Fitting a full flow filter and external oil cooler to a T1 engine

Discussion in 'How To' started by mikedjames, Aug 10, 2014.

  1. Fitting an Oil Cooler

    My T2 has a 1641 engine with a progressive carburettor which I have spent some time tuning and as a result while it is capable of running constantly at over 65mph on the motorway, it tends to run quite hot. I have seen 118-123 degrees C oil temperatures, consistently about 17 miles from Portsmouth on the M27 towards Southampton. Long hills are the cause.

    Once the bus slows down, the engine temperature drops to 95-100 degrees C at tick over so I knew the stock oil cooler could control the idle temperature without any problem. The issue is cooling at speed.

    The bus has a working thermostat, flaps and a stock oil cooler. It is dragging a roof rack, and a pop-top and sun visor. It has been lowered about 100mm so there is less space underneath.

    This How To is inspired by the fact that despite a lot of web searching and youTube searching, I could not find a lot of information on how to fit an external oil cooler to a T2.

    The basic oil cooler setup seems to be to full flow the engine and then fit an external full flow filter. In the simplest setup, the cooler loop would feed one of the Bugpack “72 plate” coolers and then the oil would be returned to the engine via an external fitting putting oil back into the rear oil presssure spring bore.

    It was recommended to fit an additional oil thermostat so that the cooler plate would be bypassed until the oil got hot, and then another thermostatic switch would turn on the fan.

    Odd pictures of oil coolers with air scoops for splitties popped up which gave me some ideas.

    Other people seem to fit the BugPack oil cooler with fan in some inappropriate position almost flat against some surface. Some installations are arranged to mistakenly feed hot air from the cooler to the rest of the engine.

    I considered the various oil coolers on the market - for instance the Mocal selection gives a wide range of coolers of different sizes, but the choice of cooler, hose fittings and hoses confused me.

    I decided to go for a different solution. I reckoned that starting with an EMPI full flow kit intended for use instead of a stock oil cooler would provide some of the parts I needed, and guide me to the next step. I chose the smallest '24 plate' cooler (which is a 12 plate using Mocal terminology as they count both sides as a plate in EMPI land..)

    I decided to full flow the engine by the use of the CB performance Maxi 3 pump, as I had a suspicion my stock oil pump was a bit worn out, like the rest of the engine..

    This provides a no-machining (to the engine …) solution to full flow oil feed as there are two pipes on the pump cover, an “out” feeding from the pump and an “in” returning oil to the oil bore going off to the relief valve. The top of the pump is much taller than the stock pump and the pipes stick out.

    You do not need to pull the engine to fit this solution.

    I then decided that the best way to provide an oil thermostat was to use a Mocal sandwich plate which stacks between the filter and the oil filter head fitting.

    I went for a staged approach so if there is a problem with the cooler and its pipework you can drop the sandwich plate and refit the filter direct to the filter head.. And still have a working full flow system. And then if there are problems with the filter head, you can loop an oil pipe from in to out of the pump.

    Shopping List : Basic Full Flow system

    One 24 plate EMPI full flow kit. Includes 5 feet of hose, oil cooler, hose clips, oil filter head with ports to the left, hose fittings (3/8 inch NPT based, apart from the oil cooler which has ½ inch NPT) . It also has a set of springs and oil relief valve parts (not used) and an adaptor plate to take oil flow from the stock cooler position (also not used)

    This requires but does not include something like a FRAM HP-1 filter to allow for high starting oil pressure.
    Oil filter : FRAM HP-1 . Made in Europe, imported to USA, exported to Europe. This has a ¾ inch UNF thread on it which dictates the sandwich plate centre tube required.

    Oil pump :
    One CB performance Maxi 3 pump (comes with gaskets) but no oil fittings. I decided to take a stab in the dark and guess that although my engine had been upgraded to 1641cc the invoice price (£800 in 2005) seemed to reflect no upgrade to the cam, and the valve springs looked like stock springs. So the cam shaft would probably be a late model cam. This proved to be correct.

    One 8mm x 40mm hex headed bolt – all the bolts provided are the same length. One of them is too short as it only goes 4 threads into the block (see later)

    Oil fittings:Two 1/4 inch NPT to ½ inch ID hose fittings for the oil pump.

