Valve Stem Seals Replacement

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Old 25 Sep 2005, 05:08 pm   #1 (permalink)
bauz
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Default Valve Stem Seals Replacement

1991 4cyl 3SFE DX auto 104KM
During the last 4 years I tried to get used to the smoke during start-up.
The car runs great and passes the CA emission test like a champ.
Nevertheless, I am still getting embarrassed every time I start the car.
On the other hand, I am not so excited about removing the timing belt,
distributor an all other components that are needed to be removed in order
to get to those little seals, and I am also not excited about paying
someone else to do it.
I never opened the head cover and I would like to hear advice/opinions
regarding the following questions:
1. Is it possible to remove only the exhaust camshaft (without removing
the timing belt and the distributor)?
2. Is there a point in replacing only the exhaust stem seals? my theory is
that they go bad faster since they are exposed to more heat, but I am not
an expert.
3. Should I go with OEM seals, which would probably fail again 2-3 years
from now, or should I try Viton or Teflon or any other recommended type
(please add you recommendations)?

Thanks,
Boaz

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Old 25 Sep 2005, 10:08 pm   #2 (permalink)
Rob
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Default Re: Valve Stem Seals Replacement


bauz wrote:
> 1991 4cyl 3SFE DX auto 104KM
> During the last 4 years I tried to get used to the smoke during start-up.
> The car runs great and passes the CA emission test like a champ.
> Nevertheless, I am still getting embarrassed every time I start the car.
> On the other hand, I am not so excited about removing the timing belt,
> distributor an all other components that are needed to be removed in order
> to get to those little seals, and I am also not excited about paying
> someone else to do it.
> I never opened the head cover and I would like to hear advice/opinions
> regarding the following questions:
> 1. Is it possible to remove only the exhaust camshaft (without removing
> the timing belt and the distributor)?
> 2. Is there a point in replacing only the exhaust stem seals? my theory is
> that they go bad faster since they are exposed to more heat, but I am not
> an expert.
> 3. Should I go with OEM seals, which would probably fail again 2-3 years
> from now, or should I try Viton or Teflon or any other recommended type
> (please add you recommendations)?
>
> Thanks,
> Boaz


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Old 25 Sep 2005, 10:10 pm   #3 (permalink)
Rob
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Default Re: Valve Stem Seals Replacement


bauz wrote:
> 1991 4cyl 3SFE DX auto 104KM
> During the last 4 years I tried to get used to the smoke during start-up.
> The car runs great and passes the CA emission test like a champ.
> Nevertheless, I am still getting embarrassed every time I start the car.
> On the other hand, I am not so excited about removing the timing belt,
> distributor an all other components that are needed to be removed in order
> to get to those little seals, and I am also not excited about paying
> someone else to do it.
> I never opened the head cover and I would like to hear advice/opinions
> regarding the following questions:
> 1. Is it possible to remove only the exhaust camshaft (without removing
> the timing belt and the distributor)?
> 2. Is there a point in replacing only the exhaust stem seals? my theory is
> that they go bad faster since they are exposed to more heat, but I am not
> an expert.
> 3. Should I go with OEM seals, which would probably fail again 2-3 years
> from now, or should I try Viton or Teflon or any other recommended type
> (please add you recommendations)?
>
> Thanks,
> Boaz


before you tear your engine down have you been using a high mileage
oil?
They contain additives to swell the seals slightly. I had the problem
on
my 97 camry at 60,000. Now over 200,000 with no smoke on Pennzoil
high
mileage oil.

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Old 26 Sep 2005, 09:42 am   #4 (permalink)
bauz
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Default Re: Valve Stem Seals Replacement

Thank you for the tip - I heard about this solution. If it turns out to be
too difficult to replace the seals, I would probably try it. I heard some
other opinions against using any additives, therefore I would like to try
the conventional way first. The other reason that I would like to do it is
because I enjoy working on the car. Therefore I would like to hear more
tips about replacing the seals. My goal is to complete the job in one
weekend, which would be impossible (for me) if I have to remove the timing
belt - in that case I will switch to a high mileage oil.

