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Author Topic: Corsa, Engine Problems  (Read 4578 times)

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JamesV6CDX

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Re: Corsa, Engine Problems
« Reply #105 on: 19 February 2018, 23:06:48 »

Been slow progress on this, due to holiday, bereavement, bad back, and numerous other unrelated things going wrong, but I've managed to move it forward a bit, now.

As you've seen from previous posts on this thread I removed all the pistons, and number three was broken. A thorough inspection shows the bores to be as good as new. I cleaned them up with some clutch cleaner, and all the cross-hatch hone marks literally look like they've come from the factory.

I decided to replace all three pistons, with new piston rings. The old ones had engrained dirt in the ring gaps etc, and to be honest, price wise, it wasn't that much more to buy a piston included with the rings, than just the rings themselves (30 a pop with rings).

So here are the three new pistons, out of the box:



And here is one with the rings fitted (note, gaps not spaced yet)



You'll have noticed earlier on that I mentioned issues removing the wrist pins, but I got there in the end with the aid of some heat and patience -

Here are the pistons and con-rods, with the little-ends fitted



You can see here, there appears to be a little (albeit not excessive) wear, to the big end shells:



So I decided to replace them all for brand new. Here is one of them:



I realised at this point I didn't have a ring compressor, so off to Halfords I trot. They had a Laser piston ring compressor which certainly looked ok, so I went for that. In hindsight, that was a mistake, but it got this job done.

At this point, I installed the number one piston. I followed the instructions in the tech data to the T, and upon advice of numerous video's I had watched, coated everything generously in oil.

Following the confident blow with the handle of my hammer, with everything lined up, it popped smoothly down into the bore with a nice satisfying little noise, leaving me with this:



Here is where the fun started.

Upon attempting the same with number two, I just felt that the compressor wasn't gripping the rings evenly. I couldn't see this, it was just a strange hunch that it was out of round.

I removed the compressor, double checked everything, and it all seemed ok, so went to fit number 2 in the same way as I did one.

This time, the piston didn't go straight into the bore. For some reason the middle compression ring didn't go in, and popped out, meaning the piston didn't go fully in.

I again removed everything, thankfully the rings were unharmed, so attempt number two, this time it went in, as did number three.

Here is the end result with the pistons fitted:



As you can see, the engine is at a safe position just prior to TDC, ready for head fitment.

With the new pistons fitted, and a light smear of oil in the bores, and assembly lube used on the new bearings, the engine turns over very smoothly indeed. There is a bit more resistance than there was before, but I put this down to the fact the bearings and rings are new. There's certainly no abnormal resistance.

Next job is to rebuild the cylinder head and have a big clean up of everything.

It's going slowly, but I'll get there in the end :y
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Andy B

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Re: Corsa, Engine Problems
« Reply #106 on: 19 February 2018, 23:27:27 »

  ......

You'll have noticed earlier on that I mentioned issues removing the wrist pins, but I got there in the end with the aid of some heat and patience  ......

 :y :y :y :y ;)

Looking good. It's been a long while since I've seen that much of an engine's internals  :)
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Bigron

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Re: Corsa, Engine Problems
« Reply #107 on: 19 February 2018, 23:34:11 »

I'm not sure that I should admit this amidst all you experts, but back in the days of my old A30 (Austin, not the road!), I fitted the pistons without a compressor (couldn't afford one) by squeezing the rings as tightly as I could and gently offering the piston into the bore, a ring at a time, gently tapping the piston crown with a hammer handle.
I did get sore fingers, of course!

Ron.
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henryd

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Re: Corsa, Engine Problems
« Reply #108 on: 19 February 2018, 23:35:19 »

James,did you de-glaze the bores before fitting pistons,didn't see you mention it ::)
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JamesV6CDX

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Re: Corsa, Engine Problems
« Reply #109 on: 19 February 2018, 23:41:11 »

James,did you de-glaze the bores before fitting pistons,didn't see you mention it ::)

The chap from my local machine shop (who lives locally) popped round for a couple of beer tokens. He brought with him what I can only describe as a lot of balls on the end of a coathanger wire, that goes in a drill.

He took one look at the bores, however, and said it would do more harm than good, and to put it back together with new pistons and rings.

If he's given me duff advice then so be it, I can't see how it can possibly run any worse than it did before  :-\
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Kevin Wood

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Re: Corsa, Engine Problems
« Reply #110 on: 19 February 2018, 23:46:07 »

The idea is that the new rings won't seal perfectly against the bores unless both wear a little on initial running, and, if the bores are smooth, that won't happen.

