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> Relief, Oiling system in a type 4
worn
post May 13 2013, 08:33 AM
Post #1


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If anyone has read my previous threads my two week vacation turned from driving to lying on the creeper under the new engine and transmission. Low oil pressure after warm up. I ordered a new Melling 30 mm pump and we shall see, but at the same time I looked into the pressure relief system - especially where it shunts oil away from the cooler because it is easier to see in the car.

What I found surprised me. First, looking at two different cases (72 1.7 and 76 2.0) I found that the piston seats on a shoulder in the bore that is at most a mm wide, and is not at all uniform in width across the piston face. OK, maybe it isn't supposed to seal.

Second I found that by the time you have opened the valve to shunt past the cooler, you are also dumping into the sump. That is there is a small overlap between the outlet to the oil gallery and the grooves cut in the bore leading to the sump exit.

Finally, the piston is simply loose in the bore. I can understand a fear of seizing, but there is no way that with my system oil isn't streaming into the sump, and it will stream faster as it thins - much faster.

I also spent a long time cruising the Samba - they ought to know whats up. What I found is a recurrent theme of new engines built in a variety of ways making low oil pressure. Many people were happy with what I ended up with - 10 psi at idle. On a new engine.

It is steel against untreated aluminum, so wear would be expected, but mine do not look worn - just poorly made. Maybe they are worn and I cannot tell. I got a face full of oil on one attempt at examination, so I may have missed things.

It seems an ideal situation for machining or sleeving during the rebuild, and I actually found a manufacturer of a sleeving kit with a ball bearing valve.

Thoughts ladies and gentlemen? (IMG:style_emoticons/default/idea.gif)
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Posts in this topic
worn   Relief   May 13 2013, 08:33 AM
reharvey   I've been following your posts about the oil p...   May 13 2013, 08:57 AM
worn   I've been following your posts about the oil ...   May 13 2013, 09:33 AM
worn   I've been following your posts about the oil ...   May 13 2013, 01:28 PM
reharvey   I've been following your posts about the oil...   May 14 2013, 03:28 PM
worn   [quote name='worn' post='1863422' date='May 13 20...   May 14 2013, 03:39 PM
Cap'n Krusty   How is a larger oil pump, which will definitely in...   May 13 2013, 09:20 AM
worn   How is a larger oil pump, which will definitely i...   May 14 2013, 12:56 PM
worn   Here is a drawing about what it looks like. Sorry...   May 13 2013, 09:22 AM
FourBlades   Keep in mind this is just a guess... The oil pres...   May 13 2013, 09:22 AM
nathansnathan   I've experienced this same thing, low oil pres...   May 13 2013, 09:24 AM
worn   Yeah Nathan, I looked at that site too. I am way...   May 13 2013, 09:38 AM
r_towle   Check the case main bearing seat size. Check the m...   May 14 2013, 02:33 PM
worn   Check the case main bearing seat size. Check the ...   May 14 2013, 02:49 PM
r_towle   [quote name='r_towle' post='1863940' date='May 14...   May 14 2013, 03:44 PM
worn   [quote name='r_towle' post='1863940' date='May 1...   May 14 2013, 09:16 PM
r_towle   [quote name='r_towle' post='1863972' date='May 14...   May 15 2013, 07:17 AM
worn   So, now what are you planning to do? Not sure I ...   May 15 2013, 12:08 PM
eyesright   FWIW I'm just now rereading the Haynes manual,...   May 14 2013, 02:33 PM
worn   FWIW I'm just now rereading the Haynes manual...   May 14 2013, 03:00 PM
yeahmag   Interesting for sure: http://www.headflowmasters....   May 14 2013, 03:14 PM
cary   Did you get a case yet? I have one that had a hol...   May 15 2013, 06:00 AM
r_towle   Please post some pics of what you are doing.   May 15 2013, 09:46 PM
worn   Please post some pics of what you are doing. OK...   May 16 2013, 08:44 AM
nathansnathan   aircooled.net used to rent out a 5/8" end mil...   May 16 2013, 09:05 AM
worn   aircooled.net used to rent out a 5/8" end mi...   May 16 2013, 09:24 AM
396   [quote name='r_towle' post='1864740' date='May 15...   May 20 2013, 10:16 AM
FourBlades   :popcorn: :popcorn: :popcorn: You have done a ...   May 16 2013, 01:21 PM
brant   This is what I described in your other thread it m...   May 16 2013, 01:59 PM
yeahmag   Just to refresh my memory, you are trying to get m...   May 16 2013, 02:08 PM
r_towle   Interesting. Might be worth getting a custom pisto...   May 16 2013, 04:52 PM
Jake Raby   All these rules and myths change when bearing clea...   May 16 2013, 09:31 PM
worn   All these rules and myths change when bearing cle...   May 17 2013, 09:10 PM
nathansnathan   What I think is interesting is we have numbers fo...   May 18 2013, 06:53 AM
worn   What I think is interesting is we have numbers f...   May 19 2013, 08:53 PM
worn   [quote name='nathansnathan' post='1865830' date='...   May 19 2013, 08:57 PM
cary   I learned another lesson as well. You cannot tune ...   May 19 2013, 10:29 PM
worn   [color=#330099][i]I learned another lesson as wel...   May 20 2013, 08:41 AM
yeahmag   So you went from 10PSI to 20PSI at idle with all t...   May 19 2013, 09:23 PM
worn   So you went from 10PSI to 20PSI at idle with all ...   May 20 2013, 08:45 AM
r_towle   So you went from 10PSI to 20PSI at idle with all...   May 25 2013, 11:49 AM
worn   [quote name='worn' post='1866719' date='May 20 20...   May 26 2013, 09:13 AM
r_towle   [quote name='worn' post='1866719' date='May 20 2...   May 26 2013, 02:30 PM
396   Sub as its very interesting read. After reading t...   May 19 2013, 10:09 PM
eyesright   My (home rebuild) engine is back in the car, oil l...   May 20 2013, 10:01 AM
eyesright   Warn I located the relief valve seat by looking u...   May 25 2013, 06:49 PM
76-914   Verify your "cheap gages" or you'll ...   May 26 2013, 07:53 AM
yeahmag   The VDO CHT is not temp compensated. You have to d...   May 26 2013, 09:44 AM
eyesright   worn I agree with yeahmag. My VDO CHT shows 350F....   May 26 2013, 03:19 PM
eyesright   PS Worn, oh yeah, one more thing. When you open th...   May 26 2013, 04:35 PM


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