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Funky cylinder heads

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by archer, Oct 21, 2000.

  1. archer

    archer 1/2 ton status

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    I pulled off my valve covers to replace the leaky gaskets (no small job on an '85) and had gobs of crud in and around the rocker arms. The oil drain back holes (i assume that's what they are) were all completely occluded. There are 4 of these holes, one at each end of the head. I thoroughly cleaned these out as with the rest of the top of the head and installed the new gaskets. Do these provide oil to the rocker arms, or just allow it to drain back to the crankcase? In any case I hope to have better oil distribution now. I have heard that on an old high mileage engine like this 305 you can put a quart of tranny fluid or marvel mystery oil in it for 1,000 miles or so and it goes a long way in cleaning some of this sludge. any other suggestions?

    "who dares wins"
     
  2. Goose

    Goose 1/2 ton status

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    From what I understand the oil comes up the pushrods and then out from under the rocker arms and gets slung everywhere by the rocking of the rocker arms. The holes are just oil drain back holes. I've heard that mixing the weight of oils (ie adding 10w40 to straight 30w oil) can cause sludge to form. So that makes me wonder about adding theat mystery oil or stuff like that. Having said that, in my '87 MonteSS I used the oil additive stuff that's supposed to seal up the sratches in the cylinder walls and whatnot. I had a noticeable improvement in power and mileage. It would only last a couple oil changes tho.

    Cruisin in my '73.
     
  3. Smitty

    Smitty 1/2 ton status

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    Be careful of putting some of the solutions in the engine to clean out caked oil. Sometimes you end up removing more than you intended and end up rebuilding an engine that might have gone on for quite a while. Most of the engines that I've found gunked up came from a lack of oil changes, short distance driving or problems with the PCV. If the oil is really caked on the only way to really get it off is to scrape it or tear the engine down and tank it. I'd recommend that you step up the oil change schedule and check the PCV for proper operation. I'm not really a big fan of oil flush products, just feel they're too much, too late.
     

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