Pictures of piston, valves & spark plus: what does this tell you?

Pictures were taken right after the head was taken off. No cleaning at
all. Pictures of cylinder 1 & 4. They seem dirty, is this what I
should expect from a '92 NA width 115.000 miles? Must say it looks
worse on the pictures than IRL.

http://www.netwave.be/Images/Piston1.jpg
http://www.netwave.be/Images/Piston4.jpg

Valves look strange. Why are the middle intake valves black???

http://www.netwave.be/Images/Valves.jpg

Then the spark plugs. Do they look ok?

http://www.netwave.be/Images/Sparkplug.jpg

I don't intent to break down the engine further than this unless I
really really have to. Should I clean the pistons? Maybe it's better
NOT to touch them because some of that stuff might get stuck between
piston & cylinder wall? What about the valves?

Thanks for any feedback!

Steven

- - -

One Cylinder is running leaner that the others (#4?) (Typical for a Miata.)
How long were the plugs in the engine?
Do you know what the compression was before you opened things up? This is
usually a good indication as to what to do further.
What caused you to pop the head for a look? This might also help in making
a decision.
The pictures may be misleading, but it looked like there might be some
pistion damage on one piston at the edge.
There are ways to keep the crud from cleaning out of the piston cylinder
wall gap, if you really want to de carbon.
One method was to move a given pistion down from the top of the cylinder,
lay a small bead of RTV between the pistion and the cylinder.
Move the pistion up slightly while the RTV is still wet, so it seals the
gap.
Removal -- move the piston down, Remove the RTV. If you are not going to use
a solvent in the cleaning process, a bead of grease will also work well.
You can even use grease, remove the excess with a rag wet with solvent, let
the solvent dry, and then put the bead of RTV down.
This helps to keep the RTV from going too far down between the piston and
cylinder wall.
Before RTV we used to use just heavy grease.
Ideally, the engine has enough milage and age to justify an overhaul, or
possible replacement with a low milage used engine or short block.

> wrote in message
oups.com...
> Pictures were taken right after the head was taken off. No cleaning at
> all. Pictures of cylinder 1 & 4. They seem dirty, is this what I
> should expect from a '92 NA width 115.000 miles? Must say it looks
> worse on the pictures than IRL.
>
> http://www.netwave.be/Images/Piston1.jpg
> http://www.netwave.be/Images/Piston4.jpg
>
> Valves look strange. Why are the middle intake valves black???
>
> http://www.netwave.be/Images/Valves.jpg
>
> Then the spark plugs. Do they look ok?
>
> http://www.netwave.be/Images/Sparkplug.jpg
>
> I don't intent to break down the engine further than this unless I
> really really have to. Should I clean the pistons? Maybe it's better
> NOT to touch them because some of that stuff might get stuck between
> piston & cylinder wall? What about the valves?
>
> Thanks for any feedback!
>
> Steven
>
> - - -
>

Chuck,

The pictures are a bit misleading. They make the piston top look like
moutains and canyons while in reality it's very flat. The damage is
not there (went out to check the car), want you probably see are valve
cut-outs (is that english?).

I had a leaking waterpump I'm about to replace. So that's why I had to
do the timing belt stuff.

Then why did I pop the head? Two reasons: some months after I got the
car (about 7 years ago) I noticed the coolant was very dirty and had
an "oily" look to it. I replaced the coolant but it stayed more or
less clean. Still, I was unsure what to think about the head gasket.
Second reason is the engine block is always very greasy below gasket
level. Not the front, but the back (also both sides second half).

So I didn't plan to pop the head, but after doing the timing belt it
seemed to be a small amount of extra work to (finally!) get a chance
to check the head gasket.

So, stupid me, I don't have compression figures (really should have
done that!).

I'm not planning on replacing the engine yet.

Would you de-carbon the pistons? Like the RTV story, but it scares me!
Grease might be a better solution for me if I decide to clean the
pistons.

Steven

- - -

Nothing looks alarming to me there. There may be a little oil getting onto
some of the inlet valves, could be stem seals. I would replace them anyway,
if you already have the head off. Carbon buildup in minimal, I think I would
just put a can of cleaner through it one I had everything together.

