Lubrication Notes (upd 03/08)

Moderators: Sluggo, Amskeptic

Gnasha
I'm New!
Status: Offline

Re: Lubrication Notes (upd 03/08)

Post by Gnasha » Sun Aug 02, 2020 11:41 am

SlowLane wrote:
Sun Aug 02, 2020 8:04 am


Gnasha, I think that getting 3 bar in a score of seconds just from using the starter is quite good. Don't forget that the starter only cranks the engine at a fraction of idle speed. Once the engine catches your oil pressure should come up quickly. I would suggest a pre-oiler to load the passeges for your first startup, but you've already done so with your cranking.
I should also add during the initial start up on the starter all plugs were out to further reduce bearing pressure and increase the rpm.

User avatar
asiab3
IAC Addict!
Location: San Diego, CA
Contact:
Status: Offline

Re: Lubrication Notes (upd 03/08)

Post by asiab3 » Mon Aug 03, 2020 12:49 am

You started it without plugs? You should file a patent ;)

What oil pickup tube was used, in which case? A new (short) pickup tube must be matched to one of the newer cases that has the Technical Service Bulletin (TSB)-described modifier oil pickup holes.

Are you familiar with these changes or should we post some diagrams?

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

Gnasha
I'm New!
Status: Offline

Re: Lubrication Notes (upd 03/08)

Post by Gnasha » Mon Aug 03, 2020 2:21 am

asiab3 wrote:
Mon Aug 03, 2020 12:49 am
You started it without plugs? You should file a patent ;)

What oil pickup tube was used, in which case? A new (short) pickup tube must be matched to one of the newer cases that has the Technical Service Bulletin (TSB)-described modifier oil pickup holes.

Are you familiar with these changes or should we post some diagrams?

Robbie


It’s a GE case , it’s was built as stock with the shorter oil pick up tube converted from hydraulic tappets. The next engine GD will have a long oil tube. I’ve decided not to use the cross case drain from relief valve to oil pump suction.

sami
I'm New!
Location: Chattanooga, TN
Contact:
Status: Offline

Re: Lubrication Notes (upd 03/08)

Post by sami » Mon May 03, 2021 3:09 pm

Hi everyone,
First time posting on this forum. My name is Sami and I'm the proud owner of a '79 convertible bug and a '75 Westfalia.

I read this informative thread, though I'm not sure I'm ready to be tested on it yet :)

So here's the issue with the '75 bus, which has a 2-liter AVP-rebuilt engine on an AE case with hydraulic lifters, but is otherwise stock with the original fuel injection. I installed the engine over 15 years ago and it has about 15k miles on it. After spending 10 years overseas, I'm back in the U.S. and trying to get her back on the road, and reliably so.

Symptom: Castrol Syntec 5w-50. Solid oil pressure when cold: 40 psi (on VDO gauge) at idle and 50 psi at speed. As the oil warms up, oil pressure drops continuously: 180F/28psi, 220F/22psi. These figures are all at speed, over 3,000 rpm. At idle, the idiot light is a bright and ominous red of course.

The leading hypothesis is that despite the low miles, the engine has loose bearing clearances, though I’d like to try a few simple things before tearing the engine down.

I took out the oil pressure relief valve. I assumed from reading Colin’s original post in this thread that there should have been some tension on the spring as I unscrewed the plug, but there was none.

Question 1: Is this normal?

The piston has some scratches, though I see no reason why these scratches should impede travel. But pushing the piston up and down the bore with a magnet, I find that travel is not as smooth as it should be.

Question 2: can I and should I hone the bore?

I also accessed the hole where the oil pressure control valve used to be (between the cylinder 1 pushrod tube), but it appears to have been condemned and I found a tappet adjusting screw in there.

Question 3: is this normal procedure?

Back to the oil pressure relief valve: I ordered and received a new spring and piston from Van Café. The new spring is about 1/8th longer and feels just a tad stiffer than the old one. (Not sure how to ascertain whether either spring meets the specs found in Bentley: 39mm at 6.8 to 8.8 kg.)

As you can see in the picture, the Van Café piston on the left has square edges, whereas the edges of the old piston (on the right, the one with visible scratches) are chamfered.
oil-pressure-relief-pistons.jpeg
oil-pressure-relief-pistons.jpeg (55.2 KiB) Viewed 36 times
Question 4: Does it matter whether the piston edges are chamfered?

I also had a peek into the bore and noticed that there is small step, with the bore size maybe 0.5 mm smaller at the top. See picture.
oil-pressure-relief-bore.jpeg
oil-pressure-relief-bore.jpeg (67.64 KiB) Viewed 36 times
Question 5: Is this step typical/normal? Can the piston not get caught under this step?

I’m probably overthinking things, as usual :) :study:

Thanks,
-Sami

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: Lubrication Notes (upd 03/08)

Post by Amskeptic » Mon May 03, 2021 6:13 pm

sami wrote:
Mon May 03, 2021 3:09 pm
Hi everyone,
First time posting on this forum. My name is Sami and I'm the proud owner of a '79 convertible bug and a '75 Westfalia.

I read this informative thread, though I'm not sure I'm ready to be tested on it yet :)

So here's the issue with the '75 bus, which has a 2-liter AVP-rebuilt engine on an AE case with hydraulic lifters, but is otherwise stock with the original fuel injection. I installed the engine over 15 years ago and it has about 15k miles on it. After spending 10 years overseas, I'm back in the U.S. and trying to get her back on the road, and reliably so.

Symptom: Castrol Syntec 5w-50. Solid oil pressure when cold: 40 psi (on VDO gauge) at idle and 50 psi at speed. As the oil warms up, oil pressure drops continuously: 180F/28psi, 220F/22psi. These figures are all at speed, over 3,000 rpm. At idle, the idiot light is a bright and ominous red of course.

