6 cy engine problem

84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
popping out of carb. Found out that the # 1 cylinder exhaust valve and
rocker/pushrod were not moving. Exchanged intake pushrod and rocker with
the exhaust, same problem. Nuts and bridge are tight. Any opinions on
problem......collapsed lifter, round camshaft lobe or other???? TIA Mike

Hi Mike,
You got it, round lobe. Camshaft break-in is extremely critical to
prevent your new camshaft from
flattening. Follow the camshaft break-in procedure religiously:
http://engineparts.com/Motorhead/tec.../cambreak.html Your engine in
1929 had a side cover, to pull the lifter:
http://www162.pair.com/nashram/nash/...onid= &carid=
Unfortunately with better sand cores they did away with it and you have
to pull the head to remove the lifters.
God Bless America, ßill O|||||||O
http://www.billhughes.com/

MikeG wrote:
>
> 84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
> popping out of carb. Found out that the # 1 cylinder exhaust valve and
> rocker/pushrod were not moving. Exchanged intake pushrod and rocker with
> the exhaust, same problem. Nuts and bridge are tight. Any opinions on
> problem......collapsed lifter, round camshaft lobe or other???? TIA Mike

Definitely a cam lobe that went flat. I had an interesting conversation with
an engineer at a cam company I deal with for circle track engines. He said
that in the last few years cam failures have increased approximately 30% on
non-roller camshafts. When I asked him why, he said that it was because many
of the oils we buy for our vehicles no longer have sufficient zinc in them,
which is critical to camshaft life. This was something I did not know, and I
haven't researched the oils yet to determine which ones, if any, still have
zinc in them. There is probably an additive available too.

When you install a new cam, make sure that you use the proper assembly lube
on the lifter faces and the cam lobes. The first 20 minutes of a camshaft's
life are the most critical. There are proper break-in procedures available
all over the net and from any cam manufacturer. The standard rule of thumb
is to run the engine for 20 minutes at a minimum of 2000 RPM. I have also
read that it is a good idea to vary the RPM between 2000 and 3000 by slowly
revving the engine. I also run an extra quart of oil to promote more splash
lubrication for the cam, but make sure you correct the oil level before
driving, or you could have other problems. I was also told not to use
synthetic oil for cam break-in, but I think you'll get mixed reviews on
that.

Chris

"MikeG" > wrote in message
news
> 84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
> popping out of carb. Found out that the # 1 cylinder exhaust valve and
> rocker/pushrod were not moving. Exchanged intake pushrod and rocker
with
> the exhaust, same problem. Nuts and bridge are tight. Any opinions on
> problem......collapsed lifter, round camshaft lobe or other???? TIA
Mike
>
>

Hey Bill I realy wanted to read that page,
http://engineparts.com/Motorhead/tec.../cambreak.html as I have under 80
miles on my remanned engine, but the link doesn't work, any others?

"L.W. ("ßill") Hughes III" > wrote in message
...
> Hi Mike,
> You got it, round lobe. Camshaft break-in is extremely critical to
> prevent your new camshaft from
> flattening. Follow the camshaft break-in procedure religiously:
> http://engineparts.com/Motorhead/tec.../cambreak.html Your engine in
> 1929 had a side cover, to pull the lifter:
> http://www162.pair.com/nashram/nash/...onid= &carid=
> Unfortunately with better sand cores they did away with it and you have
> to pull the head to remove the lifters.
> God Bless America, ßill O|||||||O
> http://www.billhughes.com/
>
> MikeG wrote:
>>
>> 84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
>> popping out of carb. Found out that the # 1 cylinder exhaust valve and
>> rocker/pushrod were not moving. Exchanged intake pushrod and rocker
>> with
>> the exhaust, same problem. Nuts and bridge are tight. Any opinions on
>> problem......collapsed lifter, round camshaft lobe or other???? TIA
>> Mike

Copy of: http://engineparts.com/Motorhead/tec.../cambreak.html
"Camshaft Break-In Procedures
Coat the camshaft lobes & distributor gear with an EP lubrication such
as CL400
"Cam Guard" or a moly-paste.
Apply the EP lubricant only to the lifter contact faces - not the bores.
Prime the lube system using new oil and filter.
Use only oils that meet or exceed the latest API ratings.
Do not use non-detergent oils, they do not have the anti-scuff additives
found in
modern detergent oils.
Start the engine and increase the RPM's to 1500-2000. Operate the engine
for
15-20 minutes at this speed. The higher speeds increase splash
lubrication and
decrease nose loading.
Avoid excessive cranking, no start donations and fuel/ignition
adjustments. The
break-in procedure must commence as soon as the engine has oil pressure.
If the
engine fails to start within 15-30 seconds, it is recommended to
re-apply the EP
lubricant to the lobes.
If possible, following break-in, the idle should be adjusted to high
specifications."

