Relief, Oiling system in a type 4 Options

[eyesright]

My (home rebuild) engine is back in the car, oil leaks from bad oil filter/case seal (D'oh!) and flywheel O-ring cured...pools of oil on the floor reduced to only a drop here and there.

I also changed the stock oil temp sender to the appropriate sender for the VDO gauge (miscommunication with the guy taking my order @ PP probably, whom I thought said just use the stock sender) so now I have oil temps, oil pressure, and head temp.

Okay, oil pressure is way low (less than 5 @ idle, 15-20 @ speed but 80 when cold.) and on my first drive last night (probably 70F outside temp) my oil temp worked its way up to 225F. So, higher than normal oil temps and lower than normal pressures suggest I'm losing pressure as the relief valve allows oil to return to the sump instead of passing to the cooler. I'll get some marking solution to see if that's the problem and probably figure out a way to hone the seat. I understand I don't want to take off too much, maintaining the chamfer

Warren, thanks for your research and work. If not for that and the gauges I bought just to be cool, my engine would be toast soon.

Tim

[0396]

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.

Pm sent on tool. Thanks

[r_towle]

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.

you got 10 psi from honing the relief bore?
Did you change the oil pump?

Rich

[eyesright]

Warn

I located the relief valve seat by looking up the bore. It didn't make sense the times I inspected it before, tryiing a spacer under the piston, different spring, honing the piston top, etc. but your photos and explaination made it all clear.

So I got some marking fluid which showed a bung on the seat. The seat, incidently, appeared at most to be 1 mm on one side and probably 2mm on the other. for what ever reason, the bores didn't apper to be concentric. In any case, just a small seat like that actually is a comparatively large area since its on the outer circumference and should make a differrence in opening and closing pressures.

So with wet/dry paper glued to the top of the piston and trimmed to the bore, I spun it by hand against the seat. I ended with 600 grit and the seat shined! Nice and smooth.

So I run it and ....same low oil pressure, about 5 @idle, 15-20@ speed and oil temp slowly climbing to 220F. Went Ace hardware and found a stiffer spring, the gauge was about 20% larger and it was 1 cm longer. Maybe under heat it faded but anyway...., same pressures and temp!

Well, shucky darns! So my options are still

!) clearance problems

2) pump problems

3) some other relief/regulator problem

4) cheap gauge/sender

5) or NO problem... VW Porsche made this one this way and its going to run like crazy for 200K miles. I've put 1000 break-in miles on it now and my know-it-all advisor/pal says I if it was really a problem I'd probably know it by now.

I think I will order a new piston just to rule out the piston bore being part of the problem. Any comments anybody?

[76-914]

Verify your "cheap gages" or you'll be chasing your tail. It's the same as trying to tune your engine w/o an AF meter. Hit n miss. (IMG:style_emoticons/default/mad.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.

you got 10 psi from honing the relief bore?
Did you change the oil pump?

Rich

I got five to ten in the end. So I am at about 15 at idle. I can easily make the Porsche manual spec, which is stated for 70 degrees c. But I am at more than 110 degrees c. That still leaves me in the white with the new style gauge, or probably wher the beginning of red used to be. The pressure runs strong until about mid gauge. So the first twenty minutes are great. Btw cooling system works like new.

Now I am worried about cylinder head temps vdo under the spark plug. Going up hill, and hills are gentle here, at 65 brings me quickly to 400 plus. I went with 2056 and calculated 8.5 compression and am about ready to indefinitely jack stand my 914.

[yeahmag]

The VDO CHT is not temp compensated. You have to do math to use it. Switch to an M1000 from Aircraft Spruce. I love mine!

[r_towle]

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.

you got 10 psi from honing the relief bore?
Did you change the oil pump?

Rich

I got five to ten in the end. So I am at about 15 at idle. I can easily make the Porsche manual spec, which is stated for 70 degrees c. But I am at more than 110 degrees c. That still leaves me in the white with the new style gauge, or probably wher the beginning of red used to be. The pressure runs strong until about mid gauge. So the first twenty minutes are great. Btw cooling system works like new.

Now I am worried about cylinder head temps vdo under the spark plug. Going up hill, and hills are gentle here, at 65 brings me quickly to 400 plus. I went with 2056 and calculated 8.5 compression and am about ready to indefinitely jack stand my 914.

Per post above me here, what was the ambient temps outside?
What is your timing set at for full advance?
Type of fuel used?

All three affect the temp reading.

Test with better fuel.
Test one degree at a time as you reduce overall advance at 3500 rpms.

Between the fuel, your type of plug, and your advance, you should be able to dial it in for your elevation and climate.

Rich

[eyesright]

worn

I agree with yeahmag. My VDO CHT shows 350F. Len Hoffmann did my heads so I wasn't too worried while I sorted out some other stuff. Then I got an IR thermometer which showed 200-210F inside the tin on #3.

Like 76 says, verify. I'll dump the temp sender in a pot of boiling water when I get a chance. Then I want to try different gas grades. And do the same with the oil temp sender at the next oil change. And double check the IR thermometer too. And after all the stuff I've done behind you I wasn't TOO worried but I have a direct reading pressure gauge that I'll hook up.

If I was serious I'd spend the bucks on aircraft stuff ....good advice. Mine's a driver. The VDO's look good and I just want to calibrate and look for consistancy. But I may put some greeen and red stickers on the gauges. That'll make my aviation buddies smile.

[eyesright]

PS Worn, oh yeah, one more thing. When you open the engine lid after a run, does it SMELL and FEEL hot?

I had my cooling flaps hooked up wrong once on a prior car and when I got back from a short break in run I could tell things were not right. This was a stock car with no gauges. It just SEEMED too hot. And I knew I didn't understand the cooling flaps when I put it together so that's the first place I looked into. Figured out the error of my ways and set things right and ran it again. The engine bay was hot but a "normal" hot.

My gauges are/will be good information but my engine runs smooth, starts hot or cold, plugs look good, doesn't ping on regular even when I floor it @2000rpm, and when I open the engine bay after a good run it smells and feels normal. (Hoffmann heads and case decked, Raby 9550 cam kit, 2.0L, FI)

I'll keep looking into the gauge readings, but mine's been on jack stands too long and too often. The next time it takes an indefinite rest on jack stands it will be because of REALLY bad news. I hope I don't have to eat my words here on the forum but so far my engine runs well enough that I think I am enjoying worrying it just enough to keep looking as I DRIVE!!!!

Good luck and keep posting. I'm getting good ideas from you and the rest of the posts.