rocker arms

Hi all I am doing a basic head gasket and I have a question about the instaltion.. Chiltons says suppost to adjuts the valves with the crank #1, but since I have a pushrod set up and since I have just removed the one side (didn't move the crankchaft at all) do I need to go though all of the adjusting of the valves or can I simpliy put it back right as is and when I torqe the rockers arms won't the push rods be in the exact same place where they were when I removed them and in turn put the valves back exactly where they should be?

yea you've gotta reset the lash on the side you pulled, different dead gasket sizes and whatnot will affect it. and besides it's just smart to do it right and not be lazy, it's really simple to do.

http://shbox.com/1/4th_gen_tech2.html#adjust_valves

That will show you how to do it.

Rockers aren't torqued down; they need to have their lash set. The above post points to lashing techniques.

Ok, I did it by the spin the push rod method ( in two stages following the instructions + Chiltons about adjusting certain valves with the crank in #1 TDC then others with crank in other position) and looks like it is working...
but when I crank the engine after putting all back together no luck :( I could hear the engine turning but no spark; cranked it about 3 times and before battery died ( am charging over night )

Now, when I did the work I had the fuel wires tied up out of the way to prevent any spillage so I am thinking my lines are dry and that is my problem.

or could I have screwed the timing as when I adjusted the valves I had to move the crank manually to get to #1 TDC ( manually with the battery disconnected)... or with the PCM detect this through some sensor which tells the ICM which position the crank is in ???

Thanks for your time

You didn't screw up the timing because you rotated the engine manually with the key off.

What kind of engine is it? LT1? If so, the PCM gets the cam position from the low res pulse in the Opti, and as long as you have the Opti indexed correctly to the cam, the PCM knows exactly where the cam and crank are at all times, assuming that you also indexed the timing sprockets correctly.

Its a 3.8 1997 firebird.. does the PCM get the info about where the cam & crank are simmilarily to the V8 motors?

you need to ad 3.8L to your sig I think everyone assumed you had an LT1
if you did a head gasket and only did one side......your fine tq em down you don't need to do the other side.....the ignition on the 3.8 is totally different

I think I am misunderstanding something....The car will not start now?

Since it s V6, the whole thread should have been posted in the V6 Engine Tech forum in the first place

:rolleyes:

Moving........

I think I am misunderstanding something....The car will not start now?
yeah the enginge turns but does not get combustion... could this be caused by the valves being out of adjustment?? I hear of people saying valves out of adjustment makes the car run rough or whatever but could it totally stop the enginge from getting combustion

p.s. before I did the work the enginge did run fine and the only problme was the head gasket went... but even after that happened the enginge did run (codes said running on 5 cylinders only with a constant misfire of 6th - turned out the leake on the head gasket was by that cylinder)

On the 3.4 v6 you have to worry about setting valve lash. On the 3.8 there is no adjustment, you simply torque the bolts to spec. According to Haynes this is 11 foot pound + 90°

You did put all the pushrods in the same spot right....I know some of the gen 2 60* v-6 had 2 diff length PR.
I will read on it today and see.....you check compression on those 3 cyl.?

You did put all the pushrods in the same spot right....I know some of the gen 2 60* v-6 had 2 diff length PR.
I will read on it today and see.....you check compression on those 3 cyl.?

yeah I kept track on where the pushrods went by labeling each one.. I will try to run a compression test afterwork today.

thanks for your help

yeah I kept track on where the pushrods went by labeling each one.. I will try to run a compression test afterwork today.

thanks for your help


ran the compression test.. 150 on the rear cylinder but 30 on the front cylinder ( din't get time to do the middle one as the wife wanted dinner)... anyways I want to belvie that somehow one of my vlaves are stuck open due to the rocker nuts beign to tight.. but then in all reality I think that most likely there is some lower end damage there, perhaps slipped piston ring from when the head gasket blew... what do you guys think??

thanks for all of your time looking at this + helping me out it is apprachiated

The readings should all be pretty close to each other on a healthy motor. It sounds like it may be time for an overhaul.

I don't see how a blown head gasket would mess up a piston or ring.I need more info.
Give me the story of when the gesket blew....temp, overheat? did you drive it like that, how have you tightened the rockers? let me know exactly what you have done....do a comp. on all cyl. take all 6 plugs out and do the check. If it was running fine before I don't see why you would loose comp from the bottom end. How did you tq the head etc. You sure you did everything right? Even if I took that one piston out and laid it on the floor and put it back together that thing will still start......Give as much detail ass possibly b/c I think it is something simple you must have overlooked

thanks again for all of your help with this.. it is much apprachiated


here is the full story of what happened when the head gasket blew: recently took a road trip and when car was on the interstate she drove fine.. then when I pulled of to eat and hit a stop light the temprature started to raise but didn't quite hit the red line.. light turned green and I quickly parked the car in first parking spot & looked it over & all seemed OK... had a sit down lunch and after that car was cooled so started to drive home.. she drove home on interstate just fine (no stopping.. got lucky and caught all of the lights after getting of the highway).

