TheSamba.com :: View topic - Can someone explain full flow oil systems to me

Wed May 21, 2008 7:16 am

Im not the smartest guy on the block and I am having a hard time understanding what full flow oil systems are. All I know is that my 1776 dual carb motor is not full flow. I have been thinking about doing it but I have I some questions if you dont mind

What is Full flow?
Why do people do it?
what do I need to do to my case?
what do I need to buy?
Can I do it to an already built case or do I need to rebuild it?
what advantage will I get from full flow?
will my bug run cooler?

Thanks a bunch!

Wed May 21, 2008 8:02 am

A full flow oiling system simply means the oil is pumped through a filter and sometimes a cooler before being returned to the engine.

The VW engine has no filter. It just has a screen. So the addition of an inline filter will extend the life of the engine.

Another draw back to the VW engine is the small oil capacity of the crank case. Adding a filter and lines will increase tthe amount of oil available to your engine.

Adding a cooler will also keep oil temps down and add additional capacity.

Should you do it? Well, the answer isn't simple. I would say yes to adding a filter simply because it helps to remove abrasive particulates from the oil.

As for adding a cooler, you first need to monitor your oil temps. DON'T add a cooler simply because it is the "cool" thing to do or because someone who sells them in a catalog says you need one!

Oil MUST be in the proper temperature range in order for it to lubricate properly. If you add a cooler and oil capacity, you may end up running too cool with your engine temperatures. This can be more damaging then running hot and also increases the warm up time of the engine.

So, if you want to spend money and buy cool stuff for your car, start with a few gauges. This will let you know whats going on and if you should add additional oil capacity or coolers.

As for filters, I prefer the oil pump/filter deal. It's simple, not expensive and won't add additional complicated plumbing to the engine. It only adds a minimal amount of capacity and some say it is too close to the exhaust, but this is a simple way to keep your oil clean.

If you are concerned about heat from the exhaust, a simple sheet metal heat shield can be fabricated to keep the radiant heat away from the filter.

Wed May 21, 2008 8:24 am

I have a bunch of gauges and I don’t like them because all I do is look at them and worry but that is another issue.

The oil temps get pretty hot in my mind. After about 30 minutes of city driving the gauge is around 210-220 and going up. That alone is not making me worry much but I feel like if I keep driving longer the temps will keep going up.

I also have a oil pressure gauge and it reads in the 40's when it’s cold and 20’s when its warm while I am driving. However sometime when I am at idle the oil light comes up. If I give it a little rev then it goes out but comes on again when I am back to idle. My tach shows my idle is around 800rpms. I also have the dual VDO oil pressure sender and was reading that it turns the light on at around 10-15psi and the stock sender comes on at 7psi. When at idle with a warm car the gauge reads at the 10 hash mark.

So I am a little worried that car is running on the hot side. I have the doghouse cooler and 1.5qt sump. The timing and carbs where just tuned by my local VW shop.

I was thinking that I would go full flow to add a filter and possibly another cooler but I don’t want to just cure a symptom. Also to do full flow the case needs to be tapped right? Can I do that on an already built motor or does it need a tear down? My motor is only a year old.

Wed May 21, 2008 8:49 am

I have been looking into this also and have been told, you MUST drill and tap the case for the return line and it's best to drill and tap the case at the pump to plug it also (prevents oil leaks). I don't want to disassemble my engine at this time so does this adapter really work as well as tapping the case?

Oil Return Adapter (Full Flow Adapter)
http://www.aircooled.net/new-bin/viewproductdetail.php?keyword2=ECO0027&cartid=0520200857901380

Here's their whole kit it minus the adapter . . .
http://www.aircooled.net/new-bin/viewproductdetail.php?keyword2=ECO0011&cartid=

Wed May 21, 2008 4:39 pm

I was told oil temp is should run between 180 and 210F.
Can someone flesh this out for me.

thanks,

Fred

Wed May 21, 2008 5:08 pm

180-210 is normal
210-230 is warm
230-250 is hot
250+ is turn the engine off

Tue Oct 13, 2020 2:18 am

Greetings members.

I've a question on the CB performance full kit link below:

https://www.mooreparts.com/vw-bug-full-flow-oil-fi...ished-cam/

1.Does it mean one uses the stock oil cooler(mine is Doghouse type 71 up)

2. The piping from the Oil filter,where does it terminate? In other words how does the engine get oil supply?

Checking to be sure...I seem to have a missing link.

