Lancia Beta Forum

Technical stuff => Engine => Topic started by: Betargovia on September 10, 2013, 08:30:40 PM

Title: crankshaft mechanical halt
Post by: Betargovia on September 10, 2013, 08:30:40 PM
Hi there,
Wanted to call my topic "looking for a new hobby" as I am totally devastated after todays experience... but lets start from the beginning.
A certain noise from my 2.0Ltr Carb. Engine led me to search for its cause, after the cam drive was clean and the secondary drive could be exclude it was determined to be from the crankshaft-pushrod bearings. My engine is a used one with no clue how much accumulated but mainbearings and axial play checked befor installation some 20tkm and 4 years ago.
Head off Engine out, shaft dimensiond taken correct bearings organised and with plastigage the correct 0.05mm play measured during assembly, all turning fine and tight. Pistons in correct direction installed and with new sump gasket closed, main bearings and axial play remained un-touched.
Engine back in, all hooked up again and the Head back on.
Timing belt on with timing perfectly set, first hand driven spin of the Engine it halts after 3/4 spin just before pistons 2 and 3 are at top position!
Head off, no issue with valve timing, bending etc. But crankshaft stops at same position again during manual spin, without head!
Kick against flywheel and the shaft is doing what it is supposed to do! Turning full rounds without halt!
A beer and alot of consideration later, Head back on, timing belt on and set.
AGAIN crankshaft halts with mechanical stop after about 3/4 of a turn!

I dont get it! Can someone please give me a good idea what this could be before I set fire to the thing and learn to play Tennis, Badmington or something else instead...

Cheers from Switzerland

Title: Re: crankshaft mechanical halt
Post by: targa2000 on September 10, 2013, 08:57:37 PM
Have you set the auxiliary shaft in the correct position ? its possible that the lobe on the shaft is fouling.

Title: Re: crankshaft mechanical halt
Post by: Betargovia on September 10, 2013, 09:14:01 PM
Hi Targa2000,
Thanks for your reply.
The auxliary shaft is at same position as before even though the ignition was out and the bevel gear came out too when the Engine block was turned.
Will check and put it in 34° to engine centerline but assume it doesnt change anything as it was off the belt when the head was off and the crankshaft locked anyway.

Title: Re: crankshaft mechanical halt
Post by: HFStuart on September 11, 2013, 07:16:58 PM
If it turned OK with the engine out and wasn't hitting anything the about the only thing it can be is the auxiliary shaft.
I've had it in what I thought was the right position and it's still hit.

I'm assuming you've checked that it's not something on the flywheel or clutch that is hitting?

Title: Re: crankshaft mechanical halt
Post by: Betargovia on September 11, 2013, 08:13:47 PM
Thanks to HF Stuart and Targa2000,
the key was the correct position of the aux shaft as it carries at its end an ex center that can collied with the inlet side con rod bolt of the second cylinder.
In my case it must have been due to a slight change in the con rod bolt position that now it was colliding as the very same position as the timing had been set before replacing the con rod bearings.

Will give the aux shaft in the future a bit more attention, as till now it was considered simply as the drive for the oil pump and ignition and not as a potential cause for a collision alike the cam shafts.

Lesson learned  ::)  Anyone a clue what tool can be use for the precise aux shaft position?

Will get her back together again soon and hive it a spin, look forward to hear the engine with the new con rod bearings  :D

Thanks and Gruezi from Switzerland

Title: Re: crankshaft mechanical halt
Post by: gengis on September 11, 2013, 10:17:56 PM
Good to hear you got it resolved.  I think it's the lobe for the mechanical fuel pump that collides with the con rod bolt, as HFStuart said it's the only thing it could have been.

Title: Re: crankshaft mechanical halt
Post by: WestonE on September 12, 2013, 06:22:18 AM
If you use an electric fuel pump you can cut off the lobe on the Aux DS and plug the oilway then you do not need to time the Aux DS and there is no chance of it hitting No2 con rod and destroying your engine. The guy croft books describe this process and the standard mechanical pump will not handle any power increases anyway.

There is a lancia tool that fits the holes in the belt wheels for timing but I do not have one. I always went with very careful marking with a protractor when I still had a the lobe on the Aux DS.

So much better that you found it before starting the engine!!


Title: Re: crankshaft mechanical halt
Post by: Betargovia on September 16, 2013, 07:19:02 AM
Hi Gents,
thanks for the good tips and advise in respect to the aux shaft, and of course the engine would not have been started this way, actually the head is off again for purpose of finding the cause.

To be honest I went down the path of removing the oil sump to find out where and why my crankshaft was held by something  :o
Was surely faster but not easier than pulling the engine after it had actually just been back in from con rod bearing replacement and already filled with water and ATF oil
The tip with cutting of the shaft is good and great but too much of a hazel while it's still in the bay, and yes I am running and electrical pump that's pretty much why I forgot about the fuel pump drive excenter shaft  :-[
Might do so when the engine is out next or if I am going to built up another one, but currently there is the plan to run this engine to long that might be with a Beta  :-\

Now I will have to get the bits back together by installing the oil pump with the oil sump at hand while the engine is jacked up some 10cm.
It should be spinning again later the day.

Thanks again, best regards and Gruezi from Switzerland  ;D