Cylinder Head work?

vwbill · Post by **vwbill** » Wed Apr 30, 2003 7:44 pm

Hey, does anyone know what should be done with the rebuild on the heads? Most places say new exhaust value and new silicone-maganese bronze valve guides. Three-angle performance valve seat machining. Leak tested. What does it mean by number of sensors i.e. 1sensor or 4?
Is there a different head for the injection and carb.? Is a bus 1700 head the same as a 412(EA) head? Can you just get the rebuild head and exchange or is the 412 head differant? Do you need to rebuild the rocker arms or just check? Thanks Bill

raygreenwood · Post by **raygreenwood** » Wed Apr 30, 2003 8:39 pm

First...are ytour heads good? No cracks? never been cut? DO NOT SWAP THEM WITH A REBUILD SERVICE! You will have no idea what their history is or what has been done.
If you do not know the miles or history of the engine, you need seats, valves, guides. A three angle valve job is pretty much stock on these engines.
Take them to a shop that does VW work only. If they don't do many type 4's....ask a lot of questions.
Do not let anyone flycut to "clean up the sealing area" unless there is a huge ding or a burned spot from burning a head gasket. In that situation the head may be less than desirable.

Yes the heads are pretty much the same. Go by part #'s under the rocker shafts cast into the box. Also make sure the breather tubes are in the heads if yours had them.

In a decent shop, what it costs to properly rebuild your heads is what it costs to properly rebuild any head...unless you are having repair work like welding done. So that should beg the question...if someone is supposedly saving you money by swapping your heads with rebuilt ones....what corners did they cut to make it cheaper? Look for my back posts in the forum about replacing exhaust studs. That should be done too. Ray

vwbill · Post by **vwbill** » Wed Apr 30, 2003 8:53 pm

Hi Ray, thanks for your info! I did read alot of places saying flycut! I'll check it out with them. I just checked with Importmotor.com(soCal) and Mofoco so far. Thanks Bill

raygreenwood · Post by **raygreenwood** » Thu May 01, 2003 5:48 am

Yep, you should only flycut the cylinder mating surfaces if needed...and only a few thousandths. On most heads, you can simply lap the cylinders into the sealing surfaces with valve grinding compound. Fly cutting can very quickly ruin a 1.7 head. You already have higher compression and lower valve clearance because of the domed pstons. Ray

vwbill · Post by **vwbill** » Fri May 02, 2003 9:25 pm

Hey talked with a shop today and they said you should get new heads because the T4 heads would drop seats and valves. Then spoke with another and they said the guide wear would tell the wear on the seats.
The new is twice the price! Man is there a lot of tin screws,

and the heat exchanger connection, yikes thats wrench work,

. Is there a better way? Man, the engine has stuff to take apart! Hoses,Hoses, lol! Thx Bill

vwbill · Post by **vwbill** » Sun May 04, 2003 10:01 pm

Hey, I got the numbers off the head 021-101-3710 and a "8" or "15" stamped in the center of the head on the bottom. Is there a site to look thoses up? Thx, bill

vwbill · Post by **vwbill** » Mon May 05, 2003 6:31 pm

vwbill wrote:Hey, I got the numbers off the head 021-101-3710 and a "8" or "15" stamped in the center of the head on the bottom. Is there a site to look thoses up? Thx, bill

Hey forgot to say that when I pulled the rockers off and the pushrods, one of the pushrods had a banded(1 inch) wear pattern in two equal segment with a space of equal size in the middle around the spot of the head, cyl connection. Tried to get the heads pulled but the front tin or something is holdin it up! Hope its not the front cooler housing! Thx Bill

vwbill · Post by **vwbill** » Mon May 05, 2003 8:48 pm

vwbill wrote:
vwbill wrote:Hey, I got the numbers off the head 021-101-3710 and a "8" or "15" stamped in the center of the head on the bottom. Is there a site to look thoses up? Thx, bill
Hey forgot to say that when I pulled the rockers off and the pushrods, one of the pushrods had a banded(1 inch) wear pattern in two equal segment with a space of equal size in the middle around the spot of the head, cyl connection. Tried to get the heads pulled but the front tin or something is holdin it up! Hope its not the front cooler housing! Thx Bill

Hey Wahoo, got the heads off

. They look Good, I think, it looks like lite brown burnt oily coating on the domes and valves; not carbon thick flacks. There is oily stops on the bottom of the head fins near the rim. for the cylinders. I was expecting maybe chips or pieces missing but who knows how the seals look!

