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Rebuilt Engine Has Seized After A Short Drive


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#1 Syma

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Posted 14 May 2018 - 12:04 AM

dropped in my 998 that has just been rebuilt and overboard to +60. made it around 3 km then it stalled and would only click. It started back up again and I parked it for 15 min. Started up again just fine but stalled again and had to get towed home. Lots of oil, it will only click so I check the battery, thats fine, check the ground and other wires, their fine, took the starter out and tried to move the flywheel with a pry bar and it will not budge. I read the the slave cylinder bolts could touch the flywheel if they are too long so I backed them out and nothing. At this point in time I'm not sure what my next step should be.



#2 nicklouse

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Posted 14 May 2018 - 12:17 AM

Contact the builder if it came as a complete unit.
Contact the assembler if it was put together for you.

If you did it then first thing is what voltage is the battery and have you checked its ability to supply a good power. If ok check the timing.

#3 russo

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Posted 14 May 2018 - 12:19 AM

Guess the first question I would be asking is who machined and assembled the engine? If it was done professionally Id be returning returning the vehicle ASAP.



#4 Syma

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Posted 14 May 2018 - 02:56 AM

Local shop did the machining and I put it back together. I'm worried cause when i picked up the block the guy who did the work said he bored it to fit the pistons that I supplied and mentioned that he didn't go as big as the spec said to. Said he based it off the pistons. Since I don't know anything about that type of thing I'm worried the tolerance was too tight.



#5 Syma

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Posted 14 May 2018 - 03:02 AM

Contact the builder if it came as a complete unit.
Contact the assembler if it was put together for you.

If you did it then first thing is what voltage is the battery and have you checked its ability to supply a good power. If ok check the timing.

Battery tested fine and the timing didn't change as I didn't change the cam or crank. 



#6 Moke Spider

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Posted 14 May 2018 - 03:35 AM

Local shop did the machining and I put it back together. I'm worried cause when i picked up the block the guy who did the work said he bored it to fit the pistons that I supplied and mentioned that he didn't go as big as the spec said to. Said he based it off the pistons. Since I don't know anything about that type of thing I'm worried the tolerance was too tight.

 

Sorry, but I have some less than encouraging words here,please, don't misunderstand me though, I am indeed very sympathetic to what you may now have to face. That is in fact the correct way to go about business (to base the finished bore sizes off the pistons), however, be aware too that ultimately, it is up to the assembler to check everything prior to and during assembly. If some of the machining operations or parts are not correct, then all that (say) the machine shop is liable for is rework on that.



#7 Syma

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Posted 14 May 2018 - 03:40 AM

 

Local shop did the machining and I put it back together. I'm worried cause when i picked up the block the guy who did the work said he bored it to fit the pistons that I supplied and mentioned that he didn't go as big as the spec said to. Said he based it off the pistons. Since I don't know anything about that type of thing I'm worried the tolerance was too tight.

 

Sorry, but I have some less than encouraging words here,please, don't misunderstand me though, I am indeed very sympathetic to what you may now have to face. That is in fact the correct way to go about business (to base the finished bore sizes off the pistons), however, be aware too that ultimately, it is up to the assembler to check everything prior to and during assembly. If some of the machining operations or parts are not correct, then all that (say) the machine shop is liable for is rework on that.

 

If thats the correct way to do things I have no problem with that at all, this is the first time I have had an engine machined so I am unfamiliar with the process. Guess the engine is coming back out. Thanks 



#8 Homersimpson

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Posted 14 May 2018 - 07:17 AM

Hi,

 

Just a quick thing to try, take the plugs out and see if it turns more easily, if not put it in fourth gear with the handbrake off and push the car, does it turn reasonably easily?

 

This will give you an indication of how tight the engine is and whether there is actually a problem.  Although you are struggling to turn it with the starter removed this isn't the best place to try, the end of the crank is but on a mini its a pain to get at with the radiator.

 

A new engine should be more difficult to turn, sometimes though it can be too much.

 

One tip is when you put it together everytime you bolt something up in terms of crank, pistons etc. turn it over, that way you should see if/when it goes tight and can examine that step.

 

You may be lucky and your fault might not to be to do with then engine (maybe something electrical).  Did it have good oil pressure when running?



#9 Chris.Williams

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Posted 14 May 2018 - 11:54 AM

So did you do the gapping of the rings yourself? This is a very important process and if done incorrectly will lead to engine failure.

#10 Pete649

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Posted 14 May 2018 - 06:20 PM

Just echoing what others have said, are you sure it has actually seized? When I rebuilt my first engine (many years ago) it was rebored a bit on the tight side and by the time I had all four pistons back in it would hardly turn over even using a long handle. Started fine though and eventually ran in just fine. Have been more careful since. As Homer says, perhaps try to (gently) turn it in fourth gear and see if that works.



#11 russo

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Posted 14 May 2018 - 09:55 PM

Very important to check all clearances along the way on re assembly, ie check each individual ring in the bores they are going into, mains and big ends nip and crush of bearings etc. I wouldn't try turning it over any more to avoid any further damage. Remove engine and strip it, check for any damage and re machine and maybe get some professional help to re assemble it.



#12 Syma

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Posted 15 May 2018 - 04:23 PM

update. 

Engine out yesterday and striped down... again. The pistons and the cylinders are fine thankfully. The issue is one of the bearing on the connecting rod seized heating the metal and filling the oil hole causing it to become dry and lock up. The crank on that rod journal has signs of wear so the crank is going to go to the machine shop and have all seven surfaces machined. I don't know why this happened as we had to correct bearings, torque was good, clearance was fine and it turned over fine. I will have the machine shop order the bearings to make sure they are correct for the new size and assemble. Thank you all for your help and advise.



#13 Rorf

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Posted 15 May 2018 - 04:58 PM

Well done for finding out what the problem is. Bad luck. You will have to clean out all the oil ways and main galleries to get rid of any contamination, that means removing the brass oil plugs. Do a dry build first; Crank in and plastigage all three main bearings to check clearances. Remove, clean and reassemble if ok (crank spins easily with two fingers). Remove rings from all pistons, install each one and plastigage each big end. Remove and clean big ends, reinstall all and then see if crank turns over easily with the pistons (without rings) in the bores.

 

If ok strip everything down and clean clean clean - then reassemble as per norm..



#14 Syma

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Posted 15 May 2018 - 11:49 PM

Well done for finding out what the problem is. Bad luck. You will have to clean out all the oil ways and main galleries to get rid of any contamination, that means removing the brass oil plugs. Do a dry build first; Crank in and plastigage all three main bearings to check clearances. Remove, clean and reassemble if ok (crank spins easily with two fingers). Remove rings from all pistons, install each one and plastigage each big end. Remove and clean big ends, reinstall all and then see if crank turns over easily with the pistons (without rings) in the bores.

 

If ok strip everything down and clean clean clean - then reassemble as per norm..

I was just talking to be dad about that  process in fact. He just rebuilt an engine for his MGB and has way more experience then me plus he has experience using plastigage. We used some to check clearance when we put it together but obviously not enough. In the end this has been a learning experience.. an expensive on but it could have been way worse.  The machine shop said there end will come to around $200 and the only parts I will need are new bearings and gaskets. We are also getting really good at pulling the engine out of the car and putting it back in. Good practice for when we swap engines on my dads MGB in the fall



#15 Allrounder

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Posted 16 May 2018 - 09:22 AM

Dont forget to check the big end on the the rods for roundness.




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