Relief, Oiling system in a type 4 Options

[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.

[r_towle]

Please post some pics of what you are doing.

[worn]

Please post some pics of what you are doing.

OK, I am making some progress. If the bearings are loose, this will be a bit of an extra, but that hasn't been tested yet.

It is hard to show, but here is what I found:

The first image shows a comparison between the Prussian blue rub off in my old worn out 2.0 and the new 2056. The pistons are identical.


You can see a clear seat in the old, but you can hardly see contact with the new. In fact, there is a small rim around the chamfer where dye has transferred.

OK, getting a photo of the cylinder was tough. Here is my best and it shows the problem:


The green arrow shows the offending ridge running all round the circumference of the cylinder. A slightly smaller final bore perhaps? At any rate, that is what stops the piston a couple of mm short of the seat. the line between the pressure bevel and what is supposed to be the seat is shown with the other arrow.

What I did was to get a piece of scrap iron. It should have been steel - I made a bad choice based on what was lying around and made a cutter at 15.9 mm. It is shown below with a before and after prussian blue test. I used grease to catch the swarf, which in my case was a very fine powder - like anti seize. At first I thought this would go quick, but it took quite a lot of turning the tool because basically the tool I made is not at all aggressive - it dulls fast and there was purposely no relief cut for the cutters.



I have to rinse well, clean like the dickens and get it back off the stands to find out how things go. Since I changed two variables at once with the new pump, I will never know. What I can say is any oil that gets by the piston is back to the sump. The bores tend to wear and there is nothing to stop it but viscosity at the valve. So if as I suspect the valve wasn't sealing, I would expect what I found. Low pressure with hot oil.

[nathansnathan]

aircooled.net used to rent out a 5/8" end mill to dress the seat as you have done there. Pretty bold, making your own cutter!

It's weird the poor attention to detail the factory had for this mechanism. I have seen pics where there is a stamped VW logo on the face of the piston, right on the edge interfering with the seal.

-Seems like cleaning the bore up though, might let oil get by when it is off idle. I've been tempted to use a reamer to oversize the bore, but would want to turn a new piston. Shoptalkforums awhile back, we came to the conclusion the best thing to turn a new piston out of would be "Torlon" which is a high temp lubricating plastic, like high temp teflon. Pricey, but it would never wear a ridge in that bore again.

[worn]

aircooled.net used to rent out a 5/8" end mill to dress the seat as you have done there. Pretty bold, making your own cutter!

It's weird the poor attention to detail the factory had for this mechanism. I have seen pics where there is a stamped VW logo on the face of the piston, right on the edge interfering with the seal.

-Seems like cleaning the bore up though, might let oil get by when it is off idle. I've been tempted to use a reamer to oversize the bore, but would want to turn a new piston. Shoptalkforums awhile back, we came to the conclusion the best thing to turn a new piston out of would be "Torlon" which is a high temp lubricating plastic, like high temp teflon. Pricey, but it would never wear a ridge in that bore again.

That's funny - both of the pistons shown have a small VW stamped on the mating face, but very small. Also they used a bench grinder to dress away the piston cutoff nub from the lathe. The system is brilliant, but vulnerable to wear and I think in my case poor construction. You may get something you like, but you won't get the sophistication with a ball valve. Might solve the headache though, I dunno. Can't wait to get it back on the ground. The turbo tie rods will have to wait.

[FourBlades]

(IMG:style_emoticons/default/popcorn[1].gif) (IMG:style_emoticons/default/popcorn[1].gif) (IMG:style_emoticons/default/popcorn[1].gif)

You have done a very systemmatic investigation of the relief system.

Nice job!

John

[brant]

This is what I described in your other thread
it may not be the factory attention to detail.
I think you would find if you cut a case open and inspected the surface that often shrapnel from a previous engine melt down can cause this problem.

I've used an old piston in the past with valve grinding compound.... (and lots and lots of time manually hand turning it) to clean up the face.

your tool looks better and quicker

[yeahmag]

Just to refresh my memory, you are trying to get more than 10PSI at hot idle? If that's not it can you remind me of what condition you are trying to cure?

[r_towle]

Interesting.
Might be worth getting a custom piston made and reaming the hole out just a bit larger....

[Jake Raby]

All these rules and myths change when bearing clearances are altered. I prefer to move a higher volume of oil through the engine and to do that requires a higher volume oil pump and altered internal clearances.

There are no rules, if there were I wouldn't enjoy it so damn much.

[worn]

All these rules and myths change when bearing clearances are altered. I prefer to move a higher volume of oil through the engine and to do that requires a higher volume oil pump and altered internal clearances.

There are no rules, if there were I wouldn't enjoy it so damn much.

Replying to Jake and Yeah.
I was worried that 10-15 psi at hot idle was too low for a new engine. That is what started it. I will find out tomorrow and if it worked will start tuning my mps - the horror.

What I think is interesting is we have numbers for bearing clearances, suggested tolerances for oil pump lapping and lash, but nada, zipperino, nothing when it comes to the system that is designed to actually control oil pressure. I had to hunt for diameters and spring constants and never found them.

So, I will post cylinder head and oil temps, rpms and hopefully oil pressure. And God willing I won't pop the cooler instead. This ruined my vacation and added stress when really, I wanted seat time with the world flying by my narp. (IMG:style_emoticons/default/driving.gif)

[nathansnathan]

What I think is interesting is we have numbers for bearing clearances, suggested tolerances for oil pump lapping and lash, but nada, zipperino, nothing when it comes to the system that is designed to actually control oil pressure. I had to hunt for diameters and spring constants and never found them.

