valve clearance uncertainty - damaged seats or valves ?

Hello,

If someone can shed some light on this I would be very happy. I read
about the dangers of too little valve clearance.

I had my valves adjusted some days ago. And it was fine until I did
some motorway ( 150 mi. ) at 60 mph. Now torque has gone down,
especially at low throttle or low rpm. Fuel consumption is about the
same at cruise, but higher at accelleration ( which has suffered ).

I seem to hear more noise from the engine, and when I open the valve
cover plug, oil keeps squirting out ( at idle ! ) I suspect from valve
stem seals ? I seem to remember it did not do that when I checked it
before once .

Now settings for a 4G13 engine in a Space star service manual are wide
ranging, I informed and heard "15/20 cold", over "20-25 warm" to "25-35
warm".

Mine were set at 20-25 but the mechanic said he found them to be too
loose before. Maybe they'd better stayed so. I found them to be set at
10-15 cold now, and could that make the difference ?

Is there any chance the damage if it exists could be limited when the
clearance is widened again ? Is there anything else which could help
restore some better valve seating ? Maybe some additifs in the fuel ?
And are there any other problems which I have not read about yet about
this problem ?

Thanks very much in advance,

Carl

Hi,

and thanks for the reply. There are no unique manufacturer's values. I
found lots of different values at garages. Really, I informed.

Is there a way to check whether there is slight damage to the valve seating
? I really suspect something has happened, because even with tight valves,
the engine ran fine before the motorway trip.

Thanks,

Carl

carl wrote:
> Hi,
>
> and thanks for the reply. There are no unique manufacturer's values. I
> found lots of different values at garages. Really, I informed.
>
> Is there a way to check whether there is slight damage to the valve seating
> ? I really suspect something has happened, because even with tight valves,
> the engine ran fine before the motorway trip.
>
> Thanks,
>
> Carl
>
>
A leakdown test is a good way to confirm the engine sealing. It is a
different tool than a compression gauge, and is used after pressurizing
the cylinder with air. Not only does it quantify the leakage, but you
can listen for the escape path and pinpoint a problem.
John

My owner's manual says not to adjust the valves unless there is
"excessive" engine noise. It says to err on the side of a wide gap rather than
tight. I've adusted them three times over the years, in spite of not
hearing any engine noise. Always with the engine warm.
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Hello,

Thanks for the replies.

Well, a leak test is around here probably "very strange to ask", because
people tend not to bother. They "hardly ever adjust valves and take
compression". Last mechanic said he did not even have the proper hi-gauge.

As for correct valve settings, well, I heard a couple of times "15-20 cold",
and I measured, and had 10-15 cold. Some exhaust valves even had more of 10
valve lash ( these are all in 1/100ths of mms ) ...
While torque and smoothness has gone down, and the engine stalls more
easily, I tend to suspect damage to valve seating.

I only hope that since I hardly ever push the throttle really open, that
damage is slight. The only problem was the motorway trip, even at 60 mph.

Is it possible that the problem at this stage is mostly dirty valve seats ?
I believe there are additifs which can clean injectors, and possibly also
that clean valves and seats ?

Someone said yesterday these additifs are best used on a low tank, so that
the concentration is high. But I always heard they are used for a full tank.
I would not risk more trouble following the former advice. And can anyone
recommend a good brand of additif ?

Thanks very much again for all the replies,

Carl

Hi,

I know, it is a habit of mine never to use what power is left in an engine
if it does the job on low throttle. It feels too nice if a car seems to want
to drive and accelerate by itself.

If there is carbon build-up, would it show on the spark plug ? These were
just plain colour free, now seem to have a lightish brown, or rather beige.
What I experience is trouble when driving up slopes, the engine does not
seem to have enought breath.

I enquired further, and will check the valves myself, warm at evening, and
cold in the morning, and see for myself what the values are, and the
difference.

If I have to service the head and valves, I think it would be wise to have a
look at the rings as well ?

