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454 timing chain replacement

Discussion in 'The Garage' started by 77crewcab, Apr 3, 2005.

  1. 77crewcab

    77crewcab 1/2 ton status

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    Well I believe my timing chain broke today. While running down the road the engine just died and wont restart. I thought at first it was a fuel issue but after walking to the gas station to get some more gas it still wont start. Finally I pulled the dist cap and cranked the engine and the dist doesn't move at all while the crank spins VERY freely more than I have ever felt. So heres the questions
    1. Am I correct in assuming this is the timing chain or could it be something else?
    2. Other than a balancer puller/installer is there any other special little things I would need to do the job?
    3. I plan on replacing timing chain, water pump, fuel pump, oil pump and distributor and all related gaskets. The dist and fuel pump are strait forward but on the water pump and timing chain are there any little tips I should know?

    Thanks in advance and any tips are greatly appreciated. BTW this happened 4 blocks from home as I was coming home from running erands. One guy stopped to help push the truck into a parking lot to get it out of the street. But then I had to pay $40 to get it towed 4 blocks to the house :mad:
     
  2. dirtwarrior17

    dirtwarrior17 Banned

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    did it make any wierd nosies when you turned it over?

    Water pump removal/installation is real simple... although i don't have a bbc... you should just have to pull off your fan and maybe your fan shroud, unbolt any brockets or accessories that are bolted to it and pull it off... when you put it back on its a good idea to use a sealer on the bolts because they go directly into the water jacket.

    Don't know about the rest.
     
  3. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    could have snapped the cam or stripped the dizzy gear too...
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Let me suggest that when the timing chain breaks the valvetrain becomes out of sync with the crankshaft and almost always the valves hit the pistons and bend. So when you get it all back together if it still doesn't run or runs poorly do a compression check and you should find compression low in some or all cylinders indicating bent valves. I'm sure i don't have to tell you what that means, but with any luck you weren't going fast when it happened or kept trying to crank it over.
     
  5. 77crewcab

    77crewcab 1/2 ton status

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    re

    No funny noises when it happened but now cranking it over it does sound a little odd in the timing cover area. Like after breaking, the timing chain just fell to the bottom part of the cover and is rattling against the crank sprocket. I can pull the dist and check that, it needs to be replaced anyway, but is there an easy way to check the cam?
     
  6. 77crewcab

    77crewcab 1/2 ton status

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    Actually no noise from the valves at all even when cranking it. Also no oil pressure, so possibly just the dist broke. I haven't had a chance to see if the valves are actaully moving when cranking yet.
     
  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    When the timing chain breaks you will have no distributor turning, no oil pressure, and no valves moving. The oil pump is driven off the bottom of the distributor and unless the roll pin holding the distributor gear has broke then you are faced with the broken timing chain which i'm certain it is since you said it cranks easier now. Also, you would not hear any noise if the valves are bent or even when they did bend becuase it happens so fast. All it takes is for the timing chain to break and the crank to turn one more full revolution and the valves could get bent.
     
    Last edited: Apr 3, 2005
  8. 77crewcab

    77crewcab 1/2 ton status

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    When you say the valves would be bent are we talking about visible damage that can be seen when taking the heads off or something that is so minor that it can't be determined without taking the valves out to check them?
     
  9. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Sometimes they are noticeably bent and other times they are bent but you can't tell until the heads are apart and you spin the valves in a valve machine. Once the heads are off you might find evidence of the valves hitting the pistons by seeing a "smile" mark where the valve has hit.
     
  10. 77crewcab

    77crewcab 1/2 ton status

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    Okay thanks! I was already considering having the heads rebuilt with new springs to match the cam I am looking at. Or possibly just getting a rebuilt set of heads from Advance and putting in new springs. I just hadnt planned on doing it just yet but it looks like that might be a good idea to go ahead and have done. Would the smiley on the piston if it is there cause problems that need to be fixed or could they be left alone?
     
  11. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Typically on chevy engines that smiley won't hurt a thing. On some smaller/import engines the valves would hit way out near the edge of the piston which could cause the top ring land to crush and break the ring. You should have no worries here though.
     
  12. kgblazerfive

    kgblazerfive keymaster Premium Member GMOTM Winner

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    Pull off the valve cover and you can see if the the cam is moving the valves or anything else for that matter. When you do the timing chain I would do the oil pan also the timing chain cover is so much easier to do when the pan is out. Most stock engines do not have enough lift to have the valve hit the piston, most of the time when that happens it is because the valve fell out or dropped. So unless you have small cc heads and big cam I wouldn't much worry about a bent valve. Get the timing marks right the first time cause a chevy engine will run with the cam 180 degrees it dosn't run well but it will run.
     
  13. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Any engine that is an interference engine has the possiblity of the valves hitting the piston when the timing chain breaks. SBC, BBC are both interference engines. Also if the timing chain is hooked up 180* off the engine will not run.
     
  14. 77crewcab

    77crewcab 1/2 ton status

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    Thanks guys! It will probably be next weekend before I get a chance to work on anymore to even determine what actually happened I just need some things to look for. I'm just lucky I dont have to depend on my truck to get to work. So it can sit for a while without being a inconvenience to me. I get about 3 hrs each Sat. to work on it so it may be a while before I get it going again.
     
  15. diesel4me

    diesel4me 1 ton status Premium Member

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    Pull distributor ??

    Might be a good idea to yank out the distributor and make certain the roll pin that holds the gear on didnt shear , or the gear itself didnt break...hate to see you pull he timing cover off and see the chain is still intact! :blush:

    I had only 1 timing chain go on a 454,I was cranking it over first thing in the morning,and the engine "spit back" thru the carb--it started and ran several seconds,then stalled,and trying to re-start it,it turned over fast like the spark plugs were out..I put in a new chain,no damage to the valves...I've had a few chevy's "jump" time when the nylon cam gear teeth dissapear,but only a few pushrods got bent--I wasnt aware of chevy's V8's being "interference" motors,but they very well could be!

    By the way--those nylon cam gear teeth usually end up in the oil pump screen--if not the pump itself!--a new oil pump is cheap insurance while your in there... :crazy:
     
  16. BlueBlazer

    BlueBlazer 1/2 ton status

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    Proof? I have never heard this before, unless like someone else said it has a high lift cam.
     
  17. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The proof is when you remove your cylinder heads after a timing chain has broke and you find bent valves. :rolleyes:
     
  18. BlueBlazer

    BlueBlazer 1/2 ton status

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    Nice reply, you have something a little more concrete than that?
     
  19. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I will make a copy from our book at work tomorrow and post it up for all to see.

    I'm not really sure why you would possibly think that SBC, BBC aren't intereference engines if the valves bend when the timing chain breaks. That should be solid enough proof for anyone.
     
  20. BlueBlazer

    BlueBlazer 1/2 ton status

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    I will admit, I haven't worked on too many GM gas engines, but just looking at them it seems hard to believe that the valves could hit the pistons in a stock or near stock engine.
     

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