5.3L V8 with cracked head

Discussion in 'GM Powertrain' started by SC Tiger, May 22, 2013.

  1. SC Tiger

    SC Tiger New Member

    Hello everyone. I have a Chevrolet Silverado 1500 with the 5.3L V8 that apparently (opinion of my mechanic anyway) has a cracked head. It has gotten pretty bad and now will overheat when idling, and actually put enough pressure into the cooling system to crack the radiator.

    First question - will the Cracked Head issue cause this?

    The truck has 185,000 miles (original engine) so I am considering changing out the entire engine. However, it really doesn't make much sense to do this unless I can get a replacement engine pretty cheap. The pros are the entire engine will be "new to me" but there is a lot of labor involved and I don't have a good place to do an engine swap. My house has a garage but it isn't big enough. I haven't done this type of thing by myself before but I think I can get some experienced help (inlaws).

    I am also considering just putting new heads on it. The pros to this are that I could get new heads probably cheaper than an engine, and ensure that they are the latest generation head. The cons are the labor involved and the fact that the new heads will be going on a bottom end with 185K miles. Some water has gotten in my oil but I don't think it has been very bad.

    Here are my questions:

    Has anyone had experience with either of these options, and how did it go? A "junkyard" engine would probably cost about what new heads would cost but you don't know what you are getting. Plus, I will probably wind up with the Gen 1 head (that was known to crack). If I get a rebuild (say a Jasper) then I will be into this for more than half the value of the truck and may as well pay a little more and have it done professionally.

    I have also heard that new heads on an old bottom end are not a good combination.

    How do you get the old engine out? The concerns I have are A) grabbing the engine to pull it and B) the air conditioner. The AC Compressor is on the bottom but the condensor (or whatever the tank thing is called) is on top.

    Thanks in advance.

    - - - Updated - - -

    Just to add - the truck is in very good shape. Never wrecked, no body damage other than a few dings and dents. The fuel gauge is a little iffy but other than that it runs well. Trans and rear diff seem to have no issues.
  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Yes the problems you listed can be caused by a cracked head or a blown head gasket.

    At 185k you really have choices to make and most of them revolve around whats financially best for you.
    Questions to consider are:
    Whats the realistic budget for the repair?
    How much longer do you plan on keeping the truck?
    With mileage/age in mind what previous work has been done to the truck, specifically the transmission the next large drivetrain item thats sure to require attention soon if its still factory.
    Budget and expected time/mileage should give you a good idea sbout whether to choose a remanifactured engine or a recycling yard engine.
    Dont sell a recycling yard engine short, theres many reputable yards that stand behind their products and back them with warranty comparable to a factory crate or reman engine.
    Replacing heads or head gaskets (if thats an option) is worth thinking about but I would only recommend that option if you plan on selling the truck soon or its a temp (6 months or less) tepair while you get together everything for a permanent fix. Ive rarely seen new heads on a high mileage block turn out good for any length of time.
    At this point you should decide a plan, if its doing heads only then dissasemble and plan for new heads but keep open the option of gaskets. Maybe you can get off cheap.
    As for the A/C compenents they can normally be swung out of the way without disconnecting and loosing freon.
    If you plan on pulling the engine look around locally for a rental center that rents cherry pickers/engine hoists and other speciality tools or if you plan on more work like this in the future look at craigs list for low cost second hand tools.
  3. SC Tiger

    SC Tiger New Member

    Thanks. The one saving grace is that this is not my daily driver (good thing because I can't even drive it around the block w/o it overheating). Therefore I can take my time. I have considered going ahead and pulling the heads but then I lose my ability to move the truck around my yard. I will probably at least pull the valve covers.

    I've been offered an engine hoist (as a loaner) and I think my inlaws have one anyway. The biggest thing is finding the engine itself. I've only been looking for a few days (not nearly enough time to give up mind you) but haven't seen anything really good.

    How do I get ahold of the engine? Many engines have a loop or something to grab it but this one does not. I have seen a plate that bolts on the intake to lift the engine but with a plastic intake manifold I don't know how good of an idea that would be.

    What I would like to do is put a later-generation 5.3L in this truck since it should have the second-generation heads. However, that kind of change can be a nightmare when you get into everything else that has to be swapped (or would it?)
  4. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

  5. SC Tiger

    SC Tiger New Member

    Thanks Pikey.

