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May Need New Big End Bearings

Discussion in '"Stock" Alpine' started by ChrisR, May 20, 2020.

  1. ChrisR

    ChrisR Platinum Level Sponsor

    I am thinking that I may have to change the big end bearings.

    Over the winter, I refurbished the oil pump. I reassembled everything, filled with oil, injected oil down the filter supply to aid in priming and cranked the engine over a few times with the spark plugs loose. Then tightened the plugs and cranked the engine with the distributor cap removed. I did not managed to register any significant oil pressure.

    I went ahead, put the distributor cap on and started the engine. After what I am thinking was about 5- 8 seconds, the oil pressure shot up from 0 to 40 psi. I ran the engine for a few minutes with rpm around 1500 rpm (Choke still on) until I noticed a coolant leak so I shut down. I addressed the leak (15 mins), then started up again.

    I noticed a distinct new noise a like noisy tappets. I am thinking that as I have not touched that part of the engine, there is no reason for the rockers getting out of adjustment suddenly and maybe the 5-8 seconds of no oil has damaged a big end bearing. I will do a check by pulling plug leads and see if the sound goes away.

    If it is a big end bearing, my question is, how do I determine what size to order? Do I need to pull the old and measure the crank? Are the current journals marked with size? I read in the workshop manual that the main bearing journals do have their size marked, but I cannot see a reference to the big end journals.

    I hope that I have not scored the crank
  2. jumpinjan

    jumpinjan Gold Level Sponsor

    First question - What does "refurbished" the oil pump mean and what made you do that?
    puff4 likes this.
  3. ChrisR

    ChrisR Platinum Level Sponsor

    I did the rework defined on the TE/AE site. - smoothing the housing surfaces with fine emery cloth. Was actually in pretty good shape so did not require much work.
  4. RootesRooter

    RootesRooter Platinum Level Sponsor

    That short amount of running time should not be enough to damage your bearings. And bottom end rattling shouldn't sound like tappets.

    I'd try listening thru a length of hose to try to narrow down the source. Are you getting oil at the rockers?
  5. RootesRacer

    RootesRacer Donation Time

    The goal of the pump rework is also to set the rotor to case clearances (not just smoothing the surfaces). Since the case is aluminum and the rotor is steel, the case wears and picks up extra end clearance which will reduce the oil pressure a bit at low rpms. 5 to 8 seconds to build oil pressure is not going to get fixed with pump clearances. I would ask, what kind of oil filter are you using and are you sure it has an anti-drainback valve inside?
    You really want an anti drainback valve when the filter is positioned to dump all its oil back to the sump after shutoff.
  6. hartmandm

    hartmandm Moderator Platinum Level Sponsor

    If in essence you had done a full oil change, the oil filter was brand new and empty (you didn't do a partial fill on it prior to installation), and the oil cooler had drained out, then on the initial startup it could take 5 seconds before oil pressure registers. I had that happen to me once...

  7. ChrisR

    ChrisR Platinum Level Sponsor

    Last year I was only getting about 20psi pressure with warm oil at highway speeds, so I decided to open the pump to see if the rotor to case clearances needed to be restored. I think that the oil pump is fine now. My issue is the new noise. Have not had a chance to isolate the exact source of the noise yet.
    will pull the cover, check if oil is getting to the rockers and use a hose to listen at the weekend.

    But back to my original question, if I have damaged the big ends, and decide to replace. How do I determine what size to order? Ideally I would like the parts in my hand before opening things up, but I fear I may need to remove the old and measure the crank journals to determine what size to order. Is that correct?
  8. alpine_64

    alpine_64 Donation Time

    If you havent seen the crank you cant know what size bearings. You need to see what size it has.. If its find and can take new bearings at the same size.. If the crank is lightly damaged and needs a linish or if it is badly damaged and has to be reground and then new size bearings
  9. 65beam

    65beam Bronze Level Sponsor

    Pull the bearings and you'll find they are stamped on the back showing whether they're standard, .010 or what ever other size. This is usually stamped near the end where the two shells come together.
  10. husky drvr

    husky drvr Gold Level Sponsor


    Are you sure your oil pressure relief valve is not sticking open?
  11. sunalp

    sunalp Platinum Level Sponsor

    That's the first place to look. I have an Alpine in here now that came in with little to no oil pressure.
    First I checked the gauge with one that was known to be accurate. I disconnected the oil line from the
    block and put another line to the new gauge directly on the block. There was no difference so I accepted
    that the gauge was OK. On to the OPRV. I pulled it out and it was indeed stuck open. I had another
    known good one. Put that in and now we have 60lbs on startup which goes to 40 at idle, 25-30 at hot
    idle. The owner had complained that OP was low and that after 5 minutes of driving he heard a knocking
    sound. Turned out to be valves that were way out of adjustment. Car runs really well now!

    Check that OPRV!!
  12. ChrisR

    ChrisR Platinum Level Sponsor

    Don, Steve, I pulled, cleaned and checked the PRV last year and it did not seem to be sticking. I think my oil pressure issue is ok now. But am thinking that I may not have primed sufficiently when I re filled and started (The engine had no oil in it all winter and the oil pump was removed and re installed) maybe causing damage to the big ends (Yet T.B.C.).
    As for the valve adjustments. I will check, but cannot see why they suddenly go from ok to out between two engine starts.
    Hoping to do some more investigating this weekend.
  13. Mike O'D

    Mike O'D Gold Level Sponsor

    You say 5 - 8 seconds, so obviously you weren't timing it. Sometimes when you are expecting/wanting something to happen quickly, it seems like it is taking longer than it actually is. Even if it was actually that long, I don't think you could damage the bearings significantly. Some oil film will remain even if it sits for quite a long time.

    Regarding anti-drain back valves in oil filters - how do you know if it has one?
  14. sunalp

    sunalp Platinum Level Sponsor

    If you read the box, and sometimes the filter itself , it will say that it has one. Also, if you look at
    the bottom of the oil filter you'll see what looks like a gasket inside the filter, otherwise you can look
    inside the filter.
  15. RootesRooter

    RootesRooter Platinum Level Sponsor

    I've had several PRV's start sticking open. I removed and inspected all of them. NONE of them showed any inclination to stick open while on the bench. No ridges or damage was visible in the bore. I cleaned them thoroughly. Despite all that, once they went back in, it was only a matter of time (from a day to a month) before the pressure started dropping again.

    Last edited: May 22, 2020
  16. RootesRooter

    RootesRooter Platinum Level Sponsor

    How about a little history on the engine? How many miles on the current rebuild?
  17. ChrisR

    ChrisR Platinum Level Sponsor

    Not really sure how many miles on the latest rebuild. P.O. said not many. I am guessing no more than 5K. Started the engine yesterday and there was no unusual noises. Oil pressure was over 40 psi at 1200 rpm (assuming Tach is accurate). Then as the oil got warmer I began to hear the tapping sound. Didn't get a chance to isolate from where as there was steam blowing from near the Thermostat. Well, out of the crack in the thermostat housing........ another part to order.
    Going to check the rocker clearances next
  18. Mike O'D

    Mike O'D Gold Level Sponsor

    Thanks sunalp - I'll have to look into that. I have no idea if the one I am currently running has the anti -drainback.
  19. RootesRooter

    RootesRooter Platinum Level Sponsor

    Having the tapping start only after the engine is warmed up is a little worrisome, and could mean big end bearings. I had an Alpine just like that once. Turned out the PO's machine shop had overground all the journals by several tho.

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