Oil Pressure and Temperature (Part 3)

Hapy cinco-de-Mayo. My last post ended with some testing of the Porsche combination gauge with the modern VDO sensors. I'll pick up where I left off.

Where Were We?

Porsche combo gauge

After I wrote all of those posts about the TDI install, I realized that the little UltraGauge does not show my oil temperature or pressure. I can see the coolant temperature, though. When we drive up a long grade, we can see the coolant temp climb, and I wondered if the oil temperature was leading that charge upward, dumping heat into the oil:coolant temperature exchanger. So, I started collecting sensors to compliment the gauges I had lying around from back when I had the original air-cooled engine and thought that having an effectively oil-cooled engine without a gauge about oil was just silly. That's especially true when that engine was 5 meters away. In my usual fashion, I can't just run wires from sensors up to the dash and stick a couple gauges in back of my windscreen and call it good. Oh no. That would just be too easy. Instead, I got this notion that a combination gauge from a 70's-era Porsche could fit into the 3rd hole in a VW bus dashpod. I was right. But, does it work with the new VDO sensors? Why, yes it does.

Simple Initial Testing
I did some very simple tests of the sensor-to-gauge circuit in my last post. All I did was demonstrate that the gauge would respond to 12V, and if I had a sensor hooked up, the gauge would lift slightly off the bottom post. This is no casual "who cares" moment, in my opinion. Most important, this indicated to me that the big circular thing that I had shipped halfway around the world had operational gauges. But, would they respond correctly to real-world input from modern VDO sensors?

Temperature

water still steaming, needle at 9:00

Testing the viability of the oil temperature circuit was fairly easy, once I had the circuits set up again. While Boo loves me, I still had to tear down the tests for dinner. So, things needed to be set up again. This time, I included a small glass cup and a meat thermometer. Into the cup I set the sensor, wrapped with a grounding wire with a sender wire on the end. With the circuits powered by a big auto battery, I poured boiling water into the cup. The gauge moved from pointing down to 9 o'clock (correct for water boiling-point) which should be around 210*F. I thought I could confirm the test with the meat thermometer, but instead I found that the meat thermometer was not correct. How fun! In subsequent tests, I discovered that the probe on the meat thermometer needed far more surface area to reach the correct temperature reading. So, rather than triangulate on the proof that 9 o'clock means 210*F, I learned that my meat thermometer reads cool unless at least an inch of it is inside the target. Good to know for future baking. Anyway, this test passed.

Pressure

decoding the no-number gauge

Testing the pressure was not as fulfilling as testing temperature. For temp, we know the boiling point of water so if the gauge doesn't rise to halfway, then we would know that the sensor is on a different resistance gradient than the gauge. That would have been a real bummer. For pressure, I needed to depend on my Mity-Vac. The Mity-Vac has already proven its worth of the years as I have tried to bleed brakes and pull fuel through lines after running the tank empty (I know; bad owner). It also has a pressure setting though. With the circuits wired up, I set to it. I keep a short stretch of fuel line in my Mity-Vac kit, and that fuel line is the perfect size for the threads of the pressure sensor. I threaded one end onto the sensor and put a basic auto-adapter from the Mity-Vac kit in the other end. To that, I connected one of the short clear lines and then the Mity-Vac. This set up allowed me to send a pressure signal to the sensor. I jammed the grounding wire between the end of the fuel line and the sensor housing on the threads (establishing a viable ground) using that friction to hold the wire in place.

around 15 psi and around 1 BAR

Once everything was powered, I simply applied pressure with the Mity-Vac and watched the needle rise off the post. Translating "Druck Pressure" to PSI is a brief exercise in understanding German. Druck is effectively barometric or BAR and 1 bar = 14.7 pounds per square inch. So, to confirm the gauge is operating correctly, I needed to get "Druck" = 1 when I had just shy of 15 pound of pressure on the Mity-Vac. That succeeded: the needle on the gauge climbed to 1 and then slowly dropped as the pressure was slowly released, matching the needle drop on the Mity-Vac. I would have liked to have proven the mid-range of the gauge, but the Mity-Vac and my cobbled-together plumbing couldn't handle more than 15 pounds of pressure. I thought about getting my air compressor involved, but concluded that the test was already successful.

