Tech Question - Condition of block

[RS-Jo]

Started out with this:


Putting him in charge of the workshop manual might have been a bad idea


But still... after a few hours I've ended up with this:


Anyway... plan was to have the head rebuilt because of the blue smoke that's still causing me headaches.
I know the engine had come out previously and looking at it now I suppose the reason for that back then was that the valves kissed the cylinders (marks were under the sooth and not visible before cleaning them up).

Now I'm not quite sure if the block is still ok or not so maybe you guys can shed your light on this?
I've read that these marks are "quite normal" and I shouldn't worry about them but of course Cosworth paranoia kicks in so I'd like to have some other opinions...

[jimcallear]

It might be an idea to whip the block out put new shells and rings in throw in a new oil pump and deglaze the bores hey presto as new engine just don't start thinking about upgrading anything apart from the oil pump. The pistons look fine

[richyx]

you can see at some point its been over revved and the valves have hit the tops of the pistons slightly hence some have indents some dont

every engne ive took apart has these as lets face it all cossies would of been off the limiter at some point in there life

but what smoke did you have? and when did it smoke

[RS-Jo]

you can see at some point its been over revved and the valves have hit the tops of the pistons slightly hence some have indents some dont

every engne ive took apart has these as lets face it all cossies would of been off the limiter at some point in there life

but what smoke did you have? and when did it smoke

Lots of blue smoke on overrun. The turbo is freshly rebuilt, inlet cleaned out as it was oily, but the car is still smoking. Now taken the head off to see if there is some wear on the valve guides and stem seals. The bores in the block look ok at first sight.

[Cossie col]

It might be an idea to whip the block out put new shells and rings in throw in a new oil pump and deglaze the bores hey presto as new engine just don't start thinking about upgrading anything apart from the oil pump. The pistons look fine

Might aswell get pistons pocketed if ya got it all apart so if you fancy a cam change later on it's ok

[mark shead]

It might be an idea to whip the block out put new shells and rings in throw in a new oil pump and deglaze the bores hey presto as new engine just don't start thinking about upgrading anything apart from the oil pump. The pistons look fine

Then you end up with to big bore clearance and oil useage, Rebore is the only way to do it.

Mark

[RS-Jo]

The valve marks worried me and I thought it was a reason for a block rebuild.
The oil pressure is still good, so I guess the big ends are still ok. Only thing is the condition of the piston rings, which is a shot in the dark at this point.

[Davecos 4x4]

you have gone this far to sort it out, might aswell go a bit more and do it properly,sadly more costly but worth it imo.

[Sunnysidebb]

You should have done a compression test and cylinder leakage test before you took the head off.
Bit late now the horse has bolted. However, you can still get the cylinders checked for size using a DTI ( Dial test Indicator). You can at least check part of the bores without removing the pistons. A good indicator of excessive cylinder wear is a ridge at the top of the cylinder. You will aslo be able to check ovality as well.
If you dont want to have a re bore I would suggest ( so long as there not too much bore wear) I would hone the bores and replace the piston rings with a new set.
You can remove the pistons whilst the engine is still in the car. you can also change all the bearing as well if you do them one at a time.
Checking valve guide wear is a little harder for a DIY'r so you might have to have the head looked at by a pro. Get new guides and guide seals fitted anyway at this stage once you have the head off.

NB:
Smoking engine on over run is normally associated with a worn engine. Ie rings or bore.
Oil on start up is associated with worn valve guide seals and or guides.
Constant light smoking is associated with a worn Turbo. (unless the engine is really badly worn)

[DaveEsccos]

Its very difficult to tell exactly whats wrong from just the pics, but id say the bore glazing you have there has been caused by borewash IE too much fuel. This will ruin the oil control rings and cause the smoking your experiencing and create a too big piston-ring-bore cleareance.

The pistons show no signs of det marks but if your running a different spec cam to cause that valve to piston contact, you definately need them pocketing. If its a stock cam, check the head thickness. Excessive skimming will cause the same symptoms.

[Simon T]

I guess the valve marks in the pistons could be caused from incorrect cam timing or a cambelt failure at some point.

As some have said above, you've gone this far so its worth getting the bottom end freshened up now too. I'm sure you'd be well annoyed to put a fresh head back on to find that it was still smoking due to rings.

[CossieGirl]

We did a cylinder leakage test and everything seemed ok
1st: 10% loss
2nd: 3%
3rd: 12%
4th: 12%

[Sunnysidebb]

We did a cylinder leakage test and everything seemed ok
1st: 10% loss
2nd: 3%
3rd: 12%
4th: 12%

That variation is fine.

Can you remember your compression test readings

You did check out the Turbo I presume, normal giveaway is oil in the pressure piping.

DTI the cylinders and check the wear. you could very well get away with a Hone ( to deglaze the bores and fit a new set of rings. By far the cheapest option.
Whilst the head is off and being tested its well worth having at least a new set of valve stem oil seals or even new guides as well. If at some point in the cars life the valves had decked the pistons its not unlikely that if the car still ran ok then any minor bend in a valve stem would put increased wear on the guides and seals. Causing rapid wear out and oil consumption.
If your not convinced about the reason the valves might have touched the pistons you should do as DAVE suggests and check how many times the head has been skimmed. Its very possible to eventually get to the point where a standard or YB611 (GPA) gasket is not thick enough.

[CossieGirl]

Didn't check compression and turbo is brand new.
But we're having it completely rebuild as I don't want to take any risks...
Thanks for all your help!