Oil Pressure and External Oil Cooler

[Piledriver]

Good point.

Oddly, inaccurate instrumentation/dashboard bling is one of the few things I agree with from Gene Bergs little blue book.

OTOH you can actually buy good instrumentation//sensors these days.
They're just ~never sold in auto parts stores.

[Mitchell]

Steve, I do not particularly like the adapter, but it was easy to install with the engine together. I am trying to decide where to install the return oil on the next engine while it is apart.

I also agree with the comments regarding the gauges. The one currently installed is a VDO gauge with the sensor being a combination sensor. One for the oil light and one for the gauge. I do have a mechanical gauge, so for peace of mind I will install it just to see how they compare. I also know about Lucas, my MGTD and Triumph Stag both have Lucas components. This is what makes it fun.

Mitchell

[Marc]

...The one currently installed is a VDO gauge with the sensor being a combination sensor. One for the oil light and one for the gauge....

I've run many of those. American General even used them (the 0-150psi model) on the `78/`79 "Jeeps" they built for the USPS. Be aware that they were made in both 70 and 80psi models, and if those gauges and senders are mismatched there'll be a slight error in the reading - ~14%.

Their biggest liability is the potential for sluggish gauge response, as Berg alluded to in his article. It's not really true though, IF the sender is oriented so that an air bubble cannot build up inside. Those old mail trucks were all "mechanical totals" by the `90s - worth more in scrap than they were on paper. We weren't allowed to put any more money into them than the absolute minimum. They had AMG versions of the 2.0 Audi/Porsche motor, and it was classic for carriers to drive them without checking the oil until they had less than a quart (including filter) left in them...and more often than not, almost no coolant either due to headgasket leakage. They'd seize a piston and be abandoned, the route would get finished with a spare vehicle and later that night someone from the shop would head out with a tow truck, 3 quarts of oil and a couple jugs of coolant - all that was needed to put them back in service for a little longer (those little suckers were tough!). Point is, if you started one up without adding any oil you could watch the pressure gauge bounce back and forth against the pegs almost faster than the eye could follow as the pump alternately gulped air or oil....sluggish gauge response, my eye!

Always mount these senders "upside-down" (with the fittings at the top and the electrical connections pointed down) so no air bubble can build up, and they work just fine.

[E_bug]

Sorry to cut in but i think my question belongs here.
Is it bad to mount the oil cooler in the front. (Extra oil cooler) Is the stock pump adequate for such a task. Is it advisable for hot climates hot street situations and occasionall track use?

[Marc]

By front, do you mean all the way in the front of the car? That's popular with the road-racer set; personally I find it foolish to push oil all the way up there and back, with all of the inherent potential problems, when it's so much simpler to just duct air to a rear-mounted cooler - even if it needs a booster fan sometimes.
IMO all of the work needed to put a cooler up front would be better put into a dry-sump installation.

[Piledriver]

I tend to agree.

A near stock ACVW, particularly including a properly done t4 conversion, is in it's element in high temperature locales.

If you have oil temperature issues with a stock doghouse cooler, the better solution is typically to figure out what you are doing wrong, because the hardware works fine installed/sealed properly.

(if you have a huge hipo or boosted motor, additional help may be needed, but then a dry sump becomes a really good investment)

[E_bug]

Yes i mean in the front. The car will be boosted and driven in Greece where i live now and we get pretty hot here around summer time. Today was around 22c noon time .
I was thinking that for at least 100% hp increase over stock i would have to overbuild the oil cooling system too.
I am open to suggestions from the pros,!

[Marc]

The advantages to a dry-sump system include increased oil capacity and slightly improved weight distribution, but the big attraction is that you'll never have to worry again about starving for oil in a hi-G corner or under hard acceleration. You also don't need an extended sump, improving your ground clearance and potentially allowing lowering of the chassis.
I'm unaware of any system which doesn't have size limitations on the lower pulley, so if you need to maintain stock cooling fan speed you'll have to run a smaller-diameter generator pulley (from a 912) OR there's now at least one cogged-belt solution.
Even the most compact single-stage dry-sump pump (like CB Performance offers) may have some interference problems with some exhaust systems - it may be necessary to extend the pipes a bit, which can make for a tight fit with a stock Beetle rear apron. You mention "boosting", if that's going to be via turbocharging the exhaust-clearance issue may be more involved.
All things considered, dry-sump is the way to go if you'll be doing any road-racing.

