Topic: CB750 crankcase breather improvement. Several connections on clutch cover?

[PeWe]

I have installed an additional breather hose adapter connected thru clutch cover after a hint on this forum.
I used 1/8 NPT thread tap, hose 10mm ID. Glued thread with Loctite 638 that hopefully will keep together unless physical forces will hit it.

The clutch cover has place for more.
- Anyone tried 2, 3 hose fittings?

[slikwilli420]

Would not really be a reason for more than one fitting there. My configuration is a breather box plugging the starter hole, one line to the cam cover, one to the back of the cases, and one to a fitting on the top of the clutch cover. If any oil were to be pulled, it would drain back through starter hole, making it self regulating. The "out" fitting is a one way valve that takes very little pressure to activate. Now I can easily vent things without pulling crap in from the air. After 2 weekends of racing, it was bone dry. Oddly, an overfilled oil tank and some unanticipated suction was causing my oiling issues.

[PeWe]

Hi, I have seen your setup. It look really nice! I stole your photo for future reference.
I have the starter motor in.
It pumps more now with 1005cc than with 836cc that could get some case weep I earlier blamed on Hylomar blue as not good enough as case sealer. Holidays going south with constant high speed for long time.

I got some oil weeping out between the cases so i had to do something about it. First an extra plumbing of a T connection between rear breather and oil tank. That helped the case weeping but could spray some oil when riding 6000-8000 rpm for a while. I had to refill expensive oil too often too. I have plugged that hose for now. Will remove that plumbing later on.

I'm not sure that this little extra breather will be enough. I have my eyes on where oil has weeped out. Sealer might be flushed away and leak will continue. I used  Permatex aviation no 3 which seems to seal despite over pressure and oil weep.

I ordered Loctite 518 together with 638. Loctite 518 might be next sealer if I need to reseal cases. Pull engine and lift lower case is not something I look forward to.

[Tracksnblades1]

I Think Lycoming (10,000ft) still recommends the Loctite 515 plastic gasket. The 518 may be to new to make it in their service manuals. I think the old International Harvester just called it Plastic gasket and is still available at CaseIh dealers. The 515 takes 72hrs for aluminum to cure 50% as strong as it would be cured in 24 on steel surfaces. Never used the 518, it's supposed to be better on aluminum surfaces Used the 515 for years in applications with no vents, dozer final reductions and planetaries. where temps can go from ambient to 230* with 50% trapped air above the oil. I've worn the 80w-90 all day before from checking them hot only once. Most dozer manufactures use the 515 or their own relabeled version. Most Caterpillar dealers around here are Loctite dealers. Back when the sohc were in vogue everyone used yamabond or Mercury outboard case sealer.

[PeWe]

Seems to be a good sealer. Easy to take it apart next time?
515 seems to be not available on the Loctite product chart here. Available on eBay though.
518 specified to cure much faster.

I must open the cases and use it before end date will be reached, right?
It last longer if kept in the fridge, +5C (41F)?

[MessnerMoto]

518 is much better....

[PeWe]

518 is much better....

I hoped and thought so when I read the descriptions. Good to know that 515 is very good, 518 even better.
I hope the cases will be possible to take apart in the future when sealed with 518.

[Tracksnblades1]

The specs look better for the 518. My experience is only with the 515 and caseih branded 515. 515 on dowels will disassemble readily after many years. The 515 off-road applications split mating cases are generally time air tested 3-5 psi after cure before fluids are refilled. Even that envious JMR big block wouldn't see 3psi would it? Maybe on a healthy dose of CH3NO2 + belt driven aircleaner.  Then em eddy bitty rings might complain. Do you have enough miles on the JMR to predict oil consumption if any with the narrow oil rings...?

[PeWe]

Thanks for the feedback about the sealer.
Oil consumption is not measured yet. I have had some external oil consumption Billet block bone dry on both sides, lower as well as upper. RCS base gasket, MLS head gasket.

Last oil leak yesterday when a tappet cover leaked, oil leaked from 3 IN to 1 EX when sitting on centerstand.
Aftermarket covers (DSS) look really good but the supplied o-ring thinner than CB750 stock. Hopefully fixed now with new thicker O-rings from a CB750 gasket kit. A friend parked his shiny, non leaking CB750 Auto  beside mine and felt the Triumph smell direct.

I'll see if it will weep any more oil. I used Permatex Aviation 3 as case sealer. It seems to keep together rather well.
Ill see if I'll re-seal cases coming winter or next. I have a CB750 K2 to assemble. Paint tank + covers this summer.

I do not feel any smell of burned oil nor any smoke from the exhausts when revving it. It work really fine with 295 cam profile, carbs finally jetted correctly.
I guess the oil rings will scrape the bores rather good and keep the oil on the right side.

[Ilja]

I also had breather issues with the turbo, especially with more boost.
First I thought I had cooked the pistons again, but on high revs it simply throws out oil easily.

I made an additional one on the top cap in the middle of the valve cover with a 12mm hose on it.   

[PeWe]

The square sized breather cover bolted by 3 ? Where to drill that cover?
I have thoughts to add a hose here too. I have an extra AN6 with hose connection as the one I have in clutch cover but 90 degree angle.
No oil that can be spitted out via that hose?  I have seen that it will leak oil if that cover is not completely tightened.

[Ilja]

The square sized breather cover bolted by 3 ? Where to drill that cover?
I have thoughts to add a hose here too. I have an extra AN6 with hose connection as the one I have in clutch cover but 90 degree angle.
No oil that can be spitted out via that hose?  I have seen that it will leak oil if that cover is not completely tightened.

I found a pic... its the rear tube welded on the cap.

The AN4 on the front is the vent from the turbo oil catch can.   

[PeWe]

The square sized breather cover bolted by 3 ? Where to drill that cover?
I have thoughts to add a hose here too. I have an extra AN6 with hose connection as the one I have in clutch cover but 90 degree angle.
No oil that can be spitted out via that hose?  I have seen that it will leak oil if that cover is not completely tightened.

I found a pic... its the rear tube welded on the cap.

The AN4 on the front is the vent from the turbo oil catch can.   

OK, inside the cover no oil trap needed? The hose fitting will have a stick out that stop oil flowing over the cover surface and direct out via the vent. There might be oil spraying around inside.
I have this to be used.
https://www.ebay.co.uk/itm/1-8-NPT-to-9mm-10mm-3-8-BLACK-90-DEGREE-ELBOW-PUSH-ON-BARB-TAIL-Hose-Adapter/272173001160?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649