98 3.1L top end rebuild (pics)

[kevinb70]

after you remove the intake manifold,

get under the car, unbolt the two nuts at the main exhaust collector (connects to the catalytic converter).... soak these two nuts in Parts Blaster for a day or two in advance. For me, one of these two nuts was *very* difficult to remove. I also needed about 2 foot of socket extensions.

Then you remove the heat shield and exhaust pipe that connects the front exhaust to the rear.

Disconnect the egr tube, disconnect the O2 sensor, and various brackets, ignition module, etc... then you can remove the heads.

For the rear, you can leave the exhaust manifold on the heads. I highly encourage this!

AFTER REMOVING THE EXHAUST HEAT SHIELDS, SOAK ALL MANIFOLD STUDS/NUTS IN PB BLASTER OVERNIGHT. Don't be tempted to continue disassembly or you will break off frozen studs.... I lost two that way.

[jeranamo]

Will I be able to break the exhaust manifold free from the head once they are removed together as one piece though?

[kevinb70]

yup. just soak the studs in PB blaster for a day. I never let the combustion side of the heads touch the ground, flip the head/manifold upside down and loosen the manifold nuts. those dont take much effort.

the two collector nuts are the hardest. I finally got them loose with a 600 ft/lb air torque wrench. would not budge until i soaked the 2 nuts in PB blaster for a couple days then came off fairly easy.

also.. unbolt the 4 bolts (soak in PB blaster) connecting the back of the cat to the muffler pipe... easier to get the head/manifold on and off.

[jeranamo]

I've got the ac compressor unbolted, where are the other bolts securing the bracket to the engine? I've been trying to look from every angle.

[kevinb70]

ok sorry, got bolts mixed up.

remove the two bolts from the a/c compressor as they go thru the bracket. the third bolt is a few inches directly below the water pump inlet hose! Altho in the b/w drawing, the bolt appears to be just above the left a/c bolt, just FURTHER in. I think i found it by feel.

the three bolt heads are all the same size...


and dont forget there is a top bolt, you get to after you take the horizontal bracket arm off the top of the mount. right next to left most head bolt which has that round protrusion which the bracket sits on.


3 bolts down below... 4th bolt on top.

[kevinb70]

argh. did a compression test before i got everything together. Should have done this before i put the intake on.

almost no compression in cylinder 3. All others were good. Might have a pushrod misaligned, and the pushrod is not resting in the center of the lifter. The reason I suspect pushrod is because i forgot to torque down the rockers before installing the intake (grrr)

I know I don't have intake/exhaust mixed up because i bagged each separately and made sure correct length anyway, when reinstalling. Going to pop the rockers off those two valves on cylinder 3 and do a leakdown test.

Really doubting the rings are worn out on just this one cylinder, most likely carbon buildup has the rings sticking, which will eventually clear up with clean oil. Also being a cold engine, sitting for a long time, all the more likely - if not the misaligned pushrod.

Doing the wet compression test last.

[jeranamo]

Where'd you jack up your car? Mine has horrible and i mean HORRIBLE rusting on the pinch welds to the point where it is eating through the surrounding metal. I definitely do not trust jacking it from that area. I've tried the crossmember with my floor jack but due to the angled shape of the crossmember, the jack slipped (good thing it was early on rather than later). I'm thinking of buying a new floor jack with a bigger saddle and possible a rubber insert to accommodate this.

[kevinb70]

near the wheel. roll the jack in from behind the wheel at a 45 degree angle, there's solid steel there. probably not an accepted jacking point

[kevinb70]

well the threads for a rocker arm on cylinder 3 was stripped. might have been cause of lack of compression in that cylinder. torqued ok when i installed it the first time... but not when i tried to torqued it down today....


took the head off ...grr.. got some heli-coil and went ahead and replaced all the aluminum threads for the rocker arms (M10-1.5 threads) and then the diagonal intake manifold threads (M8-1.25 threads)

stainless steel > aluminum !

had to get new head gaskets and head bolts

still debating on whehter i should open this new box of intake gaskets or use the one I just put on there...

[jeranamo]

Originally Posted by kevinb70

had to get new head gaskets and head bolts

Were new intake manifold bolts required the first time around or just head bolts?

[kevinb70]

if you buy the lower intake bolts, you can only use the 4 long ones, the 4 shorter bolts were too short and one stripped some thread out (helicoiled now)

so im not getting new lower intake bolts

and by the way, i recommend helicoil type steel inserts in the aluminum threads. next time i'll use the drill press so i can setup the perfect angle and depth

[kevinb70]

got the head back on and no more compression issues. installed lower/upper intake and other various parts.

i decided to reuse the lower intake gasket. it looked in perfect condition... this metal/rubber gasket looks lot more durable than the old plastic type. i did use a new head gasket and new head bolts.

[jeranamo]

Congrats for being done man. I got the rear head pulled off thanks to all of your support and answers to my dumb questions. The spot behind the wheel worked well with my new jack. Instead of using jackstands on the rusting metal, I went ahead and placed my ramps under each wheel by jacking one side up at a time. I was able to use both a 16 inch and a 24 inch extension as well as my breaker bar attached to that for collector bolt removal (it was a bitch, but I got it). I'll go ahead and pull the front head tomorrow which will be much easier. Thanks again for the detailed explanations and pictures. It has helped tremendously.

I do have one concern. While I was inspecting the lower intake gasket I did notice rear right water jacket area was cracked. I simply touched this piece (about an inch and a half long) and it FELL INTO the coolant passage I tried to fish it out but it went further down and I think its in the actual block... Is this piece of plastic going to destroy my hoses or worse CLOG some of the smaller passages? What can I do? I can't help but worry that that one little thing is going to cause some kind of damage when everything else so far has been fine... haven't broken one thing.

[kevinb70]

after you reinstall the heads and intake, take your thermostat out and flush the plastic piece out ... remove your upper rad hose from the rad and point the hose down into a bucket. do this before complete reassembly so you can put the thermostat back in fairly easily.

and im *almost* done.. still got power steering pump, alt, electrical connectors, egr, ignition, etc to put on... i didnt spend much time today working on it.

bout to close on a house, 2 car garage... i wont spend 50% of my time hunting for parts and tools

compression btw was 50-60psi on first rotation, then 168-175 ish on the 4th compression stroke. I had the intake off when doing this, after i was done i put the spark plugs in, easier to get to, before installing the intake and accessories.

[jeranamo]

It probably wont make it through some of the passages (or the metal coolant tube) even if i flush it though... I wonder if I could shoot compressed air in the coolant passages on the block and see if it comes flying out of an adjacent one?