Topics

Inlet valve


Mick O'Connor
 

Stripped heads today, found this strange black deposit on the backs of all 4 inlet valves. It scrapes of very easily, any ideas what it is ?
Mechanic friend suggested rich mixture ?
Mick


John Miller
 

Carbon.

Does it come off easily as a black powder?

John M



Sent from my Verizon, Samsung Galaxy smartphone


-------- Original message --------
From: "Mick O'Connor via groups.io" <mickoconnor909@...>
Date: 2/15/21 12:36 PM (GMT-08:00)
To: JabCamit <main@jabcamit.groups.io>
Subject: [JabCamit] Inlet valve

Stripped heads today, found this strange black deposit on the backs of all 4 inlet valves. It scrapes of very easily, any ideas what it is ?
Mechanic friend suggested rich mixture ?
Mick








Mick O'Connor
 

John,
Yes, scrapes off easily with a Stanley blade. Not really powdery, more gritty 
Mick 

On 15 Feb 2021, at 20:43, John Miller via groups.io <skypics234@...> wrote:

Carbon.

Does it come off easily as a black powder?

John M



Sent from my Verizon, Samsung Galaxy smartphone


-------- Original message --------
From: "Mick O'Connor via groups.io" <mickoconnor909@...>
Date: 2/15/21 12:36 PM (GMT-08:00)
To: JabCamit <main@jabcamit.groups.io>
Subject: [JabCamit] Inlet valve

Stripped heads today, found this strange black deposit on the backs of all 4 inlet valves. It scrapes of very easily, any ideas what it is ?
Mechanic friend suggested rich mixture ?
Mick








Jay Scheevel
 

Interesting. Do you have any deposits back inside of the induction pipes, or
just on the back of the valve?

Jay

-----Original Message-----
From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick
O'Connor via groups.io
Sent: Monday, February 15, 2021 1:36 PM
To: JabCamit <main@jabcamit.groups.io>
Subject: [JabCamit] Inlet valve

Stripped heads today, found this strange black deposit on the backs of all 4
inlet valves. It scrapes of very easily, any ideas what it is ?
Mechanic friend suggested rich mixture ?
Mick


Mick O'Connor
 

Jay,
A little back into the head but not as far back as the inlet manifold flange
Mick

On 15 Feb 2021, at 20:48, Jay Scheevel <jay@scheevel.com> wrote:

Interesting. Do you have any deposits back inside of the induction pipes, or
just on the back of the valve?

Jay

-----Original Message-----
From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick
O'Connor via groups.io
Sent: Monday, February 15, 2021 1:36 PM
To: JabCamit <main@jabcamit.groups.io>
Subject: [JabCamit] Inlet valve

Stripped heads today, found this strange black deposit on the backs of all 4
inlet valves. It scrapes of very easily, any ideas what it is ?
Mechanic friend suggested rich mixture ?
Mick













John Miller
 

On my Gen 3 engines I used Techron additive and found it kept the inlet valves much cleaner of carbon and what carbon was evident could be easily removed with a dull blade.

Techron is used in most auto fuel.

John M


John Miller
 

Mick

Make sure to check guide wear with a ball gauge or small hole gauge or whatever it is called today.

The go/no go gauge only works with concentric guide wear which is not common.

John M


Clive James
 

I always figured it was oil, why I think a look-see in the heads every few hundred hours is a good thing. 
Whether is burns off when it gets to a certain thickness I don't though I've never seen it as thick as that. 

How many hours is it since anyone was in there? 
CJ


Mick O'Connor
 

Clive,
All inlet valves the same. 1, 2 & 4 never opened since new, 3 opened for a new Piston 650 hrs ago.
My first thoughts was oil being sucked down the inlet guide ?
Mick

On 15 Feb 2021, at 21:12, Clive James via groups.io <zcrj90@...> wrote:

I always figured it was oil, why I think a look-see in the heads every few hundred hours is a good thing. 
Whether is burns off when it gets to a certain thickness I don't though I've never seen it as thick as that. 

How many hours is it since anyone was in there? 
CJ


Jay Scheevel
 

My guess is hot oil down the guide mixes with fuel on the hot back of the valve and alchemy happens there. Does not look like it has impacted the valve seat of the stem where it slides into the guide.

 

Jay

 

From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
Sent: Monday, February 15, 2021 2:57 PM
To: main@jabcamit.groups.io
Subject: Re: [JabCamit] Inlet valve

 

Clive,

All inlet valves the same. 1, 2 & 4 never opened since new, 3 opened for a new Piston 650 hrs ago.

