Breaking in New Engine, Leaks...crankcase pressure? |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Breaking in New Engine, Leaks...crankcase pressure? |
BeatNavy |
Sep 6 2019, 03:06 PM
Post
#1
|
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 |
Dec 18 2019, 04:51 PM
Post
#2
|
Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
Ok, circling back on this to add to the 914World knowledge base.
About 6 or 7 weeks ago I was having more trouble starting (and restarting) the car. Finally broke down and did a compression test. Based on the results, I pulled the engine and here's what I had: YES! Special compression rings that have TWO gaps, not just one! (IMG:style_emoticons/default/blink.gif) Ok, yes -- cylinder #1 had not just one but two broken compression rings. I probably broke at least one when I installed piston in the cylinder a while back. I had cold compression numbers of roughly 60 on #1 and more like 140+ on the others. The broken rings could explain a lot, including elevated oil temps and oil leaks due to all the blow-by. Anyway, I dropped the engine and pulled the heads. I replaced the broken rings and also re-gapped all the #1 rings based on KB's guidance that Tom pointed out in an earlier post in this thread. Also put installed a new RMS (although the old one probably wasn't really bad). Most of the time over the last 6 weeks was spent cleaning up the underbody like I've been meaning to do for years -- removing / replacing undercoating, fixing isolated rust spots, and repainting engine bay and underside of trunk. What a LOT of work, and dirty too (IMG:style_emoticons/default/sad.gif) Finally got the engine back in today, and got her fired up! Too early to say all my drivability and oil temp/oil-leak problems are solved, but I am encouraged so far, and glad to be back on the road (with a nice clean underside) (IMG:style_emoticons/default/aktion035.gif) Several lessons learned: 1. When chasing your tail, break down and do a compression test earlier rather than later. I don't know why I tend to avoid it - it's only a minor PITA but can give good info. 2. I went with Jake's advice on ring gapping (go with out of the box gap) -- which is fine, unless the manufacturer of the product engineered something different. Read the (****) instructions. 3. A type 4 can run surprisingly well on less than 4 full cylinders. 4. This came in handy both for engine drops/installs and installing the HE's and exhaust -- basically just lifted everything in place. If you have a lift and do lots of engine drops, you may want to treat yourself to something like this if you haven't already: (IMG:http://www.914world.com/bbs2/uploads_offsite/images.homedepot-static.com-17042-1576709465.1.jpg) 5. Even with a scissor lift and that cart, pulling the engine is still a PITA. Hope I'm done for a while. Thanks for everyone's help. I'll post more when I get a chance to road test it more. In the meantime, here's my cleaned up butt (it's ok, you can look at it). Not perfect, but much better than before. |
Lo-Fi Version | Time is now: 8th June 2024 - 02:27 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |