I picked up my finished 6G72 heads today and paid the damages. $487! Ouch!

They have around 170K on them and were pulled for the first time. They pressure checked OK, heads were resurfaced, valves and seats ground (three angle). Of course the stem seals were bad. The surprise was that the guides were ALL bad. Some were even cracked. So that's where the extra cost came in. They pressed in new guides and cleaned both heads very well.

Looks like Bearing Service company does good work (for those of you in the Portland area). Time will tell... I forgot to ask them where they get the new guides and seals from. I don't know if they have to buy that stuff from Mitsu or if there are aftermarket suppliers?

I was going to clean up the ports a little before sending them off, but frankly, there's nothing to clean up. Port openings match intake and exhaust very well. No casting flash in the ports, bowls and transitions are already very smooth and nicely contoured. Even the guide and surrounding metal have a good shape. I don't think there is much to be gained porting these heads.

Check the exhaust manifolds against the gaskets and you'll see what can stand some port matching. I spent about 2 hours port-matching and cutting a reversion step in mine - don't know if it made any difference, but I felt better doing it. <img src="/forums/images/graemlins/coolg.gif" alt="" />

Frank

did you pull the headds yourself? Any advise to a newbie trying to undertake that?

Yes, I pulled the entire engine myself - and reworked the heads as well as the block. Pulling the heads is straightforward.

First - get a factory manual if you can.

I suggest getting some pint sized plastic zip-lok bags (freezer bags) from the grocery store and label the hardware that goes with each assembly and put the parts in the bags as you progress. That'll make things a lot easier on re-assembly.

I suggest having a machine shop replace the exhaust guides with the newer style with the clips that keep them from dropping - a common problem caused by heat (mine had 3 dropped guides). I would also replace the VLAs (lifters) - about $12 each from the dealer, but can be bought elsewhere for about the same price. If you're on a strict budget you can soak-clean the old ones, but the results might be disappointing and you won't know until the engine's running. Replace the cam plugs and seals. Replace the valve stem seals, of course.

If you can, have a good machine shop do the head work. They're set up for it and have all of the reference specs at hand to test the valve springs, guide clearances, dress valve seats, grind valves, etc. I think the cost here is modest and worth it, but that's not to say you can't do it yourself if you have the equipment.

Reassembly requires paying close attention to a few areas to avoid leaks and blown gaskets. Since you aren't pulling the block you can't mill the deck, but you should make certain the deck is clean. Stuff rags in the cylinders and scrape anything off the deck. Buy a true M12x1.25" bottoming tap to clean the bolt hole threads in the block. Good service here:
MSC Industrial Supply
Use a vacuum cleaner to get out as much "stuff" as possible when you're finished. Wipe the deck (and head surface) with acetone or lacquer thinner just before putting on the head.

If you'll reuse the head bolts, check them for length. I think they should measure 4.0". It'll be difficult with the block installed to measure clamping range of the bolts, but as long as the threads are clean you should be ok. To clean the bolt threads, chase them with a die. Before installing the bolts, oil the threads and head and the washer lightly with 30W motor oil. I use a coffee can and just dip the threads - then wipe the bolt and washer with the extra oil on the threads. Tighten the head bolts in a spiral pattern, starting in the middle of the head and "sneak up" on the torque value by using incrementally larger values. The manual has incorrect values for head bolt torque - should be 80 ft/lbs. Retorque is not necessary.

Use a very small amount of anti-sieze on all aluminum threads and reduce torque values slightly - lower end of a stated range should be fine.

Use new valve cover gaskets, clean the head with acetone or lacquer thinner where the valve cover gaskets seal and put a bead of RTV (1/2" long) in the corners of the cam towers - as described in the manual.

I'm sure I've missed a lot of "tips". Others may have more. As you get into the job, post any questions on a new thread. There are plenty of experienced folks here that can answer your questions.

Good luck,
Frank

awesome, thank you.I am thinking, since heads problems are pretty common on gen 1 with more then 100K miles and since there aren't any usable guides on disassemble/reinstall in the archives, maybe it would make sence to keep this thread and make it a repository for all the experiences on pulling heads-after all many guys here do it themselves, many have many tips and advise.How about it, Phil? I personally could use all the advise I can get if i were to do this on my own; by the way, Douglas, thanx for the PDF on the engine, I recieved it.

Ditto, and makesure you get the FREEZER BAGS. They have the white label area that makes it much easier for writing/reading the contents. Plus they are thicker than regular non-freezer.

Also, for anything bigger or still hanging on the bay, go to Office max and get some of the blank manilla shipping tags that have wires on them.

Yes, that helps, but for wires and hoses, I stick on some masking tape (freezer tape really) and write on it with a marking pen.

Whatever works and makes the job easier. It really is amazing how you think you'll remember, but later have no clue. Sometimes the manual is a help, sometimes the parts list diagram is better.

Frank

A good trick for removing gasket material from the decks with the engine still in the car: get a powerful shop vac and locate the nozzle right next to a fresh razor blade as you scrape old gasket material off. Change blades often, and be careful not to scratch the surface of the deck. Once you start to use a blade, don't turn it over, you will scratch the gasket surface. The vacuum will remove the material as it is scraped off, preventing it from falling into the cylinder, head bolt holes, and coolant passages. Rotate the crank so that each piston comes through top dead center, and vacuum the space between the piston and cylinder to remove anything that may have fallen in there. Make sure each cylinder bank has been drained of coolant before using the vacuum, otherwise, you will end up with coolant splashing into the cylinders from the vacuum. Put some oil onto each bore with your finger and rotate the crank again. any particles that are contaminating the bore tend to stick to the oil, which is left near the top of each cylinder after the piston begins its downward stroke.

Make sure to remove the cylinder head bolts in the reverse pattern of torquing, in a couple steps, just like when you torque the heads upon assembly. This will eliminate potential warping.

Don't use tri metal head gaskets unless you also are rebuilding the bottom end as well (block decks resurfaced). They only seal well on perfectly machined surfaces. For the typical head job, composite gaskets work the best. Use Mitsu factory gaskets or a higher priced aftermarket type (except for the Felpro blue, I've heard of poor results for those).

Make sure to replace all the stuff you can get to during this job (water pump, timing belt, cam seals and plugs, etc.).

Not a difficult job, just take your time and be meticulous.