You're past the critical ring break-in:
http://performanceunlimited.com/docu...nebreakin.html
God Bless America, ßill O|||||||O
http://www.billhughes.com/

Greg wrote:
>
> Hey Bill I realy wanted to read that page,
> http://engineparts.com/Motorhead/tec.../cambreak.html as I have under 80
> miles on my remanned engine, but the link doesn't work, any others?

What a drag....

On a remanned engine, that just screams faulty cleaning work. That
strongly implies dirt or metal shavings have plugged up one or more oil
passages which caused the cam to burn off. If it was just dirt in the
lifter, the pushrod would still be moving with a loud clacking noise at
it hit the rocker.

The only fix I know is a complete tear down with each oil channel's flow
verified before reassemble. Just putting another cam in it will end up
with the same result likely.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

MikeG wrote:
>
> 84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
> popping out of carb. Found out that the # 1 cylinder exhaust valve and
> rocker/pushrod were not moving. Exchanged intake pushrod and rocker with
> the exhaust, same problem. Nuts and bridge are tight. Any opinions on
> problem......collapsed lifter, round camshaft lobe or other???? TIA Mike

Collapsed lifter would be my first guess. As I went to look for the lifter
hiding in the bottom of a very deep hole, I might find the real problem, but
I think the lifter is where you need to start. I am not sure why you would
swap a rocker or the push rod, but checking for a bent push rod makes sense.
If the pushrod was straight, I would have kept looking for the lifter, and
not bother swapping the rod and rocker.




"MikeG" > wrote in message
news
> 84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
> popping out of carb. Found out that the # 1 cylinder exhaust valve and
> rocker/pushrod were not moving. Exchanged intake pushrod and rocker
with
> the exhaust, same problem. Nuts and bridge are tight. Any opinions on
> problem......collapsed lifter, round camshaft lobe or other???? TIA
Mike
>
>

Thanks for the very informative replys. As much as I can tell, and my
limited logic on this, the majority of answers I have received is pointing
to a rounded camshaft. I grounded out the coil, so that the engine would
not start and 'jiggled' the rocker arm while cranking. It never got tight.
I was able to look down the small push rod hole and observe the lifter. It
was not doing a thing. I changed the rocker and push rod just incase one
was bent etc. that I could not detect with my eye. The push rods were of
equal length, and straight when rolled across the floor. The major concern
now is that: if by chance the oil passage to that lifter or all lifters for
that matter are clogged with crud of unknown substance, I don't feel safe
unless I somhow clean them all out. Perhaps not ideal with the engine
installed, and 2nd...what has happened to all the metal that was ground off
of the cam? I know most of it is suspended in the oil, the filter probably
has taken out some, but I am sure it circulated throught all the bearings.
Last oil change was about 1000 miles ago, and I am guessing that this grind
down has taken several thousand miles. Never noticed anything unusual in
the oil. So.....my strategy will be to first pull the head, then the lifter
and look at the cam. Priced a cam yesterday = $200.00 Yipes. Stay
tuned!!!! TX Mike



"Jeff Strickland" > wrote in message
...
> Collapsed lifter would be my first guess. As I went to look for the lifter
> hiding in the bottom of a very deep hole, I might find the real problem,
> but
> I think the lifter is where you need to start. I am not sure why you would
> swap a rocker or the push rod, but checking for a bent push rod makes
> sense.
> If the pushrod was straight, I would have kept looking for the lifter, and
> not bother swapping the rod and rocker.
>
>
>
>
> "MikeG" > wrote in message
> news
>> 84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
>> popping out of carb. Found out that the # 1 cylinder exhaust valve and
>> rocker/pushrod were not moving. Exchanged intake pushrod and rocker
> with
>> the exhaust, same problem. Nuts and bridge are tight. Any opinions on
>> problem......collapsed lifter, round camshaft lobe or other???? TIA
> Mike
>>
>>
>
>

I discounted the possibility of the rounded cam shaft because I like to
think the problem will always be the cheapest thing to fix. In this case,
even if the cheapest thing isn't the broken part du jour, it rests right on
top of it. If the cam is rounded off, odds are good that the lifter will be
seriously worn too.





