Oil Leak.

[CYYJ]

I agree with @BakerBoy , in fact, I think his analysis is absolutely dead-on the money.

At some time in the past, someone took the camshaft cover off to adjust valve clearances, and they didn't put it back on carefully. As a result, you have oil leaks from several places where the valve cover mates up with the top of the block. One of these locations is at the forward end of the valve cover, the other is, as @BakerBoy pointed out, from a spark plug well drain hole.

Fortunately, the fix is "fairly easy". You just need to take the valve cover off and then re-install it in accordance with the instructions in the Service Manual.

Here are two photos that will give you a better idea of what you are dealing with.

The photo below shows the rubber gasket that goes around the bottom of the camshaft cover. It is reusable, but the Service Manual calls for adding a little bit of high temperature tolerant room temperature vulcanization (RTV) sealant to the two half-moons you see at the extreme right of the photo. My guess is that your gasket has been permanently damaged (deformed) as a result of not being installed properly, so you might want to plan on getting a new gasket.

Gasket Around Camshaft Cover


RTV Sealant Application Area


The left side camshaft cover can be a bit of a pain to remove and replace - if I recall correctly, there is very limited clearance between the forward upper corner of the cover and either the frame of the bike or various hoses & cables that run by that area. I suspect that the previous owner was having difficulty properly seating the camshaft cover because of this interference, and as a result, he tried to slide it upwards and inwards, and in the process of sliding it the gasket pulled away from the camshaft cover.

When I did my valve adjustment, I had the bike disassembled in other areas (the upper fuel tank was lifted and tilted, and I had removed the upper and lower components of the airbox). This made it possible for me to move the interfering cables & hoses out of the way and properly seat the left side camshaft cover. It will take you about an extra 2 to 3 hours of work to remove the upper and lower airbox pieces, but I suggest you do this because the problem you have now implies that it was not possible in the past to correctly reinstall the left camshaft cover due to various other components being in the way up in the top forward corner of the cover.

The photo below shows the top of the cylinder head when the camshaft cover has been removed. This picture is of the right side of the bike, your problem is on the left. You can see how on the right side of the bike (the 'easy' side), I had to pull a hose away in order to allow me to drop the camshaft cover straight down over the cams. This interference problem is worse on the left side.

Right Side of Engine, Camshaft Cover Removed


Lastly, like @BakerBoy said, DO NOT OVERTORQUE THE BOLTS HOLDING THE CAMSHAFT COVER IN PLACE! If you do, they will strip out the threaded holes that they screw into in a heartbeat. They are steel screws that fit into an aluminum casting. The specified torque value is very, very low. Use a torque wrench, and do not be tempted to give them that "extra snug up", or you will regret it.

Michael

 

[Igofar]

I agree with @BakerBoy , in fact, I think his analysis is absolutely dead-on the money.

At some time in the past, someone took the camshaft cover off to adjust valve clearances, and they didn't put it back on carefully. As a result, you have oil leaks from several places where the valve cover mates up with the top of the block. One of these locations is at the forward end of the valve cover, the other is, as @BakerBoy pointed out, from a spark plug well drain hole.

Fortunately, the fix is "fairly easy". You just need to take the valve cover off and then re-install it in accordance with the instructions in the Service Manual.

Here are two photos that will give you a better idea of what you are dealing with.

The photo below shows the rubber gasket that goes around the bottom of the camshaft cover. It is reusable, but the Service Manual calls for adding a little bit of high temperature tolerant room temperature vulcanization (RTV) sealant to the two half-moons you see at the extreme right of the photo. My guess is that your gasket has been permanently damaged (deformed) as a result of not being installed properly, so you might want to plan on getting a new gasket.

Gasket Around Camshaft Cover


RTV Sealant Application Area


The left side camshaft cover can be a bit of a pain to remove and replace - if I recall correctly, there is very limited clearance between the forward upper corner of the cover and either the frame of the bike or various hoses & cables that run by that area. I suspect that the previous owner was having difficulty properly seating the camshaft cover because of this interference, and as a result, he tried to slide it upwards and inwards, and in the process of sliding it the gasket pulled away from the camshaft cover.

