Blueprinted oil pump - almost ready to install!

[fspGTD]

Just wanted to let you guys know, I'm nearly ready to install a new beating heart into my GTD...  It's a splined shaft 30mm oil pump, which will allow removal of the vacuum pump.  But that's not all... it also has its inlet and outlets ported out nice n' large, and all its internals moly impregnated so it will slip n' slide really well.  In fact, by hand it seems to turn more freely than the worn-in original oil pump!

In blueprinting it, I even disassembled the pressure relief piston and reinstalled the retaining cap and pinned it into the housing by drilling a hole through it and the housing and tapping in a roll pin.  My only set back was when I tried to transfer the plastic restrictor baffle from the old pump to the new one, I broke a tab off of it, so I will need to track down a new one of those maybe tomorrow.  Anyway, I hope to have a report on the new oil pump and the vacuum pump removal soon.

[Anonymous]

Good work

[cheng]

so how do you drive the pump?
do you have the gear off of the vacuum pump splined to the oil pump?

[Anonymous]

Joe, you should install a baffled, trap-door oil pan for your autocross racing.

[Dr. Diesel]

Joe, you should install a baffled, trap-door oil pan for your autocross racing.

Jake not Joe.
Joe doesn't like us anymore.  :wink:

[fspGTD]

Regarding the oil sump - I sure wouldn't mind a baffled/trap door oil pan, but I'd want only a pan that has the stock VW oil return fitting...  Trouble is most VW aftermarket stuff doesn't have the oil return fitting.  The other thing is, the stock "restrictor" (plastic baffle that clips to the oil pickup) seems to work fine; as I have never encountered an oil starvation problem even under high-G cornering on race rubber with oil level at the low mark (I usually don't run with the oil level very high, as it seems to rob a little bit of power.)  Should I be upgrading my oil pan to better baffles?

Regarding how to drive the oil pump without the vacuum pump - if you use the stock splined shaft oil pump, then you can drive it with the stock oil pump drive gear (for non-vacuum pump diesels).  I learned that the stock vacuum pump block-off plate functions as a pressure-lubricated thrust bearing for this drive gear too!

This picture shows all the parts I am talking about.  (Although the oil pump pictured is a small 26mm gear model, which is not big enough for a 1.6l TD.  The oil pump I used (not pictured) is a 30mm gear depth splined shaft model, which is also stock on a 1.8l 16v gas engine.)


If you want big gear 36mm model for a hydraulic head motor, I think that is stock on a 2.0l 16v gas engine.

My oil pressure seems a little lower than my previous oil pump... 1.5-1.8 bar at hot idle.  I don't really understand why yet.  I think the previous oil pump gave 1.8-2.0 bar at hot idle.  It could just be an inaccuracy in the oil pressure gauge... the gauge reading jumps by that much from the voltage drop when I turn my headlights on!  I will continue to monitor it.  It makes good pressure (4 or more bar) at higher rpms.

[VWRacer]

Jake, you probably already know this, but hardly any serious racer uses an electric oil pressure sender. They are simply too susceptible to voltage error. Hook up a mechanical oil pump gauge and be done with it.

[fspGTD]

Does any one know at what pressure the relief valve inside the oil pump is supposed to start bleeding off oil flow at?  Also, are all 4-cyl watercooled VW oil pumps set to the same relief spring opening pressure?

As for the gauges, I gotta say I am pretty happy with my OEM-based VDO "cockpit" style gauge set.  The oil pressure sending unit and gauge are all OEM stuff, so it all looks and fits like stock parts are expected to.  The oil pressure sending unit just screws right in to where the dummy light sender used to go, and has a terminal for the dummy light so it was pretty much plug-n-play installation.  Also, I'd rather not pipe oil pressure into the cabin, if I can help it at all.  Not just because I run a full interior and would like to avoid possibility of a mess inside the car, but also because it's fewer failure points where oil pressure can be lost at.  I also do have a volt meter now, so I am aware of what voltage the gauges are seeing, and can take the voltage-induced gauge reading variation into account when reading the other gauges.