Conclusions
So, what did this tell us? That sensors bought today will correctly align with a gauge pulled from an old Porsche. We demonstrated earlier that the gauge would fit in the spare or "third" hole. I think we have a winner and I'm beside myself with excitement about it. I will clean everything up, replace some bulbs, run a wire bundle, and road-test everything, etc. when I have some time outside with Hapy. You can see in the pictures on this post taken during the tests that the gauge now sits nicely centered in the hole. I think it looks fantastic, but it's my bus, so its my choice. Knowing that I will have visibility into the lubrication system, and can start analyzing whether the oil temps are leading the temperature increases on long climbs is pretty exciting.. for me anyway. If my theory is proven, I can start looking into improving oil temperature management so climbing hills or mountains eventually have a much reduced impact on engine temperature. First, we need to see the data.

Thanks, as always, for following along. More next time-

Brake Fluid Replaced

When I had the wheels off, I tested the brakes, replaced some parts and replaced the brake fluid. Today's post covers that adventure.

Brake Check
The wheel saga I just recently posted about all started because the camping festival season is coming and I wanted to make sure my brakes were up for another season. I had remembered that my old rear hydraulics were bad and I hadn't checked the wear since the beginning of last season. Even then, it was a visual without removing the rims. So, after I got the wheels off, I checked things off.
Front pads: 60% remaining
Rear shoes: 70% remaining
Front rotors: unblemished along friction surface, rust along outside edge
Rear Drums: some scoring
Front calipers: unblemished, bleeder caps missing
Rear hydraulics: some surface rust, one bleeder cap missing

This was a far better state than I feared. I knew, however, that the brake fluid hadn't been changed in a long time. I couldn't remember doing it, but I must have when I replaced the rubber lines on the corners. That would have been 8+ years ago, so that fluid is way past due.

DOT3 or DOT4
Sometimes, I think the internet is the great religion creator. If you have a relatively straightforward yes/no question, you can find all kinds of long treatises waxing the pro's and con's but getting a real yes or no can be nearly impossible. In the case of DOT3 or DOT4 brake fluid, I have found some level of consistency, which I found rather surprising. So...can your older car which required DOT3 brake fluid can use DOT4: Yes. Can your newer-ish car which required DOT4 use DOT3? Only in tiny quantities, with the expectation that the system will be bleed-filled with DOT4 later. In other words, if you are running low on fluid and somewhere that you cannot buy DOT4, you can put in some DOT3 to get you back to civilization. DOT3 cannot handle as much heat as DOT4, so to prevent failure of your DOT4-requiring system, you should stick to DOT4.

As to me, and the old bus, I can run either. DOT4 can handle higher temps. Some folks say the DOT4 absorbs less water (and that's why it can handle higher temps), so you can change it less often. Like any good pseudo-science, there are great theories (sometimes with great single-experience stories), with little science, to support both of those claims. Enter religion. Regardless of whether they are accurate, I chose DOT4 for the higher temperature tolerance. I will assume that I need to change the fluid on a 3-year interval just like I was supposed to before. I was apparently a brake-system sinner before, letting it get so outdated.

Vacuum or Pedal
Once you decide on the fluid, you need to arrive at a method. If you have a helper, I encourage the pedal method. If you don't have a helper, but you have a MityVac, you can do the fluid change with it. Take ibuprofen first; your wrists and hands are going to hurt later. Regardless of your choice, the pattern is the same:
keep the reservoir topped off with new fluid while bleeding old fluid out of the bleeder furthest from the master cylinder. Once it changes color, and stops changing color, move to the next-furthest bleeder. Don't let air into the system at the bleeder or you will have that to deal with. Move from furthest to closest wheel until you've done all 4.

