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Hello. I'm going to keep this brief but feel free to ask any questions. I've searched many posts but haven't found quite what I'm looking for. I recently finished a complete engine rebuild on a 98 e-glide classic injected to stock 80" specs as sold new with exception of new S&S oil pump #31-6206 and a new ultima steel breather. Within 200 miles it pushed out the crank seal and polluted the primary with engine oil. Prior to present disassembly I did a hot leak down test at 90 psi, only a 4% loss both holes. Hot compression test is 150 psi both. Engine does have breather pulse at the head ports.
I've installed a new crank seal using permatex sleeve mount compound and am presently reassembling the primary. What I'd like to do is test the crankcase pressure. Thinking this would help me determine If I need to dig back in to find a cause if too much pressure. Mistakes can happen. Maybe I can get some results using a cylinder compression tester at the timing plug hole. I could test my 94 evo bagger for a comparison. So, has anyone here devised a method to actually test crankcase pressure while cranking or running? And if so, what would be acceptable pressure or too much? Thank you.
Hello and Thank You for your feedback. Yes breather timing was the first question that crossed my mind. But I'm all but certain it's aligned. I recall I even compared the design and likeness of the new steel to old plastic breather gear to assure myself of compatibility when I assembled the engine on the bench. Of course the only way I could truly be certain at this point is to remove the cam cover. I would like to avoid probably wasting that time. But I am concerned, which is why I'm looking to do an actual crankcase pressure test to confirm or deny there is or is not a problem. And I'm not convinced the initial seal was adequately installed at the crank shop. That metal seal was not coated red or green around it's circumference and I did not find much evidence of retaining compound used on assembly. Also, the compound used was loctite 620, which doesn't specify required use of a surface prep activator. As such my preference is permatex. Finally that seal may not have withstood much pressure before it pushed out lacking any other cause but potentially a bit higher crankcase pressure until the new rings seated.
UPDATE: FWIW I just finished the primary assembly and cranked engine cold with spark plugs installed. I used an old Sun vacuum / pressure test gauge I have in my tools arsenal. At this point I'm encouraged. There is no pressure, just 1 inch of vacuum. I believe this indicates I must have the breather gear timed correctly as crankcase is being evacuated and not pressurized. Getting a bit late so I won't test again until tomorrow when I oil up the primary and start the engine. I'm thinking at that point at idle rpm and above I should be able to see both vacuum and pressure as the pistons travel up & down in the cylinders. I'm also thinking the vacuum & pressure differential should be relatively equal to achieve atmospheric pressure, which I think is what the breather is supposed to be doing from what I understand.
I put a "reed valve" breather in my 98 FLHRCI, Been a year or so no issues, doesn't need to be timed or to spin in the case bore. Could take one thing out of the equation..
Looks like it might be a poor seal installation as you expected. Was the seal pushed out on one side more than the other? I usually install the seal like I'm running a dry primary, and I never used any sealant.
Thank you both for your thoughts and feedback. I'm aware of reed valve breathers, seems a mixed bag of opinions about them out there. I've never tried one but yes using one does eliminate timing.
Pic attached, the initial seal installed by the crank rebuilder was completely out of the case all around. Like it got pushed out or simply walked out of the bore. I don't think sleeve retaining compound should be necessary but rather a bit of insurance to help keep the seal in place. Probably more an issue on a worn engine with too much blow-by potentially resulting in too much crankcase pressure.
As I continue testing today I'm going to compare my results to my 94 tour glide. I'd expect a bit more crankcase pressure in that engine as it's an older build and had more cylinder wear. And I'll probably pull the oil return hose on the problem engine to assure I'm getting oil flow back to the oil tank with no restriction or potential sumping. Again, the point of all this is an attempt to determine if there's a problem that caused the crank seal to push out without needlessly removing the cam cover, etc. And lacking any other approach to testing I've been unable to find, maybe my diagnostics will help others faced with a crank seal failure.
CORRECTION: My bad. I thought about why on my initial test I only got a nominal vacuum signal and no pressure. I looked at the rubber tipped compression tester adapter I plugged into my old Sun vacuum tester gauge. The adapter had a schrader valve at the tip. I removed the valve and just tested it cranking again. Now I get about 7 inches of vacuum and about 2 psi pressure. This makes more sense to me having both a vacuum and pressure pulse. I attached a pic of my tester setup in event someone is following along that may want to run tests on their own engine.
CONCLUSION: I've now tested my 94 tour glide for crankcase vacuum & pressure at the timing hole same way I did the 98. The 94 results are very similar to the 98 that had the seal failure.
94 hot idle vacuum at 1000 rpm, 3 inches no pressure. (Would show nominal pressure if idle dropped to around 750 rpm and slightly less vacuum around 2.5 inches. Carbed engine, ev13 cam, older build with some miles on it now).
98 hot idle vacuum at 1000 rpm, 4 inches no pressure. (No noticeable difference when revved a bit. Fresh build, stock cam).
On the 98 I did remove the oil return hose from the filter return pipe and it does have oil flow when cranking.
Given the similar test results between both engines I'm pretty confident I don't have a crankcase pressure or breather problem on the 98 that would've caused the crank oil seal to come out of the case. I did expect some difference with the 94 due to wear and frankly I'm not very gentle on that engine from time to time.
I'm going to put some miles on the 98 and keep an eye on the primary oil level. Hopefully the seal failure was a fluke in assembly at the crank shop and won't reoccur.
Guess that's all for now. Hope this post and threads might be of some help to others.
I have measured the seals outside diameter and have found them to vary in a10 Pack of James.. Sometimes it is necessary to use Loctite 680 green retaining compound and let sit for 24hrs...
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EVO crankcase pressure test?
