Relief, Oiling system in a type 4 Options

[worn]

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)

[r_towle]

Check the case main bearing seat size.
Check the main bearing thickness.
Check the main bearings in the case all torqued down, no crank.

I recall Jake mentioning that the main bearings halves were slightly large and needed to be hand files down on the top edges to allow the case to close all the way.

Rod bearings may also be having the same issue, not sure.

Pretty sure Jake measures everything with bearings and not with bearings to verify the bearings are right.

With his higer volume of motors, he sure has seen all the wierd product issues coming onto the market.

Just because the bearings are new does not mean they are right.

Rich

[worn]

Check the case main bearing seat size.
Check the main bearing thickness.
Check the main bearings in the case all torqued down, no crank.

Just because the bearings are new does not mean they are right.

Rich

Thank you Rich. It isn't as though I don't believe I can make a mistake. I work in a checklist environment and I have made many many of them. Believe me, I know I get things wrong on a regular basis.
My worry though is what happens if I take it back apart and there is nothing that I can find wrong in the clearances? So I want to cover other avenues first. The tranny build went just like that, but I spent months on the engine measuring. When I was a post doc at Berkeley my advisor told me something that stuck forever - if you do an experiment and get a result, and then do it again the most likely outcome will be the same result.

Also, the fact that we have data about 100 VW engines is pretty mind blowing to me. No, it is the fact that it is data we get to look at.

Thanks again Rich. The advice I get here is always appreciated.

[r_towle]

Check the case main bearing seat size.
Check the main bearing thickness.
Check the main bearings in the case all torqued down, no crank.

Just because the bearings are new does not mean they are right.

Rich

Thank you Rich. It isn't as though I don't believe I can make a mistake. I work in a checklist environment and I have made many many of them. Believe me, I know I get things wrong on a regular basis.
My worry though is what happens if I take it back apart and there is nothing that I can find wrong in the clearances? So I want to cover other avenues first. The tranny build went just like that, but I spent months on the engine measuring. When I was a post doc at Berkeley my advisor told me something that stuck forever - if you do an experiment and get a result, and then do it again the most likely outcome will be the same result.

Also, the fact that we have data about 100 VW engines is pretty mind blowing to me. No, it is the fact that it is data we get to look at.

Thanks again Rich. The advice I get here is always appreciated.

So , I appreciate that you measured quite a bit of the motor, but what I am asking is not typical.

Did you measure the roundness of the main bearings mounted in the torqued case with no crankshaft in place?

This would produce an oval measurement if the bearings are as Jake has found some of them to be, which is to large.

Did you do the same process to the rods on the big end, bearing in place, measure for round.
Again, same condition, same results.

Using an internal bore measuring device, done in a systematic way will produce the results of round or oval...

Just putting that in the back of your mind...again, its not a typical thing to ever do when building a typical motor...but with Jake finding these bearings coming from the factory to large, I now do this extra set of steps just to be sure.

Mind you, I build maybe two a year....
Jake builds alot more, so he will see more issues.


Lastly, I would look into the heavier spring and new piston for the pressure relief system.
http://vwparts.aircooled.net/Bugpack-Oil-P...lief-p/3041.htm

Not the exact part, but call them, they are cool and they have the right one...
I would go for that...20 bucks that may help..

Rich

[worn]

Check the case main bearing seat size.
Check the main bearing thickness.
Check the main bearings in the case all torqued down, no crank.

Just because the bearings are new does not mean they are right.

Rich

Thank you Rich. It isn't as though I don't believe I can make a mistake. I work in a checklist environment and I have made many many of them. Believe me, I know I get things wrong on a regular basis.
My worry though is what happens if I take it back apart and there is nothing that I can find wrong in the clearances? So I want to cover other avenues first. The tranny build went just like that, but I spent months on the engine measuring. When I was a post doc at Berkeley my advisor told me something that stuck forever - if you do an experiment and get a result, and then do it again the most likely outcome will be the same result.

Also, the fact that we have data about 100 VW engines is pretty mind blowing to me. No, it is the fact that it is data we get to look at.

Thanks again Rich. The advice I get here is always appreciated.

So , I appreciate that you measured quite a bit of the motor, but what I am asking is not typical.

Did you measure the roundness of the main bearings mounted in the torqued case with no crankshaft in place?

This would produce an oval measurement if the bearings are as Jake has found some of them to be, which is to large.

Did you do the same process to the rods on the big end, bearing in place, measure for round.
Again, same condition, same results.

Using an internal bore measuring device, done in a systematic way will produce the results of round or oval...

Just putting that in the back of your mind...again, its not a typical thing to ever do when building a typical motor...but with Jake finding these bearings coming from the factory to large, I now do this extra set of steps just to be sure.

Mind you, I build maybe two a year....
Jake builds alot more, so he will see more issues.


Lastly, I would look into the heavier spring and new piston for the pressure relief system.
http://vwparts.aircooled.net/Bugpack-Oil-P...lief-p/3041.htm

Not the exact part, but call them, they are cool and they have the right one...
I would go for that...20 bucks that may help..

Rich

Thanks for the in depth reply. The answer is often but not always. With the round bearings on the mains I quickly found that plastiguage wasn't gonna help. So I did measure roundness mostly with a set of snap gauges and an internal mic, not the ideal tools.

I won't have the hard data for a few days but tonight I found what appears to be the smoking gun. How much smoke remains to be seen, but it looks to me like folks are underestimating the complexity of the relief system, and that may extend to factory machinists. At this point I can clearly say that at high temp my oil relief should have been sendinding oil all to the cooler. It was instead bleeding oil into the sump at a rapid rate. Nothing to do with the pistons or the springs, but instead either case wear or sloppy machining. Look at the samba post - it is an eye opener about where and at what pressure oil in this class of engine goes.
I cannot thank you and others enough.
Warren

[r_towle]

Check the case main bearing seat size.
Check the main bearing thickness.
Check the main bearings in the case all torqued down, no crank.

Just because the bearings are new does not mean they are right.

Rich

Thank you Rich. It isn't as though I don't believe I can make a mistake. I work in a checklist environment and I have made many many of them. Believe me, I know I get things wrong on a regular basis.
My worry though is what happens if I take it back apart and there is nothing that I can find wrong in the clearances? So I want to cover other avenues first. The tranny build went just like that, but I spent months on the engine measuring. When I was a post doc at Berkeley my advisor told me something that stuck forever - if you do an experiment and get a result, and then do it again the most likely outcome will be the same result.

Also, the fact that we have data about 100 VW engines is pretty mind blowing to me. No, it is the fact that it is data we get to look at.

Thanks again Rich. The advice I get here is always appreciated.

So , I appreciate that you measured quite a bit of the motor, but what I am asking is not typical.

Did you measure the roundness of the main bearings mounted in the torqued case with no crankshaft in place?

This would produce an oval measurement if the bearings are as Jake has found some of them to be, which is to large.

Did you do the same process to the rods on the big end, bearing in place, measure for round.
Again, same condition, same results.

Using an internal bore measuring device, done in a systematic way will produce the results of round or oval...

Just putting that in the back of your mind...again, its not a typical thing to ever do when building a typical motor...but with Jake finding these bearings coming from the factory to large, I now do this extra set of steps just to be sure.

Mind you, I build maybe two a year....
Jake builds alot more, so he will see more issues.


Lastly, I would look into the heavier spring and new piston for the pressure relief system.
http://vwparts.aircooled.net/Bugpack-Oil-P...lief-p/3041.htm

Not the exact part, but call them, they are cool and they have the right one...
I would go for that...20 bucks that may help..

Rich

Thanks for the in depth reply. The answer is often but not always. With the round bearings on the mains I quickly found that plastiguage wasn't gonna help. So I did measure roundness mostly with a set of snap gauges and an internal mic, not the ideal tools.

I won't have the hard data for a few days but tonight I found what appears to be the smoking gun. How much smoke remains to be seen, but it looks to me like folks are underestimating the complexity of the relief system, and that may extend to factory machinists. At this point I can clearly say that at high temp my oil relief should have been sendinding oil all to the cooler. It was instead bleeding oil into the sump at a rapid rate. Nothing to do with the pistons or the springs, but instead either case wear or sloppy machining. Look at the samba post - it is an eye opener about where and at what pressure oil in this class of engine goes.
I cannot thank you and others enough.
Warren

So, now what are you planning to do?
Not sure I understand what you found or what the cure might be...
Very curious here.

rich

[worn]

[/quote]

So, now what are you planning to do?
Not sure I understand what you found or what the cure might be...
Very curious here.

rich
[/quote]

Well, I figured this was worth documenting so I am making a cast of the relief cylinder so that people can see the problem. The problem is working upside down and not contaminating the motor.
What I found was that the piston does not reach the seat because of a raised shoulder about 2 mm above the seat. Maybe they cut the seat and the chamfer with two bits and the ridge is where the boring didn't go down quite far enough. My other case does not have this problem, but also shows evidence of careless manufacture - the chamfer is too big. The system is more complicated and elegant than it looks - the diameter of the chamfer sets the opening pressure. Because the chamfer diameter and the bore diameters are different the opening and closing pressures can be different. Cool. I doubt most factory machinists recognized this.

IF it ain't bearings, and I get rid of the ridge by careful boring, then I should have big pressure when I start it up again. If not, I fold and tear the engine down. More later when I know. Fingers crossed.