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Author Topic: Engine locked up on dyno  (Read 17348 times)
baz
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« on: March 05, 2016, 18:05:53 pm »

Had my 2276 on a dyno this morning, everything ok for around 2 hours running time going through the mapping process. After hitting 6k and returning to idle it stopped solid.  Temps and pressure were seemingly good.
Now engine has cooled right down it's turning over again by hand. Any suggestions as to what might have caused this?
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mr horsepower
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« Reply #1 on: March 05, 2016, 18:13:38 pm »

Check youre oil filter for particals
Do a leak test and check oilpress

Was the power ok
Or did it die slowly ?

Good luck
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baz
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« Reply #2 on: March 05, 2016, 18:22:11 pm »

Power was increasing,  mapping 250-300rpm increases at a time. It was making 140hp at hubs @6k and 140lbs torque from just over 2k to 5.5k. Dropped off then but mapping wasn't complete. Sounded great at 6k then returned to idle for a second or two then cut out and was stuck solid. No noises or sign of trouble, temp and pressure were good.
Will need to find out whats in the filter, need to ask my guy on monday what he finds
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spanners
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« Reply #3 on: March 05, 2016, 18:56:32 pm »

One positive is seizing with no load and decreasing rpm so luckily limiting damage, if it's solid it's likely seized a main bearing, as you say oil pressure was good, I'd go with no 1 main seizing, maybe too tight on end float ? I ike around .006" or .008" on all out race motors, the lower limit of .004 can be too tight if things get very hot, then add in some heat sink Angry, dyno work can be tougher than some owners use of their motors, yours had been running for a good bit and was likely fully expanded in width and length, also oil pressure would be dropping as you backed down the rpm, good luck with it anyway.
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baz
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« Reply #4 on: March 05, 2016, 19:15:58 pm »

Yes we were lucky it went at idle speed not 6k. The fact it now turns over as it has cooled down leads me to think it was tight endfloat and not a spun bearing?  I don't know much about these engines but that sounds more plausible to me?
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spanners
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« Reply #5 on: March 05, 2016, 19:48:14 pm »

Hi baz, a lucky and welcome break Wink so Yes, correct as I suggested, heat sink grew the case length ways, probably your end float was factory minimum at .004" you need to add a couple of thou to the end float, it will show on the shims when you pull the fly wheel, luckily you have good crush on the bearing so it never moved. I would be concerned tho if end float was around .006/007" and all the shims look good with no witness marks or bluing, I would want to pull the heads in that case and eyeball the bores and Pistons as a starter.  Let us know please.
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Best regards, spanners.
baz
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« Reply #6 on: March 05, 2016, 20:25:24 pm »

Hopefully have the flywheel pulled next week and find this is the case.

What's the norm on metallic residue in the filter?  On a new engine what should you expect to find?

Just trying to weigh up if its worth stripping the engine completely against just finding tight endfloat and going on dyno again once its been loosened up a little.

I've waited a year to hear this engine run, 3 years since i started buying parts, I don't mind having it stripped if its best option as another few weeks wait won't hurt as bad as another seizure at the dyno and possibly expensive damage and a third run on the dyno after it's fixed
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Iryanu
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« Reply #7 on: March 05, 2016, 20:29:33 pm »

I had my 1835 seize under load in 2nd gear at about 5k locking the rear wheels solid (fun). It didn't spin over again ever by socket, no way by hand! Rear main bearing had spun, end float too tight. Engine was built by a well known and good rep builder I won't name and had about 300 miles on when it let go. Needless to say, I'll not be bothering with them again for anything.

Count yourself lucky it happened at idle and is now free'd off. Next step.... Re-shim it, hope for the best?

