Honing advice

[geeks]

DVandrews said:

geeks said:

DVandrews said:

I'd give It a flex hone first and then inspect the bores. I have a number of flex hones here at various sizes, so depending on where in the country you are it might be convenient to pop in and give the bores a going over, it will save the cost of a new one.

Dave

Clicked in here as I may have to do a similar job. DV I notice you are in MK, where abouts? Would you be able to come and have a peek at an engine for a fellow PHer in MK? I make good coffee

I might be able to, it will depend on timings. I am in Bancroft BTW.

Dave

Well there is no rush. I will fire you a PM with a pic to see what you reckon. I am Coffee Hall so not massively far away so could always come to you..

[TaneDog]

Are flexhones any good then?

[Auchnagiggle]

Them bores look pretty stuffed mate to be honest.

[HRCM]

Thanks again for all the replies, advice and kind offers of assistance.

Having given it some more thought I think I'm going to look at taking the remainder of the engine out and leave the gearbox in.

I'll post back when I've a bit more to add. Thanks again to all.

[Mignon]

Probably a wise course of action. Trying to fix damage like that with the engine in the car is unlikely to lead to a happy outcome.

[one eyed mick]

I have witnessed many block in situ rebores , ok there is cleaning to do as there is if its done in a machine shop ,a little more awkward but not impossible

[Little Pete]

OP, what are you hoping to achieve with this engine? If you are looking to do a standard rebuild and move the vehicle on, a flex hone will be fine. If you are looking to keep it for any length of time you need to check the bore for ovality and taper etc. If either of these are excessive no amount of honing is going to stop oil consumption.

[HRCM]

It's a bit of a project really - mainly something to learn on without too much risk. Having got this far I decided there wasn't much to be gained by cutting corners, that's why I've decided to take the block out and do as best I can.
I've got a bore comparitor gauge so I'll be making some investigations soon.
Eventually I suppose I will sell it on but not until I'm confident it's all ok. If I did make a real hash of things then i suppose I'd just have to break it for spares.

[Little Pete]

HRCM said:

It's a bit of a project really - mainly something to learn on without too much risk. Having got this far I decided there wasn't much to be gained by cutting corners, that's why I've decided to take the block out and do as best I can.
I've got a bore comparitor gauge so I'll be making some investigations soon.
Eventually I suppose I will sell it on but not until I'm confident it's all ok. If I did make a real hash of things then i suppose I'd just have to break it for spares.

If you have a bore gauge you are one up already!
Your project sounds like a good way to learn about engines, good luck.

[PaulKemp]

My Top Tip
I did a similar recovery job on an engine before fitting new rings
The reason for the new rings was that the so called freshly reconditioned engine was thrown together.

I used a 3 leg flexi hone to give me an even set of clean bores.
I spent a long time cleaning out the first bore with thinners and rags but always found ligh grey metal dust, a lady desperate move was to use a cloths lint roller, (the ones with the glue covered sheets) I used 2 of these for the 4 bores, when the bore is getting close to metal particle free you see no grey on the roller and finally it will try and stick to the bore wall.
I then finished off with thinners and clean white rags, oiled everything up then gapped and fitted rings.
So far it's been good.

[HRCM]

That's good to hear Paul.

I've got the rest of my engine out of the car now. I just need to strip the block down now.

I'm going to practice using my new mic and bore gauge before I attempt to measure the bores as they stand. Then I'm considering getting a local reconditioner to do the honing on their machine as they only want £30 for all four bores. I'm thinking it would be best to advise what I need in terms of finished size.

The manual says my bores are 73.400+/-.005 mm. Can anyone advise what is the most I could hone out before needing a rebore? Apologies if it's a stupid question (i.e. Top limit).

[Shelsleyf2]

In respect of the bores, are you planning to use the original pistons?. The rings will need to be replaced as they have corroded in the bores. You need to check the ring grooves in the piston and make sure they are within tolerance.
The purpose of the hone is two fold, to size the bore, and to create grooves in the cylinder wall to retain oil and keep the rings cool. Honing should produce angled scratches at about 45 degrees to the vertical in the cylinder wall.
A flexi hone would be fine if you were just re ringing a good bore. As this is not the case I would suggest you have a good engine reconditioning shop measure your bores ( they may be tapered or where the piston corroded on the bore may be out of tolerance). If you want to throw it back together it is false economy, it doesn't cost a great deal more to build it properly.

[227bhp]

When your engine was new the piston fitted the bore perfectly, when you hone you take away metal, you don't add it on.
You're kidding yourself if you think you can hone a damaged/worn bore and it still fit.
You buy bigger pistons and hone until they fit.

[HustleRussell]

227bhp said:

When your engine was new the piston fitted the bore perfectly, when you hone you take away metal, you don't add it on.
You're kidding yourself if you think you can hone a damaged/worn bore and it still fit.
You buy bigger pistons and hone until they fit.

You have no idea.

[227bhp]

HustleRussell said:

You have no idea.

Explain why you think that.

[HustleRussell]

227bhp said:

HustleRussell said:

You have no idea.

Explain why you think that.

First of all I have never even done a bottom end and in present company would never have posted in this thread as the knowledge assembled within dwarfs my own.

With that in mind;

Pistons don't 'fit' bores as such but have a running clearance which is expressed as a range. It depends on how damaged / worn the bore is. If you are just honing the bores as the OP initially intended to and putting new rings on you probably aren't going to use oversized pistons. Bit Heath Robinson but excusable.

If the bore is damaged and you are going to the trouble of removing the block then you're probably going to rebore it. It will be bored out and then honed. You don't buy bigger pistons and 'hone until they fit'- that sounds terrible. You take the bore out to the next oversize which eliminates the wear or damage, order oversize pistons, and honing is merely the process which provides the correct surface finish. Two different processes. One requires a machine shop and the other can be acheived at a pinch in a shed using a power drill.

Semantics really but nonetheless...

[GreenV8S]

HustleRussell said:

You don't buy bigger pistons and 'hone until they fit'- that sounds terrible.

The bore corrosion problems this thread is about is going to need more than just taking the glaze off the bore, isn't it? In that case it's pretty likely that getting back to a true bore will remove so much material that the bore is out of tolerance for the original piston size and will need to be taken up a size. If that's the case, boring and/or rough honing would get you to the right ballpark and then you would hone the last few thou to fit.

[Boosted LS1]

He's never even done a bottom end but I bet he's got a degree.

[AW111]

The gospel according to Toyota (4AGE 1.6l 4 cyl) :




Note the maximum honing of 0.02mm (0.8 thou).

[HustleRussell]

GreenV8S said:

The bore corrosion problems this thread is about is going to need more than just taking the glaze off the bore, isn't it? In that case it's pretty likely that getting back to a true bore will remove so much material that the bore is out of tolerance for the original piston size and will need to be taken up a size. If that's the case, boring and/or rough honing would get you to the right ballpark and then you would hone the last few thou to fit.

Yup

Boosted LS1 said:

He's never even done a bottom end but I bet he's got a degree.

Nope

But clued up enough to run a mile if an engine builder told me he was going to ‘get bigger pistons an hone until they fit’