VW Bus Cold Air Intake

Back when Hapy was getting regular long summer drives, I noticed that the engine bay would get pretty warm. Recall back to the Newberry trip report for example. So, I put together a cold air intake concept to drop the temp going into the turbo inlet. I really do not expect to notice much of a performance difference. While I understand a cold air intake can reduce intake temps, and improve engine performance by a handful of HP, I just don't think what I did will have that kind of impact. Still, it was fun to do.

For someone running the original engine, with the engine tins and surrounding foam in place, this modification makes absolutely no sense. The tins already effectively separate the hot side of the engine from the air intake. If you have lost your tins (or foam), and for some reason cannot replace them -or- you are running a modified engine where tins cannot be fitted, something like this might work for you too to keep the hot side from meaningfully impacting your intake air temperature. This whole bit is triggering memories of that old Burger King advertisement about keeping the hot side hot and the cool side cool.

 

Before I begin, today marks the Ides of March. I am not really sure how to recommend ways to celebrate that. Pay off your debts? Enjoy a celebration picnic with revelry and drinking? Wander out of town in an animal skin? Perhaps we can all just hope Putin will suffer Caesar's fate this day for the inhumanity he is visiting upon our Ukrainian friends. Whatever transpires, in a couple days, it will be St. Patrick's Day. So, I will just get some rest to prepare for that. Hopefully, we can tip a drink within 2 meters of dear friends to celebrate a post-pandemic Spring.

Orientation Thoughts

On topic, consider the VW bay window bus engine bay from the rear hatch (picture on the right is of a '68). Most to the rear on the left is an otherwise unused battery tray. Some folks (like late-bay Westy-drivers) have a luxury battery there to power the fridge when shore-power is not available. On Hapy, there are just a lot of wires, so it's actually not much to look at. The spare tire well hangs down towards the front, meeting the rear tire well. Above to the rear there is a tall open area that eventually reaches the finned ear behind the rear window. Running along the bottom edge, front-to-rear, there is a small lip or perhaps a pinch weld that's about half an inch tall. My thought: wall this in, and create a pass-through for my engine intake, isolating it from the heat generator (engine exhaust and the turbo). Keep the cool side cool.

Parts

My go-to for all things metal fabrication these days (at least for air movement) is HVAC flashing, and this is no exception: I started with some basic 20ga HVAC flashing that I had lying around ($0). Onto the air intake, I need to add a 90* turn ($14US from siliconeintakes.com) so the air filter which used to sit next to the rear end of the spare tire well can instead go into the new cavity. The last piece is pipe flashing (like this) which cost me about $18US to provide safe passage for the aluminum pipe through the HVAC. The air cleaner needs to fit through the hole left in the basic wall when the pipe flashing is removed, so getting one large enough for this purpose was important. I had some HVAC flashing lying around, but at the time I did this, a 4 foot by 3 foot sheet (common size) would have run about $20US. A smaller sheet would cost a little less, but not much. So, all-in this would cost around $50US plus your time.

Cleanup

paper model

I learned along the way that this wall idea is not as straight-forward as it looked. As I started trying to model with a large sheet of brown paper, I realized there were some wiring clean-up items left undone. I tidied up the wiring a little bit, and strung as much as I could into the upper rear corner where the fuel vent line passes into the new cavity, securing them together (and to the vent line) with a cable/zip-tie. Below this bundle of wires, at the rear-most bottom, a couple of wires need to pass as well, so that makes 2 gaps to manage. The front-to-back T-12 cable (See the Chasing the Hapy Electrical Gremlins posts for context) routes into the engine bay where the flat rear meets the upward angle of the rear tire well, so that's a third gap to seal. Last, the stock TDI engine management cable routes into the engine bay from under the center-point of the spare tire well, so that's 4 gaps. Had I planned for this when I did the wiring, I could have potentially cut this list in half, or even reduced it to one. I preferred to not revisit the electrical again this winter, after last winter's adventure. So, I made 4 distinct gaps for wires to pass through. I numbered them in the image of the paper model on the right, here.