[Piledriver]

FWIW, the CB dry sump pump will clear on a T4 upright conversion or with the stock cooling fan etc with only minor clearancing and resetting the pump drive depth.

It will work better on a T4 than on a T1, if modified so each stage goes straight across and the maze of tiny passages are plugged off... Not even hard to do. Adding much larger fittings to the suction side of the 21mm pressure stage highly recommended. On a T4, this gives you a 26mm scavenge stage where the original pump in<>out are, and the pressure stage must be plumbed externally. (The T4 is already full flow, so it's quite flexible as to plumbing)

[Mitchell]

I tried to post a reply Sunday evening, not sure where it went. Sorry for taking so long to post a reply, but I was gone this weekend and did not have access to the internet.

The sending unit installed is a VDO -360-006 that mounts in the original oil pressure port. It has two electrical connections, one for the idiot light and one for the gauge. Marc in your post you mentioned to mount the senders "upside-down". Are you referring to a different type of sender?

I will order a new gauge. The one installed is a 70 psi gauge and the sender is for an 80 psi gauge.

[Mitchell]

I finally switched to a mutligrade oil I had been using 30W, but finally changed to 20W50 Castrol Oil this past Sunday. Before changing the oil I took some readings to compare the grades of oil. One thing to remember is the 30W oil had been used and was 3 to 4 months old. When I change oil again I plan to use 30W and take reading with fresh oil.

30W Oil, Outside Temp 79 F
RPM Oil Temp Oil Press Head Temp
450 cold 40 <120 ( lowest reading on gauge)
900 120 20 250
900 160 8 270
900 175 5 270 ( oil light on)
2000 190 11 270
2500 190 20 270
3000 190 25 270

20W50 86 F
450 cold 56 <120
900 160 56 <120
900 200 52 <120
900 250 40 120
900 260 20 140
900 270 10 170
2000 270 19 170
2500 270 23 170
3000 270 29 170

After allowing the engine to run for 40 minutes the oil pressure at 900 rpm's was 7 and the light was on.
Reading such as 7, 23 56 are estimates I read from the gauge. I do not have any digital gauges. Also all reading were taken while the car was sitting in my garage starting from cold.

Thanks,
Mitchell

[helowrench]

5-30 is a bit to thin, and gives me a flickering oil light.
10-40 seems to be what my car likes (well over 100k miles)
Edit: I only bring this up, as we have seen quite a few cases where too high a viscosity of oil, can actually cause low pressure when hot, as the bypass valve engages, and more oil does not flow through the cooler.
From what I have seen, the trick is to run the thinnest oil that your particular engine will take, and not trigger the warning light.

[Mitchell]

Thanks for the information. I replied last night, but for some reason the reply was not posted. Instead of using 30W for the next oil change I will use 10-40. I live just South of Houston, so our temperatures are relatively the same.

Thanks,
Mitchell

[Mitchell]

I recently made a few changes to attempt to improve the oil temperature. I noticed the hot air coming from the # 3 and 4 cylinders passes over the return line from the external oil cooler. I made a small deflector plate to prevent the air from blowing directly over the fitting. While under the car I was checking the fan on the external cooler and noticed there was not much air flow through the cooler. I never checked this when I installed it, I only made sure it was working. The cooler is installed over the trans axle and bolted onto the rear shelf of the beetle. I reversed the fan direction and air movement was improved significantly. Apparently the fan was blowing directly into the shelf and not allowing the air to move. Now the air is being drawn through the cooler.

After doing this I took the car out for a test drive and was pleasantly surprised by the results. The oil temperature barely reached 200 F. It was 95 F outside. The oil pressure was higher and at idle the oil light stayed off.

I just returned from the Eureka Spring show in Arkansas and the car ran very nice. I did not drive the entire 600 miles as I was meeting someone and we towed the car part of the way. Before I left I did add a tennis ball to prop the deck lid open and noticed a small improvement. When driving the oil pressure is real close to the 10 psi per 1000 rpm.

The car is running better than it has in a long time.

[Piledriver]

Cool. (Literally)

Sometimes it helps to just look at everything from 30,000 feet (or laying on your back for awhile) to gain clarity.

I bet you could run straight 30 again if you desire, but I use Rotella T6 5W40 in everything.
(Plenty of zddp, but so does Rotella HD30 or HD40, at much lower cost... Wolfs Head's finest, with a Shell label)