How do you fix head gasket repair for a 305 V8 5.0?

Answer 1

I'm actually doing this job right now on my '89 TBI 305. First, have everything on hand and ready to complete the job (don't just replace the bad head gasket, replace both):

Tools:

- Metric and SAE deep and shallow sockets and ratchets

- Breaker bar (at least 18 inches long, 1/2 inch drive)

- Torque wrench (capable of measuring up to 65 foot/pounds)

- Metric and SAE wrenches

Equipment:

- Sandwich bags (for organizing removed bolts and small parts) and a sharpie marker for identifying contents within

- Hand Cleaner

- Shop towels (paper or cloth)

- Any solvent that can help you in cleaning grease/grime off parts

- Drain pan to catch anti-freeze/coolant

- Gasket Maker/Sealant (for high temp AND water/oil resistance)

- Chilton or Hayes Repair Manual that covers your specific motor/year

Fluids:

- 1 gallon of anti-freeze/coolant

- 5 quarts of appropriate motor oil

Parts:

- Head Gasket Set (includes head, intake, exhaust, TBI/Carb and various other gaskets)

- Head Bolts (MUST BE REPLACED!!! MUST!!!)

** Optional and accessible parts that I would recommend replacing at this time **

- Water Pump

- Timing Set (Chain & Gears)

- Push Rods

- Oil Filter

Quick Tear-Down:

First, remove the battery, spray the engine with degreaser and wait for about 30 minutes for it to penetrate any grime that may exist then spray down the engine with a garden hose (preferably a power washer if you have one available). DO NOT SPRAY INTO THE TBI OR CARB!

Drain anti-freeze/coolant and oil from the engine.

Remove the TBI or Carb from the intake. Disconnect any wires that are going to the intake, heads and exhaust manifolds (tag them if need be for later reference). Remove the plug wires, distributor cap. Remove any hoses that are going to be getting in the way of removing the heads.

If you've decided, as I have, to replace the water pump and timing set while the engine is torn down, remove the fan guard, fan, belts, radiator hoses, brackets and any pullys, water pump and timing cover. Make sure you have the timing cover gasket when you buy your timing set. Remove the gears/chain BUT DO NOT TURN THE ENGINE CAM OR CRANK while either removing or replacing the timing set. Replace timing set, timing cover gasket and cover. (install water pump, pullys, belts and hoses after the heads and intake have been reattached to the engine).

Remove the bolts holding the intake manifold and carefully remove the intake manifold and set it aside. Remove the exhaust manifold bolts and the bolts connecting the manifolds to the exhaust system under the vehicle and set them aside.

Remove the valve covers and bolts connecting the bottom of the heads to the block. Remove the rocker arms, push rods and internal bolts holding the heads to the block.

Carefully remove the heads and set them on a perfectly flat surface with the bottom of the heads (surfacing connecting the engine) at bottom. Heads can warp if not properly at rest and that can destroy them, costing hundreds of dollars to replace.

Inspection:

Here you have an opportunity to inspect the heads for signs of cracks and the cylinder walls for signs of damage (gouges, deep scratches). Check the valves for signs of excessive wear and replace as needed.

Rebuild:

Reinstall the heads with the new gaskets, making certain that the seating is right before placing the new bolts. Refer to your repair manual for tightening sequence and torque specifications... not all 305's are the same.

Reinstall the intake manifold with its new gaskets. Reinstall the valve covers with their new gaskets to the proper torque specs indicated in the repair manual.

Reinstall the exhaust manifolds, attaching the to-pipe bolts first then to-head bolts and use the gaskets that came with the set. Again, refer to your manual for specific installation instructions. This, however, is being skipped at my end because I'm scrapping the stock manifolds and replacing with headers. Same principles apply though.

Reinstall the water pump, pullys, belts, hoses, TBI/Carb and reconnect wires that you've disconnected. Reattach the cap and rerun the plug wires (refer to your repair manual for cylinder order and distributor caps usually have the electrodes marked, by number, for each cylinder).

Reattach the fan and fan guard and replace the oil filter, refill the engine with oil, the radiator with anti-freeze/coolant. Leave the radiator cap off.

Install the battery, check for anything that might have been missed (connectors, tools left on the engine, 'extra parts'... etc... ). Once you're positive that you've got everything back together and there are no loose tools floating around in the engine compartment, hit the ignition.

Go back to the radiator with your anti-freeze/coolant and continue to fill, while the engine is running, until it overflows. This will work out any air in the cooling system. Replace cap and you're done. :D

Final Note:

2 other parts that you might want to consider changing while in there are the oil pump and thermostat. Since a blown head gasket usually points to a cooling issue, something had to have caused the gasket to overheat in the first place. It won't hurt to replace these even if they're still working.

Disclaimer:

This is a quick and dirty outline. You should invest in a good repair manual and follow their step-by-step instructions.