    Shopping list : Additional cooler loop

    Sandwich plate:
    Mocal OTP-SP1 with ¾ UNF centre filter thread, mine came with a pair of ½ inch male to male BSP fittings and washers. The cooler is designed to open at 80 degrees C.

    Additional oil hose : 3 metres of ½ inch inside diameter oil hose – because of the way I bought mine I made the mistake of buying a couple of pieces 2 metres long

    If you are buying stainless braided hose, buy 5 metres. Also buy 10 extra stainless steel hose clips (above and beyond those provided in the kit)

    Additional pipe fixings : another pair of ½ inch to ½ inch BSP male to male adaptors, (should be ½ inch NPT to ½ inch BSP) and two Dowty washers.

    Also a pair of ½ inch hose to 1/2inch BSP straight connectors and a pair of 90 degree 1/2inch hose to ½ inch BSP connectors.

    Cable ties
    Spare oil pump sealing gasket for stock pump in case you need to put it back.
    Stainless sheet or similar to fabricate air scoop.


    Two leg crankshaft puller
    Oil pump puller with T shaped end
    Angle grinder with cutting and grinding discs.
    Welder or friend with welder for air scoop and rear engine support bar.
    Hammer, big adjustable spanners , drill
    Half inch imperial ring spanner for spigots going into the cover on the oil pump – you need it because the flats of the hex part of the spigot are a bit soft.
    5/8 inch imperial ring spanner for the spigots on the filter (I used an adjustable spanner here)

    Last edited: Aug 10, 2014
  2. Fitting and bodges

    Do not remove the new oil pump from its packaging yet – you will measure it before unwrapping it so you can easily return it if you bought the wrong one.

    Remove rear tinware.

    Drain the oil. The bottom of the oil pump can be below the oil fill level if you are lucky.

    Remove rear engine support bar and clean up if it is dirty. You are going to be hacking this quite a bit.

    Pull crankshaft pulley as you need to get at the oil pump.

    Remove additional behind pulley tinware.

    Remove oil pump cover and look at the wear. Put to one side.
    Remove the oil pump gears.
    Insert end of T piece of oil pump puller in inlet and outlet holes of the oil pump to left and right. (the CB performance pump only has an easy to access inlet pipe once it is fitted) Place the puller legs above and below the pump. You may need to loosen the engine case bolts just above and below the oil pump to get it to come out. You will need this if the bar in the puller bends.

    The old pump appears to have had the spindle pushed through a bit to get the depth to meet the late model camshaft. And it has quite a lot of endplay with grooves in the pump cover.

    Measure the depth of the old oil pump from the face which touches the engine block to the end of the drive spindle.

    The new pump spindle should be the same length . And the pump body should be the same depth inside the engine block. If it is not then stop and return the new pump and exchange it for the other model.

    At this point you can quietly put the old pump back with the new original gasket if necessary.

    Remove the four oil pump studs – using either a proper tool or a pair of M6 locked nuts and two spanners.

    Fit new oil pump with the thick gasket between it and the engine – this can be hard to get it to go in. One way is to put the new pump cover on and wind the pump in on the four Allen bolts provided for fixing. Then remove the cover, fit the gears by lining up the dots first and then rotating the two gears as you insert the gear that engages with the slot in the crankshaft. It should all go in flush.

    Fit the top to the pump, using the thin custom gasket with the extra hole in it. The holes in the gasket must line up with the holes in the new pump body. The complete hole in the gasket on the left goes over the upper outlet hole .
    Tighten hex bolts but not too tight as you do not want to strip the threads.

    Fit the inlet and outlet hose fittings to the pump using PTFE tape as a lubricant. Tighten quite firmly – until you are risking burring the corners of the flats on the fitting.

    Now for some hacking.

    In order to clearance the rear engine support bar, you will need to remove the 'fins and the flat panel' on the left hand engine support that comes up from the bar.

    Basically imagine cutting flush from the front of the engine support bar upwards. At the top you need to cut the bar so that the hose going over the pipe fittings on the pump will not touch the bar. It is just possible to leave about 1 cm of metal each side going to the bolt which holds the engine in.
    Before cutting I cleaned and welded the left hand side fitting to the top of the engine support bar, as the hacking will remove the welding from the front of the bar.
    After cutting I then had to thin the bolt support as the hose will interfere with it so I cut about 3mm off one side of the circular tube.


