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  • Engine: Overhaul or Rebuild

    I have a 135,000 mile full flow 289 from a 1964 Cruiser. The heads are leaking exhaust into the radiator water, so I know I need to take the heads off and possibly replace at least one head. The other portion of the issue is that now the oil pressure has dropped. It used to be at start up (cold) oil pressure was 65-70 lbs and after warm up/driving oil pressure would drop to 20-25 lbs. Last week while driving, I noticed after warm up the oil pressure had dropped to 5 pounds. After cooling down (next morning) the oil pressure only goes up to 45 lbs, then drops to 0-5 lbs after warm up.

    My question is, after pulling the heads, I will do a complete redo on the heads (new values, harden seats, valve guides, etc), but how do I determine if I can do an overhaul or if I have to do an engine rebuild? I would prefer not to have to do a re-build. But I also don't want to make a mistake. Thoughts? Obviously I am no longer driving the car until this gets fixed.

    Thanks in advance

    Mark
    .

  • #2
    Back in the day typically the engines of this era would have a ring and valve grind job at around 75,000 miles, (overhaul) and a complete rebuild at about 120,000 miles. I think that when you tear-down the engine for inspection, the condition of the cyl., bearings, crank journals, ect. will determine the level of repair needed. The type of service and service life should also help determine what you decide. What you want/can afford to spend, may also be a factor. Personally I would like my car to be able to run as it did new with the same dependability. With my luck if I didn't do a full rebuild, it would always be a nickel-and-dime-me-forever deal.

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    • #3
      Usually what determines Overhaul or Rebuild is the out of round, taper and oversize of the Cylinder Bores.

      But in this case you are most likely looking at the Max because it is very likely you have lost the Cam Bearings which was the cause of your Oil pressure loss.

      But as Brian said, the teardown will definitely tell all, you will have to do more than pull a head or two.
      StudeRich
      Second Generation Stude Driver,
      Proud '54 Starliner Owner
      SDC Member Since 1967

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      • #4
        ditto on the cam bearings ... act fast or you might damage the camshaft...

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        • #5
          Originally posted by StudeRich View Post
          Usually what determines Overhaul or Rebuild is the out of round, taper and oversize of the Cylinder Bores.

          But in this case you are most likely looking at the Max because it is very likely you have lost the Cam Bearings which was the cause of your Oil pressure loss.

          But as Brian said, the teardown will definitely tell all, you will have to do more than pull a head or two.
          I don't have my shop manual in front of me. However, as stated above, the truth will be the measurements and allowable tolerances that determine what extent you must do to make the engine reliable. When you open up the engine, you need to examine the crankshaft main bearings for embedded metal. The soft metal of the bearing inserts will capture and embed harder materials that have broken/flaked/fallen into the oil and passed through the screen pre-filter on the oil inlet tube. Also, check that screen for tell-tell debris like fiber from a brittle and worn fiber timing gear.

          I also like to examine the oil residue in the bottom of the oil pan sump. Mainly out of curiosity to see what may be lurking there. When you lose that much oil pressure, there is only three causes or a combination of the three. Either the clearances of pressurized oil passage surfaces have worn and increased (main bearings/rod bearings/cam), oil pump gears, or a restriction on the pump inlet.

          Besides the cam bearings, replace the cam gear too. The fiber gears can look great, but still grenade without warning. Completely tearing the engine down gives you an opportunity to open the water jacket and do a thorough flushing of the block passages and install brand new core plugs. Also, you can remove the oil gallery plugs and thoroughly clean the oil passages.

          I'm not a mechanic (not even play one on TV), but I can read and follow directions. I have done tons of back yard repairs. While in the Air Force, I overhauled more turbines than recip engines, but I have done both. There are true engine builders on this forum that can chime in and correct any misinformation from me. The main thing is to check/measure for wear and acceptable tolerances and get the engine within acceptable tolerances and back together clean. Except for machine shop work, like valve seats, cam/crank grinding, and head resurfacing...I don't see why anyone who can read and follow directions, couldn't do an overhaul. The more thorough job you do, the less expense in the long run. Also, nothing will give you more "peace of mind" afterward. Good luck and keep us informed with your progress.
          John Clary
          Greer, SC

          SDC member since 1975

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          • #6
            How do you know you are leaking "exhaust" into the radiator ?
            This would be a VERY uncommon happening..! Most likely it's just compression (bubbles ?). In that case, it's just a bad head gasket (or a possible cracked head, unlikely though).
            BUT, since the heads are off, and if you plan on keeping the car and driving it, yes, it would be a good overall decision to do a complete rebuild of the heads. As you mention, hard exhaust seats (not needed in the intake), check the guides, check all valves, new seals.
            AND...since you've gone this far, while you don't need to go the whole "porting" route, having someone remove all of the sharp edges in the ports and combustion chambers. It's well worth the effort.

            As far as the block, with that many miles on it, while it might be a good idea, if the rings are still doing their job well enough...leave it till later. Buti If you are having oil loss (blue smoke) at all, I'd vote for the rebuild.

            Mike

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            • #7
              Best way to get remote advice is to run a cold cranking compression test. Pull all eight plugs, block the throttle full open, with a screw-in gauge, test all cylinders twice cranking over at least five revolutions, writing down the PSI for each test. This gives a fair indication of the top ring and cylinder wall condition.

              A leak-down test is good to do, also as it can be done with the pistons at top and bottom of travel. The difference indicates cylinder wear and taper.

              However, with 135,000, what you are going to find is that engine is crying for a full rebuild.

              jack vines
              PackardV8

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              • #8
                Mark,
                How suddenly was this oil pressure drop? It would seem odd that you would have acceptable oil pressure and then rather abruptly have it drop. Are you losing any coolant? If your head gasket is bad, along with exhaust in the coolant you may have coolant in the crank case too. The possibility is that either you are pumping coolant (lowing pressure), or the coolant has mixed with the oil and the resulting "gel" is clogging the filter and lowering the pressure.

                Water in the engine is never good because of the corrosion factor. Checking the dipstick, or a slight drain of the oil pan (oil floats on water) should tell if there is coolant in the engine. If there is I would attempt to deal with it ASAP to avoid internal damage.

                Regarding the rest of the engine I would do a compression test. If you don't have a gauge I can loan you mine.

                Tom
                '64 Lark Type, powered by '85 Corvette L-98 (carburetor), 700R4, - CASO to the Max.

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                • #9
                  If you're going to do the full rebuild anyway, now is the time to upgrade the cam. Get one of the R1 R2 cams. They're cheap horsepower. You don't even have to do anything else except what Mike VV was suggesting on cleaning up the sharp edges, casting flash and perhaps doing a gasket match on the ports. I would recommend doing a little "hogging out" of the exhaust manifold to the head pipe, too. Essentially, just gasket match it as well. That outlet is the choke point on the exhaust and there is plenty of room to grow it. Good luck.

                  BTW, be careful not to overspend on the rebuild. Consider the intended purpose of the engine. Daily driver? Occasional driver? Any smoke?...if not, then perhaps a full rebuild is not needed. Check the cylinder walls when you pull the heads. If you don't have a ridge at the top of the cylinder, then there may have been an overhaul or rebuild at some time in its past.
                  And its possible that the previous owner simply never re-torqued the heads when needed and caused the head gasket leakage.
                  Check the main and rod bearings for excessive wear while the engine is out.

                  Reason for the rambling is the fact that its easy for us to advise from afar, but every step you take will cost more money. A complete engine rebuild, done properly, will run in the neighborhood of $2800 to $3500. An engine that is not making any noise and not smoking, but is simply having oil pressure issues, does not necessarily need $3000 worth of repairs to make it roadworthy and reliable. Be careful.

                  Just my 2 cents worth.
                  sals54

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                  • #10
                    What's the condition of the car in general ?? Body ? Frame ? seats and interior ??? Unless you're restoring a 57-58 GH or some other true value Stude....I'd recommend buying a rusted out late Lark with a 289 ... dropsie-doodle and away you go....If a nice driver or worse....especially if a Lark.....just find another powerplant and get back on the road......don't worry about matching numbers on your car.......

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                    • #11
                      Originally posted by jackb View Post
                      What's the condition of the car in general ?? Body ? Frame ? seats and interior ??? Unless you're restoring a 57-58 GH or some other true value Stude....I'd recommend buying a rusted out late Lark with a 289 ... dropsie-doodle and away you go....If a nice driver or worse....especially if a Lark.....just find another powerplant and get back on the road......don't worry about matching numbers on your car.......
                      Wow, someone sure thinks Larks are not worthy cars for number matching..

                      I've seen a growing number of Larks on the road in Phoenix and two weeks ago in LA.. Cant say that about Hawks or Avanti's..

                      I'd say the Lark's are the new Phoenix and being resurrected more and more..


                      Oh, back to the main point on the thread..

                      Mark,

                      135K on an engine and this is the first thought of rebuild? Congrats!

                      If not for the concerns of dropping oil pressure, Id say just the heads.
                      However, it looks like there are more underlying problems than just bubbles in your radiator.
                      Getting to an engine to rebuild it before it self destructs is really monumental.
                      Much of your cost is going to be in the heads putting hardens seats and all so spend a bit more on the lower end and be real happy with the results.

                      The more you bring your engine back to specs the better you will enjoy its performance and longevity!

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                      • #12
                        Thanks for all the great advise! I have located a local person that has done a number of Studebaker engines that I will be working with and determine the extent that we need to take the engine. I agree that Larks, yes even the 4 door models are becoming more popular and are being seen more. Heck within my town (just north of LA) there are three that are driven on a regular basis around town. I have added a picture of my car, so you can see that all the cosmetic work has been done, and what I am fixing is what I Called delayed maintenance by the PO. The car has been and is great and will rise again!
                        Attached Files

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                        • #13
                          That car is beautiful. I agree, give the motor whatever it needs, to be as nice as the rest of the car.

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