New Reservoir Hard Hose

I have come to realize that any time I am touching a system on this 50 year old bus that I haven't touched for a long time (or maybe ever), I should assume that any rubber part will need to be replaced. And, I should assume that I may touch something else that will fall apart on contact while the one thing I'm trying to get apart will require acts of God to get them separated. Never was this more true than the little rubber bushings that snug the connections between the hard plastic hose and the 2 brake fluid reservoirs. Yes, this bus has 2 of them. There is one sitting on top of the master cylinder like any normal car. We'll call this the lower reservoir (LR). Attached to the side of this is a plastic hose which runs up behind the driver seat to another reservoir. We'll call that the upper reservoir (UR). To be fair, it is much easier to add fluid up there, so that's probably why they designed it that way. The hard plastic hose stays connected to the hard plastic reservoir because there is a little rubber bushing between the plastic parts and then the whole thing is cinched together with a plastic thing that looks like a hose clamp with a slotted screw holding it together. Very sketchy. I figured the rubber bits on mine were gone, and that the damage to the steel behind and under the driver seat was caused by leaking brake fluid. The fact that fluid didn't stay in the UR for very long supported this theory. Knowing that parts on this old bus are either falling apart, rusted or otherwise seized, I got replacements for the hose, the rubbers and even the UR. I only ordered one grommet, and it turns out I needed 2. Check twice, order once. Don't assume the websites know your bus; you have to look yourself.

NLA
Unfortunately, the hard hose in its original length is no longer available (NLA). Only the Vanagon hose is available, and it is at least 8 inches longer. Longer is better than shorter, I suppose. That's definitely true for summer days and early Dark Star's, but this is a hard hose, so putting a few bends in it to make up the slack is not an option. On each end, the hose is fluted to fit around the nipple on the reservoir, so even though the web sites all say to cut the hose to length, that's all fine until you want to install it, and then the cut end won't fit on the nipple. And, because you cut it, it is not returnable. So, I suggest you don't cut it and do something clever... like I did.

You have 2 options:
(1) cut 8" out of the hose in the middle and figure out a way of joining the 2 ends without creating a new leak source or
(2) keep the hose the way it is and figure out a new way to attach the UR to the short wall behind the driver seat.

I went with option 2, knowing I could always fall back to option 1 if I couldn't get it where I liked it. The UR is basically a cube with a filler cap along one edge, pointing away from the dead-center of the cube at a 45* angle. Originally attached with the cap facing forward, this made filling easier than having it smack on top. We can use this angle to our advantage. If we rotate the reservoir 90* so the filler cap faces the center of the bus and then tilt the hose towards the door frame, eventually the cap faces straight up. It can be mounted to the wall like that. Before you get too far down this path, assemble the hose, rubber bits, plastic hose clamps, etc to the various reservoirs. Connecting to the LR is swear-word generating-ly frustrating, so prepare with a loud radio and sending the kids inside.

Install Hose

LR image from theSamba

I started by threading the one grommet around the hose and then the hose from above down through the hole in the floor. Since I didn't have a second grommet, I did not want to cause the hose to fail prematurely, so I did not thread it through the little hole in the driver seat pedestal. Instead. I routed it through the large square hole immediately in front of it. This may make it more susceptible to getting struck by camping gear, but I rarely put anything behind the seat, so that risk should be low. It also looks quite janky, and I will probably want to solve it properly before I re-install pedestal carpeting. Regardless, I decided to go with option 1 because I wanted to get this on the road for test drives, and knew I could change this fairly easily later.

Anyway, once threaded through the hole in the floor, it settles onto the nipple of the LR. It takes prodding to get it to sit on the LR nipple without damaging the rubber bushing and getting it deep enough that it won't leak. For me, it took wrapping the hose with a rag and grabbing on with channel-lock pliers to force it on that last bit. I found that putting the bushing on the nipple rather than seated in the fluted end of the hose was more effective as well. Tighten on the plastic hose clamp with a slotted screwdriver. Circle-back to check for leaks later, once you've put brake fluid in.

schematic from VWHeritage

The UR is easy to assemble with the hose, if you don't cut off the end. Placement of the reservoir, in my case, is temporary while I figure out a better long term solution. Ultimately, I will probably do option 2, and cut out a section in the middle. If I can do it right, I'll make the cut between the floor and the driver pedestal so the cut solution is not visible once the pedestal carpet is re-installed.

That's it for today. We got the DOT4 through out the system, using the vacuum method for the rear and the pedal-pump for the front. While the vacuum works, I greatly prefer the pedal-pump method. It is much faster and you get to hang out with a friend while you do it. After a test drive, the brakes settled down into a predictable response as the air worked it's way back through the master cylinder and up through the reservoirs. After several longer drives, the UR fluid level has remained unchanged, and the brakes are consistent. The brakes are ready for another season.

