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Royal Enfield Motorcycles => Bullet with the UCE engine => Topic started by: singhg5 on August 22, 2010, 12:53:36 am

Title: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on August 22, 2010, 12:53:36 am
After I came back from my ride today, I noticed that there is a 2 mm diameter hole on the RIGHT side of engine, in between bottom two fins of cylinder head of my motorcycle G5.  It also was wet with a bit of oil - seems to be coming out of it.

Is this hole normal ?  If so, is it supposed to leak oil ?

Here is a picture.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: r80rt on August 22, 2010, 01:10:52 am
My C5 has one just like that, no oil though,
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on August 22, 2010, 01:20:07 am
My C5 has one just like that, no oil though,

You mean your C5 and my G5 engines were made by the same guy ?  :D

What is the purpose of this hole ?  
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: ScooterBob on August 22, 2010, 02:20:00 am
Relax - It's just a cross drill oil hole used to connect the hole in the base of the cylinder with the hole that goes THROUGH the cylinder to oil the top end. After the passages are connected, the outside is plugged. That's what you are seeing. It ain't no thaing!  ;)
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on August 22, 2010, 02:45:30 am
Relax - It's just a cross drill oil hole used to connect the hole in the base of the cylinder with the hole that goes THROUGH the cylinder to oil the top end. After the passages are connected, the outside is plugged. That's what you are seeing. It ain't no thaing!  ;)

If you open the picture in new tab and enlarge (+) the picture, you will see oil coming out of it - what do you make of that ? 
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: ScooterBob on August 22, 2010, 03:39:17 am
If you open the picture in new tab and enlarge (+) the picture, you will see oil coming out of it - what do you make of that ? 

Well - There IS oil under pressure behind it ...... If it were MINE, I'd just peen the cylinder a little around the plug (if it leaked a drop big enough to drip) and be done with it.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: 2bikebill on August 22, 2010, 09:11:53 am
My G5 has that hole too Singh - no oil though, yet.....
Don't forget that fully synth oil finds its way to places other oils don't.....
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: SSR on August 22, 2010, 04:09:14 pm
This hole is for the water drainage around the plug. Try putting some water on to the plug and see it for yourself.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on August 22, 2010, 04:18:42 pm
This hole is for the water drainage around the plug. Try putting some water on to the plug and see it for yourself.

US models have only one spark plug which is on the left side of the engine, unlike Indian models that have two spark plugs.  No spark plug on the right side, here.

Will try to put some water on the left side and see what happens !  Thanks.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: r80rt on August 22, 2010, 04:25:05 pm
SSR is right, it's a water drain.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on August 22, 2010, 04:32:04 pm
SSR is right, it's a water drain.

You mean water from spark plug on the left side of engine drains through this hole on the right side ?
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: ScooterBob on August 22, 2010, 04:37:08 pm
OK - I'm pullin 'a cylinder off the shelf to SEE what this is ....... Hold that thought 'til Monday  ???
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: r80rt on August 22, 2010, 04:44:04 pm
Pour some water on the right side where the second plug would be if you had one, it will run out of the hole.  Nothing mysterious about it.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: SSR on August 22, 2010, 06:16:50 pm
You mean water from spark plug on the left side of engine drains through this hole on the right side ?

Singh JI, all the UCE engine have only one water drain on the RH side weather its domestic or export C5.

The one and only primary plug you have does not have a drain hole like on RH side. There is a gap between the fins and the block near the LH side head bolt(next to primary plug) Water does not collect there.

While on Rh side where there is a secondary plug or in export models just a deep cavity. On RH side the fins have metal to metal contact with the head without any gap(Rh side of head is wider then LH side) so they have intentionally had a drain hole because of the cavity form due to the head design.

The oil/moisture you see is from the barrel /head gasket. Tighten the head or replace the metal gasket if you dont want to see any oil there.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on August 23, 2010, 01:09:31 am
Singh JI, all the UCE engine have only one water drain on the RH side weather its domestic or export C5.

The one and only primary plug you have does not have a drain hole like on RH side. There is a gap between the fins and the block near the LH side head bolt(next to primary plug) Water does not collect there.

While on Rh side where there is a secondary plug or in export models just a deep cavity. On RH side the fins have metal to metal contact with the head without any gap(Rh side of head is wider then LH side) so they have intentionally had a drain hole because of the cavity form due to the head design.

The oil/moisture you see is from the barrel /head gasket. Tighten the head or replace the metal gasket if you dont want to see any oil there.

Randhawa Ji:

Sat Sree Akaal.  You were right on.  It is a drain hole for the cavity on the right side of the cylinder head.  I put a paper clip wire through the hole and it came out on the other side - in the cavity.  

I saw some oil on the gasket between cylinder head and cylinder barrel.  That must have drained out through this hole a bit.

Thanks for great explanation.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: ScooterBob on August 23, 2010, 01:26:20 am
So this means I'm off the hook to pull a cylinder and see? Hahaha!  ::)
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on August 23, 2010, 01:29:23 am
So this means I'm off the hook to pull a cylinder and see? Hahaha!  ::)

Yes - it is good.  You can take a break and have a lager !  :)

Thanks for your offer to check the cylinder head.  
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: ScooterBob on August 23, 2010, 01:32:25 am
I should KNOW better ..... I CAN assemble a gearbox with a blindfold on in under six minutes, tho ..... that has GOT to be worth SOMETHING! Hahaha!  ;)
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: SSR on August 23, 2010, 04:26:01 pm


I saw some oil on the gasket between cylinder head and cylinder barrel.  That must have drained out through this hole a bit.
 


