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A plan to resurrect my bent valved V6?

5K views 59 replies 13 participants last post by  muttony 
#1 ·
I started a thread about my misadventures with a broken cam chain tensioner on the passenger side. The result of the replacement of the CCT was that the car is misfiring on all passenger bank cylinders only. Drivers side is fine even though I changed the pads on that side (meaning I took the intake cam out and replaced it. It seems that the ultimate result of that was that I have some number of bent valves on the intake side of the passenger side bank. I have been dithering over the past week about whether I should try to fix it or just junk the car/donate it. I have a plan to fix it and I wanted to get people's opinion on what I might be missing from from the plan.

To start, A rebuilt head is out of the question. They cost anywhere from 500 – 1200 dollars as far as I can tell and that is without various gaskets and other parts that might be needed. If this car is to be fixed I'll need to do it myself. And it will need to be done relatively cheaply.

So the plan. I am assuming that the head is not warped or cracked. There is no reason to think it is as I did not suffer any overheating or broken chain or that type of catastrophic failure that would likely lead to that kind of damage. I tried to find used heads but they would only guarantee that the head was not warped and not cracked. There's no point buying a used head for $400 only to have to do the valves anyway.

The plan.
1) Take the front off car (in other words put it in the service position) but having removed the front bumper radiator etc.
2) Put car in TDC.
3) Remove Valve cover and verify timing is correct.
4) Rotate crank 30 degrees off tdc.
5) Mark passenger side bank's Timing chain's 16 rollers. They will not be exactly over the cam journal markings at this point, but I'll need to mark everything's place exactly.
6) Fasten the timing belt to the various pulleys not involved in the head to be removed and mark them. I was thinking of using the little fuel line clamps I have to physically attach the belt to the pulleys in the right places so that they don't move. I do not have a timing belt bar and don't know where I can get one.
7) Assuming I can adequately make the timing belt secure to the right places on the pulleys and on the other bank's cam, I could then unbolt the pulley from the passenger side exhaust cam. I understand that the pulley is not keyed and it should just come off once unbolted. It too, will need to be carefully marked for reassembly.
8) Remove everything connecting the head to the rest of the engine marking and photographing everything carefully for reassembly.
9) Remove the head bolts
10) remove the bolts from the exhaust manifold
11) remove the head
12) Mark each cam journal and lifter for reassembly
13) Photograph marked assembly for reassembly
14) One by one remove the each intake valve with a spring compressor
15) Replace Valve guides and valve stem seals
16) Manually lap the new valves using lapping compound and suction cup tool
17) Clean all lapping compound carefully to make sure it is removed.
18) Replace valve springs and keepers
19) move on to the next one.
20) When done do exhaust valves the same way
21) remove and smooth any sharp edges (from valves hitting)on the piston tops but leave in place otherwise.
22) Replace cams same way as they came out
23) Reassemble engine.

Parts needed:
(9) intake valves at $5.36 ea Rock Auto
(6) exhaust valves at 5.36 ea Rock Auto
Head Bolts set 50.95 Rock Auto
Gasket Kit includes Head, 2 exhaust, VCG and CCT gaskets 96.89 Rock Auto
Valve Stem Seals .95 ea/ 15.00 Rock Auto
Valve Guides 3.31 ea./49.65 Rock Auto
Valve Lapping Tool, Lapping Compound and Engine Assy Lube 20.35 Amazon.
Head Bolt Removal tool 9.56 Amazon
Total for job $325.80 plus shipping.


Tools Needed:
Spring Compressor
Valve Guide Remover
Head Bolt removal tool
Lapping Tool


Advice Needed:
a) Does this plan sound right?
b) What am I missing?
c) What chances of success?
d) Do I need to get the VW timing belt tool and camshaft pin (adds 50.00 plus shipping)
e) Where can I get a spring compressor and valve guide remover that will work with this head? What do I ask for at the Autozone rental counter?
 
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#32 ·
Yes you would remove and replace the head between steps 4 and 5.
Step 5 refers to the toothed pulleys on the front of the exhaust camshafts.

The head should be fully assembled before re-fitting, with valve clearances set and timing set to 16 rollers as per diagram.
It would be extremely difficult and impractical to adjust valve clearances with the head on.

Note: I wrote that as a TB procedure, head and valve work was not included.
 
#34 ·
Thanks Tom. When you say "valve clearances set" I'm not sure what you mean. When the valves are put in and the springs, retainer and keepers are put back shouldn't the valves be set properly without me having to adjust anything? In other words, the springs will pull the valves to the fully closed position.

The way I've seen it done on youtube is that I lap the valves in with lapping compound, clean that all off when done, then put the springs, retainers and keepers back followed by the properly set up cams cct and chain. That's it. What is there to adjust? Doesn't the action of the camshafts pushing down when tightened on the lifters do all the adjusting that's needed. And again, I am assuming that I get the roller count right.

I'm not being a smart aleck, just learning.
 