> wrote in message
oups.com...
> Pictures were taken right after the head was taken off. No cleaning at
> all. Pictures of cylinder 1 & 4. They seem dirty, is this what I
> should expect from a '92 NA width 115.000 miles? Must say it looks
> worse on the pictures than IRL.
>
> http://www.netwave.be/Images/Piston1.jpg
> http://www.netwave.be/Images/Piston4.jpg
>
> Valves look strange. Why are the middle intake valves black???
>
> http://www.netwave.be/Images/Valves.jpg
>
> Then the spark plugs. Do they look ok?
>
> http://www.netwave.be/Images/Sparkplug.jpg
>
> I don't intent to break down the engine further than this unless I
> really really have to. Should I clean the pistons? Maybe it's better
> NOT to touch them because some of that stuff might get stuck between
> piston & cylinder wall? What about the valves?
>
> Thanks for any feedback!
>
> Steven
>
> - - -
>

Steven,
If you ever get the engine back together, I would change the brand of
gas that you use.
It looks like the valve guide seals on the intakes (rear on #1, Front
and rear of #2 and the front of #3 ) are bad, (leaking oil) . That will
cause carbon build up, but even #4 shows crap on the cyl. top and that
is usually a sign of (bad chemical mixture) of the gas.
One of the Cyl's shows a "hot spot" on the side. That can be a "burn" or
a cooling leak. ( A look at the cyl. wall should tell you more. )

It is just so hard to tell from "just pictures". As someone has asked,
why did you pull it apart ? Did you have some other bad indications of
the power, smoke, liquid loss, oil use ??

I think, for my personal use, I will run some good carbon and cyl.
cleaners thru the engine before pulling it apart. First of all, some
times it cures the problem and next, it lets you have a clean area to
work in.

For what it's worth, (& that might not be much for you :-) ) I switched
to NGK double platinum spark plugs $11.95 each online from
Sparkplugs.com , ($29.95 each over the counter) But! they are worth it!
I run Chevron gas and you can run your fingers around the inside of the
tailpipe and not get any soot on them ! It runs that clean!! I have
60,000+ miles on my 2003 LS.

Just my shot at your problem.

Bruce Bing '03 LS

On May 5, 11:22 pm, (BRUCE HASKIN) wrote:
> Steven,
> If you ever get the engine back together, I would change the brand of
> gas that you use.
> It looks like the valve guide seals on the intakes (rear on #1, Front
> and rear of #2 and the front of #3 ) are bad, (leaking oil) . That will
> cause carbon build up, but even #4 shows crap on the cyl. top and that
> is usually a sign of (bad chemical mixture) of the gas.
> One of the Cyl's shows a "hot spot" on the side. That can be a "burn" or
> a cooling leak. ( A look at the cyl. wall should tell you more. )
>
> It is just so hard to tell from "just pictures". As someone has asked,
> why did you pull it apart ? Did you have some other bad indications of
> the power, smoke, liquid loss, oil use ??
>
> I think, for my personal use, I will run some good carbon and cyl.
> cleaners thru the engine before pulling it apart. First of all, some
> times it cures the problem and next, it lets you have a clean area to
> work in.
>
> For what it's worth, (& that might not be much for you :-) ) I switched
> to NGK double platinum spark plugs $11.95 each online from
> Sparkplugs.com , ($29.95 each over the counter) But! they are worth it!
> I run Chevron gas and you can run your fingers around the inside of the
> tailpipe and not get any soot on them ! It runs that clean!! I have
> 60,000+ miles on my 2003 LS.
>
> Just my shot at your problem.
>
> Bruce Bing '03 LS

I think Bruce has nailed this one. At the same time, giving some
leeway for pictures coming off as more gross than real life, this may
just look to me like an everyday 110k+ mileage car. If no one is able
to get a really good answer of something bad (and it doesn't sound
like you were having all that many problems) I'd replace all the
gaskets you can, brush everything down (cleaning is never a bad
idea!), replace those spark plugs, and actually replace your spark
cables too, and put it back together. These are all normal high-
mileage maintenance items anyways, and would give you some peace of
mind.

Wait a week, then pull the cables and plugs...check if the plugs are
fouled up, then go to your mechanic or miata club and borrow a leak-
down tester and try it out.

Best of luck!

-r0ll

wrote:
> Pictures were taken right after the head was taken off. No cleaning at
> all. Pictures of cylinder 1 & 4. They seem dirty, is this what I
> should expect from a '92 NA width 115.000 miles? Must say it looks
> worse on the pictures than IRL.
>
> http://www.netwave.be/Images/Piston1.jpg
> http://www.netwave.be/Images/Piston4.jpg
>
> Valves look strange. Why are the middle intake valves black???
>
> http://www.netwave.be/Images/Valves.jpg
>
> Then the spark plugs. Do they look ok?
>
> http://www.netwave.be/Images/Sparkplug.jpg
>
> I don't intent to break down the engine further than this unless I
> really really have to. Should I clean the pistons? Maybe it's better
> NOT to touch them because some of that stuff might get stuck between
> piston & cylinder wall? What about the valves?

Plugs are fine. May be a stem seal leak on nos 2 and 3 (I assume you'll
replace the stem seals at this sort of mileage anyway), but the outside
cylinders may also be running hotter due to the cooling system layout.
Most of the mess is good honest carbon.

You should put the piston to be cleaned at TDC and fill the gap between
it and the bore with grease. Then decoke it and polish it, finally
dropping it back down a bit and carefully wiping all the gritty grease
out. The valves can also be decoked, but don't touch the lapped
surface. You can relap them in the traditional way if you like, but go
very gently - I think the seats are triple-cut.

Hi,

Because the newsserver of my provider wasn't working, I used google...

The damn site used my email to publish messages!!! :-(

Anyway, thanks all for responding!

Steven

- - -

"Zog The Undeniable" wrote:

> Plugs are fine. May be a stem seal leak on nos 2 and 3 (I assume you'll
> replace the stem seals at this sort of mileage anyway)

Wasn't planning to...

I checked the manual, seems like there's a lot of work involved (remove
cams, spring, lifters, ...). If I'm only burning a little bit of oil, so I'm
not sure it's worth the time.

It might be better to clean the valves a bit, and drive the car for a few
more years until it needs a serious overhaul. At that point I might swap the
complete head or do a full valve lapping job.

Disassemble the head to replace some valve seals seems like a lot of work
with minimal gain. Does that make sense?

Since I'm still waiting for parts to arrive, I cleaned the pistons. In the
picture I was halfway, by now I'm finished. Let's hope you can see the
difference with the naked eye :-)

http://www.netwave.be/Images/Pistons.jpg

I want to do something similar with the head. My idea was to clean each
chambre & valves with a wire brush when all 4 valves are fully closed.
What's the group opinion on this one?

Steven

- - -

"Steven Spits" > wrote in message
ynet.net...
> "Zog The Undeniable" wrote:
>
>> Plugs are fine. May be a stem seal leak on nos 2 and 3 (I assume you'll
>> replace the stem seals at this sort of mileage anyway)
>
> Wasn't planning to...
>
> I checked the manual, seems like there's a lot of work involved (remove
> cams, spring, lifters, ...). If I'm only burning a little bit of oil, so
> I'm not sure it's worth the time.
>
> It might be better to clean the valves a bit, and drive the car for a few
> more years until it needs a serious overhaul. At that point I might swap
> the complete head or do a full valve lapping job.
>
> Disassemble the head to replace some valve seals seems like a lot of work
> with minimal gain. Does that make sense?
>
> Since I'm still waiting for parts to arrive, I cleaned the pistons. In the
> picture I was halfway, by now I'm finished. Let's hope you can see the
> difference with the naked eye :-)
>
> http://www.netwave.be/Images/Pistons.jpg
>
> I want to do something similar with the head. My idea was to clean each
> chambre & valves with a wire brush when all 4 valves are fully closed.
> What's the group opinion on this one?
>
> Steven
>
> - - -

LOL, very pretty. Probably make bugger all differance. I would be changing
stem seals, if they are a little iffy now, in a few years they could be
gushing.