I'd have honed the bores regardless.
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Bigron

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Re: Corsa, Engine Problems
« Reply #111 on: 19 February 2018, 23:47:13 »

Oh dear, another admission - same car! I used a wooden rod with a split longitudinally to hold some emery cloth, in the chuck of a power drill. It acted like a flail and brushed against the bore quite nicely.
I bet you will say I was wrong.....

Ron.
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Re: Corsa, Engine Problems
« Reply #112 on: 19 February 2018, 23:48:43 »

I seem to remember being told, way back, that having the bores chromed and fitting chrome plated rings was a bad idea. Must be for the same reason?

Ron.
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JamesV6CDX

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Re: Corsa, Engine Problems
« Reply #113 on: 19 February 2018, 23:50:59 »

The idea is that the new rings won't seal perfectly against the bores unless both wear a little on initial running, and, if the bores are smooth, that won't happen.

I'd have honed the bores regardless.

When you say won't seal perfectly.

Likely to seal well enough that the car will run to a good standard, but just not be at their best?

Or cause serious compression loss and oil problems?

I did have my doubts to be honest, but when he came with the kit to do it, he was absolutely adamant that it might do more harm than good, and I had no reason to disbelieve  :-\

If you think they need to come back out, I guess that's what my next free day will be doing!  ::)
« Last Edit: 19 February 2018, 23:52:38 by JamesV6CDX »
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Kevin Wood

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Re: Corsa, Engine Problems
« Reply #114 on: 20 February 2018, 09:55:16 »

Difficult to say what the consequences would be. You might get away with it. I'm sure it'll run fine, but you might find that it burns a little oil and, crucially, it won't ever "bed in" and improve.

He might well be right that the machine with the balls would have done more harm than good. I have used these in the past:

https://www.amazon.co.uk/Draper-56246-51-177-Cylinder-Hone/dp/B0001K9WDA?psc=1&SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-ffnt-uk-21&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B0001K9WDA

Just run it up and down a couple of times on the end of an electric drill. Might be worth doing while you're at a stage where it won't be too much lost work.

Also, I'd put some assembly lubricant on the big end bearings when it goes together the final time just to protect them until oil pressure comes up.
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Andy B

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Re: Corsa, Engine Problems
« Reply #115 on: 20 February 2018, 09:58:39 »

James,did you de-glaze the bores before fitting pistons,didn't see you mention it ::)

Is that just required after a re-bore?  :-\ The cylinders are as they were
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LC0112G

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Re: Corsa, Engine Problems
« Reply #116 on: 20 February 2018, 10:00:36 »

Bit late now, but....

Always a good idea to put the top ring into the bore and square it up with the top of a piston, and then measure the ring gap with some feeler gauges. Gives you a crude measure of bore wear and makes sure the piston rings are the size they claim to be.

I use a paste called Graphogen for lubricating bearing surfaces on re-assembly. It stays present on initial engine starting lubricating the shells till oil pressure builds and eventually washes it out.
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Kevin Wood

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Re: Corsa, Engine Problems
« Reply #117 on: 20 February 2018, 10:09:31 »

Clean the bores of any residue from the honing with an oily rag before fitting the pistons, of course, and it's worth putting a rag over the crank to stop any debris ending up on the big end journals.

The other thing that can sometimes be important is to check the ring end gap. I'm not sure if it's such an issue with the tolerances these things are made to these days, but sometimes when fitting new rings into a bore, there is not enough clearance at each end of the ring and they can rattle together and break the ring.

Checking this requires removing the rings from the piston, inserting them in the bore alone and measuring the end gap with feeler gauges, which is not entirely without risk of breaking them.

I'd be inclined to say that, as the pistons went into the bores easily, you might be able to wing it on that score.

EDIT: LC got there before me on the ring gaps..
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Bigron

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Re: Corsa, Engine Problems
« Reply #118 on: 20 February 2018, 10:14:45 »

I'm sure you already know this, but measuring the ring gap above and below the ridge at the top of the bore, plus some mathematics, will indicate the amount of bore wear (unless it's a Triumph Herald!).

Ron.
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Re: Corsa, Engine Problems
« Reply #119 on: 20 February 2018, 11:07:55 »

James,did you de-glaze the bores before fitting pistons,didn't see you mention it ::)

Is that just required after a re-bore?  :-\ The cylinders are as they were

Normally glaze bust even for rings to aid bedding in,as Kevin says the rings may not bed in at all leading to oil consumption :y
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