#35 ·
I think it would be best to get the head rebuilt by a machine shop.

If you want to attempt it yourself, you should look up the procedure and specs in the manual.
Checking the valve clearance is referred to as "checking the installed valve stem height"
The Haynes manual lists the correct heights but doesn't specify a tolerance; the Bentleys might give more details.
The only way to adjust if required is to grind the end of the valve stems (not recommended) new seats or new head is suggested by Haynes.
With the camshafts installed and turned to valves closed position, the valves should be fully closed, and with the lifter fully compressed there should be less than 0.008" clearance.
 
#38 ·
Ok so I've moved along. Got the head out and sure enough there's at least three bent intake valves. These ones are obviously bent. I took one of the bent valves out and replaced it with one from my junked head and started lapping it. I did that till I thought it was right. My understanding of what is right is when the valve can be rotated and makes no noise. Obviously I am going to water test these before I call it done. For giggles I put in an unlapped valve from the junked head and it made no noise at all when rotated. This raises a question in my mind which is; is it possible to put in used valves and NOT have to lap them if they spin quietly?

In any event, I am going to try one unlapped one since it seems better than the lapped one. When I say try I mean put it in and water test it. I need to water test each cylinder anyway in case any of the other valves are also mildly bent.

Having trouble getting the keepers back in. To get them out I used a piece of 1" copper pipe with a cutout for working room and then put a long 5-6' board over the top of the pipe (I covered the pipe sides with duct tape so as not to mar the sides of the spring chambers) and sat on the board compressing the spring/ I've protected the cylinder head mating surface with duct tape and I used a cushion underneath so that I don't accidentally plow my new valves into the concrete floor. But now I can't get the keepers back in the same way they came out. Ideas?

The piston tops have one gouge each for each cylinder. I each case it was the center intake valve that hit the top of the piston. No marks for the other intake valves. Also, there doesn't seem to be any high spot to the gouges, just an indentation from where the valve hit. It's my understanding from research that the gouge is ok, but that if there's any high spots to knock them down.
 
#39 ·
When valves hit pistons they usually leave a sharp edge, that needs to be rounded off.
Put a block of wood in the combustion chamber to hold the valve fully closed while fitting the keepers.
After lapping, check the valve head and seat and ensure that you have a new metal contact surface all the way around.
 
#41 ·
Update:

I lapped in all the intake valves that needed it. I used the valves from the junked head because I had already cleaned them and the suction spinny tool would work better. Out of the nine intake valves three were obviously bent. I lapped one cylinder at a time and tested each cylinder with water after I thought I got the valve lapped right. The first cylinder I tried held water very well. No leaks or even moisture on the combustion side. The second cylinder leaked drips from two other valves besides the bent one. I replaced those valves with the cleaned up ones from the junk head and lapped them in. Tested it and no leaks. Did the last one and same thing happened. So I replaced all three valves with ones from the junked head and lapped them in until a test with water showed no leaks. I believe I have lapped these in correctly although I did not do the prussian blue test.

I then tested the exhaust side and found that out of the 6 valves on that side, 4 leaked. So I'll replace them tomorrow. My arms hurt now.

Tom,
In terms of the piston tops, in order to smooth these out I would need to bring them up to the top of the block so that I can get at the gouge, is that right? If so, how to do this with the timing belt off.

At present state, the driver's side cams are set at their TDC location (where they were when the timing belt came off), passenger side cylinder head is off the car and the crankshaft is 45 degrees turned off TDC as you stated.
 
#42 ·
If the other head is on the car, you can't rotete the crank past TDC without eventually contacting valves. You could remove the cams, but if it were me, I would just smooth any sharp/jagged/raised spots out with a Dremel. Having some little valve crescents is OK. You can also check for cracks with a dye if you think you need to.

To help collect any particles, smear some grease heavily around the cylinder wall to catch them. When you're done, move the piston up a bit then back down, the grease will leave a ring you can wipe upwards and out.
 
#43 ·
A you won't believe this update!

So I've finished putting the head back together and I move over to the block to clean up the surface and smooth out the valve crescents. I hadn't really looked to carefully in there yet, but now that I'm ready to mvoe on I got a light, pushed my glasses up off my face so I could see up close and what do you know? Some old "valve crescents" on the EXHAUST SIDE!!!!. They're clearly old because they are covered in carbon deposits. Which means this car(which I've owned since it was new) had had a timing problem before. Funny thing is I never knew about it. Only time anyone ever might have gotten that far into the engine was when I had a VW specialist put in a timing belt about 7 years ago and then, probably back in the warranty days there was a misfire problem which I took to the dealership. Never broke a timing belt. When I took it to the dealership all those years ago they told me it bad sparkplug wires.
 
#46 ·
Hello:

I'm nearing the moment of truth. All that's left to do is bolt up the lock carrier refill oil and coolant and try to start it.