Model with Paper

With the wiring bundled, I could start working on the wall... with a model. I started with brown packing paper. These days, so many things ship with large sheets of brown paper as the padding, and that stuff is nice and thick, and sometimes wide enough for things like this. It is also 100% recyclable (unlike the bubble wrap), so I'm doubly a fan. Anyway, I started with a basic measurement: 22 inches deep by 16 inches tall. Of course, I discovered that the hole is not square, and the 22 inch measurement is correct from the bottom of the rear wall to the point where the engine bay curves towards the fuel tank. The top is more than 24 inches from rear to top of fuel-tank compartment. Also, the section is not flat: the bottom curves slightly inwards while the top remains straight.

 

cardboard model 1

Then Cardboard

After a few rounds of test-fit, measure/cut and some added painter tape for strength, or for adding material for sizing, I arrived at an approximate paper model. I transferred the paper model to cardboard with a pencil using some tracing and some angle-square. Consider: the rear wall makes a 90* angle with both the top and the bottom, and (I thought) the rear wall is straight. The top run is straight, though I chose to cut some of the area away which would have been pressed against the spare tire well. I made this choice for 2 reasons: first, the vacuum control valves are mounted there, and I did not want to move them. Second, having a sheet of metal against metal like that would have created rattle noise I would have to solve. With my outline and wire bundle cut-outs defined, I cut the line with a razor blade and cleaned up the edges with scissors.

test-fitting a model

With this stiffer model, I performed another few rounds of test-fit, measure/cut until the cardboard wall completely covered the gap, the wire bundles easily fit through their respective gaps and the edges of the wall were clearly in a place where I could envision mounting. The final cardboard model, in-place in the picture on the right, also eliminated a large triangular shape from the lower front corner which would otherwise have set against the driver-side wheel well. Similar to the cut out from the spare tire well, having a large metal-to-metal contact area would create a vibration-noise opportunity. Looking back, this cardboard wall looked at least as good, if not better than, the final metal wall.

Then Model with Cardboard Again

The front and bottom have a lip I can easily attach to. The top and rear will need some kind thought and some creative drilling. One additional consideration: on the rear pillar, there are grounding points which cannot be disturbed. I decided to add a small tab on either side (above and below) to hold the new wall to the rear. The top will mount directly to the spare tire well for the front 2/3rds. The rearmost section of the top, will not get any treatment at all. I thought about it, and decided that there were already enough planned fastener points to hold the wall stable without adding another hole in the cabin floor. I transferred the cardboard model to another sheet of cardboard after a few repeated fit-attempts. I want to make sure the HVAC, when cut, will fit correctly. Last, I modeled mounting tabs with scrap cardboard and more blue painters tape so I would have them in the right place and the right size when I cut the HVAC. The picture above was taken before I added the mounting tabs to the model.

Plan the Intake Pass-Thru

note imperfect rear line

With the cardboard wall in place, that side of the engine bay looked considerably better... well, it hid what looked bad, anyway. Motivated, I planned the intake route based on the placement of the new 90* aluminum intake pipe. I made a rough cut in that general area of the cardboard wall and put it back in. The 90* pipe is too long on both ends. I needed to remove about 4 inches from the end that juts into the cavity, so there would be room for the air filter (7" tall from rubber grommet to chrome top) without it touching the side of the bus. The filter housing allows for up to 2 inches of pipe before it bottoms out, so there is some wiggle room for my cut on that end. Similarly, the engine-intake end of the 90* pipe needs to be shortened. Again, the silicone collar that attaches the new pipe to the air flow meter on the end of the intake allows for a couple of inches of play. I did not make the actual cuts to the pipe at this point, though.

 

The intake looked about right, so I added in the pipe flashing. I drew the edge of the flashing on the cardboard and then drew another set of lines 3/4-inch to the interior of the tracings. I cut the smaller square out of the cardboard, making a square that was about 6-1/2 inches per side. I tested that I could pass the air filter through that hole. Otherwise, maintenance of the air filter would require removing the entire wall. It fit, but barely, leaving about a quarter of an inch on each side (the widest part of the filter is 6-inch diameter).

Adjustments

HVAC test fit

I transferred the last model above to a sheet of HVAC, but I did not fit properly and had to do another round of cardboard before I was able to get a good HVAC design. The big barrier for me was the location of the vacuum valves (so probably not an issue for anyone else). Ultimately, I removed the valves that were no longer being used (anti-shudder and EGR), and moved the turbo controller to the rear mount. This freed up the front edge of the spare tire well. The second issue will appear for everyone who tries this: I thought that the rear inner wall was perpendicular to the floor and ceiling. It is not. Consider, the contour of the rear of the bus has a slight curve; the inner skin does as well. The picture just above on the right shows the deviation from pure vertical / 90* angle. That picture also shows on the bottom rear corner that the body panels do not have clean 90* transitions either. I cut off that little tab in future efforts. With these considerations, the models were working: showing me how to get to a viable wall.