Then car sat for a couple of days; then I drove to my wifes office and got about ten miles on the interstate OK with cruise control at about 2300rpm and all of a sudden the temprature started to raise.. I let of the gas and let the car coast (also turned on the fan so I could get a smell of the engine).. temprature then started to drop and I didn't smell anything. so I put lightly back on the throttle and I hear a little rattle and the temprature startted to rasie again (still not in the red) so I imediatley pulled of the highway and called a tow truck... after gettign it home I ran the codes and it was reading P0304 which is a misfire specific to the cylinder # 4 (is the one that now reads low comprssion)... I cleared the codes then cranked her up.. she ran but rough.. kind of like hitting on some cylinders but missing on others.. so I pulled her into the garage and draine dout the oil (had water in it) then statrted into the engine

I shold not that on that last time when I pulled of the highway there was a minimal amount of smoke from under the hood, but not a bunch like you usually see with an overheated car.. thats why I thought just blown head gasket and that was that ( was water in the oil ) but maybee I am not so lucky and there is damge to the lower end???



p.s. when doign the head gakset swap I did everything identical to Chiltons and never meesed with the lower end.. just pulled of cylinder head - took of the old gasket + lighlty cleaned around surface - put in new gasket and then put everythign back on exactly how it was beofre follwing torque patterns etc.,
also I have a picture on file of the gasket I removed if you would like to see it.. gasket is still as one pice a whole but does have a hole by the cylinder that has low compression



thanks again for all of your help with this

I redid the compression test...
still only done the cylinders on driver side bc of work.

I ran the compression test 3 times.. first rockers are were tighehted (I tought maybee over tightened and valve stuck open).. second adjust rockers to exact spec... third with rockers loose (made sure the valves were closed).. same results every time:


front cylinder gets about 40 on first stroke then tries to get maybee 45-50 on second and later strokes but never get above 50.
otehr cylinder gets about 150 imdientaley

also did a wet compression test (oil in cylidner.. and ensure valves closed) on the bad cylidner.. got about 45 on first stroke and then same results.. but heres what is weird after I did the wet compression test I took out the compresion tester from the spark plug hole and then turned over the engine with nothing in there.. expecting to see oil come spraying out but it didn't see it spray out so does that say the oil slipped down into the lower end?

It's too bad you didn't do a compression test before all this happened. But from the sounds of it, you either have a leak-down past the rings, or a leaking valve that otherwise looks ok to the eye. I have to assume you did a decent eyeball inspection of your head when you had it off.

I recently pulled the driver head on my 2000 3.8 auto. Compression (car has 145k miles) on 5 of 6 cylinders was at 180-190. The one bad was about 90. When I pulled the head, the gasket was fine, and the valves & pistons looked fine. Having the head upside down on the workbench (valves closed, of course) I filled the combustion chamber up with diesel (from the shop heater).

Next day, only 1 was down, and I could tell from looking in the intake & exhaust port which valve was bad since the diesel left it's trail. I would have put this head back on if I did not know to look for a leak...it really appeared to be OK.

BTW, to check the rings (no ring land whatsoever...amazing), I also did the diesel thing with the pistons..they checked out OK.

My defective head has a tiny crack between the intake & exhaust seats that I could only see with a magnifying glass.

So, here's my advice:

(1) Do a professional leakdown to determine if it's valves or rings, or..

(2) do the technique for replacing the oil seals on the valve stems by putting compressed air into each cylinder, then listening to A-the crankcase for hissing indicating rings; B-Intake manifold for a leaking intake valve; C-tail pipe for a leaking exhaust valve.

(3) A more tedious way would be to drain the oil and leave the plug out. Then rotate the motor so that the cylinder in question is at the low point-valves don't matter. Fill the cylinder thru the spark plug hole with kerosene/diesel, etc. and let it sit overnite. At same time, put a can under the oil drain. Next day see if anything filled the can. Also, slowly rotate motor by hand to drive the piston up and watch open spark plug hole for the fluid to come out (if you're lucky). If fluid comes out immediately, chances are that cylinder has good rings.

I have a nice workshop which makes this kind of stuff bearable; if you live in an apartment and you're working on your back in the parking lot on a cold rainy day, well...just endure and good luck. If you do #3, remember to put new oil back in.

This is an open question for any knowledgeable source: The lifters are hydraulic and the rocker arms have no adjustment...or so I assume. However, I do get a very slight ticking sound under load which I suspect is either an ignition miss (but I have new wires) or valve lash. Do these 3.8 motors need a rare shim sometimes for lash adjustment? Even though they are supposed to be self-adjusting lifters? ..Or does the balance shaft make that sound?

well sorry but its not sounding good for the lil 3.8

Do what he said....I would pull that head back off and take it to a machine shop....also do what he said with the cylinder, If nothing else your learning sooo check it out

thank you all of our help with this it is much apprachaited... will take me a few days before I can work on the car (due to job homework.. aghh) but when I get it done I will post any results I find

thanks again

I am having similar problems so let me know what you find out, I would greatly appreciate it.