When I did my valve adjustment, I had the bike disassembled in other areas (the upper fuel tank was lifted and tilted, and I had removed the upper and lower components of the airbox). This made it possible for me to move the interfering cables & hoses out of the way and properly seat the left side camshaft cover. It will take you about an extra 2 to 3 hours of work to remove the upper and lower airbox pieces, but I suggest you do this because the problem you have now implies that it was not possible in the past to correctly reinstall the left camshaft cover due to various other components being in the way up in the top forward corner of the cover.

The photo below shows the top of the cylinder head when the camshaft cover has been removed. This picture is of the right side of the bike, your problem is on the left. You can see how on the right side of the bike (the 'easy' side), I had to pull a hose away in order to allow me to drop the camshaft cover straight down over the cams. This interference problem is worse on the left side.

Right Side of Engine, Camshaft Cover Removed


Lastly, like @BakerBoy said, DO NOT OVERTORQUE THE BOLTS HOLDING THE CAMSHAFT COVER IN PLACE! If you do, they will strip out the threaded holes that they screw into in a heartbeat. They are steel screws that fit into an aluminum casting. The specified torque value is very, very low. Use a torque wrench, and do not be tempted to give them that "extra snug up", or you will regret it.

Michael

Michael, as always your pictures and instructions are top notch.
I will only add one comment.
You show great detail in taking a model brush and applying the sealant to the gasket, however, the service manual clearly indicates to "Apply sealant to the cylinder head semi-circular cut-outs" as seen in the picture in the OEM service manual.
I've found better results by doing it the way the service manual indicates, rather than placing it on the gasket material itself.
Keep the great pictures and how-to's coming.
We really enjoy reading them, and learn a lot from them.
Larry

 

[stefan7n]

Thank you so much guys. Such fantastic advice and amazing pictures. It’s giving me more confidence to fix it myself. I was tempted to get the bike into Honda in Colwyn Bay Motorcycles. I’ve also managed to remove the stubborn bolts this evening to get the right side fairing off. It’s not off yet as I needed some food and got back late from work.

From what I can see the right is similar.

I think the best thing to do is replacement gaskets and some fresh sealant along with a good clean. I’m glad to now be able to replace the coolant. I want to keep the bike going for a long time and in good order.

Since I’m taking the covers off I was thinking I should check the valve clearances. I’d need to pick some feeler gauges up but seems sensible.

I’ll get some pictures of the right side when I can and post for information. Hopefully helps other people out too.

With the pictures above I can see how people say oil is leaking out a overflow hole from the spark plugs.

Really appreciate the help.

Stefan

 

[CYYJ]

Stefan:

We have what is called a "Tupperware Worksheet" here in the forum - here is the link: ST1300 - TupperWare Worksheet. If you are new to taking all of the plastic body parts off of the ST 1300, you will find this worksheet invaluable. It will prevent you from forgetting to install some hard-to-see fasteners when you reassemble things, and also save you the frustration of using the wrong length bolt (or wrong type of bolt - shoulder bolt vs. conventional) when you put things back together.

Most of the fasteners are 5 mm hex keys. It's a real time-saver to have a 5 mm hex wrench with a T handle on it. Lastly, there are no Phillips head fasteners on a Honda. What looks like a Phillips head (cross-head) screw is actually a JIS (Japanese Industrial Standard) screw. Although it will appear to you that you can use a Phillips screwdriver on these, if you do that, you will eventually mangle up the heads on these fasteners. What you should get, without delay, is a set of JIS screwdrivers. These are not commonly sold in stores, the easiest way to buy them is online - just do a Google Search on the term.

Here's a video that explains the differences between JIS and Phillips screwdrivers:

Michael

 

[stefan7n]

Stefan:

We have what is called a "Tupperware Worksheet" here in the forum - here is the link: ST1300 - TupperWare Worksheet. If you are new to taking all of the plastic body parts off of the ST 1300, you will find this worksheet invaluable. It will prevent you from forgetting to install some hard-to-see fasteners when you reassemble things, and also save you the frustration of using the wrong length bolt (or wrong type of bolt - shoulder bolt vs. conventional) when you put things back together.