Sat Sree Akaal Singh JI,

Just a small addition, the hole is located above the head gasket so the oil can not go into the cavity and drain out unless there is small leak in the rocker cover and it drips into the cavity.

In all probability the tiny oil vapors spread near the gasket and covers the drain hole to which we think it came out of the hole which is not the case.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on August 24, 2010, 03:58:29 pm
Sat Sree Akaal Singh JI,

Just a small addition, the hole is located above the head gasket so the oil can not go into the cavity and drain out unless there is small leak in the rocker cover and it drips into the cavity.

In all probability the tiny oil vapors spread near the gasket and covers the drain hole to which we think it came out of the hole which is not the case.

I will check the rocker cover.  But the most likely cause of the oil on the hole, as you wrote, is that oil near gasket spreads out and up as wind hits the engine, and it appears to be coming out of hole. 
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on September 04, 2010, 05:46:21 am
Singh JI, all the UCE engine have only one water drain on the RH side weather its domestic or export C5.

The one and only primary plug you have does not have a drain hole like on RH side. There is a gap between the fins and the block near the LH side head bolt(next to primary plug) Water does not collect there.

While on Rh side where there is a secondary plug or in export models just a deep cavity. On RH side the fins have metal to metal contact with the head without any gap(Rh side of head is wider then LH side) so they have intentionally had a drain hole because of the cavity form due to the head design.

The oil/moisture you see is from the barrel /head gasket. Tighten the head or replace the metal gasket if you dont want to see any oil there.

The oil is seeping and collecting in the cavity on the right side.  So I looked again inside the cavity.  The nut for the head is completely tight. 

But when I took a picture and looked carefully, it seems the nut is broken - can anyone confirm if your nut looks like mine or is mine is really cracked at 9 o'clock position.   
 

Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: gashousegorilla on September 04, 2010, 06:56:55 am
 That looks like its just a black piece of debris singh. like a curled paint chip?
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: SSR on September 04, 2010, 01:25:23 pm
That looks like its just a black piece of debris singh. like a curled paint chip?

I quite agree with you on that.

@Singh Ji

Anyway you could use a thin wire to feel the gap if its there. Mine does not look like that for sure.

Why dont you use some brush to wash that cavity and you will get a better picture.

Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: 2bikebill on September 04, 2010, 06:23:33 pm
It is an odd shape for a crack Singh - could well be a bit of debris. Can you squirt something down there and see if it'll clean up? A crack ought to look a bit more jaggy I'd have thought .
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: r80rt on September 04, 2010, 06:25:27 pm
A quick blast with some compressesd air will probably tell you what it is. Looks like debris of some sort to me too.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: Rusty on September 04, 2010, 07:27:11 pm
Looks like there's a piece of the nut missing. It wont be able to exert the correct torque in that sate, replacement of the nut should fix it.

The piece might be in the well unless it was fitted like that.
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on September 05, 2010, 01:54:18 am
That looks like its just a black piece of debris singh. like a curled paint chip?

I quite agree with you on that.
@Singh Ji
Anyway you could use a thin wire to feel the gap if its there. Mine does not look like that for sure.
Why dont you use some brush to wash that cavity and you will get a better picture.
It is an odd shape for a crack Singh - could well be a bit of debris. Can you squirt something down there and see if it'll clean up? A crack ought to look a bit more jaggy I'd have thought .

A quick blast with some compressesd air will probably tell you what it is. Looks like debris of some sort to me too.

Thanks GHG, SSR, WillW and r80rt
It is not a crack as you have correctly identified.  I wiped the debris off the nut and surrounding area.  The nut was intact.

After a little effort, I was able to unscrew it, cleaned it, and then put a copper washer (there is no washer originally) and screwed it back.  This is an attempt to stop the seepage of oil that may be coming from incomplete contact of this flange nut with the surface.  But there is no real smoking gun that indicates the real source of this oil. I do not see any oil drips off the rocker cover.

Thanks Rusty:  I also thought a part was missing, as you have posted.  
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: gashousegorilla on September 05, 2010, 08:12:44 pm
 Singh, just a thought. Maybe check around your rocker box covers. Maybe the gasket is seeping somewhere? If your lucky , just snug them up. It may only happen when the bike is hot, when the metal expands. I've seen this before on Honda's. Worth a try?
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: singhg5 on September 06, 2010, 12:08:30 am
Singh, just a thought. Maybe check around your rocker box covers. Maybe the gasket is seeping somewhere? If your lucky , just snug them up. It may only happen when the bike is hot, when the metal expands. I've seen this before on Honda's. Worth a try?

Dan:

I had looked at the rocker box covers and thier gaskets.  There is only a little black dirt on the gasket but no oil is visibile.  To check if it leaks when hot, I swiped it with paper towel immediately after ride, when engine was hot.  There was no real oil, just black sticky dirt on the paper towel - so gasket seems to be soaked with oil but no drip outside. 

Since I put the copper washer under the flange nut for the head, I rode the bike yesterday and today.  Yesterday I found a little bit of oil in the hole.  Then I put Loctite on the top edge of nut.  After today's ride, there was practically no oil in the hole.  Then I used a Q-tip to clean around the nut and the surface around it and there was no oil on Q-tip.  Although it seems to be better but I need a few more rides to confirm that it is a real fix.
 
Title: Re: Small Hole in the Engine Cylinder Head of my G5 !
Post by: gashousegorilla on September 06, 2010, 12:19:52 am
  Good, singh sounds like you got it. I don't think it's a big deal anyway, put I hear you, just an annoying little thing. If the lock tite don't do it, you might want to try some teflon based pipe dope.  Good for gas ;) and fluids. Plumbing supply should have it.