 

Assemble

prepping the wall

For the second time, I transferred my cardboard model to HVAC flashing, complete with marks for mounting tabs. I cut the HVAC with my tin-snips, and formed the wire pass-thru's with pliers. For clarity, I marked the outline of the hole and then cut crossing lines through the center of that marked area. I folded the triangular bits of HVAC back upon itself to create the opening while also avoiding a sharp edge where the wire bundles would pass. With a hammer and dolly, I smashed the fold-back flat. By doubling the material at the openings, the wall was effectively stiffened; I had not anticipated, but will definitely appreciate that. For the upper rear wire pass-thru, I left a tang or tab nearest the rear wall that I could bend back into place, so the rear edge of gap #1 (visible in the pictures of the installed cardboard model) could get covered up once the wall was in place. Once I drilled the mounting holes in the tabs I set the wall in-place, marked the holes on the bus and drilled them out.

Pipe Flashing

wall installed

At this point, I considered how I would attach the pipe flashing to the HVAC. First, I transferred the square-ish hole from the cardboard model to the HVAC, and cut it. I need to be able to remove this section so I can clean the air filter. I drilled out 4 holes in the pipe flashing, one each per side, where the rubber had dimples for that purpose. I set the pipe flashing in place and marked the HVAC. These spots were within the folded-back HVAC, making the area thick enough to tap. Sweet! So, with a M4 (.75 thread-pitch) tap, I tapped the 4 holes in the HVAC. Into these threaded holes, I sent bolts from the cold-air side with thread-lock so these bolts will act like studs for the pipe flashing. The picture above on the right shows the studs through the HVAC.

Finishing

cold air intake

I moved the wall into place and secured it to the side of the bus with sheet metal screws. I had thought about tapping the holes and using bolts instead. The holes were too hard to access with a tap and I don't think this wall will be coming out with much frequency anyway. Even so, removing some sheet metal screws is not hard. With the wall in, I re-checked my measurements for cutting the aluminum pipe. Once verified with the permanent position of the pass-thru, I cut the pipe down. I pushed the shortened 90* aluminum pipe through the rubber collar and attached the air filter. I sent the air filter into the cavity, and maneuvered the not-filter-end of the 90* pipe through a connecting silicone collar to the rest of the intake. I set the pipe flashing against the HVAC and threaded on the 4 9mm nuts.

 

When I maintain the air filter, the process will be the same as this initial install: remove 4 nuts, loosen the hose clamp and remove the cold air intake assembly. After I clean the air filter, I would re-install by fitting the flashing atop the studs, finger on the nuts, get the pipes connected and then cinch down the nuts.

final install

Now, Hapy has a cold air intake, and the left side of the engine bay is no longer a complete visual downer. Instead, we have a nice clean wall and the engine will get colder air than it used to. This wall does have some small gaps, of course, so the air will not be as cool as it could have been. Perhaps I will circle back later with something on top of the wall to better seal the edges and pass-thru's. Longer term, I may apply a thermal layer onto the engine-bay side to help reduce temperatures even more. The picture on the right, here, shows it in its current (final) state, though a keen eye will see that I had not yet plugged in the AFM (air flow meter) when I took the picture.

 

This took quite a while to actually complete, having started before the 2021 winter holidays. I had other things going on, and this was a lower priority for sure. Also, there were multiple modeling cycles as I figured out the unique puzzles added to the driver side of the engine compartment from adding a TDI (and related vacuum control valves) to the mix.

That's it for today. Thanks, as always, for following along-

MGB muffled

Continuing the saga of getting the MG summer-weather ready, today's post covers some fun with the exhaust system. I started this post a few months ago and forgot about it, so recognize this was before I got through DEQ. So, I was doing things that were lowest possible cost in case I needed money to get through DEQ (think engine rebuild, etc).

Quiet You

In each of the test drives where I verified my fixes, I couldn't help but notice 2 things. First, the MG was loud as #$%!. Second was the unmistakable sound of an exhaust leak (pop pop pop). Out of curiosity, I pulled out a decibel tester app on my phone and checked. Parked in the garage with the doors open, sitting in the driver seat, I started the engine, and pushed the revs up to 3k and back down. I peaked at just shy of 100dB. According to the application, that's as loud as a blender. In the driver seat.