    I pulled the drivers side valve cover off last night and didn't see any obvious cracks, sludge or anything. There was a film of oil over everything but I would imagine that is to be expected. My understanding is that the driver's side head is the one that tends to have the problem.

    Next step is to pull the passenger side valve cover.

    Something I noticed is that the valve cover gasket (not the original BTW) seemed to grow when I took the cover off. I did snag it on something which may have stretched it but I have also seen this on carburetor bowl gaskets that are not gas-and-oil proof. They tend to grow as they are exposed to oil or gas, and shrink once they dry out.

    - - - Updated - - -

    Reread tbplus10's post and realized that I did not answer a couple of your questions. The truck is all-original. The transmission is the original unit (has been serviced regularly) and so is the rear end. The only things that have been replaced are the power steering pump, both idler pullies, and the water pump and thermostat. The only dents are from backing into a tree (creased the rear bumper a little bit) and two dings from the recycle bin being blown into it by the wind.

    Still thinking on this one. The good thing is it isn't my daily driver so I have options. However, seeing it sitting in my back yard frowning at me (I swear the thing looks like it is mad at me) makes me want to get it running. If the heads are okay it may be worth the risk to put head gaskets on it. It won't likely be my daily driver even after it is fixed but I do want it running.

    And, of course, the radiator needs replacing.
  6. 73Elsinore

    73Elsinore New Member

    I can tell you what I did and the decision process I went through for this exact problem.

    On a 91 F*rd Exploder with a 4.0 V6, it had two cracked heads. They both cracked after the bonehead owner (me) accidentally left the radiator cap off, drove it, boiled off all the coolant and overheated it. As a result I cracked both heads, lost almost all compression, coolant coming out the exhaust, the whole bit. The cracks were through the valve seat and were not visible to the eye without doing a magnaflux/dye pen test. Those heads were known to be weak and would have cracked in time anyway. The truck had 190,000 on it, was paid for, wasn't worth anything, I needed a 4x4 vehicle, and I needed a cheep vehicle for my son to drive a couple years hence. So I made the decision to keep it and do the heads rather than get a motor from a recycler. Cost to do the job at a shop was $1500-plus so that was a no-go. The cost of two new heads was about the same cost as a recycle motor, about $700 total job. I had never done an engine swap and didn't have knowledgeable buddies to help, but what I did have was garage space and lots of time so I decided to do the heads myself just following the Haynes manual. I bought the heads from an automotive machine shop and he did the assembly and cut the valve seats. He checked my old heads first and that was how we found the cracks. The new heads all machined and assembled were $275. I also bought the new head bolts and gasket kit and some other stuff from him so all told out the door from the machine shop was about $450 for two brand new heads. It took me about two months to do the job working evenings and weekends, just going slow and taking my time and following the manual.

    Now. To your point on new heads on an old motor: what you don't know is the condition of the bottom end. I did a lot of research on this motor and so I knew they were stout on the bottom. A nice stout overbuilt cast iron block. I also knew the recent past smog tests were great, it wasn't using oil, and it wasn't making weird noises so it was reasonable to conclude the rings and bearings were OK. So I thought, at the worst, I'll pull one head and do a visual on the cylinder bores. If the bores look bad I'll get a recycler motor. But I pulled the heads and the bores still had the crosshatching and there was no ridge at the top. So F*rd did a good job on that particular block metallurgy and piston-ring-block combination plus I had been running synthetic oil in it. Based on that I went ahead with the new heads. In the end it worked out awesomely. Smog numbers got even better, gas mileage went up a tad, it ran great for another 6 years, I had a 4x4 desert vehicle and then my son had it to drive for a couple years. So in retrospect the new heads were the right decision, both operationally and economically.

    So you have to look at this decision from several perspectives, as I tried to share here. You didn't say what year the truck is but you have to assume you're not going to get back your investment in either new heads or a recycle motor. And you have to just write off the value of your time, pretty much. You have to look at the cost of replacing the truck to obtain equivalent functionality, vehicle-wise, to what you have now, in hand with that truck. If you can get an equivalent or better vehicle for the same or less than the cost of repairing your current truck then the smart money says to junk it and get the replacement vehicle, all other things remaining equal (insurance, relative reliability, gas mileage, etc.). For me, I needed to keep it to have 4x4 capability plus to have an el cheepo vehicle for my son to drive that was safe, cheep to insure, and didn't have any value so if he wrecked it I wasn't going to get ulcers. Good luck!

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