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

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

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

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

 

[Jonny69]

Doesn't look too bad?

That's why I said the pics were disappointing

There's about 5mm up and down play in cylinder 1. There should be no play

 

[Jonny69]

5mm was a bit of an exaggeration

Lets see what's hiding under here...

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

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

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.

 

[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 was on the motorway and not hanging about, so it would have been at very high revs for quite some time with nearly zero miles on the clock. I'm surprised it did it was well, because it wasn't a fresh grind on the crank and nothing was tight like new engines are. If I was worried about anything it was the bores because they were freshly honed with new rings.

 

[Jonny69]

They are perfect, you can just about see them in the back of the picture, they haven't even fully bedded in yet. The pump has clean oil in it (and is still pumping), so the filter has done a sterling job.

Good call on checking for ovality. I'll give it them a measure.

 

[Jonny69]

/me steals finger prints.

Did you taste it?

Could an unsuitable oil have done this, or a cooling problem?

No, it was just multigrade 20W50 like I've used in these engines for the last 14 years. I didn't bother tasting it, I know what it's like

 

[Jonny69]

In yorkshire we have lights in our house/garage

In London our rent is so high we can't afford lights, even though we earn more and are more posh. We're so poor as a result we have to own old cars like this one

At least the bearings have not gone the whole way through!

I was happy about that as well. If it had gone all the way through it definitely would have killed the crank and probably the rod. I'm sort of lucky and, er, not at the same time

 

[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