4K Will Turn Over But Locks.

[dootie]

4k will turn over but locks at the same spot each time.

[rebuilder86]

thats nice!

haha sorry it just seemed like a statement more than a request for help haha.

you want assistance :P

WELCOME.

When you say locks, do you mean the starter literally jams to a stop? if so does it then do that again when you try again, or do you have to manually turn the crankshaft back the other way by hand?

Is this a new motor for you? have you had it running yourself?

or is this something you've owned for a long time and has just suddenly started showing this problem?

[dootie]

to start things off i bought the car not running as it was leaking from the plate at the rear of the head. the previous owner did drive as his daily up until it started leaking.

i then took the motor out and fixed it.

after that i put the motor back in the car then i tried to start it, it turned over then locked up.

the motor is now out of the car with no gear box attached though when i try to manually turn the crankshaft it will turn 360deg one way then lock up, i can then turn it 360deg back the other way before it locks up in the same spot.

 

cheers

[rebuilder86]

bugger, i think u messed up the timing or the valvetrain. did you just simply remove the head? or was it a rebuild of mostly everything?

If you simply removed the head, check that when you put the valvetrain back on that the pushrods have seated properly in the lifters, and i hope you didnt leave something in a cylinder??

[dootie]

i didnt need to remove the head as it was only the plate on the rear that needed fixing.

[dootie]

i only removed the engine because 2 of the bolts were snapped and i thought it would be easier to just remove the whole engine rather than take just the head off.

[rebuilder86]

this is most odd then

Is it possible for a long bolt for that plate to go through too far and lock up the valvespring?

[rebuilder86]

either that or he conned you and the motor is damaged and he just told you it was leaking.

[dootie]

yeah i might just have to start pulling the engine apart and see if i can find the problem.

[altezzaclub]

Does it lock up sharply like its hit a wall, or firmly but gradually??

 

Check the tappet gaps as you start stripping. A bent valve will have a big gap, although its not usually a K problem.

 

Do the spark plugs look brand new, or damaged at all?? Any indications he took it apart before you bought it?? Fresh threads on manifolds or tappet cover bolts?

 

Its very odd as a moving car has enough momentum to destroy the innards of a motor completely after some disaster happens, and having a motor jam like this suggests either it was a problem caused when the motor was stopped or its an artifact. A moving car will smash a spark plug that falls apart & a dropped valve will put a rod out the block.

 

Do you reckon it stops at TDC?? Which cyls??

[Western Revheads]

lets rule out a few things first, is the engine able to move past the stop spot if you move it manually, if so, then its probably a valve or interior part that could be snapped or bent or getting court, also check your starter motor, always good to change these to new when engines are out of a bay with no gearbox on them, could be that or electrical fault in the motor to battery and the motor is drawing to much from the battery and shorting out.

[dootie]

thanks for the info guys.

turns out that there was carbon on top of the pistons that was causing it to lock up.

Edited March 13, 2017 by dootie

[rebuilder86]

lol!

if it only happened at a rotation of a full 360 degrees and not 180 then id say theres an oil burning problem in one cylinder which created all that carbon.

 

do a quick compression test and see what that reveals, but remember a good test does not mean good oil rings: then

check the valve stem seals

 

If it really is on all cylinders then, consider oil rings on all 4 fried in which case compression tests wont tell you too much.

If the carbon is moist and thick its probably oil, if its dry and scrapes off relitively easy then, in this case:

better check timing, mixture, idle screw, float level, and jet sizes in this thing before going too much further!

Possibly also the backs of the exhaust valves. just check them through the openings to the manifold.

Edited March 14, 2017 by rebuilder86

[dootie]

will do.

cheers!

[Banjo]

Hi Lochi,

Don't know how I missed your post & this thread. I love a "who done it" scenario, requiring a little collective detective work.

 

turns out that there was carbon on top of the pistons that was causing it to lock up.

 

Did you remove the head to discover this, or just peer down the spark plug holes with a light ?

 

I'm very skeptical that a running engine, could just get to a point in time, where the engine suddenly arrived at a locked condition every 360 deg, as a result of carbon build up alone.

 

Hmmm ?

 

Love to hear some more details on how you found that, & if you have permanently solved the issue, & it is running again.

 

Cheers Banjo