View original topic: Vanagon External Oil Cooler Install - Rear Fender Page: 1, 2  Next
denwood Fri Oct 12, 2012 1:44 pm

My conversion (parts and process 100% applicable to stock wbx) has been in need of external oil cooling. The stock coolant/oil cooler wasn't keeping up on long highway trips with oil temps increasing to the 120C area. At approx. 145HP, the 2.0 liter I4 conversion works hard with a fully loaded (auto) westy towing a trailer, kayaks on top etc. These temps are not an issue for synthetic, however the oil pressure was dropping to the 1 Bar/1000 rpm range which is too low, and sometimes triggers the 2K oil warning after a long run..just for a few seconds until the oil cools a bit. I didn't want the oil cooler in the D-pillar for a few reasons. One is that my drivers side has AC hoses in it. The passenger side has the air box/muffler (now with acoustic internal insulation inside) that both muffles the K&N filter and also quiets the intake further using the stock snorkel (mounted in the passenger side engine air intake. However I shortened the air box and use it to block off the passenger side d-pillar so all air coming down the vent exits via the oil cooler now.

Here's the parts list from

1 1 A25AN8 25 ROW-8AN 235mm OIL COOLER 217.50
2 2 BM810A 1/2 BSP x -8AN M/M -ALLOY 5.00
2 2 DS13/16 DOWTY SEAL 13/16" (1/2 BSP) 0.90
12.000 12.000 FBN-08 HOSE 1/2" SOCKETLESS BLACK 4.05/ft
4 4 P90-8 -8AN 90 DEG X 1/2" PUSH-ON 12.40
1 1 TN3/4-16 THREADED NIPPLE 3/4"-16 2.25

Total cost about 380 with six feet of hose. I added clamps to each push on fitting for extra security.

To make hose assembly easier, here's a few tips.

1. Use dish soap (not oil!) to lube the press on fitting. I've mounted it here in a vise, sitting on the garage floor so I could add my weight to the hose whilst sliding it on. I heated the hose with a heat gun for a few seconds, then just slid it on with a few wiggles. Very low effort this way.


The almost finished hose:

Adding a lined stainless clamp. Note the inner lining. These came from the local Parker hydraulics shop:

The bulletproof finished hose:

Here's the intake snorkel:

Installed on its rubber isolators, the snorkel is hidden from view from the outside. Here's the view looking down towards the bottom of the vent. The tube on the left connects my intake box to the stock snorkel. The original intake tube collapsed on the conversion's maiden voyage 8 years back creating quite a mysterious decimation of performance. I've cut a hole at the base of the passenger D-pillar which will direct air over the cooler.

Here's a view (don't mind the KROWN sprayed's messy) through the passenger tail light opening. The hole is about 4" x 12". The metal in this area is very thin, so very easy to manage via tin-snips or similar. I used a 3" hole saw (with carbide cutting surface) first to make things easier. The silver thing at left is the air box/muffer box slide forward. It's now lined with accoustic insulation retained by wire mesh, and wrapped with dynomat. The intake is very, very quiet :-)

The cooler kit uses a thermostatic mocal sandwich plate which stops oil cooling when the engine is cold. The cooler itself is a Mocal 25 row, 235mm cooler. These parts are all aluminum, so no rust. Note that I've removed the stock coolant/oil cooler as I don't want to worry about a failure mixing coolant and oil and destroying the engine. The coolant/transmission cooler has also been removed and replace with a smallcar air/oil version for the same reason. What you're seeing here is the accusump pre-oiler, then the Mocal sandwich plate stacked onto that.


Here's the oil cooler behind the passenger rear tire in the fender cavity, perfectly sized for it. What you don't see here is the aluminum sheeting added to force cool air through the cooler. Also coming later is the alumumum plate that protects the cooler and vents the hot air to the rear of the vehicle where low pressure will "suck" the air from the cavity. Air flow is therefore from the high pressure area at the engine vent intake, exhausting to low pressure at the rear of the vehicle. At idle, the air flow will reverse via convection stack effect and importantly, keep 100% of the hot air isolated from the engine bay.

Without taking things apart, the mounting detail seems more complex than it it is. Both the accusump and the Mocal plate use a fitting which has female/male 3/4" thread which slides through the plate...allowing you to index it where ever required, before tightening. IF you were not using the Accusump and also removing the stock coolant/oil cooler you'd just need a short 3/4" nipple to screw into the block. The female/male mocal fitting at center threads to the nipple and you're good. If you were just adding the mocal plate to a stock configuration, then attaching only requires the 3/4" Mocal fitting. It attaches about as easy an oil filter.

Initial pressure tests etc. show cooling is very good, and pressure at idle is up with a hot engine (running inside the garage, 15 minutes at 3000 rpm). I'll post more pics of the final air shrouding etc. when complete.


insyncro Fri Oct 12, 2012 6:05 pm

Very nice indeed.

denwood Fri Oct 12, 2012 6:29 pm

Thx :-)

Was even better until I drilled a hole in the cooler whilst fitting the tin tonight :shock: Scratch $217 smackers.

Darwinian bonehead maneuver award - self appointed. Crap.

The good news is that the cooler wasn't the $600 version that Eric at Batinc replaced for the racing team that did the same thing...ha.

insyncro Fri Oct 12, 2012 6:31 pm

Been there Bro.

Love the pre oiler....very jealous.

denwood Fri Oct 12, 2012 6:35 pm

I can also confirm that a 1/8" hole in the oil system will drop about 1 liter of synthetic in about 30 seconds at 1000 rpm. Makes for excellent rust protection in the squirted areas...chuckles to self.