Most of the fasteners are 5 mm hex keys. It's a real time-saver to have a 5 mm hex wrench with a T handle on it. Lastly, there are no Phillips head fasteners on a Honda. What looks like a Phillips head (cross-head) screw is actually a JIS (Japanese Industrial Standard) screw. Although it will appear to you that you can use a Phillips screwdriver on these, if you do that, you will eventually mangle up the heads on these fasteners. What you should get, without delay, is a set of JIS screwdrivers. These are not commonly sold in stores, the easiest way to buy them is online - just do a Google Search on the term.

Here's a video that explains the differences between JIS and Phillips screwdrivers:

Michael

Thanks Michael, I'll be doing that.

I'm off to Greece for the week so will have to wait for a few days

Stefan.

 

[Bmacleod]

My first thought was what BakerBoy described... check for oil in the sparkplug wells. I will add that the load placed on the valve covers, to seal properly is dictated by the rubber seals under the valve cover bolts. Over time, these will "squish" and provide less pressure on the cover gaskets. These need to be replaced over time. I think I paid like $15.00 for a pack of 6, so it's cheap insurance.

 

[Dr who]

It does look like you have some oil leak issues, however, from your first picture it makes me wonder if the fresh fluid your seeing is from a clutch slave cylinder leak. Check your fluid level at the master cylinder on the left handlebar. You may be seeing two different issues.

 

[stefan7n]

Thanks guys. Last day on holiday so hoping to get looking over the weekend. Start with the coolant. Then clean it up and see if there’s oil in the spark plug wells and go from there.

Is the part number for the gaskets this 12391-MCS-000? A number of websites make it difficult to identify the correct part. Assume they’re a matching pair.

The fluid looks good in the master clutch and front brake cylinder. The rear brake needs a clean, but I assume it’s good as brakes done all round recently.

Stefan.

 

[Upt' North]

Thanks guys. Last day on holiday so hoping to get looking over the weekend. Start with the coolant. Then clean it up and see if there’s oil in the spark plug wells and go from there.

Is the part number for the gaskets this 12391-MCS-000? A number of websites make it difficult to identify the correct part. Assume they’re a matching pair.

The fluid looks good in the master clutch and front brake cylinder. The rear brake needs a clean, but I assume it’s good as brakes done all round recently.

Stefan.

David Silver Spares

David Silver Spares Honda Part Number Search

www.davidsilverspares.co.uk

Upt'North.

 

[Upt' North]

Thanks guys. Last day on holiday so hoping to get looking over the weekend. Start with the coolant. Then clean it up and see if there’s oil in the spark plug wells and go from there.

Is the part number for the gaskets this 12391-MCS-000? A number of websites make it difficult to identify the correct part. Assume they’re a matching pair.

The fluid looks good in the master clutch and front brake cylinder. The rear brake needs a clean, but I assume it’s good as brakes done all round recently.

Stefan.

Honda ST1300A PANEUROPEAN 2002 (2) EUROPEAN DIRECT SALES / ABS CYLINDER HEAD COVER - buy CYLINDER HEAD COVER spares online

✓access the CYLINDER HEAD COVER schematic✓find Honda CYLINDER HEAD COVER spares easily✓CYLINDER HEAD COVER parts quickly delivered

www.cmsnl.com

Might be cheaper here.
Upt'North.

 

[stefan7n]

View attachment 244272There is also this - which describes how to put it all together again. I have saved it as a pdf attached to the first post of the link below, so that it can be downloaded, saved and printed.

Article [13] - ST1300 - Maintenance - Fairing Installation | ST1300 Articles

A set of notes about putting the fairing back onto the ST1300. It covers most of the fitting gotchas, which might otherwise catch you out and/or result in broken tags. Also lists all of the fasteners - photos, description,, part numbers, where they fit and why it matters. Very useful for...

www.st-owners.com

Wow. Great article. That is very useful.

I can’t believe how much support there is in the forum.

Thanks,

Stefan.

