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oil pump?

Posted: Fri May 26, 2017 6:27 pm
by neilb
i did a quick search but didn't see any previous info,

i have an oil pump that came with the engine which was low mileage (it was stored for 20 years) should i have that checked and cleaned or buy a new pump like the cb maxi 1830? or equivalent... the engine is a 2258 new build

Re: oil pump?

Posted: Sun May 28, 2017 12:11 am
by sideshow
Oil pumps wear when rods fails, seats drop, and debris flow thought its passages.
Not shelf rot, you will not find any posts on how one went bad in storage.

Re: oil pump?

Posted: Sun May 28, 2017 1:20 am
by Piledriver
If its a stock VW pump, it will most likely fit properly.
You cannot buy a new one that does as far as I have seen, except perhaps a Revtec, but its way too large @38mm.
26mm (stock T4) is ideal except in very odd cases, bigger can easily cause issues.
The pump is supposed to be a .~.003" interference fit to the hole in the case.

To test a Schadeck pump (makes the CB pumps as well), you have to pull the studs to tell as they offset one hole a hair to fake a tight fit.
It falls in the hole and flops around, and will suck air and leak oil pressure internally, frequently leading to hot idle oil pressure woes..

I suspect they do it to make them easy to install by engine assemblers. (builders!= assemblers of parts, difference)
They should not be easy to install in an assembled case.

Re: oil pump?

Posted: Wed May 31, 2017 4:12 am
by trapnm
What's the current way to go for a big t4 since the schadeks/ mellings have turned to blah and nothing else is really good? Keep sending back schadeks until you get a good one? Or blueprint a stock pump... 3.7 ish t4.

Re: oil pump?

Posted: Wed May 31, 2017 4:37 am
by Piledriver
You might get old and grey before getting a properly sized Schadeck, they seem quite consistently wrong.

You can get Mellings in 28mm, but they need double-oringed to be useful and not leak externally, they don't even grow with the case, and run smaller od than the Schadeks.
Oringed pumps really must be installed as the case goes together or you cut the orings.
I'm running a modded Melling now, after 90K its about the only dry spot on the motor. (time for a reseal and 96s)
(also ground in "pressure balance" grooves ala SBC/Ford to reduce its max pressure, while keeping the volume)

There's actually some rubber molding stuff they make bonded vacuum seals with that could be applied to the OD around the ports and at case entry to prevent recirculation, while being "stuck" well enough and thin enough to possibly allow insertion/removal... with some careful radiusing of the case oil ports so it can slide past w/o cutting.

I keep forgetting to research that. :roll:

Re: oil pump?

Posted: Sat Jun 10, 2017 9:35 am
by dunegoon
On a Schadeck, my cure for hot idle pressure was to go to full flow, sending the oil out a steel cover. For loose fit on the pump and the possibility of having problems on the suction side, I turned the pump body down a bit and sleeved it to size. A t-4 #2 main bearing is one source of sleeving material. I wish it was a bit wider but it works. I messed around with o-rings for years before deciding to just make the pump fit right.

Re: oil pump?

Posted: Sat Jun 10, 2017 9:47 am
by Piledriver
Slick and impressive fix!

I considered making at least a "ring" around the ports with a bit of TIG, then machining to only need a few thousandths, but worried about heat distortion, but there are probably ways around that.

I considered knurling as well, ~no internal distortion, but while that technically would cure the fit I'm not sure the seal would be good enough... maybe with a smear of jbweld or such to fill the resulting grooves, then machining to size?

I even considered a small DIY electroplating bath...

VW once went to the trouble of "binning" the pumps by OD, as the cases vary a little.(but not much)

I will give Schadeck credit, they do seem to be very consistent on OD, even if a few thousandths too small.
Its just infuriating they can't make them the stock OD.

It still baffles me as to why.
It's far easier to turn down a pump body for an oddball small ID case than to add material.

CB probably moves enough pumps to force the matter with Schadeck, seems odd they can't even get in spec pump bodies when they get theirs custom made.

Re: oil pump?

Posted: Sat Jun 10, 2017 11:17 am
by dunegoon
The T-4 main bearing OD is a perfect fit, but when you shrink it on the pump body, it will be slightly too large. So you have to turn the OD to size afterwards. I turned the bearing ID quite a bit so that the groove was gone and only a little bit of the pump needed turning. Here (hopefully) is a picture. I have a .050 shim to position the pump better for type 4 plus the sleeve. It's not a thing of beauty, but functional.

Re: oil pump?

Posted: Sat Jun 10, 2017 11:55 am
by Piledriver
You might consider placing it ~flush with the inner lip, and leaving the gap under the flange as a "free" oring groove.
The case stops before the inner edge tho.

Looks like an excellent (but labor intensive) solution.

Yet another reason to save used main bearings...

Re: oil pump?

Posted: Tue Jun 20, 2017 12:51 am
by trapnm