RGS Paul Fri Oct 12, 2012 8:20 pm

How are you going to protect the cooler from all the road debris from the rear wheel?


denwood Fri Oct 12, 2012 8:37 pm

3/16" plate aluminum. It encloses/protects the oil cooler 100% and forms the air box that directs oil cooler "exhaust" to the low pressure area at the rear of the vehicle. Otherwise the cooler would be destroyed pretty quick back there. More pics later.


denwood Fri Oct 12, 2012 9:21 pm

From the rear, the early tin work. The lighter aluminum sheet is just there for air flow, the 3/16" plate is there for protection from the rear wheel. You can see I've angled the oil cooler exhaust exit down a bit to make sure a low pressure zone will exist there at speed. We already know that the engine rear "air intake" vent louver has good positive pressure at I would predict very good flow thru the cooler, high to low pressure. You can also see why the oil cooler's heat output is completely isolated from the engine compartment.

Zeitgeist 13 Fri Oct 12, 2012 9:47 pm

denwood wrote: Thx :-)

Was even better until I drilled a hole in the cooler whilst fitting the tin tonight :shock: Scratch $217 smackers.

Darwinian bonehead maneuver award - self appointed. Crap.

The good news is that the cooler wasn't the $600 version that Eric at Batinc replaced for the racing team that did the same thing...ha.

Oh man, I did this just the other night. I was mocking up a fan housing for my conversion from a mechanical fan clutch over to an electric two speed fan on my offbrand car. As I was drilling into the radiator bottom bracket, the bit caught and pulled the drill enough to grab a couple of coolant rows. Grrr. Since this was a spare core, I opted to peel away the fins, clean the surfaces and then apply a series of thin layers of JB Weld. I'm hoping this did the trick, and that the epoxy and aluminum expand and contract at roughly the same rate so it holds up over hundreds of heat cycles.

denwood Fri Oct 12, 2012 9:57 pm

Thought about fixing it, but given that it took about 30 seconds for 1 litre to exit at 1000 rpm, a leak at speed would have all 7 liters gone in 2 minutes or so. Now anyone who wants a Mocal to fix/play with..have I got a deal for you :-)

Zeitgeist 13 Fri Oct 12, 2012 10:10 pm

Yeah, you're dealing with potentially 6 bar and up, while my boo boo was only around 1 bar -- big difference. Your application is probably best left to a professional solder repair. Bummer. I like your install. I plan on installing this Volvo Turbo cooler and thermostat on my eventual mTDI conversion

morymob Sat Oct 13, 2012 4:33 am

U can get 'lo-temp' alum rods to repair alum,weld supply, mine from a show,get cleaner/rods, small tip for propane torch and practice on alum can first. Make u a drill stop from old brake, gas line, plast tubing etc, fine adj depth by moving drill bit, won't drill thru other stuff.

denwood Sat Oct 13, 2012 7:33 am

A drill stop would be good for these projects yes. Truthfully this was a rookie error due to a lapse in attention, so I will pay my fine and consider it a reminder. I should have been doing the tin work with the cooler removed, or at least the tube over the drill bit stop.

midmo81 Sat Oct 13, 2012 3:57 pm

Here is the rear fender cooler on my AC 81 Westy. Came with the bus from some PO install and all I had to do is replace the filter adapter, new hoses, new clamps, flush the gunk out of the coils, and fix the broken leaking exit fitting. There is a fan located behind it in the pillar.

It worked great in the 90+ degree heat this past summer. Sixty mph on the interstate with oil not over 220. :D

denwood Sat Oct 13, 2012 8:21 pm

If I understand this correctly, the rear tire dust/mud would end up on the cooler? Also, which way does the fan blow...into or from the d- pillar space?

midmo81 Sat Oct 13, 2012 8:39 pm

Airflow is from inside to outside. Keeping this clean might be something to watch, but probably no worse than units mounted underneath. YMMV.

If I were doing this from scratch, probably would have taken easier location underneath somewhere. Since this was from some third or fourth PO way back, it seemed interesting for the work put into mounting the fan and coils this way. Out of the way when doing other fixing underneath. Like that ever happens.

denwood Sun Oct 14, 2012 10:36 am

If it isn't broke..don't fix it. After seeing what a 1/8 hole did to the Mocal, just make sure your cooler is well protected from a rock, failed tire etc. I'm also guessing you do zero driving in snow! That area is typically crusted up pretty good in winter. We do get a lot of snow here, and we do drive a fair bit on gravel in the summer..therefore the goal for my setup is a cooler that would be 100% protected in those scenarios.

Once I get the van back on the road I'm going to log some temps on the cooler to see how effective my flow predictions are. At 60mph the d-pillar intake vent drops off so I'm assuming the increasing low pressure at the rear of the van will compensate.

denwood Wed Oct 17, 2012 11:45 pm

Got the replacement cooler in place and all buttoned up. Here's the rear fender area with the cooler air shroud/shield in place. Basically you can't tell it's there unless you peak under the rear bumper where you'll see the air exit for the cooler. Note the nice new Koni now installed too. The rears were easy, the front a nightmare as the shocks in there did not have the allen's a 6mm flat which is incapable of holding the rod as you back off the top nut. Ack. Ended up drilling a hole all the way through the shock so I could put a bolt through the shock/tube assembly and hold it from spinning.

buspor63 Thu Oct 18, 2012 2:27 am

Zeitgeist 13 wrote: I plan on installing this Volvo Turbo cooler and thermostat on my eventual mTDI conversion

Is the pictured sandwich plate from a Volvo Turbo car, perhaps one found in Pull A Part yards? If so, which model?

denwood Thu Oct 18, 2012 2:07 pm

Those pics of the used bits look like Volvo 740 turbo.

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