Respectfully.

Mwanza.

Tue Oct 13, 2020 5:02 am

Welcome to the Samba!

Yes, it has nothing to do with the oil cooler, so nothing of that sot changes.

And notice there is an IN and OUT line. Oil is pushed out of the pump, then going to the filter, and then the oil makes its way back towards the engine. If you remove the pump cover, you will notice a secondary hole/entry that is isolated from the pump section thats in charged of doing the actual pumping. Oil goes into the hole, and back into the same oil galley it would be pumping through on a stack no filtered system.

This Style of pump, or an IN OUT pump, is best suited for already running engines, because it is a bolt on, and you wont have to drill any oil galleys.

Here is a picture of a filter pump, or an IN OUT pump. However, a pump body like this can also be used as a single OUT style pump cover.

Mon Oct 02, 2023 10:29 am

Chickensoup wrote: Welcome to the Samba!

Yes, it has nothing to do with the oil cooler, so nothing of that sot changes.

And notice there is an IN and OUT line. Oil is pushed out of the pump, then going to the filter, and then the oil makes its way back towards the engine. If you remove the pump cover, you will notice a secondary hole/entry that is isolated from the pump section thats in charged of doing the actual pumping. Oil goes into the hole, and back into the same oil galley it would be pumping through on a stack no filtered system.

This Style of pump, or an IN OUT pump, is best suited for already running engines, because it is a bolt on, and you wont have to drill any oil galleys.

Here is a picture of a filter pump, or an IN OUT pump. However, a pump body like this can also be used as a single OUT style pump cover.

Hi, how does one know wether to buy the "dished cam or flat cam" version? And does this mount in a specific place or do people mount the filter in different places? Also, is other hardware needed to complete the installation?I have a '74 Karmann Ghia Convertable with a 1776. Thank you!

Mon Oct 02, 2023 11:06 am

Full flow systems pump oil through a filter before it goes to the bearings.

Bypass flow systems pump only the oil released by the oil pressure regulator (bypass oil) through a filter before it goes back into the crankcase.

The Volkswagen flow system uses a bug screen at the bottom of the sump.

Full flow is best.

Mon Oct 02, 2023 11:17 am

your oil is a bit hot. make sure that the vee belt is tensioned right, no oil on it. do not use a power pulley, make sure pulley is stock diameter so that fan runs at required speed. make sure rags and leafs are not sucked into fan, which will block cooling air, make sure fire wall padding is not leaning and blocking fan inlet. Make sure ALL cooling tin and rubber seals are correct and no gaps, this also includes heater ducting hoses.

If still hot after this, make sure timing is not too far advanced, mixture correct, and fuel grade high enough. Also make sure the four wheels spin freely as a dragging brake can make engine work hard and get too hot.

The Dog House system has a tiny sheet metal internal part that is critical to be installed to prevent cooling air from by passing the cooler. This part is called the "hoover bit" a samba search will yield many posts about this Hoover bit and its importance for cooling the oil. There are also foam seals around the dog house cooler that are critical to renew.

Make sure bypass valve for cooler is opening fully when hot (it opens at low oil pressure)
Wrong wieght of oil can lead to high temps (bypass wont open with too thick an oil) use recommended oil for your climate. Generally a 10w30 works for most folks, other might use a 20W 50. but what ever of this range, assure the bypass is opening fully when hot. If you are running 20w 50 you might want to test 10w 30 to see if that lowers temps, BUT besure you maintain good pressure, minimum of 10 psi per 1000 rpm when warmed up. i.e. minimum 30 psi at 3000 rpm.

Finally, or perhaps firstly, make sure your temp gage is correct. A test thermometer can slipped down the dip stick tube when engine is off and hot to use as a comparison. That test thermometer can be tested for accuracy in a pot of boiling water.

Report back!!!! Good luck, stay cool.

Full flow related to oil filtration.

Mon Oct 02, 2023 6:06 pm

GDKARMA wrote:

Hi, how does one know wether to buy the "dished cam or flat cam" version? And does this mount in a specific place or do people mount the filter in different places? Also, is other hardware needed to complete the installation?I have a '74 Karmann Ghia Convertable with a 1776. Thank you!

