Disappointing engine damage pics inside...

Jonny69

Jonny69

Jonny69

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Kapitalist Republik of Surrey
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:

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

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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 :)
 
The head has happy faces...the valves are the eyes and at the bottom there is a mouth with a tongue.

I realise that isn't helpful at all. :p
 
5mm was a bit of an exaggeration:D

Lets see what's hiding under here...

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

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

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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.
 
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.
 
How much stick did you give it exactly? When I had my non road legal Mini 7 properly running in wasn't really possible bar running the engine for a while and those old A series engines of mine were frequently revved on the track to over 8500 rpm without anything like this happening. It seems strange that so much damage has been done to every big end!
 
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.
 
What condition are the main bearings in, especially the ones next to 1 and 2?

The loose bolt would concern me, you'll want to check the conrods for ovality. And of course see how much damage has been sustained by the the oil pump and flush out the oilways :(

I'm suspicious this was caused simply through hard running in to be honest, I suspect there may be an underlying cause. Did you check the bearing clearances when you rebuilt it?
 
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.
 
/me steals finger prints.

Did you taste it?

Could an unsuitable oil have done this, or a cooling problem?
 
Dup said:
/me steals finger prints.

Did you taste it?

Could an unsuitable oil have done this, or a cooling problem?
Click to expand...
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 :(
 
They did very well not to spin in the rod. :eek:
With the fact you've noticed a loose conrod bolt I'd suggest checking the rods as well as the crank for ovality, suggests to me that you've stretched a cap.
 
Thanks for sharing the pics, very interesting. What do you think caused it?
From what you say, I'd have thought if one bolt was loose that cap would come loose or perhaps shear off the bolts. Maybe its as you said driving the engine too hard with zero miles when it was fresh and the tolerances were still pretty tight, even if it's not a fresh grind, parts still need time to bed-in properly.
I rebuilt my old Sierra engine last year and I ran it in as if it were new.
 
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