Howdy All -

Looking for thoughts on my 89 FXRS's ever leaking rocker boxes.

Details-
Engine is an 89" S&S stroker (w/ S&S Heads & Stock cases/jugs)
S&S 585V Cam
S&S Super E
S&S oil Pump

I had the bike for approximately 4 months of riding before noticing a significant (dripping) leak between my lower rocker boxes and heads. The rear was worse, but a leak was still present on the front.

After inspection, I could see/feel the lower rocker gasket was torn. Problem solved, or so I thought. I removed the rockers and installed new/updated gaskets, torqued everything to spec and was on my way. About 100 miles after the rebuild and the leak was back.

After doing a lot of reading it seemed a warped rocker box may have been the issue. I dissassembled again and checked the rocker covers on a slab of granite; there was a very small amount of wiggle from end to end which I thought was probably OK and able to be sealed by gaskets, but I decided to look for a new set anyways. I then scored a set of billet Boyd Coddington Rockers Boxes off eBay. The machined surfaces of the lower boxes and tops of the S&S heads seemed to be about as flat as could be. After installing these with new gaskets I went riding again and within 10 miles the leak was back.

My next thought was that I have too much pressure in the rockers causing oil to be forced past the gasket interface. I verified the crankcase vent line was clear and it appeared to be venting properly, but to be sure I opened the cam chest anyways to ensure the breather timing was set correctly, which it was. (And a side note, it was a Jims breather timing gear).

I now am at a loss for where to go next. My thought is to do a complete top end rebuild so that I can inspect the pistons/rings/jugs, put new gaskets in, re-torque everything, use some of the aviation gasket sealer (read that it is the miracle worker on a different thread), AND add banjo bolts to my air cleaner mount to utilize both crankcase and head breathing. The problem is that I want to understand what is going on to fix it, NOT do a handful of potential 'helps' (not necessarily fixes) and hope one works.

Any advice (or criticism) is welcome. Please feel free to ask for any additional information I may have skipped that could help.

Thanks in advance for your time.

 

Just thinkin out loud here...

How much torque on the bolts and screws?

Do you have the correct bolts for the lower rocker supports, are they in the correct location (there are two different lengths).

Are you sure the leak is between the bottom support and the head?

 

I don't recall the torque specs off the top of my head (ha), but I referenced the factory service manual for the proper torque settings during installation.

I believe I have the correct bolts for the lower rocker supports. Are you thinking it could bottom out before securing the lower rocker to the top of the head? Or that there may not be enough engaging thread to secure properly?

I am virtually certain the leak is between the bottom support and the head. I have been able to visually observe freshly leaked oil at that location on my rear cylinder. It pools/runs off the gasket and drips down on my trans cover and exhaust at times.

 

Just did a top end rebuild on mine, I would pull the box's off and check the bolts as stated above. I even ordered a new set of bolts for everything as they can stretch when torqued. Just a thought as you seem to have covered all the bases for mating. Could be seeping down and looks like head and cylyinder.

 

New bolts and clean/ chase the female threads.

 

Cometic gaskets?
Scott

 

Are you absolutely sure it's coming from the Rocker gaskets?

I had a leak once that I thought was the Rocker gaskets but it turned out to be the o-rings at the top of the pushrod tubes...

 

Thanks everyone for trying to help sort this out.

@hillsidecycle - The first time I replaced the gaskets they were with Cometic. The second time I used the new Harley replacements...

@98hotrodfatboy - I wouldn't bet my house on it, but based on my observations, I would say about 95% sure. If the pushrod tube o-rings were leaking wouldn't there be some amount of oil deposited or weeped on the front side of the motor around the tubes?

Also, I should mention that I do see a very slight oil weep between the rocker covers themselves. It was observed on both the stock and Boyd rocker box covers. It really made me think that there was/is excessive pressure built up in the rocker covers that is forcing the oil past the gaskets, but after confirming the breather tube was clear and the breather timing was set correctly I don't know what else (if anything) could cause an excessive increase in rocker box pressure?

 

How are you venting this motor?
Head breathers?
Correct gaskets that match the S&S heads?
Notice any blow by out of your exhaust (pressure build up in heads)?
Are these Boyd aftermarket rocker boxes flat, and have everything spec with any gaskets?
Correct hardware and getting a good torque spec?
Harley cylinders, S&S heads, Boyd boxes...could equal trouble if something is not right...

Pictures?
I don't know anything about the Boyd boxes.

 

Wonder what the out come was on his leak?