Thanks, as always, for following along.

MGB brake job

Continuing the journey of discovery within my new project, a 1978 MGB. Today, I cover the brakes.

Symptoms
Like any older car that hasn't seen recent maintenance, the brakes were spongy. The pedal didn't depress firmly, but it returned relatively quickly, so I concluded it wasn't a matter of failing lines, it was a case of poor hydraulics at the wheels, possibly at the master cylinder. I took a look at the pads on the front driver wheel and concluded that routine brake service was due. I couldn't know the condition of the rest of the system without tearing each wheel apart, but I didn't want the little car in pieces in my driveway while I did my discovery and then ordered parts. So, I just ordered all 4 wheels worth of complete replacements. With Hapy, this would have been $500 or more. For the MG, it was under $300 including new drums, wheel cylinders, rear mechanicals, rubber hoses and upgraded rotors / pads for the front. The only thing I didn't get in that package was a new or rebuilt master cylinder.

Front

Like everything on the MGB, the wheel is smaller than the VW bus. In one way this presents itself is in how the wheel assembly is put together. The front rotor for the bus sits on the outside of the wheel hub. So, when you want to replace the rotors, its a fairly easy job: remove the wheel, remove the calipers and the rotor is right there looking at you. On the MGB, it goes: wheel/rim, hub, calipers, rotor. What makes this important is that the hub needs to be removed from the rotor (and from the car) for the rotor to be replaced. In the picture on the right, here, you can see the hub to the outside of the new rotor. This install gets messy. Grease can get everywhere. I replaced the rotors, pads and brake lines, and spent a bunch of brake cleaner to keep everything nice and clean.

Rear
The MGB has drum brakes on the rear, much like the old bus. Also like my old bus, removing the drum off the mechanicals was not like opening a present. That is, unless you like spider eggs and brake dust... and rust. I had expected this, so I'd ordered a complete rear replacement, including the drums. The original drums might have been re-used, but I don't have the equipment to check. Replacement original equipment manufacturer (OEM) sourced drums were not expensive and there's a confidence created when the entire set up has been replaced at the same time. The original shoes hadn't been wearing evenly. It looked like someone drove it around with the handbrake on. It happens; no big deal. Once the drum is free, getting the rest of the old stuff off is pretty quick, but take pictures because putting it back together is like an industrial puzzle. Without a target picture, it gets tricky your first time. The picture to the right here is an "after" picture. Like the bus drums, check the adjustment by spinning the wheel and tightening / loosening until you have just a little drag on the spinning wheel. Of course, this can only be done once the drums and rims are back on.

Rubber lines
The MGB has only one rear rubber brake line. It is accessible through the rear passenger tire well, I like the simplicity of the engineering: hard lines run down either side of the rear axle, joining at the rubber line. These short hard lines should reduce the opportunity for pressure to fall out of balance between the two sides. From the rubber line, a single hard line runs from back to front and up to the master cylinder In the front, there are separate hard lines from the master cylinder to each wheel. The last foot or so is the replaceable rubber line.
Remember to wrap the threaded lines with plumbers tape prior to mating the rubber lines to the hard lines or you'll get leaks. Replacing the rubber brake lines is super important. These lines fail from the inside, so if you don't know how old yours are, definitely replace them. Of course, any time the hydraulic system is opened (other than to fill fluid), you need to bleed.

Bleeding and bleeding

pic swiped from Eastwood

Once the system is physically back together, it needs to be filled with brake fluid. Unlike oil, you don't just pour it in the top and wait for it to work its way down. The fluid needs to be pushed or pulled (bled) to the edges of the system. Which wheel to bleed first, second, etc seems to be quite the debate on the internet. Just my opinion, but I think doing the lines in order of shortest to longest makes the most sense. My thinking: once the shortest run is full of fluid, that line won't factor into the bleeding of the others. I guess, if the system is closed except for the cap on the master cylinder reservoir and bleed bolt on the wheel you're working, it really doesn't matter. So, pick a side in the debate and go at it. Since I was on my own for this effort, I used my MityVac at each wheel rather than the pumping-the-pedal method.

