Oil Pressure Relief Seat

[Shawn T]

I'm replacing the stock bypass/relief pistons with the high pressure ones available from Pelican for type 4 engines.

Looking in the larger bore the seat looks a little rough. Has anyone used a 5/8" X 5/8" 4 flute finishing end mill by hand to clean up the seat? Dimensionionally it works. Probably need a 5/8" drill collar to control depth of cut?

Will the hp pistons, seat cleanup and Schradek 30mm pump be overkill on a mild 2 liter motor?

Thanks

Shawn T

[njv]

hi
these engines where made in germany using metric its possibly better to use a metric cutting tool in this area.

i have heard that sorting this seat out can make quite a difference to your oil pressure john at aircooled even hires out a tool to do this for typ 1 motors dont know if its good for typ 4 mind mayby he can chip in if hes about and confirm?

how much more pressure is on this spring from pelican than stock?

be good.

[Shawn T]

You are correct that a 16 mm (0.6299") end mill would be ideal but my local supplier doesn't have any. They do have a variety of 5/8" (0.625) that are oversized by 0.002-0.004", therefore 0.627"-0.629". The piston measures 0.6245". What do you think?

This piston set is supposed to increase oil pressure by 25%.

Thanks

Shawn T

[kdanie]

I just saw a post on the STF that John at aircooled.net does rent the seat tool for type 4s.
ken

[njv]

hi
sounds ok but are you measuring the new piston or the old one ?

what exactly comes in the kit from pelican ?

dont know if its any use to me with a late hydro case with only a single bore !

i do need to do something and was thinking along the lines of fitting a second spring inside the original one ?

be good.

[Shawn T]

I am measuring the new one. The kit includes both pistons. I will measure the length and post for your info as that is what is different. It would appear to me that the small one is additional highend pressure relief?

For a mill I ended up taking an old 4 flute 3/4" HSS to my local precision grinding guy and he's going to turn it into a 16 mm one. Says he can grind to a couple of tenths tolerance. Should be perfect. Total cost $20.00.

Shawn T

[njv]

hi
like your style that should keep it nice and tight in there .

that info would be cool .

say if its practical you wanna hire me out your tool when you done with it or sell it?

never hurts to ask?

be good.

[njv]

hi
well i was looking at the vw electronic parts catalouge and noted a few things . over the years vw used 19 22 and 24 mm tall pistons all in a 16mm diameter some with grooves some without. all pistons where available in oversize formats of 16.5 mm as well so right from the early days this has been a problem.

i have a late typ4 hydro case with only one piston up front by the oil pump so i dont think there is anykit comercialy available for that streaching the spring may give me more pressure but im thinking of buying a compression spring with an outside diameter of 12/13 mm that will fit inside the existing spring.

i need to take out whats in there and have a good look at it i should imagine that a 2mm taller piston with a stock spring would give improvement ?

be good

[Shawn T]

My original piston was 24mm. The new one is 30.66mm. I think this piston would be fine for you also. You just wouldn't use the small one in the set.

If we could find a way for you to send me lager and brauts I would gladly let you use the tool but I'm afraid the shipping would be prohibitive.

What I would really like to find from Germany is a good 5 speed Vanagon transmission for a reasonable price. UPS says about $125 to ship. Any ideas?

Shawn T

[Farmer]

Hm. - Why do you guys want more oilpressure ?
- Are you having trouble that you cant keep pressure at idle when warm, or do you generally just want more ?

Personally I think just as many engine/bearing failiures occurs from too much pressure than too little.

But of course things get worn over time, and maintenance is needed. Thats a different story. But skyhigh oilpressure alone, only gets you in more trouble. Be carefull with "overspringing" the release valve.

[Shawn T]

I don't like the hard, hot pull and then oil pressure warning light at idle. The new piston kit should increase idle pressure by 25%, that only brings it up 2 to 4 psi (12-16 psi total). In addition if you groove the rods (per VW) for additional splash cooling of the piston bottoms I believe you need to make up the pressure and flow loss that occurs there.