    The mating surface of the oil filter plate from EMPI has many small dings in it so it is necessary to finish it properly by sanding it with wet-and-dry on a glass plate or a smooth surface until you have sanded down to below all the dents.

    I then screwed the oil filter mounting plate to the left hand side of the engine bay just below the tin.
    I wanted to mount it vertically so that I could remove the filter without losing all the oil in it.

    I then wound in the ¾ UNF fitting for the filter mounting.

    Again fitting the UNF pipe fittings was a game – I was not brutal enough and they turned out leaky It is possible to wind the 90 degree fittings into the oil filter plate until only 2 or 3 threads are showing. Take care as it is easy to crush these – replacements cost a fair bit as they are American. Look on for the best deals.

    I connected up the hoses from the pump and to the filter, respecting the IN and OUT designations on the pump and filter. The OUT on the pump is the bottom pipe. I chose to use double hose clamps, but did not put them on 90 degrees apart because there is no screwdriver access if I did that .

    I was then able to fill the system with oil. I started by filling the filter with almost a litre of oil before screwing it on and then putting about 0.2 litres of oil in the main engine oil filler to make up for the hoses.

    The engine support bar went back on although with an aftermarket 4 into 1 header there is no space so things need to be sprung slightly to get it lined up.

    I pulled the Contact Breaker lead from the – terminal on the coil and powered up the engine reconnecting the battery and turning the engine over with the starter until the oil pressure light went out.

    I checked the oil level then started the engine. As I have indicated a few times there were a few seeps from some of the NPT fittings until they were tightened up enough.

    At this point, with the cooler stored to one side , I stopped work and took the bus on a 300 mile trip.

    And already with the full flow filter only and an extra litre of oil in the system the highest oil temperature seen went to about 110-115 degrees and it took a lot longer to reach that temperature.
    Last edited: Nov 25, 2020
  3. Phase 2 : the cooler.

    This was where some fabrication came in. I spent a lot of time lying on my back under the bus looking for a place to put the cooler. I could have put it above the gearbox but the EMPI cooler plate is 'taller' than the Mocal cooler plates normally as it has wide flanges above and below the cooler stack.

    The cooler has a ½ inch NPT thread but the ends of the cooler are aluminium so it was possible to smooth off the ends of the cooler with sandpaper and then fit a ½ BSP male to male fitting with a stacked Dowty washer between the fitting and the cooler using two big spanners, some grease and extreme persuasion.

    It will not be going back to the manufacturer after that …

    I liked putting the cooler plate just behind the belly pans but not sticking out down below the bus as this would expose it directly to stones.

    I decided to make an air scoop to guide air into the cooler when at speed. This was made from thin stainless steel sheet salvaged from an old Ikea medicine cupboard. It is shaped like the scoop of a dustpan and was really constrained in size by the depth of the original cupboard.

    Using tinsnips and a pair of thick gloves , parts were cut out and bent to shape using a hammer and a bit of soft wood.


    They were then 'spot' welded using MIG welder with BOC Argoshield gas and 0.8mm stainless welding wire. It proved very easy to burn holes in the stainless.

    I made some angle brackets out of 2mm stainless for the front edge including drinking some beer and making two right handed brackets before converting one of them to a left handed bracket. I welded on captive nuts and this took a few tries before I used a mild steel bolt to guide the stainless nut to the hole . Stainless bolts just distorted, galled up and sheared off.


    At the rear, of the cooler I measured and drilled two holes in the floor and fitted two lengths (aout 20cm of M6) stainless steel studding with nuts on the end. It was all a bit of a bodge and the holes miss by about 1cm but bending the studding lets it line up with the holes in the cooler and the air scoop.

    I fitted the cooler to the scoop and the scoop to the bus. It was a pig to line up everything but eventually I managed to get both bolts at the front and the studding to line up with the holes and I was able to tighten up the bolts.


    In the end the cooler is angled with its 'top' facing slightly down at about 10 degrees so the oil fittings are on the bottom of the cooler. I would have liked it the other way around so it would fill with oil more directly, but the hot air trunking going to the front of the bus gets in the way.

    Also the cooler itself turns out to be at the bottom of the oil system so it should eventually fill up.

    This time the hose fittings did not leak but getting the hose over the barbs on the straight connector was a game – I had the EMPI hose (slightly larger Inside Diameter,) and some high temperature hose with a smaller inside diameter which has only one layer of fabric in the hose wall but the strands making up the fabric seem tougher to cut.

    In fact I had to double clamp the EMPI hose because it almost slid off the 90 degree fitting.

    The nice thing about the BSP fitting is steel to steel you only need about 1/8 turn to tighten it. And then it seals.

    I fed the hoses over the rear suspension beam then over two stabilising webs up above the heater. I was able to avoid running close to brake lines or fuel lines, everywhere managing at least 25mm gap.

    I then used cable ties to hold it in place.

    Filling the new loop with oil was impossible as I could not raise one of the hose ends enough to get oil to flow in from a funnel. So I coupled up the sandwich plate between the filter and the filter head. I was able to remove the filter and only spill a little oil on a drip tray so I did not waste oil.

    The engine oil was about 25% of the way between full and empty at this point.

    I put about 0.9 litre more oil in the oil filler on the engine and again turned it over without starting it until the oil light went out. At this point the oil level was about 100% on the dipstick.

    So in total I had increased the oil stored in the oil system by a total of about 2 litres.

    The fun will come changing the oil – I will need to uncouple a hose by the oil cooler as well as removing the oil filter to get most of the oil out of the system.

    And then took it for a run and none of the new fittings leaked but one of the NPT fittings leaked – I think I damaged the hose while I was trying to get the fitting tight enough.

    Oil temperatures were never over 95 degrees even at the point where previously the 115-125 degrees temperature was seen at the end of the motorway blast.

    And it cooled down reasonably quickly idling in traffic. It certainly cooled rather than warming up.

    Driving more gently, the previous oil temperature of 100 degrees seems to be replaced by an oil temperature of 90 degrees.

    A few weeks later. I found two problems with the CB performance pump. The pump is provided with four equal length (30mm) allen headed bolts. The two on the right and the top left one go in a reasonable distance, but it turns out the bolt on the lower left of the pump only goes in four threads . So I stripped the thread as I tightened it. I replaced it with a 40mm x 8mm bolt and this found some new (old) thread to bite on

    The other problem with the pump was that the cover cracked as I tightened the top spigot. At first it was not tight enough to make a seal on the taper, then as I tightened it it split the cover.
    I did not realise that this was a problem so I drove the bus with the crack in the oil pump cover. A seep of oil came out which covered the back of the oil pump. I thought it was overfilling oil blowing from the crankshaft pulley above, but when I changed the hoses from the pump to the filter for nice stainless braided hose, I noticed the leak while I was turning the engine over with the ignition disabled and the flywheel pulley removed.. It was coming from the pump.

    In order to fix the oil pump cover, I thoroughly degreased it, and then I used a 1mm tungsten carbide tip on the Dremel tool. ( like the kind of thing used by dentists for taking the core pulp out of teeth) which I ground away the crack from the inside of the tapered thread, about half way through the metal. I then filled the enlarged crack with JB weld and tightened the spigot back into the hole, so the crack opened up and JB weld squeezed out. I checked that the end of the crack was about the same distance into the hole as the thread on the spigot when it was tightened. So now it has JB weld in the crack and I have driven it a couple of miles. No leak yet but I have not really got it warmed up yet.


    After a week of driving, I cannot make the JB welded spigot leak, so I have decided to leave the new oil pump in the box as a new spare.

    I have now replaced all of the hose with stainless braided rubber hose, using double jubilee clips everywhere.

    I cut the new stainless hose to length with an angle grinder, after wrapping the outside in tape, as the high speed blade cut the wire covering fairly cleanly. Lots of burning rubber smoke from the hose. It helps if you hold the cut open as the grinder cuts, or the blade gets gripped by the rubber and gets even hotter.

    I double clamped the stainless braided hose. The first clamp is for sealing, the second is to hold the outer braid tidily over the end of the hose.

    A good thrash along the motorway and none of my new oil pipework showed any sign of leaking.

    But there is oil leaking from the front of the engine in reasonable quantity, if I fill the oil to over 50% full between min and max on the dipstick , it empties back to that level quite quickly, and then remains there.

    I have now driven for several thousand miles including a run round France for 1600 miles in 2 weeks and we managed to keep the oil temperature below 115 degrees even thrashing down the Autoroute to Bordeaux.

    Some more views of the setup

    Showing air scoop below belly pan


    Top of filter in raised area just behind left hand engine mounting bar fixint point. Showing Mocal sandwich plate.

    Using a bit more of the Ikea cupboard, I made a little deflector plate for the bottom of the oil filter, to try and protect it from stones flying up under the engine support bar as it hangs down further with the sandwich plate.
    Last edited: Nov 25, 2020
    vwbusman and Lasty like this.
  4. some really useful info here @mikedjames .... never really considered an independent cooler, but will deffo be going for the Mocal stat....:thumbsup:
    sticky in the 'how to section'? @bernjb56
    bernjb56 likes this.
  5. nice work.............
    are the jubilee clips holding ok....
    my 1641 has the case drilled for full flow but the previous muppet fitted the cooler above the liesure battery so any heat produced goes into the engine bay(not the best decision) also no filter or stat so its just a loop and back.
    i will get around to moving it, was looking at putting it under that battery tray behind rear wheel but well out of the way. will also be getting mocol filter and stat mount.
    do you need a scoop or is just the airflow enough do you think:thinking:
  6. The setup is still holding up. Maybe seeping a bit from the hose connection to the cooler as an engine out and oil change needed the hose disconnected to drain the cooler.
    Gettin spanners on the oil cooler connections is tricky.
    This is one thing that also needs consideration and that is can you drain the oil completely in an oil change. My setup needs a hose off the cooler and the filter removed as well as the sump plate .
    Then oil comes from three places at once. It could get messy.
  7. Further in-use info.
    I was driving the bus yesterday and I forgot to take my magnetic rain covers off the air vents. Drove it 20 miles to work at up to 70mph and the dipstick oil temp, with the external cooler with a scoop being the only one working in cool air, only went to 115 degrees.
    I dont know what it did to the cylinder head temperatures :eek: but it started and ran same as usual today and managed to get to about 95 degrees oil temp at similar speeds.

    I think with a bigger cooler plate, the scoop would not be as necessary, but finding airflow where stones dont have a chance of flying would be my big worry.

    I thought about behind the rear wheel arch but I didnt want to cook the leisure battery above. Also I should have put the full flow oil filter in that space to keep the filter safe from hitting speed bumps etc.
  8. I now use the Mann W719/5 filter which is a bit smaller off a VW Golf and it is about £4 from GSF. Still a solid filter and I have not burst one even with upwards of 105 PSI on a cold start.

    I have popped one of the oil hoses off, where it was disturbed when I drained the oil, so I fitted a 30mm extension to one port on the oil cooler so that both sides of the joint that I disconnect to drain the cooler are now visible outside the scoop under the bus.

    The JB welded crack in the pump cover is still sealed and so I have not ever changed the oil pump for a spare I bought.
    Last edited: Apr 25, 2017
    paulcalf likes this.
  9. I use the same Mann filter. Much cheaper than a Fram HP1 and I'm told it's as good, just not jaffa
    Last edited: Apr 27, 2017
  10. Still all good. When I built a new engine in April 2015 all I did was move the oil cooler setup across. The pump has a tiny amount of wear on the cover after about 30k miles.
    wendygun likes this.
  11. When I fitted my new Preservation Parts engine back in 2018, the Maxi 3 pump was again moved to the new engine, but the fixing bolts bottomed out in the holes.

    As the old engine had filled with flakes and chunks of aluminium, I replaced a single oil hose from the pump to the filter and thoroughly cleaned the pump and filter head. No metal had passed the oil filter.

    The drilling in an aluminium Autolinea case is shallower than stock VW cases. It required some 1mm thick washers to ensure proper pressure on the pump cover. Just as well I had some in the field at Techenders, Victoria Farm where I fitted the pump..
    EggBoxes and Valveandy like this.

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