Main bearing and rod bearing problems - Page 2

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  1. #16
    Senior Member Array 03yllwcobra's Avatar
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    Yeah John told me I could do 5-50 since I do have GT heads, I definitely will never run 20-50 anymore

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  3. #17
    Senior Member Array badcobra's Avatar
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    Quote Originally Posted by 03yllwcobra View Post
    Yeah John told me I could do 5-50 since I do have GT heads, I definitely will never run 20-50 anymore
    I don't think it's the heads that matter, it's the style of lash adjuster. The GT ones need the 5w50

  4. #18

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    I believe John has actually measured that power difference that he speaks to in Tony's post. Something to keep in mind when you look at this problem, John's engines frequently operate in rpm ranges we do not normally operate in unless racing at an event somewhere. Additionally John did not indicate the engine power level the power difference was observed on. For a 750 HP engine that is a 2% change in power. for a 1500HP engine that is a 1% change in power. For a 3000 HP engine that is a ½ % change in power.

    Why is this significant? If you drive 5 miles (or less) you can experience a 2% change in air density. The 2% change in air density will produce a 2% change in power output for the engine. Unless you are racing in a very competitive class where the cars all qualify within a second or so of each other the effort to optimize the last 1% or thereabouts of your engine's power output for a street driven car while an interesting laboratory experiment in the real world has little value. For a race application that could be a different story — especially in a very competitive class.

    There is a concept called adequacy. it varies for different environments and different applications. It was taught to me years ago by, of all people, a stereo salesman. At the time I wanted to buy a high end set of speakers that were ~$3,500 as I recall. He wanted me to buy a proletariate set of speakers for only $1000! Can you believe that? A salesman promoting the cheaper product!

    His position to me was that while instrumentation could measure the difference in audio quality, at my advanced years (27 yrs old at the time) my ears either couldn't distuinguish the difference or in a short time would not be able to distinguish the difference. The proof in the pudding test was when he sat me down in the demo room and blindfolded me prior to testing the two different speaker designs. I was unable to distuinguish between the two, just as he had told me. I saved $2500 and learned a valuable lesson that applies to so many other situations also.

    Competitive class racing — absolutely go for every last horsepower you can find. Street driven performance car — it doesn't matter. What is far more important is reliability, repeatability and good operating manners so the driver can focus on the competitive driving event.

    In general the reason the oil companies put the smaller "xx" numbers in the xxW-yy oil name is to provide better cold start behavior in cold country. The "yy" numbers are the up to temperature viscosity equivalent. John's observation about the 20W-50 on the oil filler cap is spot on. Ford also delivered the engines with another oil filler cap that had a different oil recommendation on the same filler cap. The distinction for Ford was EPA considerations. The distinction for us ought to be reliability.

    Whenever we are attempting to resolve a problem like Nick's bearing failure it is important to stay focussed. The failure was not caused by a lack of horsepower it was caused by a lack of lubrication. The source of the lubrication failure needs to be identified fixed and then a suitable oil needs to be selected by Nick that he feels good about.

    In the end we each get to pay for the decisions we make — in particular when they could have been more informed. So the real correct answer is what you personally feel best about. My put back to you would be to eschew the +/- 1% potential power gain for the increased reliability and ease of acquiring the oil you finally decide upon for your particular engine and its most frequent usage.


    Ed
    Last edited by eschaider; 07-12-2020 at 05:45 PM. Reason: Spelling and Grammar

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  6. #19
    Senior Member Array 03yllwcobra's Avatar
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    Just to update this, I had to replace everything but the engine block.

  7. #20

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    Why did the rods, pins and pistons need replacement, Nick?

    In your investigation into the cause of the failure, what did you finally determine was the cause?

    Not withstanding what you finally determine was the root cause of the failure, be sure to use ProEFI's engine fail-safes that are built into their ECU on the new build, just in case.