 

[stefan7n]

It is quite probable that you do not need a new gasket. They are rubber and usually re-usable. Often the leak comes from the semi-circular hole at the front. The gasket seals adequately by even the low amount of force when tightening the valve cover bolts - but heed Michael's warning about over tightening.

The problem is, that part of the semi circle is at 90 degrees to the surface on which the gasket sits. No amount of downward pressure is going to press the gasket onto the surface. So it needs a bit of help with the sealant.

The last time I checked my valve clearances, they needed adjustments. I decided to give my aching back a rest and took it to the dealer. The only time I have never adjusted the clearances myself. Nothing wrong with what they did, but they just re-fitted the gasket without sealant on the half moons. Within a couple of weeks, the front and side of the engine was covered in oil. It is only a tiny seepage, but it is directly in the air stream and gets blown backwards everywhere. Aching back or not, I do it myself next time. Except just in short spells.

Whereabouts in the UK are you @stefan7n ??

Hi John. Thanks.

I’m back in the UK now. I’m based near Conwy in North Wales.

I’m hoping to get out to the bike today.

Stefan.

 

[CYYJ]

Since I’m taking the covers off I was thinking I should check the valve clearances.

Hi Stefan:

That's a bit of a time-consuming job if you have not done it before. There are some articles here in the forum that explain how to do it, and a few videos on YouTube that will give you a good orientation. Take a browse through the ST 1300 Articles section of our forum - that is the repository of the very best technical articles written over the past 10 years. Here's a link to one post that elaborates valve adjustment: Valve Adjustment.

There are some photos showing what the timing marks (visible through a little peep-hole in the front of the engine) look like at this link: Timing Marks. You will need an inspection mirror and a flashlight to view the marks.

Once again, do not exceed - even by a breath - the torque values published for the fasteners that hold the camshafts in place. Like the camshaft cover bolts, they are steel fasteners that thread into aluminum, and they will strip out the aluminum cylinder head threads in the blink of an eye if you overtorque them even a tiny bit. Don't ask me how I know this...

Personally, I would leave the valve clearance checking and adjustments until the middle of winter when you are not riding the bike and can spread the work out over a week. There's a ton of reading you need to do first, you'll need to borrow a box of valve shims (or make repeated trips to a dealer to buy shims), and there's a lot of mathematics to do (and check three times). Speaking of mathematics, here's a link to a post that provides an Excel worksheet for determining what new shim sizes to use: ST 1300 Valve Clearance Worksheet. For ST 1100 owners, there is a similar worksheet here: ST1100 - Valve Clearance Worksheet Both are outstanding tools for doing all the calculations to determine the correct new shim to install.

Michael

 

[stefan7n]

Ok. Thanks Michael.

I think that would be a beter idea. I’ve now compleed the service i wanted to achieve.

I finished removing the fairing late this afternoon. I flushed out the old and filled up with new.

I started giving the bike the damn good clean I’ve been promising. I’ll hopefully finish this tomorrow.

The last job is to re-seat the valve cover gaskets. I picked up some three bond TB1215 from a local bike shop today. I’ve also got jis bits in order, a torque wrench that goes as low as 7NM and some other bits.

Over next week and next weekend I’ll be lifting the fuel tank and removing the air box, ready to move the harnesses out the way. To assist with the valve cover job.

I’ll get reading as you advise. I saw the maths in the service manual (to deduce shim sizes), but I’ll check out the links you kindly offered. I do like to research before going in, which is why this website is so great.

Can’t wait to get riding the bike properly. It’ll be worth it once I’ve sorted the jobs I’d like to do. At least I’ve given the bike a full service so far since getting her home.

The other job I’d like to do is the rear shock oil. I found a good video on YouTube from GTs Garage. Not sure if he’s a member here. Here’s the link:

I’ve read of people advising to check throttle body starter valve sync; https://www.st-owners.com/forums/threads/st1300-throttle-body-synchronization.100936/ perhaps another one for the winter.

