Oil leak

I have a ST1300 that the oil had been overfilled to the point of oil running on to the ground while it was running. It now leaks oil out of the square weep hole. Leaves a spot if it sits for a couple of days. Never enough to make oil level low. Could the overfill create a chronic leak? The first owner told me that when it was new the dealer had overfilled it. Do dealers keep a record of repairs they do? I wonder if any damage was created that the dealer may have needed to fix. Where would the oil come out at if you ran it overfilled? I read about the mystery plug and valve covers possibly leaking. Is there anything else that could be leaking from up top?
Any suggestions would be appreciated.
Thanks
Gary

It was only over filled once back in 03 and leaking oil now?
The dealer would have drained the oil, if nothing was leaking they would have done nothing else.

If oil is coming out of the square weep hole on the right lower front side of the engine, you have a mechanical waterpump seal failure. Some coolant leaking from that is normal but oil from there means the seal is bad and should be replaced.

This is assuming you don't really have oil leaking from the upper part of the engine - oil galley plug - and it's not just making it's way down the crevice from the waterpump cover. Make sure it's JUST leaking from the square hole and not seeping to that area from above... actually, you'd prefer that as it's a little easier to fix.

That needs to be clarified before determining where the issue is.

I'm sure it is leaking out of the square hole, not the round hole for the water pump. I bought it with 7000 miles on it and it was leaking then. I keep leaning towards the mystery plug. I have the air box out to look down at vee. I pulled the rubber heat sheild back at front of motor. I see a lot of wet dirt build up on top of vee.

RANGER362 said:

I'm sure it is leaking out of the square hole, not the round hole for the water pump. I bought it with 7000 miles on it and it was leaking then. I keep leaning towards the mystery plug. I have the air box out to look down at vee. I pulled the rubber heat sheild back at front of motor. I see a lot of wet dirt build up on top of vee.

Click to expand...

I need to go look, I was thinking the square one was the waterpump seal... my memory goes from time to ti...... what was I saying?


Here's a pic of my 2008 which has the metal tube and hose connection... are you saying it's coming from the square area just under that?

Here's a couple pics of the waterpump cover exposed... as you can see, the round weep hole or the square one could both indicate a mechanical seal issue. Might also be oil leaking from the top V of the engine and making it down the water pump cover crevices.

This is a great thread which may help.

https://www.st-owners.com/forums/showthread.php?122213-Not-antifreeze-but-oil-leak

Sounds like a valve cover gasket or the plug that is located up in the "v".
Had the valve covers been off for a valve clearance check?

It may also just be residual oil from the overfill. Oil has a tendency to drip...drip....drip for quite a long time if it hasn't been cleaned up there in all the crevices. If the leak is tiny I would let it go and see if it gets smaller. If you are going to tear into it I would get all the oil out of the valley pan and other areas of the engine and run it before I would tear into seals. This is especially true if the leak only started after the oil change with the overfill.

How long has oil been seeping out of the bike?

I'm really not sure when the leak started. It was that way when I bought it. The valve covers have never been off since I owned it. I can't amagine they would have taken them off in the first 7000 miles. Seeing a I have the air intake off, I going to pull the valve covers to check the valves. I will be able to see that the heat shield dosn't get caught up under valve cover putting it back together. As mush as I would like the vee clean, I don't know that I want to pull the intake off to do it. The write ups and pictures that I see on the forum are outstanding. Being able to have access to them is priceless. With out this forum, i would have a tough time doing alot of the projects. Thanks to all of you that take the time.

I put sealant in the mystery plug. It was tight all the way out. I figured it would go in tight. After cleaning the threads, it went in much easier. Tough part is getting the thread to start. I assume that grit had worked its way into the threads. If grit can get in, it can see way oil could get out.

I just removed, cleaned and sealed a mystery plug myself tonight! I can't for the life of me understand why mother Honda would just put a metal oil galley plug in a hole that large without an o-ring, gasket, or at the very least some hondabond sealant. I've cleaned and sealed about 6 of them this month so far.
Sounds like you did a good job, as they should just thread in and out with very little effort when they are clean.
Good job.

I got my ST striped out looking for oil leak myself, after a month of searching for the oil leak all over the front cover/under of engine I couldn't find the leak, so text Gary (Ranger362) asked for helps, on the next day Gary showing up with special tool and seal compound showing me where to look for leak it was a galley plug (mystery plug) there it's right next to oil pressure censer unit. The area V-galley was all caked with oil/dirt. I'm agreed Honda engineer missing out an o-ring or sealant on this plug, or they just didn't checks every things after tested or they never have any oil leak in the galley's area. Anyhow, I knew a couple poor design so-far on this ST engine. I repaired water pump seal after 45K and now after high 80K saw oil leak is not bad for couple things, I got these fixed on my own is very fun/cheap! Thank Gary for your TIPS! :bow1: