Inline Conversion - Oil Priming Issues

[ebennett]

Here's the background info:

1995 ABA 2.0L Block
1992 Digifant 8V head
Installed with diesel carrier bars, diesel bell housing and oil pan @ 50 degrees
Oil pump is a 36mm ABA pump with diesel pickup tube
MANN oil filter W0133-1638074

When I start the van the hydraulic lifter tap and the low oil pressure light is on. It probably last for 45 seconds but it seems like an eternity! Once the oil pressure system primes itself the system is fine however if I let the van sit for a few days it seems that all of the oil drains out of the system. Meanwhile I can let any of my other 4 cylinder VWs sit for a month and they don't lose their oil priming.

Any ideas what is happening? Leaking pressure relief valve on my pump pick up? Head gasket lets the oil drain out of the head? I've already tried swapping out the oil filter. I'm going to drop the pan and pull the pump to see if anything jumps out at me.
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GDTRFB

[?Waldo?]

I had an ABA in a vanagon that acted exactly like that. I found that blipping the throttle would prime the system much faster. It still felt wrong, tho. I drove it a couple years like that. I had always planned on swapping out the oil pump and pickup tube but before I got around to it, it blew a head gasket and I replaced it with an AAZ.

[MarkWard]

Stock valve springs?
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[?Waldo?]

I think it's just a matter of the oil pump being worn enough to lose prime.

[ebennett]

[MarkWard]

Strong springs could cause the lifters to leak down when sitting and require them to pump up on start up. At least those valves that are open. What oil filter flange did you use? I recall one with a ball in it, but that is a foggy memory. I believe the filter is what prevents the oil from draining out of the top of the engine. Where is your low pressure switch mounted? It should be on the head and the high pressure switch on the pump housing.
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[outwesty]

My ABA swapped van did a similar number. I changed out the oil pump and it now only took 5-10 seconds for the tap to go away which I think is pretty normal. This is the best deal on the internet for the pump with pick up. Get the Febi one. Its better quality.

http://www.autohausaz.com/search/product.aspx?sid=...Oil%20Pump

[denwood]

My van with i4 conversion did/does the same oil prime silliness...and using the 36mm pump and diesel pickup. I have installed an Accusump as my van is sitting for long periods. This pressurizes the oil system before every start...so I've been a bit lazy on fixing the prime issue. Btw, I tried all sorts of oil filters etc...they won't fix this issue.

http://my.tbaytel.net/guskers/accusump.html

Make sure you also read this which is a warning in terms of engine oil aeration from the larger cranks with your setup.
http://my.tbaytel.net/guskers/pressure.html

I'm waiting for a new oil pump with diesel pickup custom welded from Techtonics to solve the issue and for peace of mind in case my wife or someone else starts the van without using the Accusump.

From some research, I believe the issue is incorrect spacing between the new (at conversion time) larger capacity 36mm oil pump mated to an older diesel top plate..which has the pickup tube integrated. The test would be to use plastigage between your pump gears and cap, torque it down, remove and check. The wear limit spec I've seen in a few manuals is .1mm, just over .003". With a loose fit, adding a gasket would create too much clearance here and likely is the prime problem "culprit". Too much gap here is also likely showing up as lower hot oil pressure..so really should be addressed. Cheers, Dennis.
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Cheers,
Dennis Wood
The Grape

[?Waldo?]

The pickup tube on the pump that Outwesty linked is the right one, but the pump itself cannot be used.

The face of the pickup tube/pressure relief valve is totally flat (unless scored from use) and so the space between the gears and the pickup tube face is determined by the height of the 'walls' of the pump casting and the height of the gears. The pickup tube has nothing to do with it.

I would mention that I have not had the issue with any of the 1.6TD, AAZ or AHU engines which use the same oil pickup tube.

[ebennett]

So I created this problem by building my own oil pump, the 36mm ABA pump with diesel pickup tube bolted on the bottom?

If I used a stock diesel pump I probably wouldn't have this problem?

For some reason I thought the diesel oil pump wasn't tall enough to engage with the distributor. Maybe that was my imagination.
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GDTRFB

[?Waldo?]

No, as I just mentioned above, you CAN'T use the complete diesel pump. You are correct, the shaft length is different as it meshes with the diesel vacuum pump instead of the distributor. You MUST use a diesel vanagon pickup tube with the ABA pump OR cut and weld the ABA pickup tube to match the angle and pickup location of the diesel vanagon pump.

[denwood]

Andrew, I (and this poster) did not use the complete diesel pump, but rather a new 36mm pump, (less the new a2 top plate and pickup tube) with an older diesel top plate. Because the vanagon diesel pickup tube and top plate are the same piece, you cannot just swap pickup tubes from a diesel pump to a new 36mm pump...you must take the entire top of the diesel pump, including pressure relief valve, and bolt it to the new A2 or A3 oil pump. (and I know that you know this well Andrew

So, Eb, you need to check the clearance between the top of the gears and your top plate..which was not spec'd and matched to the 36mm new pump. AFAIK, all pumps should be checked for end play, new or otherwise. In this case, because you and I have both created a non-stock assembly, the clearance here would be quite critical, so likely the non-prime culprit if you don't know this clearance. We can assume that with a new pump, that the gears have no wear issues. We can't assume however that the end play spec is under .003" as we've taken an old part bolted to new. If you added a gasket (.005" or so) with sealant, and you had end lash there already...then the gap might be .006"..and therefore oil may be draining past the gears via the route, and losing your prime.

Once I eventually replace my pump (this winter), I'll be able to post my actual clearances as well. Given that the pump housing is aluminum, and the gears steel, it makes sense that a low clearance number (.001 to .002") should be fine. If your old top plate is worn in the gear location, then wet sanding it flat using a perfectly flat surface (we have a few polished granite slabs kicking around here for that sort of thing) would make some sense..and/or tossing the gasket in favor of sealant if the clearances are high.
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Cheers,
Dennis Wood
The Grape

[crazyvwvanman]

Andrew well knows that the diesel van pump pickup tube is installed on the pump that is native to the engine. The pump pickup tube covers the gears with a flat plate at the top end of the tube section so as long as the flat surface isn't torn up there isn't much to measure. One issue I have seen numerous times is that a used diesel van pickup tube has damage or debris at the oil pressure relief valve piston on the top section of the pickup. If the piston does not fully close then the oil easily drains out of the pump when the engine is shut off and the air leak makes it harder for the pump to get primed again. A new pickup tube is preferred.

Mark

[denwood]

Agreed. I have Josh at Techtonics making up a few new A3 pumps with welded pickup tubes for the diesel pan. Definitely a back bench project for them. I could do this work myself, but if my MIG welds failed for some reason, there would an instant dead engine...

Does anyone sell the diesel top plate portion, new? I'd guess you just need to buy a new diesel and A3 pump and mix/match otherwise.
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Cheers,
Dennis Wood
The Grape

[?Waldo?]

Yup, I'm completely familiar with the parts involved. As I mentioned, I owned an ABA vanagon (until I yanked it for an AAZ). I still have the new ABA oil pump I was going to install. I also have a couple 36mm vanagon diesel oil pumps here. All the new vanagon diesel oil pumps have 36mm gears and so, the pressure relief valve for all of the new vanagon diesel/turbo-diesel pumps are appropriately sized for the 36mm ABA oil pump.

If you want to install a new proper 36mm ABA oil pump in a vanagon with the correctly sized new oil pressure relief valve, then IMO, the easiest way to do so is to buy a new ABA oil pump, buy a new vanagon diesel 36mm oil pump, swap the pickup tubes, install the ABA pump with vanagon diesel oil pickup tube in your van and bolt the ABA pressure relief and pickup tube onto the vanagon pump and sell it as a 36mm rabbit/golf/jetta diesel/turbo diesel/TDI oil pump...

[denwood]

Just an update..ended up purchasing a new diesel pump, as well as new a3 pump. I'll post some pics here of the pickup/swap process and any findings on the oil pump setup I remove. It's been in there 8 yrs or so.

If anyone is interested in the leftover parts, a "new" diesel 36mm oil pump as Andrew describes above, pm me.

Both pumps are Febi.
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Cheers,
Dennis Wood
The Grape

[denwood]

So today was "new oil pump" day. Because I had some oil prime issues eight years back or so, I had installed an accusump, which pressurizes the system before starting. The engine is a tuned/chipped 2.0 litre 3A block with oversize pistons, ported 1.8 Digifant head etc...about 140hp. It's laid over at 50 degrees using diesel vanagon bits. Compression was dropped a bit during the build on advice from Colin at Techtonics tuning, great guys to work with on a project like this.

It's bothered me though that someone failing to use the accusump (my wife, the next owner etc) might run a very carefully built/tuned 2.0 litre without oil pressure after storage. With a new diesel 36mm oil pump, as well as a new A3 36mm oil pump in hand, I transferred the diesel pickup tube over to the A3 pump and checked it for baseline clearance. Some interesting discoveries.

1. The new oil pump end play clearance between the gears and top plate was in the range of .005", about twice what it should be:

Laying out Plastigage, followed by torquing the top plate to spec, 11ft/lbs. Plastigage is crushed in the gap to be measured...then the flattened material is measured using the scale they provide. I had some left over from my engine build where it is used to check crank/cam bearing clearances.

Removing the top plate and gears, I carefully took a few thousands off the new A3 oil pump housing by laying it, machined surface downwards, on a sheet of 320 grit wet/dry paper (supported by a machined flat surface) and wet sanding. This works great as long as you're very careful to apply even pressure with the part always in full contact with the paper. Below is better...in the .002" to .003" area.

While the oil pan was off and new oil pump installed, I activated the accusump (electronic pressure switch) applying about 80 psi oil pressure to the engine and observed oil from the crank bearings, piston squirters etc. but pretty much nothing draining back through the oil pump. A good sign.

The results were surprising. With 5w-50 synthetic, the oil pressures are excellent, indicating that a switch to 0w-40, perhaps 5w-30 is next to reduce pumping loss and increase mpg a bit. The van has a Mocal oil cooler installed in the rear fender, so oil is kept in the 105C range under heavy load. A pretty hard highway run tonight showing close to 5 bar (65psi) at 4000 rpm, oil at about 105C, and at idle, 850rpm, showing about 1.1 bar (about 17psi). With this new "tuned up" oil pump, 5w-50 is likley too high viscosity.

The pump I removed (new A3 gears combined with older diesel pickup tube) was showing about 20% less oil pressure with the same temp/viscosity oil. Pretty sure this was the issue with losing prime over longer storage periods.

Oil pressure 4.5 Bar, 3500 rpm, 105C

Immediately after highway run, 850 rpm, 1.1 bar, 105C.

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Cheers,
Dennis Wood
The Grape

[denwood]

Finished installing the later model A3 one piece rubber/metal valve cover gasket to take care of an oil seep from the older cork version. This btw will work on diesel Vanagons too, providing you swap out the valve cover studs. Techtonics tuning supplies both.

The oil pressure at start up (assuming the Accusump is not engaged) with the new pump and .002" clearance top plate is pretty much instant..no prime issues so far. To follow up the oil pressure and testing experiment, I switched over to 5w30 "modern" synthetic after buttoning up the valve cover, and ran the same tests today. Results are very similar actually, with about a 5-10% reduction in oil pressure. I just buy whatever synthetic is on sale, so these numbers are using Castrol Edge Syntec "Dexos" approved oil.

Oil pressure@3500 rpm, 4.3 Bar 105C (5w30 synth)
Oil Pressure@850 rpm, 1.0 bar, 105C. (5w30 synth)

Basically if your engine and oil pump are in good shape, there is no reason not to use 5w30, providing you have an oil cooler in place. Perhaps I'll throw in some premium fuel and see if the G-tech shows any performance difference. There should be a difference in both HP to the road as well as small mpg diff based on a few tests posted on the interweb:

6.5 HP gain going from 15w-50 to 0W-20 on a motorcycle: http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=201805
7 HP in an older Car Craft test on a Ford 392 crate engine going from 20W-50 to 0W-30: http://www.carcraft.com/techarticles/synthetic_vs_conventional_oil/
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Cheers,
Dennis Wood
The Grape

[vanagonjr]

Does anyone have the part number for the diesel pick-up tube? I ask this because Bus Depot lists three different "tubes" under oil system for the 83 diesel. Also oil pumps from $55 to $428.
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John - 86 Wolfsburg Westfalia "Weekender"
Flint reversed 1.8T W/Passat 5-Speed
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FAQ thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=525798

[crazyvwvanman]

The pickup tube comes with the pump. I would get the $100 one at BusDepot.

" OEM Febi 068115105BP "

Mark