Breaking in New Engine, Leaks...crankcase pressure? |
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Breaking in New Engine, Leaks...crankcase pressure? |
BeatNavy |
Sep 6 2019, 03:06 PM
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#1
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
The last week or so I've been breaking in a new engine I built last winter and finally manage to install a couple of weeks ago. I'm pretty happy with how it pulls, and after a LOT of fiddling with the MPS and timing I think I've got it where it will start right up, idle cold (barely), idle nicely when warm, and run with nice cool head temps. I do seem to have a slight bit of ping/detonation under load around 2800 to 3000 RPM, so I guess I need to play with timing a bit more.
I am much less happy with the oil leaks. I know building a leak-free Type IV is a challenge, and given this is my first effort, I didn't expect perfection. But right now it's leaking pretty badly in a couple of places: out of the transmission weep hole (probably RMS, I guess), somewhere around oil filter console and/or pressure relief valve, and, surprisingly, what seems to be sort of spraying out and around oil filler neck. Here I need help from the World; I see a combination of three possible causes for this many leaks (when I otherwise took my time and tried to follow guidelines, using Jake's recommended sealants): 1. My own inexperience 2. Too much crankcase pressure from rings not seating yet 3. Too much crankcase pressure from no head venting. Here are some details on build: 2056 with 9950 Cam using D-Jet Brand new AA Heads built by HAM, and Len sealed up the vents 96mm KB Pistons with Hastings Rings 8.6 CR A couple of notes: I didn't gap the rings per Jake's philosophy that crankcase pressure is what causes oil leaks, and the rings come properly gapped. Also, Len (and Jake) don't like head venting for oil flow (so my heads had vent plugged). If I understand him correctly, Len told me the stock PCV vale should provide enough crankcase pressure relief on a street car. RMS is the Sabo brand (the "good" one). Any thoughts on 1, 2 or 3 above? I'm willing to pull the engine and reseal, but I wanted to see if 2 or 3 are possibilities that I need to address. Is the stock PCV valve (which I am sure is not clogged) enough pressure relief? Thanks for any help. |
BeatNavy |
Sep 9 2019, 04:07 PM
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#2
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
Just to follow up on this. I tapped a hole in the oil filler, threaded a fitting in it, and connected it with vacuum hose to air cleaner t reduce crankcase pressure. I also realized that I'm missing a sealing ring on my oil filler neck. Not the cork gasket, but there is a sealing gasket below the oil filler. Comparing with one from my other engine, I realized that must be part of the issue, so I swapped oil filler housings.
Right now the oil leaks on top have stopped. Some combo of relieving crankcase pressure, making sure the oil filler was sealed, and/or rings seating seem to have helped. I don't see anything really bad underneath, and I am now thinking at least part of the oil under the case was actually leaking from on top. Now I still have three outstanding issues to deal with: 1. Oil temps seem fairly high (240-ish after 15 minutes of driving, with ambient temps around 80). I can see a freshly rebuilt engine having tighter tolerances contributing to higher temps. Anyone have thoughts on that? 2. Can won't idle cold. Idles too low to the point of stalling until head temps get over 240 or so. AAR is working. Need to figure this out best I can. 3. Exhaust leak, probably at heads. Need to redo these, and it may be part of my issue(s) above. Not sure I trust my AFR readings at idle if I have an exhaust leak. Thanks to Len and everyone else for thoughts on this (IMG:style_emoticons/default/beer.gif) |
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