Ooh. Before I forget here’s some pics of the right side. I can seen on both sides and on each cylinder that the oil appears to be emanating from what I believe to be the spark plug well drain hole adjacent to each exhaust down pipe to engine interface. Hopefully once I reseat the covers that cures it. I have the sealant. Is it worth getting fresh rubber washers that help compress the gasket? Do you know the part number.

Thanks again,

Stefan.

 

[stefan7n]

Ah - a nice place. I used to live in Bethesda (Bangor) for a while - I haven't been through Conwy for many years - I bet its a much nicer place now that they have submerged the main road !

I went to University in Bangor and used to enjoy riding around the roads on my Bandit 600 S. Bangor to Ogwen valley to Betws and back around down the A55.

 

[BakerBoy]

Stefan-

I would discourage trying something like rubber orings, other gasket materials, or adding more gasket sealer in attempts to stop seeping leaks. Chances are the gaskets were not properly seated, have since been improperly pinched (by now heat-set), and you'll always have leaks. It is just best to replace the gaskets with new ones (with, sparingly, some sealer at the half-moons).

HEAD COVER GASKET, part number 12391-MCS-000
Both sides of the engine use identical parts (you'll have to order 2).

I think I'd also proactively replace the 6 head cover bolts if that were mine. IF any of them are stretched, even a new gasket may not seal. Here are the Head Cover Bolts:
2 per cover: 90017-MCS-000
1 per cover: 90017-MAL-600

 

[stefan7n]

Stefan-

I would discourage trying something like rubber orings, other gasket materials, or adding more gasket sealer in attempts to stop seeping leaks. Chances are the gaskets were not properly seated, have since been improperly pinched (by now heat-set), and you'll always have leaks. It is just best to replace the gaskets with new ones (with, sparingly, some sealer at the half-moons).

HEAD COVER GASKET, part number 12391-MCS-000
Both sides of the engine use identical parts (you'll have to order 2).

I think I'd also proactively replace the 6 head cover bolts if that were mine. IF any of them are stretched, even a new gasket may not seal. Here are the Head Cover Bolts:
2 per cover: 90017-MCS-000
1 per cover: 90017-MAL-600

Thanks BakerBoy,

That makes sense. And thanks for the part numbers.

I don’t think i was clear enough. I meant the mounting rubbers for the cylinder head cover bolts, as opposed to expanding the gasket some how. I read these squish over time and prevent a proper seal at the specified torque.

I’ve ordered a set of gaskets rubber mounts and bolts. Hope that cures it, fingers crossed.


Stefan.

 

[stefan7n]

The story continues. Sadly it takes me time to process jobs on the bike waiting for parts, three young children and a long commute aren’t helping. It took two hours to get home yesterday due to roadworks and I sat and wished my bike was ready.

I’ve taken the fuel tank off. It was quite irritating. The air box has come out. All screws came out fine without trouble, apart from one closest to the seat, hence needing to take the fuel tank off. My god I love the impact driver. Really saved my bacon!

I’ve added a few pics. I can see on the left valve cover there’s been some issues.

I’ll get back to the bike tonight or tomorrow and replace the gaskets and bolts. I also ordered a carburettor balancer so plan to do that too. Is it much of a bother replacing the vacuum hoses to the throttle body. I don’t want to remove the throttle body having only just replaced the coolant.

Cheers.

Stefan.

 

[Igofar]

After seeing your third photo, I would abort worrying about leaks and Flush/Bleed both the Clutch and Brake systems.
Both the viewing windows look pretty dark and nasty.
If you don't correct that you may be looking at a new secondary master cylinder in your near future.

 

[NobodySpecial]

...

I’ll get back to the bike tonight or tomorrow and replace the gaskets and bolts. I also ordered a carburettor balancer so plan to do that too. Is it much of a bother replacing the vacuum hoses to the throttle body. I don’t want to remove the throttle body having only just replaced the coolant.

What's the current status, if I may ask?

FWIW, I now own the bike that started this thread. And yes, it leaves *one* drop of oil on the garage floor about every 2 out of 3 rides. I'm 95% certain it's the output shaft seal, for which I have parts, but no ambition. Wish I could find that in a store somewhere.