My 3.4L Adventure.....

[TopHatJimmy]

For you guys who have done this pay me no attention.

For you guys who have not, please take a few minutes to look through here and learn from my hard work and mistakes.

Situation: Very bad oil leak from rear of the engine. Determined to be coming from the lower intake manifold (or so I thought......).
I initially took the top end off to stop an oil leak. I've had this thing apart several times now for problems ranging from the same feking leak to improperly adjusted valves to a dented valve cover that contacted a rocker arm and clacked like all hell.

I didn't take any photo's of disassembly. Partly cause I was pissed that I had to take my car apart again and partly cause I hadn't planned on documenting any of this. If you have a Chiltons or a Haynes manual, diassembly is in there and pretty straight forward. I don't think mine says to remove the EGR valve, but I recommend it.

Here's the aftermath of disassembly:




One thing I noticed and I'm not sure what causes it or if it's normal, but the passenger side rocker arms are nice and clean looking, while the driver's side are kinda cruddy and chunky lookin. If anyone knows the reason, please let me know.


Now on to the fun stuff.....

The gaskets for the lower intake manifold were a fun surprise. See the over/under thing going on there with the pushrods? That means in order to R & R the gaskets, the pushrods gotta come out, which means the rocker arms gotta come out. ***Note*** My Chiltons manual makes NO mention of this, it just says 'replace gaskets'.


CONTINUED......

[TopHatJimmy]

Re: My 3.4L Adventure.....

Now my repair manual is pretty specific and accurate in it's section about readjusting the valves and setting the correct lash, so I won't go over that except to say DO IT EXACTLY LIKE THE BOOK SAYS. I took advice from a couple different sources and they were very wrong - lucky I didn't bend or break anything.
My manual says to rotate the crank to TDC of the #1 cylinder and to line up the timing mark on the crank with the timing tab, BUUUUUUTTTT.....my car has NO timing tab. So for the record here is the location of TDC for the #1 cylinder (ignore my makeshift timing tab):


Now since I had it all apart, and I'm trying to be thorough this time, I'm doing a compression check after I set the valves. Thanks Dad for the stuff!


Here are the results. My repair manual does not state what the target PSI reading should be. It only states that the cylinders should not be more than 25% different in readings, which really seems like a lot to me. According to the local Chevy service center, my numbers are within spec and pretty good for having 150k on the clock:


That's all for today. My upper and lower manifolds are off being blasted clean, so I can't do any more till they get back.

MORE TO COME.

[tkoforpresident]

Re: My 3.4L Adventure.....

yeah, i've done all this before, it's like riding a bike, it gets easier by about the 4th time you do it =)

i adjusted my valves wrong once, thinking i had it cranked to TDC for cylinder 1 but it was really cylinder 4.

an easy way to check:

1. you can take your spark plugs out and put a screwdriver in cylinder 1 to check the valves to see if you are at TDC

2. Do what I did, don't bother with that crank TDC crap and just look at the lifters (since you've got the LIM off already) and watch them on cylinder 1 until both of them go all the way down, this is TDC for cylinder 1, then you can adjust accordingly.

I had my car buttoned back up and then started it up and it died out like 10 minutes later cuz it drowned itself in gasoline lol

had to do it all over again. gotta love those bolts on top of the plenum.

[3.4grapeofwrath]

Re: My 3.4L Adventure.....

yeah, i've done all this before, it's like riding a bike, it gets easier by about the 4th time you do it =)

i adjusted my valves wrong once, thinking i had it cranked to TDC for cylinder 1 but it was really cylinder 4.

an easy way to check:

1. you can take your spark plugs out and put a screwdriver in cylinder 1 to check the valves to see if you are at TDC

2. Do what I did, don't bother with that crank TDC crap and just look at the lifters (since you've got the LIM off already) and watch them on cylinder 1 until both of them go all the way down, this is TDC for cylinder 1, then you can adjust accordingly.

I had my car buttoned back up and then started it up and it died out like 10 minutes later cuz it drowned itself in gasoline lol

had to do it all over again. gotta love those bolts on top of the plenum.

Someone told me a very easy method to adjust the valves. Let's say I'm adjusting cylinder #1. I rotate the crank until either rocker/valve just starts
to push down. Lets say the intake valve moves first at this point I adjust the exhaust valve. Since the intake and exhaust valves never open together as soon as one starts to open the other one must be closed. You can use this method on any motor. Then you don't have to worry about lining up timing marks and all that other stuff.

[TopHatJimmy]

Re: My 3.4L Adventure.....

Yup I did a combo of the screwdriver and the lifters to determine EXACT TDC of cyl #1.

The manual states to tighten the valves 1 1/2 turns past lash. A mechanic buddy said 1/2 to 3/4 is plenty. WRONG! holy crap that makes a lot of noise when the rockers are too loose!!!

[tkoforpresident]

Re: My 3.4L Adventure.....

as a general note, you will want 3-4 threads showing on top of the rocker studs after you tighten it down. The time i adjusted them wrong i'm pretty sure i had like 7 threads showing lol, way too tight.

[tkoforpresident]

Re: My 3.4L Adventure.....

Someone told me a very easy method to adjust the valves. Let's say I'm adjusting cylinder #1. I rotate the crank until either rocker/valve just starts
to push down. Lets say the intake valve moves first at this point I adjust the exhaust valve. Since the intake and exhaust valves never open together as soon as one starts to open the other one must be closed. You can use this method on any motor. Then you don't have to worry about lining up timing marks and all that other stuff.

yeah that sounds about right.

[cam98aro]

Re: My 3.4L Adventure.....

