made head gaskets being the best. Im not sure what we got from KIP Motor company in Dallas, TX last year. Is the NZ gasket more of a MLS style or fiber copper sandwich, so to speak, style?

[Srenner]

Cant speak to what Kip sold. Some years ago, he claimed to me he makes his own gaskets, yet the photo he sent me clearly showed "Auckland" stamped into the gasket. I could go deeper into fixing a car Kip "restored", but that would not be helpful here.

Yes, the rest of the world uses the NZ gaskets. They are copper/fiber. As these do not compress like the copper/asbestos/cooper gaskets, liner height should be .006" to .008" and torqued to a max 37.5 ft lbs in several steps. Some prefer to let the heads rest overnight and check torque again.

Drop me a PM. I have NZ gaskets on the shelf.

[ajs76]

Drop me a PM. I have NZ gaskets on the shelf.
[/quote]

Sent PM

[jowettgeoff]

For many years I've used copper/steel ones, supplied by Bill Lock. I run a calculated compression ratio of 9:1 on my Jup and competition Javelin, and have had no problems at all. (Famous last words?!!!).
Geoff McA.

[Forumadmin]

The cracking of the copper there is very common. In dozens of head gaskets I have the copper also sags there.
I made a stainless steel support from 2mm plate and filed off the aluminium support tube to compensate.

[ajs76]

The cracking of the copper there is very common. In dozens of head gaskets I have the copper also sags there.
I made a stainless steel support from 2mm plate and filed off the aluminium support tube to compensate.

Do you happen to have a picture of the support you made? I think i know what you mean by that but would like to see.

[Keith Clements]

There probably is one on JT. just shape it to fit most of the unsupported area. it is something like the shape of a butterfly.

20200611_112255.jpg

[Mike Allfrey]

Just found this topic.

Over the years I have seen steel plates, that seat on the cylinder liner base lips, visibly bent. Have always put that down as a result of fixing liner sinking problems when gaskets were used as liner to crankcase seals. I have always used the aluminium cast supports, with careful setting to liner outer lip protrusion. I have never seen cracked copper at that part of the gasket. Such cracking suggests considerable vibration in that local area.

I have a theory that our aged engine crankcases and over-bored cylinder liners are yielding and, possibly, this could contribute to head gasket failures.

What torque wrench setting has been used? Tightening studs 4, 7 rear, 10 rear can be heart-in-the-mouth stuff while tightening the head studs.

An interesting topic,

Mike Allfrey.

[Keith Clements]

I agree that the cylinder blocks yield, quite often due to deep corrosion of the water jacket or overstressing at the water inlet.

My technique of testing for such creep by torquing the head down to 20 lbft without a gasket and checking for consistent gap in some cases proved such creep or cracking. I leave the heads for a week to allow any creep to develop.

The use of not annealed copper liner seals might also stress.
I probably have 50 used head gaskets and could do some analysis on them to see if the cracking was also accompanied by liner sinkage demonstrated by carbonisation of the cylinder sealing ring.

The copper too sags a lot possibly due to local boiling in the asbestos filler or expansion. This causes the copper to separate from the sealing ring in some cases.

I designed my support having seen this sagging in many engines I dismantled.