Oil leak at base

96 R1100RT, leaking on left side at base of cylinder, looks like it is wet pretty high up. I've heard there is no gasket there, just sealant. What sealant is correct for the cylinder base? Dave

96 R1100RT, leaking on left side at base of cylinder, looks like it is wet pretty high up. I've heard there is no gasket there, just sealant. What sealant is correct for the cylinder base? Dave

Evening Dave

Book calls for 3-Bond 1209 but I usually just use Yamabond if I don't have fresh 3-Bond 1209.

Both side of joint need to be squeaky clean, like extremely clean with no wicking oil or finger contamination.

Ok, I figured after getting all of the bits and schmuck off of the surfaces I'd clean all surfaces with alcohol or maybe brake cleaner. would that suffice? NO finger oil. 3-Bond 1209 can I get that at Napa? Dave

When I rebuilt the top end(s) on my bike, I followed DR's advice to use Yamabond (#4). It was readily available at my local Yamaha dealer. I used it at the base of the cylinders, and also used it to seal the front alternator mount (different repair). Worked awesome. I think my prep order was brake clean, then isopropyl. The original sealant pretty much just peeled off the mating parts. I also gleaned the advice (maybe from DR, as well) to use a trimmed solder flux brush to help apply a thin layer of Yamabond. Definitely don't want to goop it on too thick.

96 R1100RT, leaking on left side at base of cylinder, looks like it is wet pretty high up. I've heard there is no gasket there, just sealant. What sealant is correct for the cylinder base? Dave

Is it definitely from the cylinder base? I have experienced some where the oil was migrating from the L/H cam chain tensioner. It was weeping past the crush washer. It sure is easier to check this than take a pot off.

It could also leak from the oil pressure switch, the oil line that is also ther or perhaps you just need to re-torque the 2 x M6 screws holding the base of the cylinder.

Wash it, ride for 5 kms and observe where does it leak from.

Dan.

96 R1100RT, leaking on left side at base of cylinder, looks like it is wet pretty high up. I've heard there is no gasket there, just sealant. What sealant is correct for the cylinder base? Dave

 

Is it definitely from the cylinder base? I have experienced some where the oil was migrating from the L/H cam chain tensioner. It was weeping past the crush washer. It sure is easier to check this than take a pot off.

+1 on this. I had the same issue and it was the tensioner. At that point it needed the upgrade and that was a good time to do it. If yours has not had the upgrade it would be a good time to do it. If not the tensioner then good luck with the project.

Original post guy here- I was hoping maybe it was that oil pressure sensor, but that area actually looks pretty dry. The side of the engine block, about 3/4 of the way up is soaked with oil. Since the block is wet I figure it's leaking at the base.

I don't think it's a gusher- I cleaned it off maybe 5000 miles ago so it has accumulated and that's why it looks so wet. Leaves little drip spots on the garage floor. PO mentioned replacing that tensioner somewhere between 70 and 100k, it's got 117k on it now.

Now that it's a bit warmer I've got several little issues to take care of on the old girl before my riding season officially begins. I hate working on a dirty bike- maybe my first task is to clean the whole bike including a nice engine degreasing, then do the talcum powder examiniation. But to me it looks like it's leaking at the base. Dave

Dave P

I would check the torque on that tensioner. I found mine was loose, so with that found, I updated the tensioner. And yes it did look to me also that the cylinder base gasket was leaking. But checking this was a easy fix. It could be the OPS but I would check torque on the tensioner also. Especially if it was replaced.

Pictures???

SAS- ok, I dont know whats involved in checking the torque on that tensioner, but I'll look it up in my Clymers and check it out on the bike- maybe tomorrow. Dave

Well, it's more a case if checking its tight, more than torquing it. Why? Cos it's a beat to get a torque wrench into. However a spanner gets in there just fine.

Basically it's Tupperware and tank off, and you are able to get in there to pinch the tensioner up. Original tensioner require a 17mm AF spanner and upgraded ones require 15mm AF spanner.

Andy- Well the Tupperware is off currently and soon the gas tank will be as well (SS brake lines are on my springtime list).

So am I just checking with the 17mm (original) or 15mm (upgraded) "spanner" as you call it (ha ha) and see if it's tight? Do you mean the mounting bolts / nuts? Dave

ps- I spent 23 years crawling over and under a 66 MGB.....

