Former VWDieselParts.com Forum

Hi, I have a 1990 jetta with a na 1.6 and a 1985 jetta with a na 1.6. Both of them have mechanical heads even though I guess they were made with hydraulic heads. The 1990 will need a new head. I've searched the forums, but haven't been able to tell if the engine blocks are different for the hydraulic and mechanical heads or if you really should mix and match the two styles if the blocks are different? What is interchangeable and what isn't? Thanks for your time.

Blocks are different. (matches head)

In jacks picture here you can see the hump. The engine block will have a corresponding hump.



Basically some folks have made hydraulic work on mechanical, by plugging the hole ect, but I dont think you could do the other way without major work.

I was considering doing that, converting my mechanical block to hydro head. So, plugging the extra return hole is the easiest solution? Also there is no difference between the cams correct? I have a 1.6NA, and I am considering doing the convert the next time I do anything major to it again. Cost is going to be a factor too I guess, but from what I hear it is worth it.

viperkepr wrote:I was considering doing that, converting my mechanical block to hydro head. So, plugging the extra return hole is the easiest solution? Also there is no difference between the cams correct? I have a 1.6NA, and I am considering doing the convert the next time I do anything major to it again. Cost is going to be a factor too I guess, but from what I hear it is worth it.

I've never done the swap. Would be nice to not have to adjust lifters.

I guess I have a frank-n-head. I have a mech head and block. but the head has hyd lifters. well, it ran so I was game. should I pull the cam and put in mech lifters?
I have never adjusted or tested lifters. I had taken the head to be "rebuilt". I never thought to change the lifters. I thought they came that way.

Can you post a picture of your head and block highlighting the extra hump between 1+2?

Is the hyd head an OE head or aftermarket? Some of the aftermarket heads use the same casting for both heads and so you can't tell externally if they are hyd or solid. If it has hyd lifters (you're sure?) then you cannot just swap in solid lifters. The hyd valves are shorter and the recess for the lifter is large in order to accommodate the taller hyd lifters.

I would be interested to know how a motor would run that was supposed to be using a mechanical lifter and has a hydraulic lifter installed. The lifter would never pump up fill of oil, and thus valve operation would be a very small amount of movement, unless the valves were ajusted that removed all the "play" in the valvetrain within the lifter body itself.

That's not accurate. The oil supply to the head is exactly the same for hyd and solid lifter engines. Even the oil supply to the lifters is the same, although that's not relevant as the hydraulic lifters will not fit into a solid lifter head or vice versa as I stated earlier. The only issue with using a hydraulic head on a solid lifter block and vice versa is where the coolant channel in the solid lifter motor component lines up with the oil return of the hydraulic motor component. Resolve that issue by plugging the channels and the hydraulic lifter head will function EXACTLY the same on a solid lifter block as it does on a hydraulic block.

there is no extra hump. I have no idea if it is oem or after. the lifter cam contact point is solid not shelfed with shim. I had them out when I did the head gasket.

libbybapa wrote:That's not accurate. The oil supply to the head is exactly the same for hyd and solid lifter engines. Even the oil supply to the lifters is the same, although that's not relevant as the hydraulic lifters will not fit into a solid lifter head or vice versa as I stated earlier.

Ok. I was thinking vintage V6/V8 engine lifter/valvetrain operation.

so if there is no second hump, does that mean that it is mech?

Thank you Kap'tn Cool for posting the pictures , very handy for me.
I prefer mechanical Heads , matter of taste I guess.

hagar.

so if there is no second hump, does that mean that it is mech?

It's supposed to .

Fatmobile wrote:

so if there is no second hump, does that mean that it is mech?

It's supposed to :) .

well I thought I had hyd. I looked at some pics of the lifters and recognized the notch on the mech lift. so went out and pulled the valve cover.
yep it mech.
I guess better late than never.

I have never measured or switched the shims. maybe that is where some of my fuel ec. is going. time for the bentley.

hippiehulahooper wrote:

Fatmobile wrote:

so if there is no second hump, does that mean that it is mech?

It's supposed to .

well I thought I had hyd. I looked at some pics of the lifters and recognized the notch on the mech lift. so went out and pulled the valve cover.
yep it mech.
I guess better late than never.

I have never measured or switched the shims. maybe that is where some of my fuel ec. is going. time for the bentley.

With the cover off, look for the two oil drains corresponding to where the two cast ridges should be.
Maybe there is a drain there anyway....

To be perfectly honest, to fill the head up with oil neccessary to require the extra drain could only happen when the bearings are slacker than safe to drive... IMO