Can anyone give me an idea of what to expect from a successful start up. I read somewhere that because the car's been sitting without oil (I did use plenty of assembly lube) that it will seem rough at first. Please avoid the jokes at my expense, I just want to have an idea of how the car should react normally following its major surgery.

BTW, I did completely flush the cooling system till water ran clear from every orifice it should. But should I fill it with plain h2o to start and then drain it by the radiator plug and refill or just put the antifreeze mixture in right away?
 
#48 ·
Hopefully you changed the oil already. Make sure you turn it 2 full revolutions by hand before trying to start it. Go ahead and put the coolant in now.

The CCT and lifters will rattle like crazy for a few minutes. Don't panic, it's normal and goes away after 10-15 minutes of running.
 
#49 ·
Well, I tried to start it, but it wouldn't turn over. It cranked and almost did, but didn't. I plugged in code reader and had new codes for an open circuit on fuel injector cylinder 4, but that was just that I had not pushed the fuel injector connector all the way on. It also had a p1602 code for not enough power. I checked the battery with my multimeter and only had 11.62 volts. I think the battery maybe drained a bit from trying to start it when the valves were bent. Anyway I have the charger on it and we'll see when the charging's done.
 
#50 · (Edited)
It lives!!!

I charged it up for three hours and then tried it again. Cranked and cranked but no start but got a STOP!!! Oil Pressure message. Checked the oil level and it was a bit low. Added 1/4 quart of oil and tried it again and voila it fired up!!!!

Muttony rebuilds a cylinder head all by himself and with his shitty little valve suction cups. And with a ton of Help from every one here!!! I am so psyched up. Can't believe it worked.

Went out for a quick spin. Got a little alarmed when the engine temperature shot right up really quickly, but it levelled off at 1/2 way and stayed there, but I only drove it for less than 15 minutes.

Tomvw and/or anyone else who knows. I followed Tom's writeup for bleeding the coolant and it's doing something a bit strange. As I was driving I turned on the heat and it kind of blew really hot air and then it would go lukewarm and then it would heat right up again and it repeated this during the drive, but when it was hot it was scorching. Also I noticed the lower radiator pipe was cold while the upper was hot when I got back. I assume I've air in the system. I did not yet bleed it again after the start up. When I bled the coolant I bled the bleeder screw next to the combi valve first, then the one at the front under the coils and finally the heater core. I assume I did the heater core right because when I lifted the reservoir tank up a little spurt of coolant came out of the outlet weep hole. As it was spurting I shoved the outlet pipe back to close off the weep hole. On the other two bleeder screws I added coolant til they overflowed. IIRC your write up indicates a need to bleed again after running it, so I'll do that tomorrow and see if the uneven heat up stays the same. I'm going to keep it to short trip till I am sure I've got the cooling system sorted properly. I used 2 gallons of diluted coolant less maybe one quart which leaked out during the bleeding process.
 
#55 ·
I bled the coolant again this morning while engine was cold. Saw coolant level was maybe a 1/4 inch below the "min" line. Added coolant to get it to the "max" line. Opened the bleeder under the coil pack first, coolant bubbled out. Then the bleeder next to the d/s combi valve. Coolant bubbled out. I should say also that when I opened the bleeders I also opened the reservoir cap just after. Finally redid the heater core bleeder. I went out for a 30 minute ride and everything seems great, The surging heat is gone. Car came up to normal temp and stayed there with climate setting on coldest, hottest and also using a/c. Car seems to be running very normally. One question in my mind, though, is that lower radiator hose. When I got back, of course, I popped the hood and felt the upper radiator hose. It was hot as it should be. That lower hose however (the one leading from the thermostat to the radiator), was still only lukewarm at best. Should that lower hose equalize in temperature with the upper one? Or is there some difference between their expected temperatures that might only equalize after a longer ride?

Hirnbeiss: Of course I used new head bolts. Tom would've let me have it if I hadn't :) (BTW I have one side of a car's worth of new head bolts if anyone wants them). I don't recall the initial torque (I don't use Nm but rather foot pounds) but I specifically looked it up in Bentley and did exactly what it said down to 1) the proper torque specs in 2) the proper order and 3) 1/4 turn with a rigid wrench ( I used a breaker bar ) in the proper order and 4) another 1/4 turn with a rigid wrench in proper order.
 
#57 ·
I'm noticing perhaps more wear on the outside (the non-grooved side) of my new serpentine belt than I would expect. I kept the old one and a sort of cross pattern (from manufacturing) is still visible. The replacement was a Advanced Auto Parts house
brand that was very slick/shiny on the outside. After running the belt it looks like there are two wear lines running parallel with the belt and a central other wear line. It seems that the surface is like pilling or rubbing off. Little crumbles of rubber. I don't know if this is normal or not as I've never changed a belt before. I don't smell any burning rubber, I don't hear any squeals or anything abnormal and everything appears to be working fine.

I know its possible the serp. tensioner may have gone bad, but it appeared to be working fine when I took it off. So maybe I didn't put it on right...can you over tension one( meaning make it too springy )?
 
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