The specs are as follows, from the Porsche 914 Technical Specs book
Spring for oil pressure relief valve length loaded: 39mm, on installation new 6.8-8.8 kg (15-19 3/8 lbs lbs)
Oil pressure switch opens at 6.6-8.8kg (2.1 -6 psi)

I don't see bore sizes anywhere, possibly 16mm bore?

[worn]

What I think is interesting is we have numbers for bearing clearances, suggested tolerances for oil pump lapping and lash, but nada, zipperino, nothing when it comes to the system that is designed to actually control oil pressure. I had to hunt for diameters and spring constants and never found them.

The specs are as follows, from the Porsche 914 Technical Specs book
Spring for oil pressure relief valve length loaded: 39mm, on installation new 6.8-8.8 kg (15-19 3/8 lbs lbs)
Oil pressure switch opens at 6.6-8.8kg (2.1 -6 psi)

I don't see bore sizes anywhere, possibly 16mm bore?

And of course springs mean nothing without the area of oil pressure they push against.

But I digress. Back on the road to full temp on a warm day. I made about 20 psi at idle with 10w30 oil. Not the Oil I would normally run, but I was worried about hitting the oil pressure trifecta. Bottom line, I see no reason to tear apart the motor now, I have the case I just pulled out and it shan't be wasted. A swap may be in the future.

I think the lesson to be learned is to check everything including bearing clearances, and not forgetting oil relief.

I learned another lesson as well. You cannot tune the factory fi without both an inductance meter and an a/f gauge. You may shy away from pbanders warning that all inductance meters aren't alike, but I scored one from ebay for 30-40 dollars that works like a charm. As with Ohms or Farads, Henry's are standards. A little change makes a world of difference and while the result are obvious on the air fuel gauge, it isn't from the seat. My goodness, what a sweet engine.

[worn]

What I think is interesting is we have numbers for bearing clearances, suggested tolerances for oil pump lapping and lash, but nada, zipperino, nothing when it comes to the system that is designed to actually control oil pressure. I had to hunt for diameters and spring constants and never found them.

The specs are as follows, from the Porsche 914 Technical Specs book
Spring for oil pressure relief valve length loaded: 39mm, on installation new 6.8-8.8 kg (15-19 3/8 lbs lbs)
Oil pressure switch opens at 6.6-8.8kg (2.1 -6 psi)

I don't see bore sizes anywhere, possibly 16mm bore?

And of course springs mean nothing without the area of oil pressure they push against.

But I digress. Back on the road to full temp on a warm day. I made about 20 psi at idle with 10w30 oil. Not the Oil I would normally run, but I was worried about hitting the oil pressure trifecta. Bottom line, I see no reason to tear apart the motor now, I have the case I just pulled out and it shan't be wasted. A swap may be in the future.

I think the lesson to be learned is to check everything including bearing clearances, and not forgetting oil relief.

I learned another lesson as well. You cannot tune the factory fi without both an inductance meter and an a/f gauge. You may shy away from pbanders warning that all inductance meters aren't alike, but I scored one from ebay for 30-40 dollars that works like a charm. As with Ohms or Farads, Henry's are standards. A little change makes a world of difference and while the result are obvious on the air fuel gauge, it isn't from the seat. My goodness, what a sweet engine.

And I should add. Buy the DVD if you must, but the tranny rebuild is just what the Dr (me) ordered. Being able to count on shifting is so cool. You either know what I mean, or things are working the way they should. (IMG:style_emoticons/default/driving.gif)

[yeahmag]

So you went from 10PSI to 20PSI at idle with all things being the same?

[0396]

Sub as its very interesting read.
After reading this, I pulled out my clean case. Looked down the by pass area and noticed that there's a ridge on one side. I measured the other non ridge side. The difference is .25mm. Ridge measures 72.25 non is 72mm.
Since this has been my long long over due project, can some one direct me to a shop for such a tool to clean out this ridge?
Thanks for the education on these type 4's

[cary]

I learned another lesson as well. You cannot tune the factory fi without both an inductance meter and an a/f gauge. You may shy away from pbanders warning that all inductance meters aren't alike, but I scored one from ebay for 30-40 dollars that works like a charm. As with Ohms or Farads, Henry's are standards. A little change makes a world of difference and while the result are obvious on the air fuel gauge, it isn't from the seat. My goodness, what a sweet engine.


Wasn't it amazing when you dialed it in with the A/F meter/gauge. (IMG:style_emoticons/default/welder.gif)

[worn]

I learned another lesson as well. You cannot tune the factory fi without both an inductance meter and an a/f gauge. You may shy away from pbanders warning that all inductance meters aren't alike, but I scored one from ebay for 30-40 dollars that works like a charm. As with Ohms or Farads, Henry's are standards. A little change makes a world of difference and while the result are obvious on the air fuel gauge, it isn't from the seat. My goodness, what a sweet engine.


Wasn't it amazing when you dialed it in with the A/F meter/gauge. (IMG:style_emoticons/default/welder.gif)

Well, I am still breaking it in. I fixed the odometer so not only do I know the mileage of the car I can count down to 500. With that said...preliminary results are way promising! (IMG:style_emoticons/default/laugh.gif)

[worn]

So you went from 10PSI to 20PSI at idle with all things being the same?

No, I changed to a thinner oil too. I agree though, I expected more - that is why I went with the 30 weight to start up with. At this point when I change the oil I am going with a heavier oil from a reputable company and just drive it. It is a summer car. I think I won't see the oil light and will be able to enjoy the car. New bearings and excellent journals, but the case - well I am not sure. Bearings - well maybe they aren't right. I just don't know, but my mood has improved.