The leading hypothesis is that despite the low miles, the engine has loose bearing clearances, though I’d like to try a few simple things before tearing the engine down.

I took out the oil pressure relief valve. I assumed from reading Colin’s original post in this thread that there should have been some tension on the spring as I unscrewed the plug, but there was none.

Question 1: Is this normal?

The piston has some scratches, though I see no reason why these scratches should impede travel. But pushing the piston up and down the bore with a magnet, I find that travel is not as smooth as it should be.

Question 2: can I and should I hone the bore?

I also accessed the hole where the oil pressure control valve used to be (between the cylinder 1 pushrod tube), but it appears to have been condemned and I found a tappet adjusting screw in there.

Question 3: is this normal procedure?

Back to the oil pressure relief valve: I ordered and received a new spring and piston from Van Café. The new spring is about 1/8th longer and feels just a tad stiffer than the old one. (Not sure how to ascertain whether either spring meets the specs found in Bentley: 39mm at 6.8 to 8.8 kg.)

As you can see in the picture, the Van Café piston on the left has square edges, whereas the edges of the old piston (on the right, the one with visible scratches) are chamfered.
oil-pressure-relief-pistons.jpeg

Question 4: Does it matter whether the piston edges are chamfered?

I also had a peek into the bore and noticed that there is small step, with the bore size maybe 0.5 mm smaller at the top. See picture.
oil-pressure-relief-bore.jpeg

Question 5: Is this step typical/normal? Can the piston not get caught under this step?

I’m probably overthinking things, as usual :) :study:

Thanks,
-Sami
Try running 20-50w. As temperatures warm here in the Northern hemisphere (and you better not be posting from Auustralia or Santiago), we need to keep the minimum viscosity up where the factory recommended. Compare your new spring to stock specification, and you can even do a pressure test to "installed height" with a simple bathroom scale. Can't say I like any roughness or hanging up in the bore, and I do not like the lack of chamfer. Any honing you may choose to do runs a grave risk of contaminating oil galleries in places you cannot easily clean out if this is an installed engine. Run your original piston if it is not noticeably looser in the bore. Piston is not likely to get caught unless it gets caught during your practice run up the bore. Oil pressure does act upon the crown of the piston, 22 psi is certainly enough. The only pressure "dump" that occurs in that bore is if the piston gets pushed down enough to open the relief port. Low oil pressure usually means the spring will have the piston right up against the seat.

I am far more interested in the control valve bore. That has a relief port too. If your case is machined for a control piston, there better be a piston and a spring behind the screw your report. Otherwise, serious loss of pressure. Have you taken this engine in to a mechanic or have you been the sole caretaker?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 206,865 miles
Naranja - 77 Westy . . . 132,040 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 94,225 miles

sami
I'm New!
Location: Chattanooga, TN
Contact:
Status: Offline

Re: Lubrication Notes (upd 03/08)

Post by sami » Mon May 03, 2021 7:53 pm

Hi Colin,
Thanks for your reply. Yes, I'm in the midst of an oil change with Mobil 1 20W50 "red label" waiting to be poured in.
I've been the sole caretaker, except for the 10-year period while abroad, during which my brother took it to "this neighborhood guy" for brakes, steering, and an oil change (the "Dynalube" oil filter does not inspire confidence.)

I appreciate the warning on honing, as the engine is in situ. Even past the small "step" in the bore, the piston's travel feels gritty, but not so gritty that the piston would defy gravity.

For the control valve bore, I took a couple of pictures. There's something in there, but it won't budge, almost if glued in.
Thanks,
Sami
IMG_5408.jpeg
IMG_5408.jpeg (107.71 KiB) Viewed 26 times
IMG_5417.jpeg
IMG_5417.jpeg (60.41 KiB) Viewed 26 times

kreemoweet
Getting Hooked!
Location: Seattle
Status: Offline

Re: Lubrication Notes (upd 03/08)

Post by kreemoweet » Wed May 05, 2021 6:50 am

sami wrote:Question 5: Is this step typical/normal? Can the piston not get caught under this step?
All VW-produced Type 1 engine cases I've seen have that step, and VW provided .5 mm oversized relief/control pistons
for those engines, for use with appropriately resized relief piston bores. It seems reasonable that the same would apply to the Type 4 engines. The top of the piston never
goes below that step in operation, so can't get caught, even with non-oem unchamfered pistons. I've seen troublesome
burrs produced at that step where folks have been sticking screwdrivers or other rude tools into the bore.

sami
I'm New!
Location: Chattanooga, TN
Contact:
Status: Offline

Re: Lubrication Notes (upd 03/08)

Post by sami » Wed May 05, 2021 7:58 pm

Quick update:
I used a bathroom scale to compare the old and the new oil pressure relief springs. At a compressed height of 39mm, both springs gave the same reading of 18.6 lbs (8.4 kg).
I (very gently) polished the bore with 1000 grit, then 2000, then 5000 grit wrapped around a peg. That did the trick and the piston now travels smoothly.
Reassembled everything, including the plug in the oil pressure control bore with the odd tappet to limit piston travel. Filled the engine with 15w-50 Mobil 1 and started the engine.... The cold oil pressure at idle is now at a miraculous 60 psi, the pressure at which the oil relief valve is supposed to open.

As far as I can remember, the oil pressure has never been this high. And only two adjustments were made: the polished oil pressure relief bore (unlikely to have mattered) and the slightly heavier oil. Maybe a third adjustment, too: conceivably, the tappet in the oil control bore may not have been properly centered when I put it back in, pushing the piston further in? But I'll take the bus for a spin tomorrow to see what happens once it warms up.
Thanks for listening.
Sami

Post Reply