MGB: New Head Gasket Is Leaking ('72 B GT)

Guys,

I just replaced my cylinder head (which was cracked) with another cast iron head that has been skimmed and cleaned up. Upon re-assembly, I used the copper head gasket from Victoria British, thinking it must be a higher quality gasket than the standard head gasket they sell.

While I did clean it well, I did not remove the block from the car, so it hasn't been machined. I followed the torque procedure carefully and brought each bolt up to 50 ft/lbs slowly.

After getting everything back together, I fired the engine up only to see water seeping out between the block and head. I re-torqued to 55 ft/lbs and that didn't help.

Am I missing something obvious? Is the copper gasket possibly to blame? Or am I ignoring the fact that my block has not been skimmed to match the "new" cylinder head? Any help would be most appreciated.

Not sure how effective (or safe!) they are, but I've heard you sometimes have to use a stop-leak additive with those copper gaskets. Maybe someone else will chime in and put more light on this. But, I remember talking to a guy about it when I was going to try the copper. I then found the Payen. The copper ones don't have as much leeway as the Payen ones do. The Payen ones can support a little bit of uneven-ness on the block deck. They certainly aren't the cure for a messed up bottom end, but they do have a little bit of leeway.

The block shouldn't have to come out of the car. You typically do not have to skim a block. Cleaning it well and degreasing it should be enough. Warped or cracked blocks are rare although it is possible. But highly doubtful like I said.

Did you use new studs? Laugh, but the studs do stretch. I told that to several people and they didn't believe me and said the new studs were a waste of money. Those ARP studs are some of the best money I've spent on my MGB.

I just recently finished my head gasket job. I used ARP studs. We did an initial torque to the ARP spec of 40 ft-lb. I ran it in for about 15 minutes, shut the car down, and let it cool. We re-torqued to 50 ft-lb, did another run in of 15 minutes. There was still the famous weeping you speak about on the distributor side. I then did a final extra 5 lbs, bringing it up to 55 ft-lbs, which is the higher end of the factory spec. The car is running great now and there is no leakage.

I wish you luck my friend!

Hi David -

If you do a search, you'll find the contributions of the real experts on this subject. Short of that, I'll summarize what they say.

The reason that normal head gaskets are typically used is that they do fill in minor imperfections as they compress. Traditionally, head gaskets have been installed using copper-based gasket sealant spray. This spray goes on the gasket, and acts to fill in tiny imperfections in the head and block. These days, people say it's not necessary anymore. I personally still use it, as I installed a Payen head gasket and got an immediate and severe blown head gasket. I installed a second identical payen gasket with a ton of copper spray on it, and it worked perfectly installed the same way.

When using copper head gaskets, it's very important that the surfaces be perfect. Even then, everyone I've ever heard from has used a LOT of copper sealant on them. 7-10 layers is not unusual, from the reading I've done.

Unless you're building quite the race car, I'm not aware of any reason to use copper head gaskets. Our own Hap Waldrop has spoken very highly of using Payen gaskets even in high compression racing applications. I believe that he uses copper spray on them, but a search will tell you definitively.

I have personally had very bad experiences with stop leak. I ruined a perfectly good radiator and heater core in an older Toyota using that stuff. It cost a heck of a lot more than just doing the job right. In an MGB, replacing the head gasket with a Payen won't take hardly any time compared to the cost and effort of replacing the radiator and heater core.

Daniel,

Thanks for the input on the stop leak---I was hoping someone would chime in about that. I always wondered because of the nature of it, thought it could possibly be not so good to use. But I did have a guy selling MGB head gaskets on ebay tell me that, so I figured I would throw it out there as a question.

Stop leak isn't ever a great idea. It's a short-term stop-gap when you need a punctured radiator to stop dripping long enough to get home. Using the copper head gasket may have been an error. The all-black Payen gasket is the preferred gasket for the street, racing, any application. The copper gasket became obsolete when the all-black, composite gasket became available. As mentioned above, to get the copper gasket to work, you should spray it with several coats of Copper-Kote although I have seen people use Rustoleum "Cold Galvanizing Compound" quite effectively. When you replace a head gasket, both the head and the deck of the block should be milled perfectly flat. If there's any imperfection in the deck or the mating surface of the head, you could leak. If you take it apart and want to stay with the copper gasket, get some thin, stripped, copper wire and create rings around each cylinder, oil passage and water passage and glue them to both sides of the head gasket with very thin smear of silicone. Then Copper-Kote the whole thing and install. As you torque the head, the wired will dig into the gasket and flatten out and fill any milling marks in the deck or head. But a ringed gasket like that is a one-use item. If you need to pull the head off again, you must replace the gasket because the wire actually deforms the gasket a little. . The Payen black gasket can be re-used. Let's hope that your "new" head was properly prepared and that this will be an easy fix. Basil

Basil,

What is the difference between the Payen black and the regular Payen? I chose the Payen regular because it looked fairly complex and planned out---with all the brass rings, the strip for curing the weeping head, etc.

Did you counterbore the stud holes? Their edges get pulled up, which leads to an out-of flat block surface leading to an imperfect seal. Did you check the block surface for flatness?

If you re-used your old head studs, do they have anything stamped on the top? A lot of times your safe reusing them if they're either marked with a dot or the numeral 22, but check them carefully for streching, mucked up threads, etc..

When you get another head gasket, get a Payen (mail order) or Fel-Pro (local parts shop), same product. You shouldn't have to do it, but you can put a VERY thin smear of high-temp RTV silicone on the new head gasket along the outer edge on the distributor side.

If you get it together torque it down to 50lbs, you should get no leaks. Having to fix head leaks with extra oomph or gunk means something's wrong.

[quote="Wade Keene"]
Did you counterbore the stud holes? Their edges get pulled up, which leads to an out-of flat block surface leading to an imperfect seal. Did you check the block surface for flatness?[/quote]

X2 These are critical bits and IMHO your most likely problem.