Oil cooler added (and sway bar improvements)

Testing the Spyder on public roads brought new data: she was running too hot. Even on a cool morning, ambient temps 80F, driving easy (30-45mph) on flat roads, the oil temperature gauge crept up past 80, past 100 (i.e. 212F), up near 110C. That’s close to 230F, and at that temp VW gurus say you better shut ‘er down and investigate. Good modern oils like the Brad Penn we’re using don’t really mind those temps, and racers run long-term with oil over 260F.

But 230F in a Type 1 means the heads are probably too hot. Hot heads on a Type 1 engine are bad for longevity.

I ran the car for over an hour one morning, took video, and shut down when the gauge got up over 105C.

There were issues along the way as well: the front tires rubbing a bit on the turns, so I raised the front a little. But the temp issue meant immediate action.

I installed the underpan and tested again.

—And that got us no significant relief.

I went ahead and rechecked the tappet clearances (they were good) and pulled the cover off the oil cooler on the off chance there was an obstruction (nope, all clean). I carefully arranged the spark plug booty thingies over the holes in the fan shroud and drove the car again for an hour in ambient 80F.

Temp rose very slowly this time and ended up around 210F.

Oil pressure was about 45 lbs at 3000 RPM at that temp. 

I had not yet allowed the oil temp to plateau or stabilize at whatever its max was going to be, but after an hour of slow stop and go driving I figured my readings were getting close to what they’d be at max. Given the low ambient temps I decided I needed additional oil cooling to take them down 20-25F.


*Mocal “Sandwich” adaptor plate with 180F thermostat and adaptor fittings to run AN-10 fittings.

*Mesa/Empi 48-plate oil cooler and fittings to adapt that to AN-10

*6-inch universal fan

*190F thermostat switch for the fan

I looked one more time at mounting this thing to the beam in front, and decided yet again not to risk trying to plumb hoses or hard lines through the passenger compartment of the car. I don’t know if the oil pump on the engine would be enough to keep pressure up with such long runs, and there are two spots where it would have been necessary to drill big holes through steel crossmembers. I decided not to weaken the structure of the vehicle that way.

So the cooler got tucked in the rear corner of the passenger side of the engine bay. I like that spot because it’s out of the way, mainly under the spare tire, and because air pressure under it should be low.

So the idea of the two thermostats: oil from the engine goes to the filter, and through the filter only, until it exceeds 180F, at which time the sandwich diverts it to the oil cooler, which it passes through before returning to the sandwich and the engine. When the oil leaving the cooler exceeds 190F the fan turns on.

The cooler is somewhat compact, but space is tight. I made an L bracket to lift the front of it high enough to clear the crossmember so there would be room for the hose fittings.

Cutting up my underpan to exhaust the fan air was hard, emotionally.

Initial fitment was too tight.

But after a few hours of snipping and hammering and riveting, I got the fan nestled snugly under the cooler and tight under the deck, so air is sucked through the fins and exhausted into what I hope is the low-pressure slipstream just under and behind the car.

I wired the fan to the hot starter lug, through a 10-amp inline fuse and the thermostat switch. The hardest part was drilling the hole in the crossmember for the grounding lug.

I gave up trying to color coordinate the dang fittings. Black, red and blue work well enough on this chassis. There is not a large amount of excess space.

With this all buttoned up I ran the car on the same roads again and got 80-85C. The fan ran for about two minutes after I shut the car off. Success!

I also tested air flow over the back deck and grills by taping three-inch lengths of yarn and pointing my GoPro camera at it. By the way the yarn moves, it appears that air flows in through the grills at low speeds, especially when the engine is revving. That makes sense, since the fan is pulling strong then.

At about 35-40 mph the yarn kinda goes limp, dipping in and out of the grills listlessly. Seems pressure is equalized at about that speed, with the scoop and louvres under the car pulling in just enough air to balance the pressure on the deck above. No wonder the temperature crept up at that speed!

At 45 or 50 it looks like air flows out through the grills, the pressure under the deck lid exceeding what’s above it even as the fan and carbs pull air through the engine and out the bottom of the car. Having a high pressure area in the engine bay at high speeds is exactly what we want.

A half-hour highway run seemed to confirm: temperature steady at 80C.

While I was waiting for the oil cooler bits I decided to move the sway bar bushings out closer to the edges of the beam to make the bar actually work. This proved to be something of a project as well.

I got some 1×2 steel box from my scrap pile and test-fit the pieces on a spare axle beam. It looked like they’d just fit between the grease fittings and the shock towers, and could be clamped to the beam with exhaust U bolts. Easy!

Alas. As with most of my theories, things quickly got complicated.

First, to pass the U bolt around the lower beam, I had to drill holes in the gussets I’d previously welded to the beam, which was nigh impossible given the space under there.

I finally got one hole drilled and….the bolt still would not go through.

So that meant I had to weld a bracket to the bracket and drill through the side of the other gusset to secure the lower half of the thing.

And also: the top U bolts were too short to go through the swaybar bushing carrier. So I had to weld extensions onto those.

Then it came clear that, mounted here, I’d not have room to get a grease gun on the fittings. So to shuffle the box stock tighter against the shock towers I had to cut the corners off them….

—which meant I also had to reinforce them internally so that they would not crush when the bolts were tightened…

So in the end I spent several hours messing about with this thing, which I could have saved by just starting with simple angle steel which I could have welded directly to the shock towers.

Anyway I got it done my way and it works and looks fine. And it’s removable—as if that matters!


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