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Old 26 Sep 2005, 10:56 am   #5 (permalink)
Daniel
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Default Re: Valve Stem Seals Replacement

How are you going to remove the head without removing the timing belt?
~~~~~~~~~~
I believe it is possible to replace the valve seals using compressed
air to hold the valves closed.
Something like a large socket with the side ground away can be used to
compress the valve spring and remove the keepers.
You still have to remove the camshafts.
Doesn't make any sense to me to try just the exhaust to avoid removing
the timing belt.
What is so difficult about removing the timing belt?
Let me answer my own question.
The most difficult thing about removing the timing belt, is removing
the side engine brace with very limited clearance to reach the lower
two bolts.
Secret?
Remove the crankshaft pulley first, then you can reach those bolts much
more easily from beneath.
How to remove the crankshaft pulley bolt?
Electric impact wrench worked on mine.
Then later acquired a high torque air driven impact gun for the axle
nut. This would be more than adequate for the crankshaft pulley bolt.
An impact gun allows you to remove the bolt without the engine turning.
~~~~~~~~~~~~
My personal opinion.
Not worth changing the valve guide oil seals if they're just going to
start leaking again.
However, that puff of smoke on cold start could shorten the life of the
oxygen sensor, and I was getting (sometimes) a large cloud of blue
smoke which just didn't seem right.
The following worked for me.
First, having acquired the car with 80,000 miles - conventional oil
changed at 5,000 mile intervals, I changed the oil more often several
times.
Then added auto-rx (auto-rx.com) and drove 500 miles on the freeway,
drained the oil, added Mobil 1 10W30 and 3 cups (20%) Lucas heavy duty
oil stabilizer.
Problem solved.
That was in August of 2002, still no problem.
Oddly, I too, will not use most motor oil additives. Many have been
proven useless or harmful and the companies fined for deceptive
advertising practices by the FTC.
I do not like the idea of adding anything that doesn't belong in the
engine or could alter clearances.
The Lucas is a pure petroleum product with no solvents or particulate
additives.
If the viscosity is 50w, the effective viscosity of the blend when warm
is 34W - not excessive in my view. But the Lucas is different than
10W40 for example, in that it clings to parts and doesn't seem to drain
off over night.
I searched these groups extensively before first use, and of those
actually having tried it, they seemed to have around 300,000 miles on
the engines and be pleased.
It does not "swell the seals", so in theory, you can just drain it back
out and be back to the original state with no harm done, but I've
continued to use it because that blue smoke on cold start is gone.

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Old 26 Sep 2005, 11:07 am   #6 (permalink)
C. E. White
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Default Re: Valve Stem Seals Replacement


"bauz" <b_avta@nospam.hotmail.com> wrote in message
news:3519d957fe6f31dab78ad0c40544e692@localhost.ta lkaboutautos.com...

> 1991 4cyl 3SFE DX auto 104KM


Seems like low mileage (65,000 miles) for the valve seals to go bad. Have
you made sure you PCV system is in good order? I suppose the valve seals may
have hardened becasue of the age. If this is the case, the high mileage
motor oils as suggested by others might be worth a try.

> On the other hand, I am not so excited about removing the timing belt,
> distributor an all other components that are needed to be removed in order
> to get to those little seals, and I am also not excited about paying
> someone else to do it.
> I never opened the head cover and I would like to hear advice/opinions
> regarding the following questions:
> 1. Is it possible to remove only the exhaust camshaft (without removing
> the timing belt and the distributor)?


No

> 2. Is there a point in replacing only the exhaust stem seals? my theory is
> that they go bad faster since they are exposed to more heat, but I am not
> an expert.


Actually, the intake valve seals are more critical. The exaust seals are on
the positive pressure side of the engine (exahust side has a positiove
pressure compared to the atmosphere). The intake valves are on the suck side
of the engine. It is possible for oil smoke to be generated from oil leaking
from either side, but doing just the exhaust side is likely to result in
disappointment.

> 3. Should I go with OEM seals, which would probably fail again 2-3 years
> from now, or should I try Viton or Teflon or any other recommended type
> (please add you recommendations)?


I don't believe Toyotas are noted for leaking valve seals. I'd recommend
going with the OEM parts.

You seem hesitant to remove the timing belt. However, sooner or later it is
going to need to be replaced. Why not combine the belt replacement with the
valve seal replacement? Do you have the equipment needed to do the job (air
compressor, spark plug adapter for the air hose, valve spring compressor,
etc.)? If not, you might consider letting a professional handle the job.
Have you considered just removing the head, and letting a local shop do a
complete valve job? If your engine is smoking badly, it is likely that you
have worn valve guides as well as bad seals. You might also investigate the
cost of a rebuilt head. http://www.headsonly.com/toyota.htm lists a head for
3SFE engine at $350. If you do the work yourself, you can probably do the
job for less than $500 and you will have a new timing belt and head gasket.