Good dyno results by the way. Hope it's not nobbled!  Cry Sounds like it could be sorted without major pain.
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spanners
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« Reply #8 on: March 05, 2016, 21:32:41 pm »

Baz, I doubt there will be any debris made it to the filter, it only has the rear thrust flange working on the shims, remember it had no load or revs on it and stopped real quickly, if it looks clean and proves out on inspection to be the end float, give it a flush and filter change and go again, I had a ram air cooled motor that would never re start to go on home the trailer after racing, I left it an hour and away it went, all was fine after increasing end float.
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baz
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« Reply #9 on: March 05, 2016, 21:47:02 pm »

Fingers crossed this is the case, the more i think about it the more it seems like it. Thanks for the help,  I'll report back next week with what we find.
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spanners
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« Reply #10 on: March 05, 2016, 22:33:14 pm »

I had my 1835 seize under load in 2nd gear at about 5k locking the rear wheels solid (fun). It didn't spin over again ever by socket, no way by hand! Rear main bearing had spun, end float too tight. Engine was built by a well known and good rep builder I won't name and had about 300 miles on when it let go. Needless to say, I'll not be bothering with them again for anything.

Hi iryano,I wouldn't be blaming the builder, not his fault, he likely used handbook clearances, race motors are picky, anything can happen, all it takes is a temperature spike or odd fuelling due to altitude or barometric pressure changes, they are at or beyond they're design limits, thousands of race motors run the lower end float settings problem free, I know builders that set them up at that with no problems, and berate myself for running sloppy end float, it does cause timing scatter for sure, unless it's crank trigger wheel timed of course, my Wassers are back at .005" end float, they don't expand like Aircooled, but what if the coolant pump failed?
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Best regards, spanners.
dragvw2180
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« Reply #11 on: March 06, 2016, 00:21:49 am »

If it was my engine I would tear it back down to check for damage , if nothing is wrong you could have it back together in a few hours. I would recheck your piston to wall clearance along with end thrust as already mentioned. Thank goodness that whatever it was did not lock up under a hard pull on the dyno. Mike McCarthy
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richie
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« Reply #12 on: March 06, 2016, 10:39:22 am »

Just my opinion, but if it tightened up due to not enough end play it will probably have marked the bearing as it prevents oil flowing through the bearing correctly, you need to split case and check the bearings for any tight spots, if not it will come back to haunt you.
Does it have a mag or aluminium case? if ally then steel or ally pulley? I have seen them lock up with ally case and ally pulley where it is to tight on snout of case

cheers Richie
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baz
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« Reply #13 on: March 06, 2016, 11:00:51 am »

Its alu case and alu pulley but there's a steel hub between the two parts, its a vwspeedshop crank trigger wheel and pulley.
I've spoken to the builder about sending it back to him for a tear down and rebuild, hopefully get it to him next week.
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Iryanu
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« Reply #14 on: March 06, 2016, 11:02:25 am »

I had my 1835 seize under load in 2nd gear at about 5k locking the rear wheels solid (fun). It didn't spin over again ever by socket, no way by hand! Rear main bearing had spun, end float too tight. Engine was built by a well known and good rep builder I won't name and had about 300 miles on when it let go. Needless to say, I'll not be bothering with them again for anything.

Hi iryano,I wouldn't be blaming the builder, not his fault, he likely used handbook clearances, race motors are picky, anything can happen, all it takes is a temperature spike or odd fuelling due to altitude or barometric pressure changes, they are at or beyond they're design limits, thousands of race motors run the lower end float settings problem free, I know builders that set them up at that with no problems, and berate myself for running sloppy end float, it does cause timing scatter for sure, unless it's crank trigger wheel timed of course, my Wassers are back at .005" end float, they don't expand like Aircooled, but what if the coolant pump failed?

I hear ya, let's just say I've heard similar stories from the same builder. It was a mild 1835, mag case, unworked big valve heads and an engle 120. Hardly a fire breathing pedigree racing mill operating on the verge of hydraulic lock, it would have been lucky to pull 80hp imo. Maybe the guy dropped his shims on the floor and put them all back in the wrong compartments! Maybe his DTI got dropped at the same time, and the numbers on his vernier are all worn off from over-use.  Tongue

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richie
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« Reply #15 on: March 06, 2016, 12:48:45 pm »

Its alu case and alu pulley but there's a steel hub between the two parts, its a vwspeedshop crank trigger wheel and pulley.
I've spoken to the builder about sending it back to him for a tear down and rebuild, hopefully get it to him next week.

