Head Gasket (Cracked Head!) - Page 3
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Thread: Head Gasket (Cracked Head!)

  1. #41
    Member Michael A. Smith's Avatar
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    Those two bolts are a whore. Remove the metal heat shield and the bracket that connects between the bell housing and the block. Remove them completely and access to start the bolts in is a breeze. The only issue is getting the bracket back on -- start all of the cap screws but leave them loose until all are started, then tighten them.

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  3. #42
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    Itís alive. Sort of.

    First the fan belt screams. Why and how the hell do I get it to stop. I replaced the water pump gasket, so I did take it all apart. The fan pulley does look a bit catywampuss. Of course I installed the shroud and everything else. So what do I need to remove to pull the fan and...

    So, kind of funny. I started it first without the valve cover. I read about a oil deflector but though whatever. Mistake, oil all over the place. Dried as best I can but know it smokes and I canít tell why. Oh yeah, I also installed a heat shield that was missing and is painted. Also paint on the head. Any of it could be smoking.

    Also I ran it with water and Prestone flush product. I canít run it to temp to get it to cycle through. Do I just drain it now and fill with normal 50/50?

    Ugh, what should I do next? I need to adjust the valves with solid lifters. Do folks do that with the engine running or just by hand turning?
    Last edited by pfj; 10-05-2019 at 07:44 PM.

  4. #43
    pfj
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    Went back out and tried again. Fan was locked up. I opened the thermostat housing and it freed up.

    Still an exhaust leak an a valve adjustment to deal with.
    Last edited by pfj; 10-05-2019 at 08:14 PM.

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    Quote Originally Posted by pfj View Post
    Having a hard time with two bolt between exhaust and exhaust manifold.
    The two centre manifold bolts are VERY difficult to tighten if the carb and heat shield are in place. I ALWAYS tighten them, and then re-tighten them, following the torque sequence for the the manifold bolts, before I install the heat shield and carb. It is impossible to get a torque wrench on the two centre bolts, so I use a long box wrench and do my best to estimate 33 ft-lbs.

    I also hate the heat stove bolts, as they can cause the intake and exhaust manifolds to be misaligned against the head, creating a vacuum and/or exhaust leak at the head. I prefer to tighten those up AFTER the manifold-to-head bolts are torqued/tightened.

    Not to mention that the heat in the intake manifold is detrimental, unless you live in central or northern Canada and drive your Opel in the winter. We don't drive our Opels in the winter... I have ditched the stock exhaust manifold on my GT in favour of a Sprint manifold. A header is a good option, or modifying the stock exhaust manifold by cutting off and flat-plating the heat riser section.

    HTH
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    Keith Wilford
    Finishing up a bare-metal, nut & bolt rotisserie restoration of my '71 Opel GT

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    Quote Originally Posted by pfj View Post
    Went back out and tried again. Fan was locked up. I opened the thermostat housing and it freed up.
    Can you please explain this more? Not making sense....

    I see those instruction for the flush say to run it warm for 45-60 minutes. I am assuming it is a mild acid. I don't think I'd leave it in too long...your radiator is older and the metal thinner in places.

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    Quote Originally Posted by pfj View Post
    I need to adjust the valves with solid lifters. Do folks do that with the engine running or just by hand turning?
    Hand turning is fine. Turn engine so that 1 and 4 are at TDC. If your timing is close to correct, you can watch the distributor rotor and be close enough, this crank positioning does not need to be perfect.
    - Find where 1 is at near TDC and firing and then adjust #4 valves.
    - Turn engine 180 degrees to where 3 is firing and adjust #2 valves.
    - Turn engine 180 degrees to where 4 is firing and adjust #1 valves.
    - Turn engine 180 degrees to where 2 is firing and adjust #3 valves.

    Use cold or hot valve lash with engine cold or hot as appropriate.

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    pfj
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    Quote Originally Posted by Manta Rallier View Post
    Can you please explain this more? Not making sense....

    I see those instruction for the flush say to run it warm for 45-60 minutes. I am assuming it is a mild acid. I don't think I'd leave it in too long...your radiator is older and the metal thinner in places.
    I think I had air trapped or something. When I first started it the fan/water pump was not turning so the belt was slipping and squealing. After I opened the thermostat housing and restarted the fan spun.

    So I ran the flush until it was at temp and drained. Topped off with coolant. Will drain again after next good run.

  10. #48
    pfj
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    Quote Originally Posted by Manta Rallier View Post
    Hand turning is fine. Turn engine so that 1 and 4 are at TDC. If your timing is close to correct, you can watch the distributor rotor and be close enough, this crank positioning does not need to be perfect.
    - Find where 1 is at near TDC and firing and then adjust #4 valves.
    - Turn engine 180 degrees to where 3 is firing and adjust #2 valves.
    - Turn engine 180 degrees to where 4 is firing and adjust #1 valves.
    - Turn engine 180 degrees to where 2 is firing and adjust #3 valves.

    Use cold or hot valve lash with engine cold or hot as appropriate.
    When the cylinder is firing both rocker arms should be loose right?

  11. #49
    Member Michael A. Smith's Avatar
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  12. #50
    pfj
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    Quote Originally Posted by Michael A. Smith View Post
    No, I have not. Thanks. This is my first classic car. I have only done regular maintenance before, and cars had EFI and OBD systems when I started driving.

