There are a couple of valve job threads floating around right now, but I didn't want to pollute them. I did read the thread about doing valve guide seal replacements on the 3.5L 24v engine by Mad Scientist, which has been very informative.

My "new" truck is a 1990 LWB 3.0L 12v. I bought it from a guy who said that it had a blown head gasket and had been sitting for 5 years. (The registration and inspection stickers expired in 2003, so it may have been sitting even longer.) He had already started tearing the engine apart, had the plenum and intake off already, so I just continued what he had started.

Now I've got the heads off and am ready to get them cleaned up, machined and back in. My local machine shop quoted me something like: $55 to clean and machine each head, $60 to pressure test each and then $110 to do a valve job on each; about $450 for the whole job. Not so much that I'm cheap ;-) as I'm hoping to learn something, I'm wondering how much of this I can/should do myself?

How can I tell how much work the valves really need? (Vehicle has about 144k miles on it.) When I pulled the heads, it wasn't obvious that it had in fact blown a head gasket. From just viewing them, it doesn't look like the valves are in particularly bad shape, not that I would necessarily know what to look for though...

My questions are:

-How can I tell what really needs to be done? Besides replacing the valve stem seals and maybe cleaning the lifters, what else should I consider doing?

-I assume that I'll need the shop to at least machine the heads for me. The pressure test is to look for cracks? Does it also tell me what kind of state the valves are in? This is something I must/should pay to have done?

-What's the appropriate order here: Do the valve job first and then have the machine work done or vice-versa?

Any other advice would be appreciated!

thanks,
steve

Re the heads, if it passes the pressure test and the valves have no wear in the guides, all that's necessary is to replace the stem seals and surface the head (They need to straighten the head if the warp is large, and they will tell you what "large" is). If you have a valve spring compressor, you can replace the seals and check the valve stems for side to side slop. I would also soak the lifters in diesel fuel to clean them up, and prime them with diesel fuel before installing them. Download the fsm from mitusbishilinks.com for the 89 model for the procedure in the cylinder head section.

I would rotate the motor to check the cylinder wall condition - look to make sure the cross hatch homing pattern is still good everywhere, especially on the thrust side (opposite the direction of rotation - pside in this case. Also inspect for a step large enough to catch your fingernail at the top of the ring stroke. Missing honing pattern or a marked step means the bore is worn.

Drain the oil out now and look for water in it. If there's water, the bearings may be acid etched from coolant contamination.

The block deck must be squeaky clean, all gasket residue removed. This takes at least a couple of hours of razor scraper work with gasket remover. Then before head install, clean the deck and head gasket surfaces with acetone which you can buy at Home Depot paint dept.

Clean out the head bolt holes with a bottoming tap, then install all the head bolts in the clean holes until they just barely touch the bottom. Measure bolt length from bottom of head to block deck. Deduct washer thickness. This is "A". Measure the head thickness at the head bolt hole ("B"). B must be greater than A by at least .040, or you will not get proper clamping force on the head gasket, and it will blow again in short order.

Note that there is a revised head bolt torque spec, I think it's 80ft lbs.

Resealing the lower intake is tricky because of the narrow vee. I always use Indian Head or KopperKoat gasket sealer with the copper stuff in it. Then I tighten the fasteners just past finger tight, tap the mani with a rubber mallet starting in the center all along the upper surface, tighten to half torque and repeat the tapping routine, then to final torque setiing.

Install a new water pump and front main seal and revised crank pulley bolt. Replace front and back halves of the water pump, and make sure you replace the oring on the back that seals the metal tube that runs in the vee. Replace all the hoses while the head is off - they've been overpressurized and maltreated by the leaking combustion products, and have several years of dry rotting while sitting empty. Ditto the acc belts and timing belt, and replace the front main seal, too, to be redundant. You may have to split the crank timing cog to get it off - it's powdered metal and if you drill it and drive in a tapered punch, it will split easily. You can't pry it off without damaging the oil pump, and there's no room for a puller.

Have the radiator rodded out, about a hundred bucks at a good radiator shop. That is a prime suspect for the cause of the head gasket failure. I'd think about replacing the fan clutch too. It should be very stiff to turn by hand if it's good...

I'm sure I've forgotten somthing...

In a past life we would pour gasoline down the intake and exhaust to see if any leaked past the valve seats to determine if a valve job was necessary. We also would buy some valve lapping paste and clean up the seats to match the valve. How cheap do you want to be?

great write up fasteddy.
I'm gonna print this out on real 3 dementional paper.

i looked on alldata and for the 92-97 Hyundai Sonata (exact same engine) they revised torque again ,and up to 83 ft. lbs.

I figure I'l be visiting the inside of my 3.0 again as I have yet to shorten and retorque the drivers side.
I didn't know (it hard to believe I don't know everything)that about the hatchmarks and amount of the step.

Ditto on what Eddy said.

Also, for an engine sitting for a long time, there is a risk that the rings are gunked up and sticking in the piston grooves. While the heads are off, load the tops of the pistons with WD-40 or a penetrating oil to loosen the rings and rotate the engine every day for a few turns, each time reoiling the piston tops.

Frank

Wow. All great tips.

John B.