Distributor drive gear failure

[Rainer]

Hello Everyone i need our help

Today should have been the day of the first start, but things gone bad.
I cranked the engine to oil pressure without spark plugs everything went fine, but with plugs and fuel the engine only ignited on one or two cylinders for a short time.

So i decided to check the ignition timing again, when i checked the distributor shaft i felt a lot of play in the shaft. I pulled the distributor and found one half of the drivegear is broken off.

I do not have an explanation to this.

Yesterday when i set the timing everything was fine, no slop in the distributor shaft.
The Distributor is a brand new 123 ignition.
I installed the drive gear according to the manual
The head has never been skimmed.
Head was aligned with dowels when i installed it.
I can't see any marks on the distributor drive part, and the shaft turn perfectly free.
The engine have been turned over several times by hand without any problems.
The drivegear was a used one i got from Salv Sacco along with my cam regrind, so it is not the one which came with the engine, but it is the correct type.

I am a bit frustrated at the moment, but already ordered a new headgasket for tomorrow but still need to source a drivegear.

Maybe someone can shed some light or have an idea what i could check, i do not want this happen again.

regards
Rainer

[Richard48Y]

  I will be watching the replies!

[GavinT]

Aaagh . . bad luck there, Rainer.
Dunno if it's an optical illusion but the dizzy drive doesn't seem to be central to the hole.
The top surface of the dizzy drive seems more shiny than I'd expect.

I suspect the issue might be elusive till you get the head off but you should check a couple of things before the removal.

1. Does the dizzy drive turn when you turn the engine over? – only turn it a little in case there's damage.
2. Can you get a feeler gauge between the top of the dizzy drive and the underside of the head?
3. With the 123Distributor in position, is there any clearance between the dizzy body and the head?

When you say "Head was aligned with dowels when i installed it", is the central hollow dowel in the block still in situ?

Understand you say the head hasn't been skimmed but I still suspect a clearance issue between the dizzy drive and the underside of the head . . or perhaps between the dizzy drive and the 123-dizzy shaft dog which might explain the shiny area.

My reason is that back in the day, I was checking something (can't remember what) and bolted the head down without a head gasket, turned the engine over slightly and heard a 'tick' sound. Many years later I discovered part of a broken gear tooth from the dizzy drive lying in it's recess. The cam also had a partly broken tooth but the engine ran fine.

[jbcollier]

This a common problem.  The head has to be properly aligned when installed.  There is one permanent dowel at the front of the head and a special  tool is used to locate the back of the head.

[GavinT]

Hmmm . . the manual shows the hollow dowel in the middle near the dizzy – same position for the crossflow engine as well.

[Richard48Y]

Just checked, hollow center dowel for mine.

[Rainer]

Should have mentioned it is a crossflow head.
The central dowel is in place.
And i used the tools to align the head.
The shiny area is the breaking edge.

I will be driving over there now, pick up a new head gasket and check all points mentioned.
I will try do do better pictures today.

[jbcollier]

Tools?

There are different tools for the different heads.

Can you tell us exactly what you did?

[Rainer]

I think i found the problem.

But first i answer all questions, maybe i have done another stupid mistake.

I used the two long locating pins, which screw into the headbolt holes and hold the gasket down.
The head was then slid down over these, when the headbolts were in i removed the pins and installed the last two bolts.
I was able to copy these tools from a Renault dealer, so they should be fine.

The dizzy drive turns free and i can get a feeler gauge above it.
The distributor does not apply pressure to the drive.

But i am sure the distributor was inserted 180 degree in the wrong direction.
The slot in the drivegear is a bit to one side to make it impossible to insert the distributor the wrong way.
But the 123 ignition have a very flexible coupling on the shaft, a lot more than the original distributor i have, which made this possible.

I double checked by installing the distributor both ways and found when installed correctly there is close to no play, even with the half drivegear broken off.
Yesterday i had massive play which is why i removed the distributor.

Totally my fault, i should have double checked this but i did not expect that the distributor would go in the wrong way around.

So if anyone have a drivegear to part with i am in dire need of one.

[jbcollier]

No, that is not how the head is aligned.

 You use the “pins” in the head bolt holes to prevent head movement from displacing the multi piece head gasket as you lower the head.  Once the head is lowered, it is PRECISELY located by the one head dowel AND a special tool inserted the alignment holes at the rear of the  head.  The alignment tool is a large tapered dowel that looks like this:



You have to have this tool, period.

If the head is aligned properly, it is impossible to fit the distributor 180 out.  If it is possible to fit the distributor 180 out, the cylinder head alignment is way off.

[Rainer]

Thanks JB,

I do not have this tool.
Could you draw me a quick sketch?
I think i can replicate this on my lathe.

Regards Rainer

[jbcollier]

Yup, should be easy to make up on a lathe.  Unfortunately I’m away until the New Year.  If you look at the rear of the head and the rear of the block, there is a round hole in both.  I think they are on the LH side as you would look at the engine from the back of the car.  The tool is a snug fit into both and the taper just helps nudge things into alignment as it is inserted.

[Rainer]

Thanks JB,

Should be an easy job.
I have a spare head and block in my business.
So i probably sneak out of the house, early tomorrow before the wife is up and get this done.

Regards
Rainer

[jbcollier]

The illustration on page 68 of 820 shows the tool in use:

http://www.renault16.com/Werkplaats%2520reparatiehandboek%2520M.R.%252096.pdf

Unfortunately it’s in Dutch.  I’ll post up the section from the R12G manual when I get home.

[GavinT]

Rainer,

Another forum member also made the alignment tool.
It's installed in the locating hole above the starter.

Here's a link to page 8 of that thread but also read page 7.

http://www.lotuseuropa.org/LotusForum/index.php?topic=3178.105