"MikeG" > wrote in message
. ..
> Thanks for the very informative replys. As much as I can tell, and my
> limited logic on this, the majority of answers I have received is pointing
> to a rounded camshaft. I grounded out the coil, so that the engine would
> not start and 'jiggled' the rocker arm while cranking. It never got
> tight. I was able to look down the small push rod hole and observe the
> lifter. It was not doing a thing. I changed the rocker and push rod just
> incase one was bent etc. that I could not detect with my eye. The push
> rods were of equal length, and straight when rolled across the floor. The
> major concern now is that: if by chance the oil passage to that lifter or
> all lifters for that matter are clogged with crud of unknown substance, I
> don't feel safe unless I somhow clean them all out. Perhaps not ideal
> with the engine installed, and 2nd...what has happened to all the metal
> that was ground off of the cam? I know most of it is suspended in the
> oil, the filter probably has taken out some, but I am sure it circulated
> throught all the bearings. Last oil change was about 1000 miles ago, and I
> am guessing that this grind down has taken several thousand miles. Never
> noticed anything unusual in the oil. So.....my strategy will be to first
> pull the head, then the lifter and look at the cam. Priced a cam
> yesterday = $200.00 Yipes. Stay tuned!!!! TX Mike
>
>
>
> "Jeff Strickland" > wrote in message
> ...
>> Collapsed lifter would be my first guess. As I went to look for the
>> lifter
>> hiding in the bottom of a very deep hole, I might find the real problem,
>> but
>> I think the lifter is where you need to start. I am not sure why you
>> would
>> swap a rocker or the push rod, but checking for a bent push rod makes
>> sense.
>> If the pushrod was straight, I would have kept looking for the lifter,
>> and
>> not bother swapping the rod and rocker.
>>
>>
>>
>>
>> "MikeG" > wrote in message
>> news
>>> 84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
>>> popping out of carb. Found out that the # 1 cylinder exhaust valve and
>>> rocker/pushrod were not moving. Exchanged intake pushrod and rocker
>> with
>>> the exhaust, same problem. Nuts and bridge are tight. Any opinions on
>>> problem......collapsed lifter, round camshaft lobe or other???? TIA
>> Mike
>>>
>>>
>>
>>
>
>

Hi Mike,
I would guess the oil filter caught the worst of the metal
fillings, unless you revved it tight enough to bypass the filter. It's
always new cam, new lifters, I'm not sure you were saying that. Then go
back to changing oil and filter every five hundred miles, like you were
doing with your new engine break-in, for a couple of times will clean
the pan without disassembly. Maybe buy a magnetic drain plug.
God Bless America, ßill O|||||||O
http://www.billhughes.com/

MikeG wrote:
>
> Thanks for the very informative replys. As much as I can tell, and my
> limited logic on this, the majority of answers I have received is pointing
> to a rounded camshaft. I grounded out the coil, so that the engine would
> not start and 'jiggled' the rocker arm while cranking. It never got tight.
> I was able to look down the small push rod hole and observe the lifter. It
> was not doing a thing. I changed the rocker and push rod just incase one
> was bent etc. that I could not detect with my eye. The push rods were of
> equal length, and straight when rolled across the floor. The major concern
> now is that: if by chance the oil passage to that lifter or all lifters for
> that matter are clogged with crud of unknown substance, I don't feel safe
> unless I somhow clean them all out. Perhaps not ideal with the engine
> installed, and 2nd...what has happened to all the metal that was ground off
> of the cam? I know most of it is suspended in the oil, the filter probably
> has taken out some, but I am sure it circulated throught all the bearings.
> Last oil change was about 1000 miles ago, and I am guessing that this grind
> down has taken several thousand miles. Never noticed anything unusual in
> the oil. So.....my strategy will be to first pull the head, then the lifter
> and look at the cam. Priced a cam yesterday = $200.00 Yipes. Stay
> tuned!!!! TX Mike
>
> "Jeff Strickland" > wrote in message
> ...
> > Collapsed lifter would be my first guess. As I went to look for the lifter
> > hiding in the bottom of a very deep hole, I might find the real problem,
> > but
> > I think the lifter is where you need to start. I am not sure why you would
> > swap a rocker or the push rod, but checking for a bent push rod makes
> > sense.
> > If the pushrod was straight, I would have kept looking for the lifter, and
> > not bother swapping the rod and rocker.
> >
> >
> >
> >
> > "MikeG" > wrote in message
> > news
> >> 84 CJ7 4.2L rebuilt engine installed 27K miles ago. Last week, noticed
> >> popping out of carb. Found out that the # 1 cylinder exhaust valve and
> >> rocker/pushrod were not moving. Exchanged intake pushrod and rocker
> > with
> >> the exhaust, same problem. Nuts and bridge are tight. Any opinions on
> >> problem......collapsed lifter, round camshaft lobe or other???? TIA
> > Mike
> >>
> >>
> >
> >