That should rule out that then, hopefully its just minor and quick clean up and maybe polish crank and good to go again Smiley
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baz
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« Reply #16 on: March 06, 2016, 13:34:24 pm »

Hope so Ritchie,  thinking I will strip it down and then take it up to the builder in kit form, this will eliminate any temptation to just re-shim the endfloat and send it back Wink
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richie
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« Reply #17 on: March 06, 2016, 14:05:55 pm »

Hope so Ritchie,  thinking I will strip it down and then take it up to the builder in kit form, this will eliminate any temptation to just re-shim the endfloat and send it back Wink

Have you checked endfloat at all now while its together? There are a few other reasons why it could lock up like that 
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baz
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« Reply #18 on: March 06, 2016, 14:17:37 pm »

No I just left the car with the guy working on it (not the engine builder) he said he'd try have a look at it tomorrow, he is busy though next week. I will be passing his way tomorrow and I hope to get a few hours where I can help get it out of the car, once out we'll measure endfloat before taking anything apart.

What other things should we look out for?
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richie
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« Reply #19 on: March 06, 2016, 15:33:12 pm »

End play 1st, might be that simple, if not Oil hole alignment & correct bearing chamfer would be next 2 things, not knowing who built it means I have no idea on there knowledge etc


cheers Richie
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baz
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« Reply #20 on: March 07, 2016, 16:18:03 pm »

So just watched the motor get stripped down, number 2 rod had stuck to the crank due to oil starvation. Bearings had not been modified to line up the oil feeds. Rookie error from a 'pro' builder! Rod bearings were all a sloppy fit and loose in the rods.
Crank has no evidence of balancing which was a surprise.

Crank needs regrind, new bearings and should be good to go again.
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baz
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« Reply #21 on: March 07, 2016, 16:33:48 pm »







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leec
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« Reply #22 on: March 07, 2016, 18:20:20 pm »

What's your plan, get it built again by someone else?

Lee
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baz
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« Reply #23 on: March 07, 2016, 18:29:03 pm »

I have been thinking about doing it myself but I really would like it fixed asap and it would take me months to get it done, so judgie is gonna take care of it this time.


Any ideas on whats going on with the loose rod bearings?  Tried a few other bearings in the rod and they all fitted fine.

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Fastbrit
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Keep smiling...


« Reply #24 on: March 07, 2016, 19:07:07 pm »

Check the crank is straight. I had a low rpm (idle) lock-up once and the crank was bent as a result.
Worth checking while it's apart...
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andy198712
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« Reply #25 on: March 07, 2016, 19:13:51 pm »

Do the rod bearings sit below the centre line of the rod cap? If you've got that it gap there the oil will just pour out and prob not create the oil film the bearing and crank would "float" on. In my mind...?
Just seems odd?

Getting someone to check it over would be a good move as you say.
Best of luck!
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baz
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« Reply #26 on: March 07, 2016, 19:17:12 pm »

Check the crank is straight. I had a low rpm (idle) lock-up once and the crank was bent as a result.
Worth checking while it's apart...

Hadn't considered that, hope it's good  Undecided
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baz
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« Reply #27 on: March 07, 2016, 19:19:18 pm »

Do the rod bearings sit below the centre line of the rod cap? If you've got that it gap there the oil will just pour out and prob not create the oil film the bearing and crank would "float" on. In my mind...?
Just seems odd?

Getting someone to check it over would be a good move as you say.
Best of luck!

I don't think so, didn't notice a gap when we reassembled the rod and bearing off the crank
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leec
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« Reply #28 on: March 07, 2016, 20:06:17 pm »

I have been thinking about doing it myself but I really would like it fixed asap and it would take me months to get it done, so judgie is gonna take care of it this time.


Any ideas on whats going on with the loose rod bearings?  Tried a few other bearings in the rod and they all fitted fine.



Good stuff. Good you have stayed positive and once it's all good you will love it
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baz
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« Reply #29 on: March 07, 2016, 20:27:57 pm »

Cheers dude,  tbh hearing it run on saturday has given my enthusiasm a boost,  summer is coming and it will be ready  Grin
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