First engine rebuild - ever

[Renaultism]

Hi!

A bit advise is needed... The engine broke down, when the connecting rod came off from the crankshaft. I'm lucky because I have friends who have built engines before. BUT no French engines...

From the beginning, we had the challenge of finding out where to point those arrows. Somewhere it said to the flywheel (front) and somewhere to the cabin (rear). AI didn't help


Now it looks like that we have installed the pistons the wrong way round (and number 1 is starting from rear). Are we right that we need to disassemble the pistons? The connecting rods are probably the right way, but the pistons are wrong around (the crankshaft turns with the connecting rods alright).

Any advice is appreciated!

 

[JdeW]

The arrows should point to the flywheel

 

[Renaultism]

Thank you very much for your reply.

 

[JdeW]

There's a bit more to it, looking at the engine damage caused by the conrod came off.
Piston no. 1 is at the front so starting from the flywheel side.
About the arrows, normally they point to the front (to the flywheel) but every brand of piston has its own thing, so if you can find documentation about the brand and type, it is often mentioned there.
Pin in piston is off center. Otherwise the piston will tilt during the power stroke.
I would take the measurement with a caliper and do the longest side on the right, from the position looking at the flywheel. You have a right turning (clockwise turning when looking at the flywheel) Billancourt engine. During the compression stroke the pressure is on the left side, by moving the balance you move the piston to the right to limit the tilting effect.
So see how far the piston pin is from the center. The side of the piston furthest from the piston pin should be on the right side of the engine.

This site give you a lot of information https://www.la4ldesylvie.fr/tutoriels-de-mecanique-et-bricolage-sur-les-renault-4

 

[Renaultism]

Thanks @JdeW! I have documents about pistons, but we need to dig deeper into them. This is huge lesson for me, but I'll let you know how it goes. As I wrote, I have friends to help me but they have far too many opinions.

 

[angel]

Note that the connecting rods must be fitted in a particular way, too: the big end bearing caps should be towards the camshaft side of the engine.

 

[JdeW]

I was very surprised when I saw that photo where the connecting rod bores through the engine block and oil pan.
Normally this would happen due to no or insufficient oil lubrication in the bearing shells. But incorrect absorption of the driving forces such as incorrect installation of connecting rods and/or desaxation of the piston (incorrectly installed) can also cause it.

 

[Renaultism]

Special thanks for link: in the pictures (above) you can find exactly the same pistons (aprotec) that we also have. And arrows are pointing towards the timing chain like we have
The real cause of the failure was a loose bolt in the connecting rod (it remained in place only for 50 years). The loose bolt was found in the oil pan when we opened it. We wondered if the freezing weather was the reason for that (-25 C).

 

[Homegrown]

View attachment 33098
Special thanks for link: in the pictures (above) you can find exactly the same pistons (aprotec) that we also have. And arrows are pointing towards the timing chain like we have
The real cause of the failure was a loose bolt in the connecting rod (it remained in place only for 50 years). The loose bolt was found in the oil pan when we opened it. We wondered if the freezing weather was the reason for that (-25 C).

-25C should not affect the rod bolts.
Most of the times a rod breaks its coursed by big end bearing size on the crank.
Maybe you need to make a thread of your Christmas tree picker.
Where in Finland are you situated?
Best regards

Ps https://www.renault4.co.uk/forum/threads/homegrown-garage-green-one-75.10989/
A link to my Billancourt build Ds.

 

[Renaultism]

Thanks for the link. Very interesting engine rebuild! I got new ideas from there.
I live near Vaasa.

 

[Homegrown]

Been four summers in Kokkola/Karleby in my young years. You speak Finnish, Swedish or both.
Happy you liked my link. All updates seem to help.

 

[Renaultism]

Here is where we are now. Next distributor.
Kokkola is only one hour drive from here. I do speak Finnish and English. My Swedish is very rusty...

 

[Homegrown]

Flywheel have to go on before the oil pan.
I guess that’s why some hate french cars.
Keep up the good work