GDKARMA, Please don't take offense in what I'm typing. I'm not trying to be condescending.

If you are asking about what cam gear you have in your engine. It's kind of an indication that you are not very experienced with your engine/car.

One way to know if you have a dished cam gear or not is to look.
Pull the oil pump and see if the cam gear is dished or flat.
On a rebuilt 1776, my money is on a flat cam gear. But you need to know for sure before ordering a full flow (FF) pump and filter setup.

If your engine is in the car and fully assembled. Installing a FF system on your running engine may bring more headaches that what you are bargaining
for installing a FF system.

There are a few alternatives to installing a FF system on a running/installed engine.
The CB filter pump is a good alternative. You remove your old oil pump and install the filter pump setup. It works, as long as you have a header on your Ghia. If you have a stock muffler, and the heat riser tube is on the left side. Your kinda S.O.L!
https://www.cbperformance.com/product-p/1792.htm
I have this filter pump on two engines. It works! But the filter pump cover needs a little clearancing to clear the crank pulley tin.

Then there is the CB FF in/out pump and cover. I have no experience with this setup. So it too, may need a little clearancing to clear the crank pulley tin.
https://www.cbperformance.com/product-p/maxi26late.htm

In both of the above examples. You still need to know what cam gear you have in your engine before ordering.

There may be a folks that say, "just drill the case, in situ." Sure it can be done, if you have the tools and are skilled at keeping the aluminum/magnesium chips out of the oil galley's.

I run FF on larger high revving engines. On the lower revving engines, filter pumps are my choice for ease of installation.
YMMV!

Mon Oct 02, 2023 6:22 pm

67rustavenger wrote: GDKARMA wrote:

Hi, how does one know wether to buy the "dished cam or flat cam" version? And does this mount in a specific place or do people mount the filter in different places? Also, is other hardware needed to complete the installation?I have a '74 Karmann Ghia Convertable with a 1776. Thank you!

GDKARMA, Please don't take offense in what I'm typing. I'm not trying to be condescending.

If you are asking about what cam gear you have in your engine. It's kind of an indication that you are not very experienced with your engine/car.
YMMV!
Or never had the engine apart.

If you buy a late model 1600DP that originally came with dished cam, it's very easy to not know if it was never rebuild or rebuilt with a dished or flat cam.

Only way to know for sure is to pull the pump and look at the cam gear.

I would ASSume that he's asking about adding full flow to an existing engine.

Mon Oct 02, 2023 8:18 pm

Glenn wrote: Only way to know for sure is to pull the pump and look at the cam gear.
To add to Glenn's response...

Cam + gear on the left is 3-rivet "flat" cam. The slot of the oil pump drive gear is immediately in front of the gear face.
Cam + gear on the right is 4-rivet "dished" cam. The slot is set deeper into the case.

Just looking at the rivet attachment points you can see the cams and gears are not compatible. The gear on the right is clearly more dished to allow room for a larger oil pump that sits deeper into the case. The dish makes room for the larger/longer pump & gear. This means the pump must match the cam gear. The cases that came with the larger pumps also had larger oil passages.

Knowing if you have a flat or dished cam is the first step. Dished cams are mostly original stock cams. Flat cams could also be stock but many/most aftermarket/performance camshafts come with a flat cams.

Next thing you need to know is if your case is a later case with larger oil passages or an early case with smaller oil passages. Here is a pic showing different pumps. Notice the smaller pump outlet on the left (earlier) pump.

One last point to note is the left (early 21mm gear) pump above uses M6 studs to attach to the case. Later (26mm long gear) pumps used M8 studs.

Since changing your cam would require a complete case disassembly you need to find a full flow pump that matches your cam and your case. Pick either a flat cam or dished cam pump to match your cam. Then select the size of the pump gears. 21mm long gears would be for early single-relief cases with M6 studs. 26mm gears with M8 studs for dual-relief cases with larger passages. 30mm gear pumps are available for even more pressure.

Even if you have a flat cam, 26mm or 30mm pumps can be designed to work with the cam by having the extra gear length extend out further out the rear of the case. You can see this when you compare the middle pump with the right one. They have the same 26mm pump gears but the middle pump will fit the more shallow flat cam gear.