Bleeding the front end was relatively quick... once I re-did the rubber hoses with plumbers tape. The rear, though, was a challenge. No matter how much I worked both wheels, I couldn't stop the bubbles from forming. Then... nothing. No more fluid passed through. There was fluid in the reservoir, but nothing passed through to the rear. Pumping the brakes didn't affect it either. I started to think that my spongy brakes cause was the master cylinder. The brake master cylinder had lots of rust on it, but costs had me on the fence to replace it. I disconnected the master cylinder and put my MityVac onto the hard line that went back to the rear end. It held vacuum. So, I concluded that it was the master cylinder that was unable to hold vacuum or pass fluid so I ordered a replacement. I'll get into the master cylinder replacement another time.

As always, thanks for following along...

Not a Water Leaker

The early Vanagon gets a pretty bad rap.  After years of service, their cooling systems start to break down and pop leaks.  Oftentimes, owners will perform "for now" changes that become permanent.  This increases the bad rap, when its really a case of owner abuse, and misguided group-think.  It was these kinds of things that awarded it the nickname "WaterLeaker".  Knowing what issues the Vanagon encounters gives perspective on my water-cooled bus.  I'm going to hit on that today, with an update on my cooling system testing.

Rad Placement

Vanagon cooling system '83-'86
pic from BusDepot

Consider first, the location of the radiator.  It sits on the front of the Vanagon like any other car or van.  Unlike any other car or van, however, the engine sits in the very back.  This creates a cooling circuit like none other in that the coolant moves 15 feet forward and another 15 feet back.  This distance is ripe for problems. Often, the pipes that run along the under-body are attacked by rust.  If the wrong kind of water is put in the system, the rust can attack from the inside as well!  Once it starts, it is hard to stop, and for a long time replacement pipes were unavailable.  They are now, but they are spendy.  More often than the main pipe rusting, the couplings fail.  These can be replaced a little more easily (but it still ain't easy!).

Rear Heat
The rear heater is most often the source of leaks.  Not the core, mind you, but the circuit to and from.  So, many owners turn off the rear heater by disconnecting the cable and shutting off the valve.  The owner is sitting in the front where there still is heat, but woe to the rear-seat occupant on a winter's drive.  It's like driving around in an old (ill-repaired) air-cooled bus back there.  Grab a blanket!  Usually, its the connecting rubber lines that fail, but by turning off the valve, no coolant tries to rush through the lines and it seems like the problem is solved.

Front Heat / Defrost
The front system (core) rarely is the leak cause.  This is fortunate, but it is one more location where the coolant goes.  Unlike the air-cooled bus where the long runs for the defroster are handled with an air-tube, the Vanagon leverages the front radiator to get coolant to the front of the cabin.  This poses junctions, more hoses and valves, and with each additional junction, there is opportunity for leaking.

Bus?

pressure testing cooling system

So, what does this have to do with the bus?  Great question; I was getting to that.  The implementation in the bus is a franken-system that is part air-cooled / part water-cooled.  With the Jetta radiator under the belly, I have some of the benefits of a more typical radiator system in that the circuit is not 30 feet long.  Its closer to 10 (still long).  My heater core (Vanagon rear-seat unit) sits in the engine compartment.  The distance from heat source to heater core is probably less than 2 feet, so it is more responsive than a Vanagon system.  I am leveraging the front third of the original air-ducting (this is the air-cooled part), so no coolant moves past the mid-point of the bus (the front edge of the radiator).  This means that when there is a leak in the bus, I have 1/2 the area to search for it.

Pressure Test Results
I did the pressure test using the Mity-Vac, but I was only able to get the air-pressure up to around 10psi (pounds per square inch).  Even that took lots of pumping.  If you look at the picture above, you can see that I attached through the overflow bottle.  When it was at 10psi, the coolant level was pushed down below the low-point on the fill indicator.  When I released the pressure, it popped back up to just under the completely full line.  I took that to mean that there was sufficient pressure to force a leak had there been one.  There wasn't.

I'll test drive this weekend around tax preparations, and a dash to the mountain on StuporBowl Sunday.  Don't get me wrong, I love football, but the SuperBowl has become a media circus where the ad's and the halftime show take center stage... and the game usually sucks.  The NFC and AFC Championship games (and the other playoff games), on the other hand, were fantastic.  More next time...