I was browsing the samba, and saw this thread with some really good diagrams of the dual relief oil system. I am not sure if the measurements were from a type I or what, but it was really good to see a good diagram of the oil system with some actual pressure measurements for different engine conditions and temps. It would be interesting to see what comments you guys that are highly experienced with the type IV engines have. JoeO

http://www.thesamba.com/vw/forum/viewtopic.php?t=280293

thanks joe, this is what i was looking for but couldn't find before finishing my build. i had 30mm pump questions about the excessive volume (in reality pressure) causing it ti bypass the cooler. this test varified that. it was also using 10 x 40 i think, lighter than 20x50 anyway. i noticed all sorts of hot running complaints with 30mm pumps. i took a crap shoot and shimmed apx. .040 under the oil relief (not control valve). my thought was to keep to oil passing through the cooler, and yes on our hot central valley days the cht's are VERY good. i think it helped.

correct me if i'm wrong the drilling of the oil control passage would help the oil return to the case quicker instead of flooding the heads... it also would be bad to shim/stiffen the oil control spring for above stated reason? actually if you have good pump volume/pressure and within spec. bearing clearances then a drilled oil control and maybe even lighter(?) spring pressure, it would be good to get the oil back to the pump. after all most oil systems dont have a check at the END of the system

just my wacky thoughts

That thread is for a 1600 dual relief VW TYPE I.

Here are the diagrams from the factory manual regarding the Type IV.

From reviewing the diagram on the Samba, and the one here, the two systems appear to operate the same way. Only difference is the location of the final control valve. From what I see, if the system pressure is too high (for whatever reason), it will bypass the oil cooler- no matter what the oil temp is on both types. That said, it all depends on the actual pressure, which is a function of the effective pumping volume rate, bearing clearance, oil dispersed through lifters or wherever else there is to allow oil to pass through. The remainder of the oil has to go through the valves.

I wouldn't recommend anyone changing their oil system based solely on the samba article, but it did give some interesting facts. And, heaven forbid that anyone change their engine based on my comments here. I am just trying to stir up some discussion to help us all better understand the systems. What if the same thing did happen on the type IV? It would be really interesting to see some actual pressure measurements similar to this on a type IV. JoeO

You're correct Joe, the info is pertinent and it's a very informative study. I just wanted to make sure that other people didn't confuse that info for direct T4 info.

how is the location different, it's at the end of the run, do you mean acual physical position in case?


i've had several threads conserning this that never resulted in clear answers. when using the 30mm h.v. pump, it seems it's common to have hotter running engines. i've heard more than once that by running 10x40 the temps where cooler than running 20x50 with these engines. i know there can be many other issues resulting in heat but to me it seemed like a huge factor. when building my 2056 i shimmed the spring (easy enough to remove). the engine runs exceptionaly cool and i think it at least contributed to helping temp.s by running the oil hru the cooler.



the t1 and t4 oil system charts appears to be identicle in operation except for the t1 not having the oil filter and related bypass... no? in operation it seems identicle, possibly different operating pressures/temps.? BTW the first couple typeIV charts didnt show the "oil control valve" at the tail of the flow

mike