Obviously high end pressure needs to be kept in check in order to limit leaks and blown filters/seals when cold. Additionally, excess pressure costs horsepower. I guess the question is: what is excess pressure and what combination of clearances, pump size, and non stock modifications is optimal. My belief is probably around 50-60 psi hot, maximum pressure.

Since I have an early case I'm going to stay stock with the small relief piston (which if I understand correctly bleeds pressure off after the lifters are fed ) and use the longer large diameter one which controls primary pressure. Is my evaluation of the system and sequence correct? The other thing I'm doing is checking to insure that the springs I use meet the original spec. Additionally my oil clearances are close to the maximum in the specified ranges.

It is obvious by inspection of my case that the piston seat is well worn and cleaning it up should have a significant effect on pressure.

Thanks for any input,

Shawn T

[Farmer]

Shawn, in your case it would most likely be a good start to try and fix the sealing of the release piston.
If the engine is on max tolerances, and you want a little more life out of it, I suggest that you buy a 30 mm Shadek pump and do the mods needed to that so it will fit in the T4. - Then you also have the pump needed to when you make the piston oiling modification of the rods. But be sure to replace the old relief spring at the same time, or you will experience way too much bypass at highway speeds, resulting in poor cooling.

[njv]

hi
got a 4 speed tranny but no 5 sorry

thinking this thru a bit it seems to me that adding more spring or taller pistons will only give higher oil pressure when cold once the oil is hot and able to flow easier it strikes me as it doesnt make much difference as the piston is not being pressed of the seat anyway or?

this is where the seat becomes important that the oil cannot get passed sneekily while it is actually seated is quite important for warm pressure .

at the moment i see just under 5 bar cold and when at start up this gradually reduces down too .5 bar 7psi at hot idle after a long pull i have not seen my oil light on and i have not checked the acuracy of my vdo either so it could be off either way by a bit?

my sender unit is screwed into a typ3 adaptor that is screwed into the top of a 5 cm tall brass adaptor screwed into the original oil pressure sender hole now it stands to reason to me that i will be showing a lower than actual pressure at my gauge with my sender just horizontally level with the base of the distributer cap base (am i making sense) .

this is the highest point of the oiling system higher than my cooler which sits to the left hand side of the tranny.

with this in mind would it be safe to assume that everywhere else will see slightly better pressure ?

im not overly concered at the moment ive a stock oil pump stock possibly tiered spring and piston and was thinking that i could at least put in a new piston and spring and if i can get hold of the tool reseat the piston seat to allow for the pressure drop i get by running an oil cooler thru a filter mounted sandwich plate adaptor.

i have decent stainless covered braided 13mm oil lines to my cooler and they are relatively short but even here there is a possibility of some buldeing (sp expanding) in the heat of the summer .

it would be reassuring to know im as good as brand new stock oil pressure if not slightly better but i completely agree that to much pressure is also not a good thing.

be good.

[njv]

hi
ok heres what ive done! i found some compression springs with a 10mm diameter fit inside the piston nicely they dont take to much pressure to compress . chopped it down so it was the same length uncompressed as the original spring (62mm long by the way) .

i then took the piston and resurface the face of it on a surface plate with wet and dry untill it was dead flat .

the results well cold i peg the 5 bar vdo and after 1/2 hour driving it seems to have raised my oil pressure by 10/15 psi.

idle with 80 0c oil temp is now 1 bar (14.5 psi) as oppose to the previous 7 psi according to my vdo.

this tells me that the resurfacing of the piston has the most to do with this as the piston would have not been moveing of the seat at idle before granted it certainly wont now with the inner spring added .

grand cost 2.50 euro 20 min of time now i have enough spring to make 4 more inners so im going to experiment with some different lengths allthough it seems to have worked out just fine as it is for now.

be good.