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Tore my race engine down #1
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: July 05, 2012 08:13AM Registered: 7 years ago Posts: 20,606

At the Mitty many of you may remember I had a oil pressure drop, on the GoPro camera, it happen pretty quickly, was 70 psi everywhere, even the high g corners, then all of sudden as I entered T7, it dropped down to 20 psi, I exited the corner, not seeing the gauge yet, got on the power, and right after the 2nd to 3rd gear change I scanned the gauge and saw the 20 psi, and shut the motor down, the whole low pressure episode took about 6-7 seconds, and the engine never sound anything other than great at the time of the shut off.

I had not had any time to play with the race car until recently, and had gotten most of what was needed off the engine to be able to pull it. Well the wifey had no real plans for us on the 4th, other than a nice home cooked dinner, and just wanted take it easy, so these plans allowed me to go work on the race car yesterday. Got the engine out and stripped down, I wouldn't say I dodged a bullet, but it was more of a flesh wound than a fatal shot. So far it looks like a oil pump drive failure, which also destroyed the gears on the cam, the oil pump itself feels fine turning it with the drive stuck into it, but does get to point every once in ahwile where it feels to have a slight snag, I'll get the oil pump apart today hopefully and get a better look at the inside of the oil pump. The rod bearings were beginning to fail, but it looks like the crank may only need a polish and worse case scenerio would be a .010" udesize, the crank is now standard, thank goodness. I'll start to measure the crank more more closely over the next few days, the main bearings looked perfect, as well as the main journals.

I'll post some pictures of the carnage later today.

Hap Waldrop
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Edited 1 time(s). Last edit at 07/05/2012 08:28AM by Speedracer.

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Re: Tore my race engine down #2
BlueMax1 Alan Gilbert Powdersville, USA	Posted: July 05, 2012 08:29AM Registered: 1 year ago Posts: 226

Good news considering, I’d call that lucky for sure, got your money’s worth from your Accusump!!! Hope you’re luck will continue your rods journals.

Edited 1 time(s). Last edit at 07/05/2012 08:30AM by BlueMax1.

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Re: Tore my race engine down #3
dickmoritz Dick Moritz Philly 'burbs, PA, USA	Posted: July 05, 2012 08:34AM Registered: 3 years ago Posts: 7,410

Hap,

Are you running the stock oil pump drive gear or the more sacrificial bronze drive gear? And do you know how old the drive gear was?

Dick

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(Often wrong, but always certain)

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Re: Tore my race engine down #4
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: July 05, 2012 08:49AM Registered: 7 years ago Posts: 20,606

Yep, that's the way I saw it too, lucky, and yes a big thank you to the accusump. I pretty good at scanning the gauges often, and that helped save my ass, but I may consider idiot warning lights now, as we get older, we need all the aids we can get grinning smiley

My summery of the damage thus far is, it will take hundreds instead of thousands to fix, and thats always a good thing.

I'm sure David H. and I will have do some head scratching about all this, we've seen two recent oil pump drive failures, first with Rick and his was a bronze gear, and it did not damage the cam, now my drive gear failure with stock type steel gear that did take the cam out, but the bigger question is maybe why these gears are failing, in Rick's motor we saw nothing wrong with his oil pump, it was perfect. I hoping to find a answer inside the oil pump, but won't be shocked if it looks good. With Rick gear failure, we ponder if something soft enough to not scar the pump internals had passed thru the pump, and baulked the pump for mere moment, which started gear damage, either that or the gear itself just failed, but lots of folks use these bronze gears and have good result/life from them, I guess reflecting back on it now, the bronze gear, in my case, atleast would have possibly saved my cam.

Hap Waldrop
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Re: Tore my race engine down #5
chormy Shaun Holmes Norwich, Norfolk, United Kingdom 1963 MG MGB MkI "3330 PE" 1968 MG MGC "Crosby" 1969 MG MGC GTS "Yippee" 2005 Land Rover Range Rover	Posted: July 05, 2012 10:48AM Registered: 5 years ago Posts: 921

My drive on the C was well worn and the cam gear like a razor blade, my builder has drilled a oil feed to the gear as it seems to have the same problem as the B. Don't ask me how or what he did in the way of drilling etc.

