Umbrella valves installation

[road_surfer]

I acquired an '87 FLHTC recently, my first H-D. The front cylinder middle rocker cover started leaking: an obvious torn gasket. After removing the uppper and middle rocker covers I found that the covers were not the ones shown in my factory manual. The illustrated covers have no umbrella valves. This rocker cover, marked "H-D", does have umbrella valves. One was installed on the high side of the cylinder, but the lower side where the gasket tore did not have an umbrella valve. This is shown in the attached picture. You can see there is only one umbrella valve. Is this correct or do I need two in each middle rocker cover?

If you can answer this question, you can probably explain what these valves do. The ones provided by the dealer do not sit tight against the metal surface like the original. There is maybe 0.020" clearance. What would be the effect of an umbrella valve that has clearance against the metal surface it is supposed to seal?

This bike has a K&N filter and a vapor coalescing "tomato can" that must be drained of water/oil sludge every 150 miles or so. I thought the sludge may have blocked the breather path resulting in the blown gasket that shot oil all over.

I want to keep this bike happy and healthy as the previous owner did. In fact, it was rebuilt at the factory about 5000 miles ago. Thanks for helping a new H-D owner.

[rcsoftail]

You only need one umbrella valve in each rocker cover. It will be the one on the intake side just above the breather bolt hole in the head as shown in your picture. It is a one way valve that allows excess pressure to be release to atmosphere as the pistons travel downward, which helps keep a vacum in the crankase and eliminate exessive presure on gaskets and rings. I would not worry about the .020 gap. It will relax and move down with the heat and pressure.

[econnor]

Evo big twins engines did not breath out the heads until '93. Prior to 93 they vented out the lower engine case. This engine has been modified. The factory may have swapped out the rocker boxes and replaced with the newer style as part of their reman process.

The question is are your heads venting or are they still closed up? Look at where the air cleaner mounts to the heads. The newer (vented) style will have a type of banjo bolt. The '92 and earlier will have regular bolts. If your AC has regular bolts, you do not need to worry about those umbrella valves.

[road_surfer]

Thank you both. I'll check to see if the heads are actually vented. It appears that the factory did put new rocker covers on during the rebuild process.

They also used that blue goo on all the lower gasket mating surfaces. I'm not a fan of that stuff: it's usually not needed and makes a mess. I don't plan on using it for the assembly since the lower surfaces are grooved. There is virtually no chance of rolling the gasket while mating the covers.

I brought the parts to the local HD dealer so they could find the correct gaskets. In general, the dealer is not much help. They told me they can't work on my bike because it's too old! Thankfully I found these forums. The archives have been useful already. Thanks again for your comments. I hope I can help someone else out someday.

[rcsoftail]

Those ruber gaskets tend to shrink a bit over time while sitting on the shelf. Sometimes I have to lightly stretch them a bit to get them to lay in the trench without popping out. If they pop out of the trench while putting on the covers and torqing down, you can ruin the gasket.

[road_surfer]

This bike is a non-breather. The air cleaner has regular bolts, fairly light at about 3/16" diameter. It's all back together. I ran it in the garage until it idled on its own (yes, it's a manual choke, too) and found no leaks and no noises. Next: the test ride. Reading the factory book I found a pressure control valve that could be malfunctioning. We'll soon find out. Thanks again!