My first thoughts was oil being sucked down the inlet guide ?

Mick


On 15 Feb 2021, at 21:12, Clive James via groups.io <zcrj90@...> wrote:

I always figured it was oil, why I think a look-see in the heads every few hundred hours is a good thing. 
Whether is burns off when it gets to a certain thickness I don't though I've never seen it as thick as that. 

How many hours is it since anyone was in there? 
CJ


Mick O'Connor
 

Jay,
Yes, valve seat is very clean and valve stem good. The valve just gently slid out of the guide under gravity. 

Mick 

On 15 Feb 2021, at 22:04, Jay Scheevel <jay@...> wrote:

My guess is hot oil down the guide mixes with fuel on the hot back of the valve and alchemy happens there. Does not look like it has impacted the valve seat of the stem where it slides into the guide.

 

Jay

 

From: main@JabCamit.groups.io <main@JabCamit.groups.io> On Behalf Of Mick O'Connor via groups.io
Sent: Monday, February 15, 2021 2:57 PM
To: main@jabcamit.groups.io
Subject: Re: [JabCamit] Inlet valve

 

Clive,

All inlet valves the same. 1, 2 & 4 never opened since new, 3 opened for a new Piston 650 hrs ago.

My first thoughts was oil being sucked down the inlet guide ?

Mick


On 15 Feb 2021, at 21:12, Clive James via groups.io <zcrj90@...> wrote:

I always figured it was oil, why I think a look-see in the heads every few hundred hours is a good thing. 
Whether is burns off when it gets to a certain thickness I don't though I've never seen it as thick as that. 

How many hours is it since anyone was in there? 
CJ


jabcamit@...
 

Oil down the guides  and then burning onto the valve seems the  most likely (the only thing I can think of). Can you feel any hint of rattle  if you try to rock the valve in its guide (both parts oil free). Also if  you push the valve up the guide so it stops a few mm short of the top of the guide, and then  drip thin oil or soapy water into the well  at the top how quickly does it run through. I've no idea what a good or bad value is but it might confirm that theat is where the oil is getting in.  

A friend's jabiru developed occassional hichups  in level flight shortly after  takeoff. We squirted a can of carb cleaner into the running engine and the problem  disappeared (might  have been sticking valve stem, might have been coincidence)

Bob


Mick O'Connor
 

Bob,
I agree, oil being sucked down the guide seems the only viable cause.
Difficult to measure guide wear but it feels very small.
I’m planning on getting the guides checked by experts !

Mick

On 16 Feb 2021, at 11:20, jabcamit@... wrote:

Oil down the guides  and then burning onto the valve seems the  most likely (the only thing I can think of). Can you feel any hint of rattle  if you try to rock the valve in its guide (both parts oil free). Also if  you push the valve up the guide so it stops a few mm short of the top of the guide, and then  drip thin oil or soapy water into the well  at the top how quickly does it run through. I've no idea what a good or bad value is but it might confirm that theat is where the oil is getting in.  

A friend's jabiru developed occassional hichups  in level flight shortly after  takeoff. We squirted a can of carb cleaner into the running engine and the problem  disappeared (might  have been sticking valve stem, might have been coincidence)

Bob


John Miller
 

I really like how easy it was to pull the heads o the earlier models. The Gen 4 requires the entire jug just like "real aircraft engines" to come off.

I have a valve compressor that I built for my Gen 3 and it looks like I won't be needing it anymore so it will go into my junl drawer.

By the way. I was pulled off this forum earlier. The forum manager said I had the forum listed as SPAM so he/she cut me off.

I checked my SPAM folder and see that this isn't true. Don't know what made him/her think that.

John M


Pete Twissell
 

Re. Being pulled off the forum:
I run a couple of groups on groups.io.
Every now and then, I get a notification that a member has been 'evicted' because they have marked a message from the forum as spam.
Invariably, this is because the members email application has automatically marked a message as spam.
If I'm quick, I can send the member an email to let them know what's happened, but often as not, they've just logged in again and sorted the issue themselves.

On Fri, 19 Feb 2021, 16:17 John Miller via groups.io, <skypics234=aol.com@groups.io> wrote:
I really like how easy it was to pull the heads o the earlier models. The Gen 4 requires the entire jug just like "real aircraft engines" to come off.

I have a valve compressor that I built for my Gen 3 and it looks like I won't be needing it anymore so it will go into my junl drawer.

By the way. I was pulled off this forum earlier. The forum manager said I had the forum listed as SPAM so he/she cut me off.

I checked my SPAM folder and see that this isn't true. Don't know what made him/her think that.

John M