No compression!! after intake gasket change
Vernon1252
together & the engine has no compression!.. but the valves & rockers are
moving up & down as the should..& i did keep the push rods & rockers in order
as i put it back to gether.. hoping to hear fron Ian..or anyone that might know
what happened..& in the mean time i will check the valve timing out i guess..
but i dont have the service manual on this car
shiden_kai
"Vernon1252" wrote
Don't do anything until you keep cranking it over. It will
run like shit for a few minutes, but it will straighten itself
out. This is assuming that you did get the pushrods back
in correctly, but you did mention that you kept them in
order.
This is very normal for these engines. Almost every
one that I do, either appears to have no compression
on the initial crank, or just runs really bad for a few
minutes. I suspect that the lifters come up to the top
of their travel, and because of the constant coolant
contamination in these motors, the lifters are slow
to return to their 'zero lash' position.
If you didn't change the oil after you completed the
repair....do it now. And then just keep cranking.
Ian
Vernon1252
now to double check they r right..& yes i did change the oil & filter after
the intake change.. , so i should just keep cranking it until the lifters pump
back up if the push rods r in right?...thanks alot for your help!
shiden_kai
"Vernon1252" wrote
Sounds like you've done everything right. The lifters actually
will be bleeding 'down', but you have the right idea.
Once it's running ok, just drop a line to let us know how it
worked out.
Ian
Vernon1252
crank sessions.. it roared to life..& it still ran like rough for a few minetes
then it smoothed right out.. thanks again for your help
shiden_kai
"Vernon1252" wrote
Good stuff!! You don't know how may tech's I've seen tear back
into those engines believing that they have done something wrong.
It scared the bejesus out of me when I first encountered it, but now
it's common place. One little thing that I do now....I will leave
the injectors unplugged (you don't want them squirting away while
you crank the engine) and then just crank the engine over for about
20-30 seconds. Then let the engine sit for a couple of minutes,
connect the injector harness back up and she usually fires up
and runs quite well.
Ian
Geoff Welsh
I'm curious, on the 3.4 while the intake is off can you see the lifters?
If so would dumping oil over them just B4 dropping the manifold into place
possibly help? Kinda like soaking new lifters B4 assembling an engine.
GW
Mike
explain why my "Mr Goodwrench" said my Montana ran like crap after the
gasket change and insisted on replacing the O2 sensor. I refused saying that
the O2 sensor was fine up until the time it rolled into the service bay. To
make a long story short, they said they replaced it....free.
I'm glad we have techs like you on this board Ian! Thanks.
"shiden_kai" <violet-lighte...@hotmail.com> wrote in message
news:QDR6b.33677$kW.5437@edtnps84...
shiden_kai
"Geoff Welsh" wrote
> This is very good info to have Ian.
> I'm curious, on the 3.4 while the intake is off can you see the lifters?
> If so would dumping oil over them just B4 dropping the manifold into place
> possibly help? Kinda like soaking new lifters B4 assembling an engine.
You can see the lifters when the intake is off. No, I don't
believe that just dumping oil over them would do anything.
I've never soaked new lifters before installing them, other
then applying whatever pre-lube was required on the
base of the lifter. Any engine that I do major work on
gets cranked over without any fuel supply until I have
good oil pressure. I've found that this works fine.
Ian
Sam Kaan
> "Geoff Welsh" wrote
>
> > This is very good info to have Ian.
> > I'm curious, on the 3.4 while the intake is off can you see the lifters?
> > If so would dumping oil over them just B4 dropping the manifold into place
> > possibly help? Kinda like soaking new lifters B4 assembling an engine.
>
> You can see the lifters when the intake is off. No, I don't
> believe that just dumping oil over them would do anything.
> I've never soaked new lifters before installing them, other
> then applying whatever pre-lube was required on the
> base of the lifter. Any engine that I do major work on
Normally what pre-lube (name/make) are used when you replace the lifter?
shiden_kai
"Sam Kaan" wrote
> Normally what pre-lube (name/make) are used when you replace the lifter?
I've always used a GM product called EOS (Engine oil supplement).
There were some years in the 80's and 90's when GM put out a
special pre-lube for non-roller lifters, but I couldn't tell you
what the part number is now. It was a dark blue/green color and
came along after GM had so many problems with small block
camshafts in the 80's. Lifter and cam problems are almost
non-existent now that the vast majority of GM engines have
gone to roller lifters/rocker arms.
Ian
Rob
Ian... have you considered that maybe the rough running is caused by a
vacuum leak at one of the intake ports? After the engine warms up
enough, the manifold gasket finally seats into position. I did my 4.3
V6 lower gasket and after starting and running like crap for about 20
seconds the check engine light came on. I immediately shut it off
fearing that I had installed the distributor incorrectly and that it
might case engine damage I had a scanner at the time but I was too
lazy to hook it up and read the code. I just assumed that I had
installed the distributor incorrectly and it was causing the error.
The next morning I took out the distributor and painstakingly
reinstalled it at TDC. it took me about and hour to get it lined up
perfectly. Surely this would correct the check engine light. I started
it up and sure enough it ran like shit and the light came on again
after about 20 seconds. After several explitives I pulled out the
scanner and it was showing a P303 ( misfire in No. 3 cylinder).
I cranked it over and let it run for about 4 or 5 minutes until the
idle finally smoothed out. The misfire counter on no. 3 I think was up
to about 900 misfires before I cleared it.
shiden_kai
"Rob" wrote
> Ian... have you considered that maybe the rough running is caused by a
> vacuum leak at one of the intake ports? After the engine warms up
> enough, the manifold gasket finally seats into position.
Rob, I'm not sure what the problem was with your gasket
installation. Probably nothing. But, no....I don't think that
your vacuum scenario is what causes the problem. If an
intake gasket were to "seat" into position only after the
engine warmed up....that would be a serious problem.
I know of no gasket that by design needs to "seat" into
position after an engine is warmed up. This would make
no sense as engines have to operate in all sorts of different
temperature conditions. A gasket either seals, or it doesn't.
I'm sure that the problem stems from the lifters taking
a bit of time to bleed down to their 'zero' lash positions.
The second generation of GM 60 degree v-6's didn't
exhibit this problem as badly, but due to the gasket
design on those engines, you only had to remove
the (I think) exhaust valve push rods. As a result,
you only had half of the lifters that could "pump up"
as opposed to the 3rd gen 60 degree v-6 which
(due to the intake gasket design) require that you
remove all of the pushrods.
Ian