Thu Aug 21, 2025 6:43 pm

ashman40 wrote: Glenn wrote: Only way to know for sure is to pull the pump and look at the cam gear.
To add to Glenn's response...

Cam + gear on the left is 3-rivet "flat" cam. The slot of the oil pump drive gear is immediately in front of the gear face.
Cam + gear on the right is 4-rivet "dished" cam. The slot is set deeper into the case.

Just looking at the rivet attachment points you can see the cams and gears are not compatible. The gear on the right is clearly more dished to allow room for a larger oil pump that sits deeper into the case. The dish makes room for the larger/longer pump & gear. This means the pump must match the cam gear. The cases that came with the larger pumps also had larger oil passages.

Knowing if you have a flat or dished cam is the first step. Dished cams are mostly original stock cams. Flat cams could also be stock but many/most aftermarket/performance camshafts come with a flat cams.

Next thing you need to know is if your case is a later case with larger oil passages or an early case with smaller oil passages. Here is a pic showing different pumps. Notice the smaller pump outlet on the left (earlier) pump.

One last point to note is the left (early 21mm gear) pump above uses M6 studs to attach to the case. Later (26mm long gear) pumps used M8 studs.

Since changing your cam would require a complete case disassembly you need to find a full flow pump that matches your cam and your case. Pick either a flat cam or dished cam pump to match your cam. Then select the size of the pump gears. 21mm long gears would be for early single-relief cases with M6 studs. 26mm gears with M8 studs for dual-relief cases with larger passages. 30mm gear pumps are available for even more pressure.

Even if you have a flat cam, 26mm or 30mm pumps can be designed to work with the cam by having the extra gear length extend out further out the rear of the case. You can see this when you compare the middle pump with the right one. They have the same 26mm pump gears but the middle pump will fit the more shallow flat cam gear.

Reviving this thread after a 2-year drought. This was a great post Ashman .. that pic of the 3 pumps was very helpful!!

So I have questions for everyone. I want to add an oil filter to my engine. I would love to add the self-contained unit like this CB one:

https://www.cbperformance.com/product-p/1791.htm

But of course I have a stock muffler, so the heat riser tube is in the way. I wonder if anyone makes a stock-like muffler that doesnt have that heat riser tube in the way. My issue is my driveway is inclined significantly, so I cant have the tailpipes stick out any further than the bumper, and cant be any bigger in diameter that a stock peashooter, or it scrapes my driveway ... and I have already raised the rear of the car 1 click on the torsion bars.

Anyways, I have a '68 bug ... but my engine is an H case out of a '67. So I know it has 6mm studs and I assume 21mm gears (I havent removed it yet).

I want a system that I don't have to tap the case, so I guess that's bypass flow vs full flow ... But they all come with 8mm bolts. I'm looking at the CB systems, with mounting an oil filter in the fender. ... Does anyone know what the difference between these two are:

https://www.cbperformance.com/product-p/maxi26early.htm

https://www.cbperformance.com/product-p/1798.htm

Can I still use one of these but swap out some 6mm studs for the provided 8mm ones? Would that cause any leaking around the holes?

Would the provided gaskets that have 8mm holes cause any issues? Maybe buy some gasket material and cut some out with 6mm holes instead?

Would the larger passage oil passage in the 26mm pump cause an issue with the smaller oil passages in the H block (well I assume the passages are smaller since the oil passage in the 21mm pump is smaller)

Any help/guidance is appreciated.

Fri Aug 22, 2025 4:17 am

Snoopy1971 wrote:
But of course I have a stock muffler, so the heat riser tube is in the way. I wonder if anyone makes a stock-like muffler that doesnt have that heat riser tube in the way. My issue is my driveway is inclined significantly, so I cant have the tailpipes stick out any further than the bumper, and cant be any bigger in diameter that a stock peashooter, or it scrapes my driveway ... and I have already raised the rear of the car 1 click on the torsion bars.

The "hot dog" style exhaust like the Empi ant Tri-mil should clear the filter pump. Empi states that it will

https://empius.com/products/empi-2-tip-exhaust-system-4/

There are also studs that are M6 on one side & M8 on the other

Fri Aug 22, 2025 6:32 am

daveblank wrote: Snoopy1971 wrote:
But of course I have a stock muffler, so the heat riser tube is in the way. I wonder if anyone makes a stock-like muffler that doesnt have that heat riser tube in the way. My issue is my driveway is inclined significantly, so I cant have the tailpipes stick out any further than the bumper, and cant be any bigger in diameter that a stock peashooter, or it scrapes my driveway ... and I have already raised the rear of the car 1 click on the torsion bars.

