Replace oil pump without pulling engine?

[kubicixfactor]

My OP has dropped - it was low already but now it's about 4psi at idle and 18psi at 3000rpm. I'm going to put a new engine in in the autumn, but I'm about to take a long summer trip so I need to get this investigated/sorted. I suspect that this is an oil pump problem (unless it's something really serious, in which case it's game over) - can I replace the oil pump without pulling the engine?
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1973 LHD Westy 2.0l Type IV, Twin Solex PDSIT, 123 Ignition Vac Distributor, CB2201 Cam

[atmellovw]

According to Bentley, the first step in replacing the oil pump is "remove the motor".
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1972 Westy ("Bubbles") - Pastel White - 1700(1974 MT) - Dual Solex

[SGKent]

why would you suspect the oil pump?

Drain your oil and replace it with 20-50 or 40 wt. If you have a mechanical pump check it to be sure there is no gas in the oil thinning it. Also check your strainer to be sure it isn't covered in gasket material etc.

I would be more inclined to believe it is thin oil in summer or a bearing going than the oil pump. Checking the strainer will reveal if there is any metal in it from a failing bearing.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[kubicixfactor]

I've got 10/40 in there at the moment. OP is slow to build when I start up - I guess it's either the pump or tired bearings. What do you suggest, a slightly heavier oil?
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1973 LHD Westy 2.0l Type IV, Twin Solex PDSIT, 123 Ignition Vac Distributor, CB2201 Cam

[busman78]

You can try 20-50, but as SGKent mentioned look for metal particles in the sump. Yes the pump can be pulled with the engine installed, and the pump change out is a lot easier to do in the vehicle than pulling the engine and having to remove the same stuff to get to the pump with the engine out.

[Wildthings]

The oil pump can certain be done with the engine in place, but it is a lot of work, so be prepared for it to take a lot of time and for things to go wrong. I would check virtually any other possibility before digging deep to get to the oil pump. For starters pull both your relief valves, and check for free movement of the plunger and the proper spring heights. If you can get the pressure to go up by replacing the spring(s) or adding washers, then the pump and bearings probably good. T4 engines don't give bearing problems very often, so unless you have run the engine out of oil or gotten it extremely hot, I would not expect to see bearing failure.

If you haven't pulled and cleaned or replaced the pickup screen, how would be a good time. Which brand of oil filter are you using? Some of the cheaper ones are reputed to cause oil pressure problems.

T4 oil pumps do fail. The o-ring goes bad causing a suction/low pressure problems and the idler shaft works it way out which can cause total engine destruction.

[busdaddy]

You may want to investigate other factors too before blaming the pump, how is the relief valve? Tried a different filter? Is the pickup tube secure and screen clean? Tried a different gauge?
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[aeromech]

My machinist says that the relief valve/bypass valve can cause this. That piston has moved over a million times during the life of the engine and causes excessive wear which leads to low oil pressure. He recently did a repair to my type 1 engine where he rebores the gallery and then machines a couple new pistons oversized. This is an area often overlooked by engine builders. His charge was $120 and he says he can do it with the engine installed.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
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[kubicixfactor]

That's coming out tomorrow then!
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1973 LHD Westy 2.0l Type IV, Twin Solex PDSIT, 123 Ignition Vac Distributor, CB2201 Cam

[kubicixfactor]

Mind you - if the relief valve was faulty would there be other problems e.g. higher oil temps as well as low pressure? I didn't look at this because I thought it would be more likely to cause high pressure?
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1973 LHD Westy 2.0l Type IV, Twin Solex PDSIT, 123 Ignition Vac Distributor, CB2201 Cam

[kubicixfactor]

meant to add thanks for all the advice here - I'm learning all the time and I try everything that's suggested. Without you folks it would have been impossible to have got where I am now.
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1973 LHD Westy 2.0l Type IV, Twin Solex PDSIT, 123 Ignition Vac Distributor, CB2201 Cam

[aeromech]

I believe he said you can check it by pulling the plug, spring, and piston. Then you use a special tool that grabs onto the piston. You slide it back up the gallery and check for side play (slop). If there's a lot of slop then you are losing oil pressure at low RPM.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[cool karmann collected]

[SGKent]

when I rebuild an engine I always polish the ends on those with 1200 to 2000 grit wet and dry on glass and make sure the sides are also smooth. On 1600's you can get new springs and pistons. As they wear the sometimes get sticky or groves at the top and leak. I usually keep a spare around as I have seen the springs weaken over time if people don't use thinner oil in the winter.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[aeromech]

[sun-bug74]

I have my engine out right now for other things. While it is out, is it recommended to replace the oil pump and the two relief valves? I was not having an oil pressure issue before but I don't know how long the existing pump has been in there. Seems like an inexpensive but important thing to do while I have such easy access. As for the valves, same thing, I don't know how long they have been in place. Thanks.
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1978 Bay Window Bus, AC Vanagon Motor, Daily Driver

[SGKent]

[aeromech]

Hmmm, a new stock shadek oil pump is pretty cheap. The oil relief pistons can be replaced with the engine completely built and installed.

The thing with the relief pistons is that it’s not the piston or spring, it’s the bore walls that wear because they are soft. So, what you need to do is check the clearance between the piston and the bore for excessive wear. If you find that then you need to machine an oversized piston and ream the bore for a tight fit. This will solve idle low oil pressure

I’m assuming type 1
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[bsairhead]

I have done it on type 1 motors installed. On my current ride 71 bus (type 1 engine) I had idle light flicker so I pulled the cover and saw and felt grooves but the gears looked great. Ruff sanded the cover on my sanding station than wet sanded it on glass with 400 grit doing figure 8's. 10 years later and 40k more miles still no light flicker. I know 4k average a year is not much but the first 2 years got 30.

[orwell84]

On a type 4 at least, I wouldn’t pull the engine to remove an oil pump.

I had issues with lowish oil pressure on an engine I rebuilt. It had new bearings all around and a new pump.

I replaced the oil pressure relief valve and spring. The spring was obviously worn as it was quite a bit shorter than the new one. I got an instant boost in oil pressure. Also, when rpm’s came down, oil pressure would take more time to drop. An easy thing to start with as you go through checking stuff.