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Discussion Starter · #1 ·
Hi all,

After some stuck valves broke a pushrod on my ‘85 Corniche, the result was a broken camshaft that I am now trying to replace.

I have the front part of the camshaft removed, along with the transmission, but cannot get to the distributor gear because of the flexplate, which in turn cannot be removed because of the transmission adapter plate interferes with starter ring.

Does anyone know if it is OK to separate the ring from the flexplate or do i have to further dismantle the starter motor and adapter plate and rear engine mounts?

Any other tips on camshaft replacement much appreciated!
30338
 

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Pull the cam thru the front, per the workshop manual.
 

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Discussion Starter · #3 ·
Pull the cam thru the front, per the workshop manual.
Thats exactly what I've done, for the front part of my 2-piece camshaft :)

The problem is the rear piece that is attached to the distributor gear.

To get to that I believe requires removing the flexplate which I cannot find documented in TSD4700, perhaps you could reference the section?
 

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The lifters and lifter boxes have to be removed before the camshaft will pull thru the front. Is the camshaft snapped? If so , there is a serious issue that would cause this which I have never seen.
 

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Discussion Starter · #5 ·
If you look very carefully at the pic i posted, you will see that the camshaft is indeed snapped

30340


This is the broken piece of pushrod that became trapped an jammed the camshaft

I would have expected the aluminium camshaft gear to have stripped, but it is unscathed

As I said, i have removed the rocker shafts, pushrods, lifters and most of the cam.

The issue is the rear part of the cam.

Does anyone know if the flexplate can be removed without removing the transmission adapter plate?

Otherwise it is basically an engine out job
 

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I don't think any of us can see where the cam shaft is snapped, it's obvious to you because you know where the break is and know where to look.
I don't doubt you, but I can't see anything in your photo.
 

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Discussion Starter · #7 ·
30341


the red circle is the break, through which you can see light reflected in the oil, the green circle is one of the 5 bent inlet pushrods

the broken inlet push rod on b4 is removed
 

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OK, thanks, I can see it now, the cam is not inline with itself anymore.
The distributor is removed, the broken piece should come out once all the push rods and lifters have been removed.
I wonder if there is a keeper holding the broken bit in place, Wraithman would know if any one would.
Maybe the break of the cam shaft damaged something in the block and that's what's keeping it in there.
 

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Discussion Starter · #11 ·
Thanks Jeff, yes , but the problem is to do this I need to remove the flexplate , which with the starter ring will not withdraw from the transmission adapter

Im just going to remove the engine, thanks for your input Jeff
 

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Hi all,

After some stuck valves broke a pushrod on my ‘85 Corniche, the result was a broken camshaft that I am now trying to replace.

I have the front part of the camshaft removed, along with the transmission, but cannot get to the distributor gear because of the flexplate, which in turn cannot be removed because of the transmission adapter plate interferes with starter ring.

Does anyone know if it is OK to separate the ring from the flexplate or do i have to further dismantle the starter motor and adapter plate and rear engine mounts?

Any other tips on camshaft replacement much appreciated!
View attachment 30338
Does anyone know if it is OK to separate the ring from the flexplate or do i have to further dismantle the starter motor and adapter plate and rear engine mounts?
You can remove the flex plate from the ring gear which then will stay in the adapter plate you should be able to get to where you need to then. good luck
 

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No, whats keeping it in is the distributor drive gear, which is why I need to remove the flexplate!
Sounds like you know what needs doing and removing the engine is a given.
Too bad RR didn't make the drive gear the same size as the cam shaft journals so it could be slipped out.
 

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Discussion Starter · #14 ·
Does anyone know if it is OK to separate the ring from the flexplate or do i have to further dismantle the starter motor and adapter plate and rear engine mounts?
You can remove the flex plate from the ring gear which then will stay in the adapter plate you should be able to get to where you need to then. good luck
Thanks @rollmech you dont think this is balanced as a unit?
 

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May I suggesest to work backwards, it has helped me. Go to the Bentley Heritage site and plug in your actual VIN and your parts are there with exploded diagrams and you can see what's ahead.

There is a possibility the camshaft has knockered the camshaft bearings, and they may have distorted. I wonder what could have caused such a catastophic failure.
 

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Thanks @rollmech you dont think this is balanced as a unit?
Not balanced as unit I would mark them with tipex ( crank, flex plate, ring gear), so it all goes back in same place. From memory I think some of the spacers between ring gear & flex plate may be machined down, I always used to draw flex plate on piece paper then put relevant bolt spacer nut on drawing so you know it all goes back in exactly the same place
 

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You can remove the adaptor plate complete with engine mounts and leave the engine sitting on the rear of the sub frame.
leave the front mount attached and support the engine from leaning side to side.
I used a wedge of folded carpet under the sump to avoid damage.
From memory i think you need to remove the adaptor plate to lift the engine vertically.
It would be interesting to know what caused it.
 

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The OP said in his first post it was a stuck valve, that would cause the bent push rod.
The cam shaft came around and tried to open the valve and couldn't _ something had to give.
Given the force to bend the push rod, I would check that rocker arm for damage and all the associated hardware on the head involving the rocker arm.

Johnathan, is this the first time you started the car in a while, if it is, how long has it been ?
You're not one of these guys who starts it up and lets it sit and idle statically for ages, and then shuts it down are you ?
 

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Discussion Starter · #20 ·
Its a sad but educational tale.

The car (50000 California miles) was sitting in the heat of the desert for a year without being started, have been running perfectly for many years previously in my ownership. I tried to start it but it had fuel problems and not enough time to look into it myself, so sent the car to a Bosch certified specialist to get it running.

2 weeks later I get the car back with the distributor removed, and « sorry it stopped working, we cant fix it »

I interviewed the mechanic who worked on it who said, « we fitted new fuel pump and injectors, and it was running well and I left the car to warm up and when i came back it was broken »

Ill never know exactly what happened of course, but i suspect a heavy footed mechanic decided to rev the engine which was gummed up, 5 pushrods bent , one unfortunately snapped, broken part became jammed under a cam lobe and something had to give.

There is some scoring visible on the rear brake pump lobe, but brake pump push rod OK. No visible damage to cam drive gear.

Obv havent removed the rear part of the camshaft for inspection yet, hopefully no damage to the rear bearing…

Moral of the story, dont give these cars to an unsympathetic mechanic, ideally do it yourself or find a specialist.

I learned the hard way…
 
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