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Re: Tore my race engine down #6
fast-MG.com Dave Headley Cortez, 4 corners, Colorado, USA	Posted: July 05, 2012 11:04AM Registered: 4 years ago Posts: 3,324

Hap, when you get the pump apart, maybe post a picture of the the pump gears and the drive spindle gear. I'm guessing an inner gerotor pin issue. confused smiley

But, like we talked about a month or so ago, pump nut tightening sequence has a big impact on the tendency to bind the pump/drive. I was assembling an engine this week and reconfirmed the exact same condition. All's good when you tighten the 3 nuts in the right sequence. thumbs up smiley

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Re: Tore my race engine down #7
dickmoritz Dick Moritz Philly 'burbs, PA, USA	Posted: July 05, 2012 12:04PM Registered: 3 years ago Posts: 7,410

In reply to # 2111768 by fast-MG.com . All's good when you tighten the 3 nuts in the right sequence. thumbs up smiley

Dave,

I'd assume that you're referring to the three nuts that hold the oil pump to the block. What would you recommend as the proper sequence and torque spec for these three nuts?

Dick

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(Often wrong, but always certain)

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Re: Tore my race engine down #8
fast-MG.com Dave Headley Cortez, 4 corners, Colorado, USA	Posted: July 05, 2012 02:31PM Registered: 4 years ago Posts: 3,324

Dick, I think it's because of gasket crush. The payen kit has a pump gasket which is a bit thicker and softer than some of the OE ones IIRC. If you look at the gasket(5-main of course), there is more gasket area on the pan rail side of the gasket.

What I found was if you start tightening the most inboard bolt, then the others the pump/gear tends to bind up. confused smiley

Next time you do this, install the cam, then the pump before the crank. Put the front plate on, then the thrust plate, and a sprocket so cam is fixed. Make sure the cam turns freely. Then install pump and gear and snug up bolts evenly, starting with the one closest to the pan rail, then rearward one, then inboard one. Play with it until your happy it's free. Repeat this sequence during final pump install. smileys with beer

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Re: Tore my race engine down #9
dickmoritz Dick Moritz Philly 'burbs, PA, USA	Posted: July 05, 2012 02:37PM Registered: 3 years ago Posts: 7,410

Terrific tip, Dave. Thank you. thumbs up

So are you saying that, tightening the inboard bolt first will result in binding that will be feel-able when turning the cam sprocket by hand when assembled in the order described above?

Dick

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Re: Tore my race engine down #10
fast-MG.com Dave Headley Cortez, 4 corners, Colorado, USA	Posted: July 05, 2012 02:43PM Registered: 4 years ago Posts: 3,324

Yes, 2 for 2 most recent builds. I started experimenting after a customer wore out a bronze gear in less than one race. confused smiley

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Re: Tore my race engine down #11
dickmoritz Dick Moritz Philly 'burbs, PA, USA	Posted: July 05, 2012 02:46PM Registered: 3 years ago Posts: 7,410

Very cool... Thanks again.... smileys with beer

Dick

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(Often wrong, but always certain)

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Re: Tore my race engine down #12
Steve64B Steve Opitz Phoenix, AZ, USA 1966 MG MGB	Posted: July 05, 2012 02:47PM Registered: 6 years ago Posts: 8,484

I've noticed that the machining in the block for the oil pump is not always flat, and can leave a lip along the block wall for the pump body to sit on. I've had to grind a little off the oil pump body to get a good seat. This might put enough of a side load on the drive to lead to failure.

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Re: Tore my race engine down #13
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: July 05, 2012 03:33PM Registered: 7 years ago Posts: 20,606

Dick it was stock steel gear as mentioned in excellent shape, the engiune had probably between 400-500 race miles on it at the point of failure, the one that filed in Rick's motor was bronze gear, as mentioned.

On the oil pump,the pin holding the star drive to the shaft is still right where it supposed to be, you'll even notice it was peened by the manufactuer, the clearence was good at .005", there was some very minor pitting on the star drive points that wasn't there on assembly, the scroll too has some very minor debris scarring. there's a tad bit of end play wear on the top housing that wasn't there to begin with, that is there now, I even measured the shaft diameter low on the shaft and at the female slot drive area, as it appeared to be very slightly spread and even had small nick on the top edge where the slot is, the top measure about .0016" larger than the bttom the shaft.

My guess is something got into the pump, even as minor as it was, it was enough to baulk the pump and cause the gear to fail, would imagine after the gear gets a nick, or slight damage on it, it would quickly wear and fail at that point. I think this is weak point in the B series engine, on the A series, with the pump driving off the rear of the camsahft, I've never seen or heard of star, slot, or pin drive ever failing in A series engine, I had A series race engine one time at one race all of the sudden starting reading about 10-12 psi lower than normal, other than that is was fine amnd ran great, Oberg filter showed clean, it did well thru the race weekend other than the slightly lower oil pressure, got home, pulled the engine, took the oil pump apart, it had X10 the scarring on the points of the star drive and the scroll while properly contained in the pump body, when removed came out in three pieces and the thing still pumped 60-65 psi of oil pressure.

Here's pictures of the drive gear, start drive, and the scroll in the pump body.

Hap Waldrop
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Re: Tore my race engine down #14
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: July 05, 2012 03:38PM Registered: 7 years ago Posts: 20,606

I'll try that too Dave on my end to see if I feel any difference, but the one thing I can tell you for sure according to the Gopro video, all this occured after 400+ race miles with solid 70 psi in a mere 6-7 seconds, which I would have never known if not for the video, but you can cleary see the gauge drop to 20 psi, I watched for many laps before and it never budged off 70 psi, until the problem occured, everything happen real quick.

Hap Waldrop
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Edited 1 time(s). Last edit at 07/05/2012 03:58PM by Speedracer.

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Re: Tore my race engine down #15
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: July 05, 2012 04:00PM Registered: 7 years ago Posts: 20,606

In reply to # 2111982 by Steve64B I've noticed that the machining in the block for the oil pump is not always flat, and can leave a lip along the block wall for the pump body to sit on. I've had to grind a little off the oil pump body to get a good seat. This might put enough of a side load on the drive to lead to failure.

Steve, I've seen that several times as well and did the same, thing, it like the extreme corner on the back side towrds the the center of the engine, that's where it does that,and it not always the case on ever block, or pump

Hap Waldrop
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Re: Tore my race engine down #16
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: July 05, 2012 05:26PM Registered: 7 years ago Posts: 20,606

Here's a look at the rod bearings, they were starting to get scary looking, they were just mere seconds before turning, when the rods caps were removed the bearings was ever so slightly stuck to the crank journals, and had to plucked away from the journals, and when test fitted back into the cap, or rods, they fit loose. Notice the center bearing in the picture, the oil holes were already filled shut with debris. If I had ran this engine another 10 seconds, if would have made a mess sure enough. Now there was some marks on the journals in places and in other places they looked wonderful still showing the luster of a good polish. I fiquired it might just be the beginings of tranfer of the bearing material and maybe, just maybe I got lucky on the crank. Well took over to the lathe, clean it off, turned the lathe on low speed and polished the journals, with first 400 emory, then #3M micro polish belt and it looked great, miced it against the records from the orignal build, dead on the same tenth of thousand it was when first built, so another bullet dodged smiling smiley

I had a buttload of work into that crank, so that was great news for me.

Hap Waldrop
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Re: Tore my race engine down #17
dickmoritz Dick Moritz Philly 'burbs, PA, USA	Posted: July 05, 2012 06:57PM Registered: 3 years ago Posts: 7,410

Photos?

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Re: Tore my race engine down #18
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: July 06, 2012 07:01AM Registered: 7 years ago Posts: 20,606

In reply to # 2112172 by dickmoritz Photos?

Yep, sorry got side tracked and forgot to post bearing pics, will do when I get to the shop.

Hap Waldrop
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Re: Tore my race engine down #19
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: July 06, 2012 01:34PM Registered: 7 years ago Posts: 20,606

Bearing pics now posted above

Hap Waldrop
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Re: Tore my race engine down #20
Denis Denis Hill Nth Victoria, Australia 1968 MG MGB MkII	Posted: July 06, 2012 07:57PM Registered: 7 years ago Posts: 651

Is it possible that a partly seized distributor drive up could load the drive enough to cause it to fail? Just another angle. Denis

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