Compression on this car is high, and keeps building up when measuring, as
opposed to my other car. There a hi-gauge stops climbing after a while.
Here, it goes up and up to 17 bars. Maybe oil leaks ? Can such readings be
obtained with healthy rings or oil duct seal in the head gasket ?
I'm puzzled, maybe a hi-gauge can't find slightly damaged seats ?


Thanks again,

Carl

Hello,

Thanks again for your comments and time. Could I add some more to this
thread ? I'm not a knowledgeable mechanic, but I try to understand and
learn. And the problem is worsening with driving the car.

I found spark plugs dirty just above the metal body, brownish. Also the gap
is a tiny bit too narrow. I will have the electrical system checked.

I checked my valves, following all of the uncertainty about it. I just seem
to find that 5 valves are too tight , 3 inlet valves on cylinders 2,3,4 ,
and 2 outlet valves on cylinder 1,2. That is, normally, overall the valve
lash values are ALL 5/100mm too low

The table is underneath, for those who are interested.

They could (have) overheat(ed) . On the other hand, compression is still
high ( 15 bars + ) so they are not leaking ?

< Do a dry compression test and then a "wet"
<compression whereby you put abot a tablespoon of oil
<directly into the cylinder theu the spark plug hole. The
<pressures will increase a small amout because of the
<presence of the oil which has the effect of sealing the
<rings. If a cylinder increases a lot when wet, you likely
<have a piston/ring wear problem. If the pressure increases
<<uniformly with the high/low spread remaing acceptable, then,
<you have no problem. You must look elsewhere. If the
<pressure does not increase, that would likely be a result of
<leaking valves

Compression is very high ( 16 bars + ) on this engine cold with closed
throttle. I fear I will find compression will drop on a hot engine, due to
valve problems. Probably this method will prove it ?

If carbonisation is present, could it have occurred when excess oil was
filled at a minor servicing ( oil and filter change ) ? It had about 1.5
liter too much oil. It was taken out after 200 mi. Afterwards I lost 0.75
liter oil on 600 mi. Maybe this was the start of all events ?

If there would be oil consumption, would that lead to the ECU lowering fuel
input under a level which is necessary for good mixture ? I tend to think
oil is seeping through the oil rings of the pistons.

Sorry for the newbie questions, but I have not found a mechanic who would go
and search for my problems. For all of the things I experience, I hope to
find what 's going on, with the help of this group.

Thank you all again,

Carl

================================================== ==================
Following table sums up my feeler results ( I hope noone finds this
ridiculous or thinks I'm a freak, I just found the presentation clear and
representave, and helpful for knowing which values you are measuring AND
checking them again. in excel it is a nice coloured overview but this is too
elaborate a system to use routinely )

cam and crank are the positions, "i" is inlet valve opened, "o" is outlet
valve opened
the upper row are the inlet valves, "n" and "c" are non measured positions
( erroneous) ,
"xx n xx" are feeler values for two valves on a position where valves are
closed and neutral
"xx c xx" are the same for a position halfway the closed period for checking
valve lash

cam crank 4 3 2 1
------------------------------------------------
225° 0° i i 7n10 10n10
o 15n15 o 12n15
------------------------------------------------
270° 90° i 10n7 7n10 10c10
15n15 15c15 o n
------------------------------------------------
315° 180° i 10n7 i n
15n15 12n12 o o
------------------------------------------------
0° 270° n 10c7 i 10n10
15c15 15n15 n o
------------------------------------------------
45° 360° 7n10 10n7 i i
15n15 o 12n15 o
------------------------------------------------
90° 450° 7c10 10n7 i i
15n15 o 12c15 12n15
------------------------------------------------
135° 540° 7n10 i 7n10 i
o o 12n15 n
------------------------------------------------
180° 630° 7n10 i 7c10 10n10
o 13n13 12n15 12c15
------------------------------------------------