The "hot dog" style exhaust like the Empi ant Tri-mil should clear the filter pump. Empi states that it will

https://empius.com/products/empi-2-tip-exhaust-system-4/

Hmm I may have to look into that even though I am hesitant to use Empi because, well Every Mistake Passes Inspection, and due to my recent Empi bolt fiasco.

The tailpipes are fatter on this one but they look shorter, so it may work. I would have to measure where the bottom-moist point of my current tailpipe is and compare tho this one. The issue is would have to find out if somebody (Jbugs, CIP1 etc) let me return it if it doesnt work.

Also of interest to note ... the Empi page says the remote oil filter will fit with it, but CIP1 says it wont.

https://www2.cip1.com/c13-3418/

daveblank wrote:
There are also studs that are M6 on one side & M8 on the other

I have a set of 6mm/8mm step studs from when I had an oil sump plate stud hole strip out ... but I dont think they are anywhere near long enough for the oil pump application ... I'll have to look if anyone makes longer ones

Fri Aug 22, 2025 9:13 am

Snoopy1971 wrote: daveblank wrote: Snoopy1971 wrote:
But of course I have a stock muffler, so the heat riser tube is in the way. I wonder if anyone makes a stock-like muffler that doesnt have that heat riser tube in the way. My issue is my driveway is inclined significantly, so I cant have the tailpipes stick out any further than the bumper, and cant be any bigger in diameter that a stock peashooter, or it scrapes my driveway ... and I have already raised the rear of the car 1 click on the torsion bars.

The "hot dog" style exhaust like the Empi ant Tri-mil should clear the filter pump. Empi states that it will

https://empius.com/products/empi-2-tip-exhaust-system-4/

I had one on my 63 & we have one on my son's 68. Plenty of room for the filter.

Hmm I may have to look into that eben though I am hesitant to use Empi because, well Every Mistake Passes Inspection, and due to my recent Empi bolt fiasco.

The tailpipes are fatter on this one but they look shorter, so it may work. I would have to measure where the bottom-moist point of my current tailpipe is and compare tho this one. The issue is would have to find out if somebody (Jbugs, CIP1 etc) let me return it if it doesnt work.

Also of interest to note ... the Empi page says the remote oil filter will fit with it, but CIP1 says it wont.

https://www2.cip1.com/c13-3418/

daveblank wrote:
There are also studs that are M6 on one side & M8 on the other

I have a set of 6mm/8mm step studs from when I had an oil sump plate stud hole strip out ... but I dont think they are anywhere near long enough for the oil pump application ... I'll have to look if anyone makes longer ones

Fri Aug 22, 2025 10:52 am

daveblank wrote: I had one on my 63 & we have one on my son's 68. Plenty of room for the filter.

What do you do about not having these pieces that connects between the heater boxes and the hoses to the fan shroud?:

I may look into a new stock style muffler here:

https://www.jbugs.com/product/113251053AK.html

You can see in the above link that the tube to the heat riser is on the passenger side on this one, vs it being on the drivers side on my current muffler:

Then the 1-piece oil pump/filter units may fit.

Oh, I found 6mm/8mm studs from Belmetric ... in different lengths:

https://belmetric.com/m6-to-m8-step-stud-class-10-...H6X8X50BLK

Fri Aug 22, 2025 12:00 pm

Snoopy1971 wrote: daveblank wrote: I had one on my 63 & we have one on my son's 68. Plenty of room for the filter.

What do you do about not having these pieces that connects between the heater boxes and the hoses to the fan shroud?:

I may look into a new stock style muffler here:

https://www.jbugs.com/product/113251053AK.html

You can see in the above link that the tube to the heat riser is on the passenger side on this one, vs it being on the drivers side on my current muffler:

Then the 1-piece oil pump/filter units may fit.

Oh, I found 6mm/8mm studs from Belmetric ... in different lengths:

https://belmetric.com/m6-to-m8-step-stud-class-10-...H6X8X50BLK

I'm not running heater boxes so that was a non issue for me.