[Anonymous]

I also do have a volt meter now, so I am aware of what voltage the gauges are seeing, and can take the voltage-induced gauge reading variation into account when reading the other gauges.

How the heck can you calculate voltage-induced gauge variation?!?

[VWRacer]

Personally, I'd rather not try to calculate it, but you can see voltage-induced gauge irregularities readily on race engines, as well as on some OEM installations. The first time I saw it was after I rebuilt a 460 for my van. After the rebuild the engine read low oil pressure, in spite of a new sender. Changing to another brand-new sender sent the gauge off the wall (yes, it was the correct sender). Finally, a third new sender agreed with a mechanical gauge plumbed in series with it, but only above 1500 RPM.

On my Ralt RT-41 with a Pi dash, the electric oil pressure sensor doesn't agree with a quality mechanical sender until the engine hits 4500 RPM. Presumably that's because the electrics aren't up to full voltage until that engine speed. On my CSR I use a mechanical gauge with a steel braided line (to prevent any oil spills).

[fspGTD]

How the heck can you calculate voltage-induced gauge variation?!?

No need to calculate it, as it can be measured directly.  IE: just read the voltage directly off the voltage gauge, and take the current voltage into consideration (IE: expect the value to be lower if the voltage is dropped) when reading the value off the oil temp & pressure gauges.  For example, with headlights, fan, or glow plugs on, I can see that the voltage gauge is probably not seeing a full 14volts, but it might be down to let's say 13 volts.  So I take that (reduced voltage effect) into account when looking at the oil temperature and pressure gauges (IE: that I expect them to be off by some amount vs their 14v readings).  If there is any question, I can easily and quickly switch off the fan/lights/accessories to get voltage to jump back to 14+v, and see how the gauges react.

But back before I had a voltage gauge, I would usually just take into consideration whether I had my fan or lights on.  Now with the voltage gauge I can monitor more accurately what accessory is effecting the voltage level and by how much.

I can see how it would pose a problem if there were a consistent voltage drop at idle.  Luckily I am seeing a full 14+v at idle (accessories off).  As probably most diesels would, given you can run the stop solenoid off a 9v battery!

Anyway I only just recently installed an oil pressure gauge at all, so you could say I'm just happy to have something more accurate than a oil warning dummy light!  

[fspGTD]

By the way, I was slow to admit it but now that I have some more time on it, I do think my oil pressure post-new-oil-pump is a little bit lower... .2-.3 bar lower to be more precise, at a hot idle.  The figures I posted above are not due to voltage variation.  I don't see it very likely that the pump is actually putting out less quantity (clearances are tighter than the old pump, would expect more quantity if any difference) and I don't see it likely that the pressure relief is open at a pressure that low.  I think a likely suspect is the extra pressure-lubricated thrust bearing at the top of the oil pump drive gear is letting a little more oil pressure bleed off than the vacuum pump version of this bearing was, or maybe the motor is running a little hotter due to a recent change in the weather (to warmer temps), or it has something to do with the change of the oil type.  (I changed oil type when I swapped the pump.)  Anyhow, I am not all that concerned, as the instruction paper that came with the pump said it should put out at least 2 bar pressure at 2000rpm, and at a hot 2000rpm it is well above that reading.  If anyone else has some oil pressure readings taken from a VW Diesel, feel free to chime in with your figures, I'd be interested in comparing.  I'd be happy to record and post a table of RPMs/pressures of what mine is doing, if anyone is interested.

[fspGTD]

By the way - the lower thrust bearing surface of the block-off plug wasn't machined perfectly flat.  It is sort of an irregular surface, although it looks like it did get flattened somewhat from wear!  (It's a used part... got it from the wrecking yard.)

Here is a picture describing this part:


Does anyone know if this is supposed to be a perfectly flat machined surface?  Seems like if it is not, it might let excessive oil flow by and sap off oil pressure.  Maybe I should remove it and have a machinist make it perfectly flat?

Not sure if this having it milled or turned flat would make much of a difference or not.

[fspGTD]

Check it out - no vacuum pump there anymore!  



New latest, greatest, engine compartment shot: