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MG MGB Technical - warped head after 5K miles?

I pulled my head due to excessive seepage of coolant
on the distributor side. It looked like coolant was making
it past the water passage copper rings (Payen gasket.)

The shop found the cylinder head was warped, and needed to
be skimmed .004" . The head had previously been skimmed
5000 miles ago as part of a rebuild, and the block was decked
at the same time. The head is the County aftermarket 4736 iron
casting (for 79 B.) It checked out ok with magnafluxing
5K miles ago.

What would cause a cylinder head to warp after just 5000 miles?
The car never overheated, and I'm using properly torqued ARP
studs. Real question is could there be something wrong with
the casting itself?

What do people think of aluminum heads? Thanks very much
in advance.
Ronald

First theory is:

Did you torque it down in the correct sequence?

If you did:

Did you un-torque it in the same sequence? When you pull off the head its equally important to un-torque it in the same sequence or else - Warp.

I've heard that the Payen head gaskets aren't as good as the Fel-Pro. So there could have been your original problem.

Also, did you re-torque the head after 500 miles? in the correct sequence?

Luis
Luis

This is a common problem with the B series engine. Someone told me they all leak there. The standard way of overcoming it is to use some jointing compound like Hylomar along that edge. Some might call it a bodge, but it worked for me.

Mike
Mike

You should also remove all the head studs from the block and chamfer the holes a tiny bit . this helps .

An old time trick is to paint the head gasket with latex flat white house paint and let dry before installation - sounds goofy but it really does work .

-Nate
Nate

Thanks everyone, although I torqued/retorqued in
the correct sequence, my "technique" may not have
been perfect. I'll try the Felpro gasket next
with a bit of Hylomar -- I still suspect the Payen
gasket.
Ronald

Ronald. The Payen gasket (and I suspect that is what is in the Felpro kits as the box states the gasket is "Made in England") is a resin impregnated type. This means that the resin softens when it gets hot and makes a better seal. It also means that you need to re-torque the cylinder head immediately after the initial starting of a new engine. Let the engine run for 20-25 minutes to bed in the new cam and lifters, let cool, re-torque in the correct sequence. Absolutely amazing what you find. Some nuts almost tight, some can take almost a quarter turn. Then, I run the car for 100 miles and retorque. Same thing, but this time the studs have not lost quite as much torque. Next run an additional 400 miles (or 500 total on new engine) and torque again. Getting close to being there now. Very little difference in how the studs are holding torque. Finally, check again at 1K miles. On my cars, the studs were all holding proper torque at 1K miles and all I was doing was confirming it. But, the amount of movement immediately after start-up/cool down and after 100 miles lead me to believe that waiting until 500 miles to re-torque might cause a problem. (I am still playing with these gaskets myself and am still learning what works best.) As to the use of some form of joining compound. That, it seems to me, might be well with a standard gasket, but it might also cause a problem with one of the resin gaskets. A note to Peter Burgess might be in order since he has more experience that most of us in using this product. A recent article in midget-Sprite magazine on head gaskets points out that modern cars using a cast iron block and an aluminum head have a need for a head gasket that will allow some movement due to the head expanding earlier and more than the block (or a comparable cast iron head). Have no experience with such myself, but, if true, it begs the question, will a resin type gasket work properly with an aluminum head? Certainly something worth considering and getting into the archives. Les
Les Bengtson

Ron,

A couple of ideas for what they are worth.......

1. If you use an extension on the head of your torque wrench a compensation is requried to achieve the desired value...

2. I have installed head gaskets dry and I have installed them with a jointing compound. When I use the jointing compound (I like the "spray on" copper compounds) the heads don't leak. Although all gaskets recommend "install dry", I have found this to be the way to go.

3. Also agree with Les's advise about re-torqueing, etc.

From your previous posts I would bet that you have done everything "by the book". It's always frustrating whem these things happen.

Good luck,

Cliff
Cliff Maddox

This thread was discussed between 24/01/2002 and 26/01/2002

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