When we had the donorZed, I noticed that the exhaust was the same smaller-diameter piping as the MG had: 2". In the interests of getting every usable part off that thing, I cut off the rear muffler (which was surprisingly not that rusty), and the catalytic converter (cat). I figured that one of the two cars could use one or both of those parts, and with DEQ smog a part of ownership of these cars for the foreseeable future, one of them would eventually have use for the cat.

So, with the blender-loud exhaust reality in my face, I decided to start with the muffler going onto the MG. One would reasonably think that the crazy-bending exhaust plus muffler wouldn't "just fit". And, it sort of did.

Soup Can Exhaust

Most of the exhaust system on the MGB is coated with rust. The pipes, the little cherry-bomb mufflers, even the exhaust manifold. There is deep rust everywhere. This makes welding replacements all the more difficult because you have to get to clean steel to have a good strong weld. Fortunately, there are no-weld joiners available for most standard diameter sizes. These are somewhat simple in their design with a straight section of pipe with an integrated band clamp at each end. You put 2 cut ends of pipe into each end of this thing and tighten. Simple. It reminds me of the old-skool way to patching a hole in the exhaust: cut a soup can into a patch and get it to hold on with hose clamps.

All of this leads us to my noise reduction. The MGB had 2 cherry bomb mufflers in sequence which were not really muffling noise at all. So, I cut off the one on the back and fitted the one from the donorZed. With some careful cutting, I was able to get the 2 straight sections to abut, but there is not an off-the-shelf no-weld joining thing to connect them. So, I went back to the old-skool roots and cut up a small can, and hose-clamped it together. Yeah, I'm not that proud of that, but remember, this was done before I got through DEQ.

I re-used the hangers that were there from the cherry-bomb muffler, and it was ready for testing. Total cost: $0. I tested the noise level the same way: car in with the garage doors open. dB levels hovered in the low 90's, so I shaved up to 10% of the noise just by putting a bigger muffler on. Truth-be-told, the muffler from the donorZed looks an awful lot like the stock MGB muffler. During the test-drive, it became clear that the rubber had completely dried up, so I had to resort to holding the center section of pipe off the ground with bailing wire. Yeah.. not too proud of that either.

I'll get after the backfire in another post. For now, the exhaust is quieter, if not in a better long-term disposition. My thinking: don't attract unwanted attention by the tester at DEQ. That includes disconnected things under the bonnet and a super-loud exhaust which might imply something non-stock is going on.

Anyway, that's it for today. I'll post on my attempts to solve the backfire and other developments as I do. Thanks, as always, for following along-

MGB - coolant pump replacement (Part 1)

Last Fall, before I got too deep into fixing things on the MG, I took it to the specialists at British Auto NorthWest in North Plains. After addressing just about everything else, I am finally getting to the most important thing they called out: the coolant pump. Today's post covers that effort. This got really long, so I've split it into pieces. So, today we'll cover parts and the tear down.

Parts
Like any project, replacement parts are needed. At the very least, we need a new pump. These pumps aren't nearly as expensive as you may fear: $40US. These usually deliver with a replacement gasket. Verify before you commit.

Hoses. How old are your hoses? You don't know? Well, they're probably really old then. Best to assume that anyway. The hoses to/from the heater and the larger ones to/from the radiator are car-specific. Again, they are not terribly expensive unless you choose to go with silicone. Even then, the set is around $60US. The other hoses (from rear of head to pipe, and the smaller ones connected to the overflow bottle) are standard 5/16" hoses and can be purchased by the foot for next to nothing.

Hose Clamps. Look at the hose clamps. Rusty like mine? Get a slew of new ones. You'll need 4 larger ones for the hoses which route to the radiator. There are 4 smaller ones for the hoses leading to/from the heater plus 2 more smaller ones for the hose leading from the rear of the head, 2 more for the smaller hose from the radiator to the overflow bottle and one extra for the overflow bottle overflow hose. The other end of that hose on my MGB routed through the radiator mount, which seemed kinda weird. I'm not sure where it's supposed to go, but it probably doesn't need a clamp on that end. I found all clamps at Ace Hardware and they cost around $1US a-piece, so around $15US all-in.