  13. #51
    Member Michael A. Smith's Avatar
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    Here is a wealth of information, available free from Gil Wesson at Opel GT Source. Over the past four years, after I received my own GT, I have downloaded and printed almost all of the information. Also, you may want to scratch around and find a copy of the Opel shop manual. The 1973 edition seems to be most common and also has the advantage that the wiring diagram is in color.
    https://www.opelgtsource.com/tips

    Here is a '73 on ebay.
    https://www.ebay.com/p/1667299797?ii...saApnsEALw_wcB
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  14. #52
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    1973 Opel Factory Service Manual/ FSM:
    https://www.opelgt.com/forums/downloads.php?do=cat&id=2

  15. #53
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    Quote Originally Posted by pfj View Post
    When the cylinder is firing both rocker arms should be loose right?
    Yessir...

  16. #54
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    Quote Originally Posted by pfj View Post
    I think I had air trapped or something. When I first started it the fan/water pump was not turning so the belt was slipping and squealing. After I opened the thermostat housing and restarted the fan spun.
    That is veeeery odd.... air in the system will not keep the water pump from turning. The pump impeller does not come anywhere close to positively sealing in the pump cavity so there's no way any backpressure or air can stop it. It will spin free in any case.

    So, something else caused your pump to hang up. If it is not a worn/seized pump shaft bearing, it is possible that the pump impeller is pushed back and hanging on the back side of the pump cavity... that is a bad thing. If it spins against the back of the pump cavity, it can wear through the housing and then will dump coolant straight into the crankcase and oil. Seen that before on these engines ..... Were there any circular wear marks inside the pump cavity in the timing cover?

    Grab the fan and wiggle the pump shaft in and out and see if there is any play in the bearing in the pump. It may be that the pump bearing is on its way out. There should be no visible movement of the pump shaft in the pump housing. If this is old, it needs ot be replaced... they are not expensive.

  17. #55
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    Lifter pictures

    I put them on a straight edge in front of a light. Not concave, but some light at scratches. Scratches donít catch a fingernail.

    Also a picture of cam lobe. Some corrosion and pitting.
    Attached Images Attached Images

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    Old or new head? So the lifter bases were actually still convex? That would be good.

    Those little marks 'look' to be deeper than are common in a good running cam/lifter contact, but not by much. Some circular swirl are normal. It is not bad grooving. IMHO, a bit of a crap shoot... .maybe consider having them re-ground.

    Can't see enough of the cam... if the pitting is very fine grained, that is not abnormal. You typically see some of that. The real key is any sign of flattening of across the lobe peaks. Pull the cam out for a better view if it is the old head.

  19. #57
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    Quote Originally Posted by pfj View Post
    I think I had air trapped or something. When I first started it the fan/water pump was not turning so the belt was slipping and squealing. After I opened the thermostat housing and restarted the fan spun.
    Check the back side of the water pump pulley to see if someone has used bolts that are longer than stock. They could be hanging on the water pump housing.
    Manta Rallier and dpre like this.

  20. #58
    pfj
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    Quote Originally Posted by SpringGT View Post
    Check the back side of the water pump pulley to see if someone has used bolts that are longer than stock. They could be hanging on the water pump housing.
    I sorted this problem. A bit embarrassing so I left it alone. The fan was rubbing the shroud. Whoops.

    I rechecked the valve lash using the distributor as a guide. There is still a distinct tapping. A different tapping, but still noisy.

    Are there good ways to isolate? Can I tighten both valve from one cylinder at a time and start. See if I can isolate the noise to one cylinder?

    Do I pressurize cylinders and listen for leaks? Not sure what to try next.

    I also read a post about the plastic button on the front of the cam sprocket making a noise. What is that about. The book says there should be a almost zero gap to the cover. To fix it, hit it with a hammer.
    Last edited by pfj; 10-09-2019 at 12:53 PM.

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    It's always good to find the reason! (For the pump not turning....)

    If the tapping is a light tapping, then, yes just tighten one pair at a time by maybe .003" and see if the tapping changes. Is it a light tapping? (I.e., not a heavy knock..) You be able to get closer to the source by taking a long wooden dowel, and place it against your ear and the other end on various parts of the engine/valve cover.

    Do you know what is the lift on this solid cam? Just making sure the valves retainers have plenty of clearance to the guides. Probably not an issue but....

    As for the gap from the button to the deep-dimpled cover, that sets the cam thrust clearance. It is a specific range checked with feeler gauges. If it is wide, you take a flat punch that is about the diameter as the bottom of that dimple and smack it in a bit with a hammer to close up the thrust clerance. If the thrust clearance is not enough, you take the cover off, lay it face down on a hard surface, and gently tap the dimple a bit to make it a bit shallower, to open up the thrust clearance. I just explained this to my son this afternoon as we were getting started on a cam change.... he is quite amused at the procedure LOL

  22. #60
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    BTW, here is another valve adjusting procedure... might give better results. Look for a certain valve to be at peak opening and then adjust a certain other valve. These numbers are the valves 1 to 8 from front to back:
    8 open - adjust 1
    6 open - adjust 3
    4 open - adjust 5
    7 open - adjust 2
    1 open - adjust 8
    3 open - adjust 6
    5 open - adjust 4
    2 open - adjust 7

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