Disappointing engine damage pics inside...

[Jonny69]

August 2009 I trashed the engine in my Anglia on the motorway just after a rebuild. Gutted wasn't the word and I couldn't face touching it for ages. June this year I picked up a 1200 Super engine to use as a quick fixer-upper. I pulled the 1700 out a few weeks ago and with it sat next to the little 1200 I was left with a quandry: do I just sling the 1200 in or rebuild the 1700...?

This evening I put my torch and camping lamp to the test and took the head off the 1700 in the dark to have a look and see what was up. Working in the dark is no fun and my eyes hurt now, but I got the head off and I'm partway into a diagnosis. S'cuse the lower than normal standard pics, these were taken holding the lamp overhead so I could see to focus the camera :D

First thing I noticed was the shape of the combustion chamber 'cleaned off' from the top of no.1 piston:

http://www.jonny69.co.uk/uploads/anglia/2010-09-14_engine%20damage/IMG_6097.JPG

Not good news because that means contact had been made with the head. The head showed the same sort of story:

http://www.jonny69.co.uk/uploads/anglia/2010-09-14_engine%20damage/IMG_6104.JPG

When I turned the flywheel I could feel that there was up and down play in cylinders 1 and 2 so that means it's killed two bearings. The odd thing was it wasn't knocking, it was making more of a piston-like scraping noise. The other odd thing was I didn't get any bits and bobs come out with the oil, so I'm hoping it is a big-end and not a little-end bearing which will be harder to fix.

Fingers crossed it hasn't trashed the piston. I'm hoping the contact hasn't compressed the top ring groove which will render the pistons useless and that's BIG expense on this engine. It's all free though and the bore has not been damaged, so it's looking good so far :)

[Pickers]

The pistons look so HAPPY in the second photo! I just want to give them a big hug!

[Burble]

Ouch. Pistons and cylinder heads shouldn't get that friendly with each other.

Any idea what caused it? It'd be interesting to see what has happened to the bottom end, if it's taken out a big end or two will it have upset the crank? I'm guessing it should be ok as I'd expect there to be a lot more audible noise if the bottom end was that upset.

Is there any reason why the exhaust valves are a different colour? Are they different material or are the inlet valves blacked up from the combustion?

[Jonny69]

I'm only guessing but it's got to be a lack of oil if it's killed two big ends. No idea of the cause of that, because the pump was working fine. I have wrecked a bottom end in another engine and the crank seemed to survive with no damage, so hopefully this one has survived as well. The odd thing was there were no bits of bearings in the oil. This is why I'm worried it might be the small-end roller bearings in the pistons. They will be much harder to fix, especially if they have damaged the pistons.

As for the valves it's only done 50 miles or so, I think the valves haven't had a chance to get properly charred up.

[kaiowas]

With it being a fresh build I guess there's always the possibility that the conrod bolts have started backing out due to insufficient torque/damaged threads or similar rather than the bearing having gone. Would still give some play and explain the lack of debris.

[Jonny69]

Ok, well here goes nothing. Lets see what's hiding under here...

http://www.jonny69.co.uk/uploads/anglia/2010-09-14_engine%20damage/IMG_6111.JPG

Yuck, here are all the mangled bits, still in the bottom of the sump. This doesn't look or feel like oil :shocked::

http://www.jonny69.co.uk/uploads/anglia/2010-09-14_engine%20damage/IMG_6113.JPG

And this is what the big-end bearings look like on 1 and 2 :shocked: :shocked: :shocked::

http://www.jonny69.co.uk/uploads/anglia/2010-09-14_engine%20damage/IMG_6116.JPG

They should be silver and smooth. It's melted them in 1 and 2. I think the crank is ok. It's covered in hard black crud which I think is a mixture of burned oil and bearing, so I'll give it a clean up and a better inspection. I noticed that one of the bolts in the no.1 conrod was already loose so I think this might have been the culprit, damnit. All the oilways are clear and all the bearings were in the right way round. I can only think I missed torquing one up when I assembled the engine in the rush last year.

Even more annoying is I pulled a cam bearing out with the cam, so that'll have to be replaced as well. Don't think I can do that at home, so it looks like the 1200 will be going in to get me back on the road and I can do the work on the engine in my own time.

[Burble]

Ouch, those shells aren't looking good. Let's hope the crank is ok.

[Darrin]

As fellow mechanic, those pics are shudder worthy.

[Jonny69]

I had all the shells laid out on the table yesterday, where the light was a bit better. 1 and 2 are completely melted, 3 is trashed right down to the copper and 4 is heavily scorched. For that reason I think the loose conrod bolt is unrelated. All the other bearings in the engine are fine and the crank oilways are clear, so there is oil getting down there. I think the cause was just giving it too much stick before it was run in.

[Jonny69]

I inspected the crank a bit more closely over the weekend. Under the black deposits on the surface of the crank it's royally royalled unfortunately, so it needs a regrind. Not the end of the world, and I'm still pleased it's not the block or the pistons. I may as well take this opportunity to get some other work done on the head, namely some new guides which will tighten up the valvetrain somewhat. So much for my budget rebuild :D

[kaiowas]

So much for my budget rebuild :D

It's still a budget rebuild, just with a bigger budget ;)

[Darrin]

And considerably less than having a "professional" do all the work for you!!

[Jonny69]

Yeah, and it could have been a lot worse :D