Personally before I started spending a lot of money, I'd make sure that the
PCV system was OK and then I'd try the high mileage motor oil. If this
didn't address the problem, and if I was planning to keep the car for a long
time, I'd probably look at a rebuilt head.

Ed


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Old 26 Sep 2005, 11:38 pm   #7 (permalink)
bauz
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Default Re: Valve Stem Seals Replacement

Thank you for the detailed reply.
I guess I'll just try the additive solution. Even if I had an electric
impact wrench, removing the timing and putting it back is just too much
work, and I'll probably wouldn't be able to finish all the tasks in one
weekend. This car never had any problem, therefore I do not have good
familiarity with the internals of the engine, and it would take me much
more time than someone with experience. Sorry that my first post was too
short and missing some details: I meant to replace the seals without
taking off the head. My intention was to remove only the exhaust camshaft,
which is not connected directly to the distributor or the timing belt.
Instead of removing the head cover, crank-pulley, timing belt covers,
timing belt, cruise control, distributor and the camshafts, I thought I
could just take off the head cover and the exhaust camshaft. Much shorter
job.
I will post the outcome of the additive solution, and maybe I will try to
implement my theory.

Thanks!

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Old 27 Sep 2005, 12:20 am   #8 (permalink)
bauz
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Default Re: Valve Stem Seals Replacement

>Have you made sure you PCV system is in good >order?
As far as I understand, this model does not have conventional PVC system,
and it is not serviceable.

>The exhaust seals are on the positive pressure >side of the engine

The smoke appears only for few seconds, after the engine was off for a
long time. when the engine head is hot (few seconds after the engine
starts), there is no smoke and the overall oil consumption is very low.
Therefore I still believe that the exhaust seals are in a much worse
condition, and when they are cold and shrunken, more oil can leak through
them.

>Why not combine the belt replacement with the >valve seal replacement?

Good question, the answer - bad decision. half a year ago I was a broke
student and the timing belt was way over due (sorry about the confusion -I
meant 104000 miles [I'm used to kilometers]). Since most of my trips were
above 300 miles each way, I decided to pay someone professional to change
my timing belt. As a student, I didn't care much about the startup smoke
and didn't want to spend more money to repair it. Now I have a nice job,
and having a car that leaves a cloud of smoke is not appropriate anymore.
But I love this car, it runs (almost) like new and I am not planning to
replace it until the wheels will fall off.

>might also investigate the cost of a rebuilt >head...

The engine is excellent, the only problem is way the neighbors look at me
after I start the car in the morning, therefore I do not see a reason to
replace the whole head.

> I'd try the high mileage motor oil.

I agree. I will try it soon. My father is sending me a special additive
that is made in Germany (I don't remember the name), and he sworn me over
the phone not to try anything else before I try this one. If that doesn't
work, I will try the treatment that worked for Daniel from the previous
post.

Thank you very much for answering my questions.
Boaz

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Old 27 Sep 2005, 08:38 am   #9 (permalink)
Daniel
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Default Re: Valve Stem Seals Replacement

Here's another reason to be glad you're not replacing the valve seals.
Was reading the factory service manual last night, and there is are
several special procedures for removing and replacing camshafts. The
one that caught my attention is the way to avoid _breaking the head_
when installing or removing them. Because the thrust clearances are so
close, if the hardened steel camshafts are inserted into (or removed
from) the aluminum bearing holders at a slight angle they can crack, so
one needs to observe the angle of the locating pin on the end of the
camshafts such that they rest evenly on, for example valves for
cylinders one and three, and with the exhaust camshaft it has to be
carefully "rolled" into position along the cam gear.

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Old 27 Sep 2005, 01:16 pm   #10 (permalink)
Rob
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Default Re: Valve Stem Seals Replacement

If you were only gonna do the exhaust ones, I think all your money and
effort and time would be wasted and you could possibly do more damage.
Change that oil to Pennzoil high mileage and put on a toyota or
purolator filter first. Then if you
need to add the additive you mention...I hate any additives myself but
at least try the oil change first. You would not put that additive into
dirty oil would you? Not sure what oil or viscosity you are using but
if your running 5w-30 maybe its time for 10w-40
which I use during the summer heat.
Here is another reason. Camrys rear main seals when they get old will
harden and leak oil, PLENTY of oil on your engine and the ground. I had
one fail on my old camry before they made the high mileage oils.
Transmission has to be pulled to replace seal, very costly.

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