Thermostat. If you haven't had any temperature issues, you probably don't need to change it. They are very inexpensive though, and getting the system apart for a thermostat afterwards just seems needless. So, I encourage spending the extra $8. I also replaced the thermostat housing ($6US), because mine was rusty and I replaced the housing gasket ($1US). The gasket does not ship with the housing, so buy them both. You may find it necessary to change the gasket even if you aren't swapping out the housing. My original gasket was smashed up against the housing and didn't look reusable. Often things like this are one-use-only. Also note that the housing does not deliver with the filler plug in the top. For a small brass cap, this is actually kind of expensive relative to everything else at $4.50US.

Temperature Sender. If your engine temp gauge isn't working, now would be the time to replace it. My gauge worked fine, so I didn't do this. They are around $7US, so in retrospect, I probably should have.

Fan Relay Switch. If your radiator fans are still triggered by the sensor in the radiator, you may want to replace this while you're in there. These range from $15US to $40US, representing the most expensive part so far. My fans are activated by a switch on the dash so I didn't need this. I highly recommend the dash switch. From talking to the British Auto Works guys, it sounds like those thermostatic fan switches are the system weak spot.

Fasteners. Of course I'm going to advocate replacing all fasteners. The thermostat housing is held on with 3 studs. These are 5/16-18 on the head-side and 5/16-24 pointing up. All of the bolts I replaced are 5/16-24 as well, just different lengths. I did not replace the tensioner bolt for the alternator, but did replace the 2 mounting bolts, the studs and nuts for the thermostat housing and the bolts for the coolant pump. Get stainless, if you can, so they don't rust-up on you again. And, they look pretty.

Tear Down
I was fortunate to have my step-son K2 available to help out again. So, while I finished routing and re-routing the fuel lines, fuel filter, flip-over shut-off valve, etc, he started the cooling system tear down. We had pushed the MG back into the garage for the Fall, with fears of the rainy season starting before we had a top. Our fears were met with sheeting rain on the other side of the garage door transom. Since we're dealing with old-skool coolant that animals like to drink (and then die from), it was all the more important to keep the cat out of the garage and the liquids well contained. Since I was working on the fuel system at the other end, we decided not to lift the front end, and used a dishpan to catch coolant.

K2 attacked the lower radiator hose from above, loosening the rusty clamp and then pulling off the hose from the lower radiator bib. Once the gush slowed to a trickle, he removed the cap from the overflow bottle. This allowed air into the system and more coolant came out. The coolant up to this point was really nice and green. I'd expected much worse. We poured the coolant into an empty coolant bottle for re-use and then returned to the job of removing hoses. Some of the hose clamps were very rusty. We used a WD-40 product for rust penetration to loosen them up. It worked for all but one which needed to get cut off.

old rusty pump on its way out

With the hoses off, and the coolant stowed away, we moved on to removing the coolant pump. After doing the work, I found a step-by-step on the MG experience forum, but I'll detail what we did... which, of course, wasn't what they had written down. First, we loosened the mounting and tensioner bolts for the alternator. These are 1/2" bolts. We released the tension on the belt and pulled the belt. We noted that the coolant pump shares one of the bolts with the alternator so we pulled both mounting bolts completely and moved the alternator out of the way. Now, we could get after the coolant pump. The pulley is reusable and the four bolts holding it to the pulley loosened by hand. I held the pulley with one hand and a small socket ratchet in the other. I still had the smog pump pulley, so in order of removal they go: bolts, pulley cap, smog pulley, accessory pulley. I set the cap and accessory pulley aside for clean-up. Once the pulleys were off, I could get after the coolant pump, using our 1/2" socket again. We were reminded of gravity as we loosened the last bolt and coolant started to flow from behind the pump. Considering how far we'd gone, this was our first spill.

We set the pump aside and shifted to the thermostat housing. The rust on the studs and the nuts on top was so bad that all three studs spooled out of the head rather than the nut threading off. The gasket was a mess and the thermostat was stuck to the head. Some quick work with a putty knife removed both. Last, I removed the overflow bottle by removing the 2 nuts from inside the passenger-side fender/wing and we were ready to clean some stuff up.

That's it for today's portion of this work. Next time, I'll cover cleaning up various parts, including the inside of the radiator, and re-assembly. Thanks, as always, for following along.