MGB: Heat Gasket Leak on new motor

I bought a rebuilt motor for my MGB and after toping off the fluids I see some small leaks coming out of the head by the serial number on the passenger side. Is it possible that the new gaskets need to heat up with the motor running to seat or am I gonna have to replace the gasket?

Thanks.

Make sure you tightened the head bolts in the correct order, and footpounds. Did it start leaking before cranking up or after?

jeremy, history says that it is worthwhile to use a quality head gasket (Fel-pro or Payen) to seal this area. Other gaskets work, for a while, but often fail sooner rather than later. Depending on the rebuild, a cheaper gasket may have been used or perhaps the deck of the block or mating surface of the head are not quite "true."

If the engine has never been fired and you already have a leak....I'd guess that there are some "untrue" surfaces somewhere...likely the bottom surface of the cylinder head, or (and you don't want to hear this about a rebuilt engine) you have a cracked head.

That area between #2 and #3 cylinder on the passenger side IS the place where leakage/seepage most often occurs. If you have run the engine, have you retorqued the head bolts since running? They are supposed to be retorqued after the engine has been run and reached operating temperature.

As has already been said, that is a real common area where MGB heads crack. Let's hope a retorque will solve your problem. If you do end up taken the head off. For sure you need to have it checked for cracks. I question if in fact the engine was REBUILT because it's ovious it wasn't vatted. Sense the serial # tag is still there. Unless it was a machine shop that would have removed the tag, and I don't see that happening, the tag would have been desolved in the hot vat. People wrongfully call an overhaul,rings and bearings, a rebuild. Good chance the head and block was not decked, and the head wasn't checked for cracks.

lhess Wrote:

Tom Bedenbaugh Wrote:

If your leaking before the engine has been cranked up then it will blow out once the system is pressurized. You need to check the torque before you crank it. I would also call the guy who did the work and let himm know what's going on.

Dont crank it !! Explain first to builder. Let him deal w/repair.
RS

It may just be a small leak from the valve cover above. Could have happened when the engine oil was dumped in. Look for a trail of oil from up higher. Might be really ahrd to see on a freshly painted engine!

What's leaking? oil ,water?

kuz1 Wrote:

tow it to the builder and have him rectify the problem.

Agree with Gil, I can't image there not being something major wrong. Either workmanship or parts , but certainly a major problem ,that would allow an unpressurised system to leak.

make damn sure you don't have a leak from the heater hose above the valve cover before you have it towed.