-Gabriel

I am having similar problems so let me know what you find out, I would greatly appreciate it.

-Gabriel

haven't got it all back together yet (long week at work) but it does look like it was a problem with the valve... will update if I ever get time to finsih the work

keep us posted i'm interested to see what it was

so the heads came back from the macine shop today and the guy said there was a problem with the valve seats... so he repalced them and did a valve job f(all together $70 ) so that should fix the problem... will verify all is OK or not with the car if I ever get time to work on it and put all of this back together

just another quick question.. Chitons says "repalce every part" but if I was trying to do a bare bones put this back together what is an absoulte must repalce: I know the head gasket must be new and thermostat gasket/seals is most likely essential... but what about some of the upper gaskets (intake etc.,) could I get away with resuing some of them? and what about the head bolts is it essential to repalce them becasue I can't find a set of them avilable anywhere (one place did say could order for $30 something and would arrive in a week)


thanks again fro your help

I would reuse the bolts....as far as gaskets..depends on what type and how they look
I have been using the same header gaskets for 7 years.
inspect that piston good....glad to hear it was the valve seat honestly

I would replace the heads bolts and all the gaskets. No sense in taking the risk and having to do the job over again.

New is always better, but I see no harm in re-using the head bolts. That's assuming you haven't galled them up when they came off. Be sure to clean the threads and under the head of the bolt so they look like new. Then oil the bolts on the threads -or- if they are going into the water passages, use thread sealer (not thread locker). All bolts get oiled under the heads to get proper torque.

I might re-use the valve cover gasket if it was really new, but would spring for new intake. Last Fel-pro head gasket kit I got for a SBC used a tube of silicone for the entire intake valley...before there was a separate rubber gasket for the front & rear valley...it was just where the valley gasket met with the intake manifold gasket that you used a dab of silicone.

just wanted to post a quick thank you.. I finally got time this weekend to put her back together and now have full compression on all the cylinders:) :) :)

thanks for all of your help diagonsing this one

Good deal, I'm sure you learned alot....now you know how to avoid the headaches from now on

OK got one more problem with this.. I fiannly put it all back together and drove it.. it idels a little higerh than before when started ( runs up to about 2K when first crank but then backs off down to normal idel.. think that is cause there is a small exhaust leake as when I did the ex man bolts I could get a tourque wrenc in there and probably just need to tighten)

but all in all seems OK

but here is the thing.. It's still reading the code P0304 ( mis on cyldiner #4.. think flashing means catlsy damaging)????

it has full compression on that cylidner (about 160PSI) and runs fine so why would that code come back?? I cleared it about 3 times but still coming back... changed spark plugs to ( thinking injector next or is there something speacial I need to do with the PCM to earase a falshing code??)
intially, thinking other than fuel/spark problem ( just to much of a concidence that its a problme on the same cyldienr that had valve probelem) I thought OK maybee there was a crack in the block or head but if that's the case why would it hold compression... then I started thinking oh crap maybee there is a problem with a barining on the crank but if that is a problem why is it just affecting cyalidner #4 and not also the one accoss from it... or is it possible that it is the bearing on the far front end of the crank and it is only affectign the connecting rod to cylidner #4 ( never seen inside the 3.8 so not sure if that is even how the rod/bearings are set up)

anyways I appreachiated all of yoru time and help so far and any ideas here will again be appracahited

have you checked the plug wire and made sure everything is plugged in good? If you have compression and its not knocking then get it on a scanner and do some checking

Sounds like you're doing this on the cheap...

Swap the plug wire with another wire that you know is good. If you still get the code, your old plug wire is probably OK, and it is something still in common with that bad cylinder. If the code moves to another cylinder along with that original plug wire...you got lucky. If not, ....

Swap the plug with .......

Swap the coil pack....

Finally, swap the injector.

If all that doesn't work, time to swap the car.

thanks again for your help



Swap the plug with .......

Swap the coil pack....

Finally, swap the injector.

If all that doesn't work, time to swap the car.




kind of the lines I was thinking along; lets hope it's not the last case... well if so soudns like a good reason to do an enginge swap to a 5.7 or maybee the dealrship will give me something on trade in for a LS1???

then get it on a scanner and do some checking

thanks again for all of your time and help... any recomendations on a reasonable priced scanner as all my actron does is reads/erases codes? or do you think it is best to take it to a shop and pay them the $60 or whatever to read it

thanks again for all of your time and help... any recomendations on a reasonable priced scanner as all my actron does is reads/erases codes? or do you think it is best to take it to a shop and pay them the $60 or whatever to read it

You won't get a scanner with the capabilities that you want for cheap. It would probably be easier on your budget just to pay the diagnostic fee for a shop to do it.

You won't get a scanner with the capabilities that you want for cheap. It would probably be easier on your budget just to pay the diagnostic fee for a shop to do it.

yeah...ask them to log it while you drive the car....For $60 you can get some good info. Try to make a friend at the shop, I barter everything when possible cause i'm poor.