Hey guys,

How hard is it to change the head gasket on a 90' EFI? I am suspecting mine is blown. Here are the symptoms: The coolant resivoir tank empties in three weeks to a month, the heater core gugles with air sometimes but there are no leaks (combustion gas gettin into the water passages maybe?) and this poppin noise that I think was a bad exhaust manifold.

What is involved in changing it? I know the upper intake runners have to be removed, and the valve cover. Is there more to it than that?

Any information would be greatly appreciated.

 

It's not too hard to change a head gasket, but the second time it's much easier. 'sounds like this may be your first? (otherwise you wouldn't be asking how). Well....My first time, I "helped" someone who really knew what they were doing.

I'm not an EFI man so it would probably be best to hope for some input from someone who is. If I were going to change the h.g. on my carbed version, I'd drain the antifreeze down below the h.g. level, remove EVERYTHING attached to the head, and then pull the valve cover. Taking notes of each step and/or laying parts out IN ORDER (left to right, rt to lt - whatever) on a bench or table will help when you go to reverse the proceedure (install). Then I'd loosen ALL of the rockers, and place them and my pushrods into a predrilled 2x6 I have for KEEPING THEM IN ORDER. Next - the head bolts - nice time for a breaker bar. Once they are ALL out, a LITTLE prying persuasion is often necessary to "pop" the head loose. Be sure ALL of the head bolts are out.

Once the head is off, inspect the head/ gasket/block to see if all this work was necessary. There should be a visible break in the gasket or some sign of seepage somewhere on the face of the head or block. I'd hate to find I'd done all this for nothing.

Clean up the head and block surface. Remove all old gasket sealant. Clean head bolts - especially the threads - with wire brush and solvent. It is critical to getting proper torque that both bolt and hole threads are clean.

Install is reverse the order, once you've run a cleanout tap into the headbolt holes. Some people don't think this is necessary, but I've NEVER blown a head gasket, and that's how I was taught to do it. Torqueing a bolt into a dirty hole is taking a chance.

I use coppercoat - both sides of the gasket.


You'll need the torque specs.: amount of torque and order for tightening sequence. I usually do a "snug" down and then go through the sequence several times, adding 15-20 lbs. torque each time. At recommended torque, repeat one last time ( or two).
As I said before, some might feel this isn't necessary, but that's the way I'd do it, and I've NEVER blown a head gasket and I've built a few screamers.

Replace pushrods and rockers IN THEIR ORIGINAL PLACES, put everything else on in the reverse order of which it came off.
Done. (If only it were that easy...) A good repair manual would help. A friend who has installed a few head gaskets would be good. If you can't find either, I'd take it to the shop. Like I said, it's much easier to do the "second" time.

 

Just make sure to do a compression test first. You can also warm up the motor until the thermosta opens, and with the radiator cap off you can see little bubbles if the gasket died.

 

Thanks for the info guys. I will get a compression guage first. A lot more work than I thought. Thanks again.