raygreenwood · Post by **raygreenwood** » Mon May 05, 2003 8:56 pm

Bill, run away from that shop. They do not know enough about what you have to help you without ripping you off or tripping over their ass. Yes...some type 4 heads dropped seats. To this day...I do not think thatanyone for sure has definitively narrowed it down to a lack of proper inerference fit from the factory...but that is possible. For sure, a lage portion of dropped seats are directly attributed to chronic overheating. Usually from a combination of : poor fuel mixture, timing, cooling/oiling issues etc. I have never had a single dropped valve seat. I also work my backside off to never overheat my stuff. But I have dissassembled many engines for other people with dropped seats. Every one of them had signs of gross overheating. Usually vacume leaks, burned or dropped valves and damage to pistons. Usually on fuel injected cars that were tampered with by mechanics used to working on carbs, or left poorly adjusted by the owners.
Its as simple as this....alll type 4's should have new valve seats on a rebuild...if you do not know for absolute sure that they have recently had them installed by a competent shop. They need about .006 interference fit. If the shop you are speaking to cannot do that...leave. This is common work. Unless your headsare severely cracked, have been deeply flycut, or have avery burned notch in the cylinder seating area.
Have them tested for cracks, bead blasted, tanked, new seats, valves and guides put in....properly....and you are done with the basics. Tell the shop that is what you want done. Don't ask for their opinion. These are the basics. Porting, port matching and flycutting to adjust compression are all options on the side. If the shop can't do teh above listed things without a hassle...leave. The stock castings in good shape are worth too much and getting too scarce to give away to someone too lazy or inexperienced to do what you ask. They are generally beter quality than all but the very most expensive aftermarket castings...like remellle heads. Even that can be questioned.
The part # you are looking at have no breather pipes? They are 1.7L?
The part # is actually 021-101-371-Q. It is a craburated bus 1.7 head with PCV tubes. The lack of tubes is the only difference from the 1.7L FI heads. Ray

raygreenwood · Post by **raygreenwood** » Mon May 05, 2003 9:03 pm

Oh sorry...forgot, The shiny band on the pushrod is from one of two things, either a bent pushrod rubbing on the pushrod guide wires, or an improperly installed guide wire or a bent guide wire...that squirrilly little wire thing under the rockers. Its not atually supposed to contact the pushrod. When it does, for whatever reason, it wears the pushrod as the pushrod spins. The oily stuff is common head gasket leaks from the cylinders. Thats why most people omit the stock gaskets and lap the cylinders into the heads with valve grinding compound. It seals much better. Ray

vwbill · Post by **vwbill** » Mon May 05, 2003 10:49 pm

Hey wow was I wrong on one of the heads!! After closer inspection when I was taking pics, there is a 1/4" blast site at a point in the gasket area of the head/cylinder rim! It looks like a pointed blast starting at the intake valve side(small valve)nearest in edge below the cyl. stud hole then it expands outward in a trench in the head edge rim about 1/2"! Looks like something drilled a hole in the head gasket area and under the pressure it
blasted a groove out in the side of the head edge! Can they fill this and grind it or is it history?? It's a big trench in there! I do believe these motors are tuff since It still ran pretty good for having a hole in the number one cylinder gasket and head! Just noisy! lOl. I use to run the crap out of my previous 412(1800)(this one is 17004sp,FI)! It would still sing when it should have had a blown engine! Thx, Bill

raygreenwood · Post by **raygreenwood** » Tue May 06, 2003 12:44 pm

Some would say to weld it. Others like jake Raby (from reading his posts...correct me if I'm wrong please)...will tell you that once you get a burn through that messes up the seat that bad...its toast. I'm inclined to agree. Welding a cylinder head seating area and then trying to flycut back to original specs, is a recipe for a leaking cylinder. The welded patch will probably never break...but it will expand at a different rate...making a lump that unseats the cylinder when it gets hot. I would get another 1.7 good used one. Make or buy a simple cc kit so you can ascertain wether a used head you are buying has been altered significantly in volume. Also bring along a dial caliper with depth foot to make sure any used head you buy, has not been flycut. Ray

vwbill · Post by **vwbill** » Tue May 06, 2003 4:28 pm

raygreenwood wrote:Some would say to weld it. Others like jake Raby (from reading his posts...correct me if I'm wrong please)...will tell you that once you get a burn through that messes up the seat that bad...its toast. I'm inclined to agree. Welding a cylinder head seating area and then trying to flycut back to original specs, is a recipe for a leaking cylinder. The welded patch will probably never break...but it will expand at a different rate...making a lump that unseats the cylinder when it gets hot. I would get another 1.7 good used one. Make or buy a simple cc kit so you can ascertain wether a used head you are buying has been altered significantly in volume. Also bring along a dial caliper with depth foot to make sure any used head you buy, has not been flycut. Ray

Hey I found another number that is stamped(looks like inked) on the outside of the heads near the head bolt holes 022-101-372D. I measured the cylinders and they measured 90mm(89.97 stamped on pistons). Could these be rebuilt heads? There is another ink stamp near the eng serial number also. The heads are fuel injected with a sensor on the 3-4 head Left side and they both have vent tube pipes on the left side of the rocker area.
The CC kit would measure the capacity of the dome of the head by putting a liquid in the dome area? Is that how you can tell if its been cut?
Thanks for the info! Bill

raygreenwood · Post by **raygreenwood** » Tue May 06, 2003 9:53 pm

I'm not sure about that part #. Are you sure its not an 021? The piston size is factory 90mm. Are the pistons domed? Or dished. Ray

vwbill · Post by **vwbill** » Tue May 06, 2003 10:44 pm

raygreenwood wrote:I'm not sure about that part #. Are you sure its not an 021? The piston size is factory 90mm. Are the pistons domed? Or dished. Ray

Hey The pistons are domed. How do you know the measurement for the head gasket? I measured the old ones. Is there a spec for it I couldnt find it. Well got the heads packed up and ready to go out somewhere just have to decide on a shop, lol! I toke the sensor and vent tube out. Thx Bill

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