Yup I did a combo of the screwdriver and the lifters to determine EXACT TDC of cyl #1.

The manual states to tighten the valves 1 1/2 turns past lash. A mechanic buddy said 1/2 to 3/4 is plenty. WRONG! holy crap that makes a lot of noise when the rockers are too loose!!!

the only way to know for sure the exact TDC of the piston is to use a degree wheel, or use a piston stop, turn the engine until it stops, mark it, then turn the engine the other way until it stops again, and the exact center is TDC

your piston stays at the same location for a bit of the crank rotation, so you can be 5-10+ degrees off

but its not like it matters much, as long as the valve is closed you can adjust the rockers, it doesnt have to be at TDC or aything

when adjusting the rockers, you should keep turning the nut until your pushrods have a very slight resistance on them when trying to turn them

if they wiggle up and down or turn very easy, the rockers are too loose, if they wont turn at all, they are too tight

[tkoforpresident]

Re: My 3.4L Adventure.....

the only way to know for sure the exact TDC of the piston is to use a degree wheel, or use a piston stop, turn the engine until it stops, mark it, then turn the engine the other way until it stops again, and the exact center is TDC

your piston stays at the same location for a bit of the crank rotation, so you can be 5-10+ degrees off

but its not like it matters much, as long as the valve is closed you can adjust the rockers, it doesnt have to be at TDC or aything

when adjusting the rockers, you should keep turning the nut until your pushrods have a very slight resistance on them when trying to turn them

if they wiggle up and down or turn very easy, the rockers are too loose, if they wont turn at all, they are too tight

what you're referring to is the point of zero play with the pushrods which is when you turn the nut another 3/4 of a rotation, which if done correctly, you will end up with 3-4 threads left on the rocker stud.

[TopHatJimmy]

Re: My 3.4L Adventure.....

Ok, well having the manifold cleaned was a bust. The shop I went to said the new hot tanks can't do aluminum. So he put it in this big washing machine type thing which did very little to the baked on gunk. Oh well.....

Anyway, to address what I did to adjust everything. First, spark plugs were all out. I put a screwdriver in the #1 hole so I could feel when the piston went up and down. I rotated through the stroke cycle until I got to the compression stroke. I made sure both valves were closed and did not move at all going a 1/4 turn in either direction. Then I used the screwdriver to tell exactly when the piston crested and started to go back down. From there I backed up just a hair and set it.
So zero lifter or valve movement and the very tippy top of the pistons travel.

Ok, only got one new pic so far.

For you fellow 3.4L owners who are having EGR issues - you know your SES light coming on either at freeway speeds or on deceleration. If you've replaced your EGR valve and it still does it....here is the culprit:


This passageway was PACKED full of carbon/crud. I mean solid. Took a combination of a metal coathanger and compressed air to clear that all out. Now I have no more EGR fault issues.
Major issue I ran into here was getting that nut out of the manifold. I had no square drive that would fit it, so I took a large diameter bolt and ground the end to a square that fit. Then I had to use a 200psi impact gun to get the damn thing off......


Anyway, I just got the LIM back on. Last time I used Permatex Ultra Black and it leaked so this time I was advised to use Permatex 'The Right Stuff'. We'll see how that does.

[tkoforpresident]

Re: My 3.4L Adventure.....

excellent pic and info ^

the reason i say this is because people (like myself) tear their hair out trying to figure out why their EGR throws a code even after being cleaned and replaced multiple times.

I'm gonna clean out my UIM egr passage when i take it off like you did.

i think i'll have a tought time getting it off though if that thing is really in there good.

are you referring to black RTV when you say Ultra Black?

when you seal that lower intake valley you need to ignore the haynes directions that say "put a cute little dab here and there" you need to say "**** that" and put as much of that on the valleys as possible, or you'll get a leak.

[cam98aro]

Re: My 3.4L Adventure.....

what you're referring to is the point of zero play with the pushrods which is when you turn the nut another 3/4 of a rotation, which if done correctly, you will end up with 3-4 threads left on the rocker stud.

well, i guess i shouldnt have said that, because im not sure how the valvetrain is designed in those engines.. like with all of these self adjusting rockers and what not

[TopHatJimmy]

Re: My 3.4L Adventure.....

Well it's all put back together. Lucky me! It fired right up and runs great.

BUT

Still got a god damn oil leak!!!!!!!!!

I don't think it's coming from the LIM though......but it's tough to tell. I really slathered that "The Right Stuff" on there. I layed a bead from stud to stud 3/8" wide and probably 1/4" thick. Plus that stuff expands a little as it cures, supposed to fill any small gaps or irregularities.

It looks like its coming from around the distributor block off plug thingy???

Ugh. I'm done......the ****er can leak.......

[tkoforpresident]

Re: My 3.4L Adventure.....

hahhahahahha thats the oil pump gear drive o ring piece o ****.

you didn't replace that while you had your upper intake off??

the old o ring gets brittle and will start to pool oil in the back of the block, start dripping down the back possibly burn off on the exhaust.

if its not that it could be the back part of the LIM gasket

what did i tell you about putting that "cute little bead of rtv on there"

you gotta use the whole darn tube!!!

glad to hear it's up and runnin!!

[TopHatJimmy]

Re: My 3.4L Adventure.....

pool oil in the back of the block, start dripping down the back possibly burn off on the exhaust.

^^ This is EXACTLY what it's been doing. I didn't know it came off. I thought it was pressed in there like a freeze plug or something. DAMMIT!!!!

Ok, what's the skinny on fixing this thing??? The UIM comes off easy as pie, maybe this can be next weekend's project......