Afternoon Dave

well thats about as easy to check as it gets! thanks for the pic. Dave

well thats about as easy to check as it gets! thanks for the pic. Dave

Evening Dave

It's not extremely difficult but it is more difficult than it looks in the picture above as the throttle body & front trailing arm somewhat block your access.

Well, it's more a case if checking its tight, more than torquing it. Why? Cos it's a beat to get a torque wrench into. However a spanner gets in there just fine.

Basically it's Tupperware and tank off, and you are able to get in there to pinch the tensioner up. Original tensioner require a 17mm AF spanner and upgraded ones require 15mm AF spanner.

AndyS,

Agreed wrong word, bad habit, you are right make sure it is tight.

I had a similar problem on the right side. There was so much oil dripping on the exhaust that I hated to stop on my way home. I kept topping off the oil. I parked the bike for two years while I enjoyed my new R1200RT. Yesterday was a nice day; so I decided to do a thorough check. After much degreaser, I let it dry and cranked the bike. With everything clean, it was obvious the leak was ABOVE the right cylinder. There is a place next to the alternator that the oil from the engine enters before the oil is directed into the oil cooler. Oil was coming out of the top where the line to the oil cooler came out of the valve. I tightened it...no more leak. I will clean up the bike, service it and give it to m y son. I have 188,000 miles on this wonderful nike; now it will get more use.

Original poster here. I checked the left side tensioner, it wasn't actually loose, but i did turn the screw a bit. and it was the replacement- 15 mm. Visually it does look like that tensioner could be the source of the leak. tomorrow I'll get a fresh can of degreaser and clean her up, ride it with no bodywork for a week or so and re-inspect. I bet (and hope) thats all the problem is. Dave

OK, so I degreased and scrubbed that sob yesterday. I took off the left side throttle body and had way better access. At first I thought maybe it was coming from that tensioner since I was able to get the 15mm hex to turn a little. But just as I thought I was about done with the cleanup, I gave a look to the front of the cylinder- greasy greasy greasy! Looks like it could be leaking from the base of the cylinder, could be at the oil cooler connection, could be at the oil pressure switch. It's like it's leaking everywhere! It doesn't leave a puddle on the floor, just little drips. I used almost a whole roll of paper towels!

I guess now that it's generally clean, I guess the idea is to ride it with no bodywork for a week or so and inspect carefully with a flashlight. Do people ever put dye in the oil and inspect with a black light?

Ack! Dave

OK, so I degreased and scrubbed that sob yesterday. I took off the left side throttle body and had way better access. At first I thought maybe it was coming from that tensioner since I was able to get the 15mm hex to turn a little. But just as I thought I was about done with the cleanup, I gave a look to the front of the cylinder- greasy greasy greasy! Looks like it could be leaking from the base of the cylinder, could be at the oil cooler connection, could be at the oil pressure switch. It's like it's leaking everywhere! It doesn't leave a puddle on the floor, just little drips. I used almost a whole roll of paper towels!

 

I guess now that it's generally clean, I guess the idea is to ride it with no bodywork for a week or so and inspect carefully with a flashlight. Do people ever put dye in the oil and inspect with a black light?

 

Ack! Dave

Afternoon Dave

Yes, I have used oil dye a number of times, sometimes with great success & other times the entire area will glow.

The secret to using oil dye is to first use a black light to make sure there isn't any glowing from your current oil leaking oil.

If no present glow then add the dye & run the engine a little to see it you can see or trace a glowing trail.

Try not to ride the bike too far between black light checks as the black light oil glowing works best if you can catch the leak BEFORE it grows

into a big mess of glowing oil all over everything.

I would suspect that all motor oils have some level of fluorescence since the base stock oils used are unsaturated (not hydrogenated). The aromatic and conjugated double bonds in the base stock cause fluorescence and as the number of these unsaturated sites go up the stronger the visual fluorescence. The key would be to know how much is there naturally in the oil VS the florescence level you get after doping the oil with an optical brightener to enhance the fluorescence.

Hopefully the base stock in the oil you use is only has moderate fluorescence so after doping with the OB you can notice a difference. As DR says some oil stocks fluoresce strongly and adding OB will be uninformative. There are UV absorbent additives that can quench the florescence of the oil to establish a low base line, but the amount needed may be more than you want to put in your motor and have it get pumped around to the leak. The best approach might be if your current oil lights up like a christmas display on its own, switch to one that is moderate to low in fluorescence before doing this test.