    Ed

  8. #21
    Senior Member Array 03yllwcobra's Avatar
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    The pins were galled from being starved of oil, I could have went with oversized pins but they PTW clearance was also more than what they liked to run. They were going to coat the pistons to help with the PTW clearance and at that point I would have been more than half way to new pistons. The Rods were all discolored from being starved of oil and were the lightweight I beam pieces from Manley I've had since 2008, So I went ahead and change them out to the standard ones that are good for 1500+.

  9. #22

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    That sounds like a repeated loss of oil pressure over a significant period of time. In your first post you indicated, it was still showing over 80 psi of oil pressure when you pulled it down..

    Where you able to determine the cause of the pressure loss and how did you go about correcting it?


    Ed

  10. #23
    Senior Member Array 03yllwcobra's Avatar
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    The cylinder heads that were in it before had cam bearings put in them due to bad journals. I talked to some people and we've all come to the conclusion that the slop in the bearing aerated the oil. This didn't cause and issue driving around normally but when we spin the motor 8000+ rpm it was just destroying the engine. That's why is still showed pressure but there was definitely an issue. The new engine builder said the journals should have been welded up and line bored to spec.

  11. #24

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    That is the first time I ever heard that explanation, Nick. I might be a little suspect yet. The clearance on the cam journals is just under 0.001" of an inch. My memory wants to say 8 tenths of one thousandth. Even if you doubled that it is less than the rods and/or main clearances. Additionally the cams are the last in the food chain to get oiled, Because of their place in the oiling food chain they should see the most oil starvation. If they looked undamaged in the heads as they came off the engine then, there is the potential for the problem to still be lurking in the new engine. Don't forget you can play around with significant changes in rod and main bearing clearances, way in excess of what is possibly on cams, and not experience a measurable increase in aeration of the oil.

    Oil aeration is usually casued by the crank counterweights whipping through the oil mist in the crankcase acting like a blender. Oil from the heads comes back through private return galleys that exit to the pan near the pan rail specifically to minimize this sort of event. Not trying to promote a sky is falling sort of thing but that's a lot of carnage you don't need to experience again.


    Ed

  12. #25

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    This is an interesting and informative (unusual combination) video sponsored by Mobil 1 that talks about oil viscosity and lubrication characteristics. The information is sourced from the Mobil 1's engineering team(s) and presented by Jason Fenske from Engineering Explained. Jason does a pretty good job of organizing and delivering the oil viscosity R&D information. Click here =>. The Oil Viscosity Story


    Ed
    Last edited by eschaider; 10-16-2020 at 06:18 PM. Reason: Spelling & Grammar

  13. #26
    Senior Member Array 03yllwcobra's Avatar
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    I wanted to update this again, the new engine builder also found the rear oil galley plug when it was tightened blocked the #5 main bearing oil passage as well as oil passage to pass side cylinder head.

  14. #27

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    Good detective work there Nick. I discovered the same thing when I removed the pressed in plug in my block and replaced it with a flush mount pipe plug. As I was tapping and checking fit, on one of the checks I noticed the pipe plug thread had eclipsed the #5 main's oil feed.passage off the main galley. I had to cut the back side of the plug to clear the oil feed hole.

    Glad you found the culprit. That kind of a whoops would have bitten you one more time had you not caught it. Good luck with the new bullet. I am now confident this build will have happy ending


    Ed

  15. #28

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    Maybe just excess carbon or oxidation in your engine. Replacing them with better rods or newer ones might help with lead build up. Also, I dont think you are using a bad oil grade or viscosity. All cars are different.

  16. #29

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    The problem was not rotating assembly component or lubricant related SVT_1999. The problem was caused by an obstruction to the block's rear oil galleys by a screw in pipe plug that was used to replace the OEM press fit plug. Nothing wrong with the screw in plugs but you need to check for oil galley obstruction and correct the problem if it exists. If you do not correct the problem, you will experience an oiling failure exactly like the one Nick did.

    Your choice of connecting rod or lubricant will have absolutely no impact on the failure. It will progress, as it did for Nick, until the oiling system blockage is corrected. Shutting off oil to an engine bearing or subassembly always plays out the same — component failures.


    Ed

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