Engine smoking badly after rebuild... HELP PLEASE!...
Discussion
There's something very odd about that cylinder bore. Normally the top piston ring produces the maximum wear on the cylinder and that's where it first rubs through the cross hatching and eventually leads to a wear ridge at the very top of the bore at high mileage. The second ring tends to produce less wear because it's running cooler and better lubricated and the oil ring usually produces less wear still if it's a low tension design.
Here though you have no wear marks at the top ring position directly under the carbon buildup like it hasn't bedded in at all, then you can see a bigger wear mark from the second ring but the oil control ring has punched right through the cross hatch already.
Never seen that before. It's all entirely the wrong way round. I'm wondering if the rings are properly designed with the right gaps and tensions but they should be given they're an OE spec.
Also I think that cylinder isn't honed perfectly circular. You can see patches where the second ring hasn't been touching it at all and others where it's worn right through. Directly next to the adjacent cylinder there's also what looks like a low spot where neither the top or second ring has been touching and carbon appears to be getting past both of them and building up in the cross hatch.
The valves are the right colour at least.
Here though you have no wear marks at the top ring position directly under the carbon buildup like it hasn't bedded in at all, then you can see a bigger wear mark from the second ring but the oil control ring has punched right through the cross hatch already.
Never seen that before. It's all entirely the wrong way round. I'm wondering if the rings are properly designed with the right gaps and tensions but they should be given they're an OE spec.
Also I think that cylinder isn't honed perfectly circular. You can see patches where the second ring hasn't been touching it at all and others where it's worn right through. Directly next to the adjacent cylinder there's also what looks like a low spot where neither the top or second ring has been touching and carbon appears to be getting past both of them and building up in the cross hatch.
The valves are the right colour at least.
What if...
the oil gets burned somewhere else - ie at the gearbox, transfer gears, crankshaft etc (for example maybe the gearbox reconditioner did some misstake at the clearances), and the oil heats up more than it should+looses its lubricating ability. Just a wierd idea...
I will fitt a capilary oil temp gauge to see. It should not exceed 80 degrees in normal conditions, am I right?
the oil gets burned somewhere else - ie at the gearbox, transfer gears, crankshaft etc (for example maybe the gearbox reconditioner did some misstake at the clearances), and the oil heats up more than it should+looses its lubricating ability. Just a wierd idea...
I will fitt a capilary oil temp gauge to see. It should not exceed 80 degrees in normal conditions, am I right?
Edited by camelotr on Saturday 8th May 08:31
camelotr said:
What if...
the oil gets burned somewhere else - ie at the gearbox, transfer gears, crankshaft etc (for example maybe the gearbox reconditioner did some misstake at the clearances), and the oil heats up more than it should+looses its lubricating ability. Just a wierd idea...
I will fitt a capilary oil temp gauge to see. It should not exceed 80 degrees in normal conditions, am I right?
How would oil burn in a gearbox? that makes no sense to me.the oil gets burned somewhere else - ie at the gearbox, transfer gears, crankshaft etc (for example maybe the gearbox reconditioner did some misstake at the clearances), and the oil heats up more than it should+looses its lubricating ability. Just a wierd idea...
I will fitt a capilary oil temp gauge to see. It should not exceed 80 degrees in normal conditions, am I right?
Edited by camelotr on Saturday 8th May 08:31
Pumaracing said:
There's something very odd about that cylinder bore. Normally the top piston ring produces the maximum wear on the cylinder and that's where it first rubs through the cross hatching and eventually leads to a wear ridge at the very top of the bore at high mileage. The second ring tends to produce less wear because it's running cooler and better lubricated and the oil ring usually produces less wear still if it's a low tension design.
Here though you have no wear marks at the top ring position directly under the carbon buildup like it hasn't bedded in at all, then you can see a bigger wear mark from the second ring but the oil control ring has punched right through the cross hatch already.
Never seen that before. It's all entirely the wrong way round. I'm wondering if the rings are properly designed with the right gaps and tensions but they should be given they're an OE spec.
Also I think that cylinder isn't honed perfectly circular. You can see patches where the second ring hasn't been touching it at all and others where it's worn right through. Directly next to the adjacent cylinder there's also what looks like a low spot where neither the top or second ring has been touching and carbon appears to be getting past both of them and building up in the cross hatch.
The valves are the right colour at least.
Just a thought Dave,Here though you have no wear marks at the top ring position directly under the carbon buildup like it hasn't bedded in at all, then you can see a bigger wear mark from the second ring but the oil control ring has punched right through the cross hatch already.
Never seen that before. It's all entirely the wrong way round. I'm wondering if the rings are properly designed with the right gaps and tensions but they should be given they're an OE spec.
Also I think that cylinder isn't honed perfectly circular. You can see patches where the second ring hasn't been touching it at all and others where it's worn right through. Directly next to the adjacent cylinder there's also what looks like a low spot where neither the top or second ring has been touching and carbon appears to be getting past both of them and building up in the cross hatch.
The valves are the right colour at least.
Has the geometry of the boring been proved?,the bedding patterns left by the rings are,I agree, really strange,if the boring was done at not quite 90 degrees in this bore similar marks would result,the wear pattern appears to be skewed off axis at the top,from the info in the previous postings it is obvious that the machine shop are incompetant and to be avoided unless absolutely necessary ,either way,I'm glad it's not my engine,would be nice to see the problem sorted though.Pity the OP lives so far away.
Also just occurs to me that a rod with the Big and Small ends out of line
slightly would give a thrust in an unusual direction,rather unlikely but were they checked,I wonder?
Mike
Edited by Auntieroll on Saturday 8th May 13:17
I've been trying to find online photos of bore wear without great success but here are a few that warrant viewing.
http://www.oldvogue.com/Harley/Front.jpg
You can see the wear from the top ring below the carbon buildup then a fair way below that you can make out the second ring mark and closely below that again you can see the oil ring has hardly marked the bore and not worn through the cross hatching and the piston has not scuffed the bore at all.
http://www.oil-tech.com/croshtch.jpg
Here again you can see the top ring has produced the most wear, less from the second, less again from the third and it actually looks like there were four rings in this engine or maybe the fourth line is the bottom rail of the oil ring.
http://iyork.smugmug.com/photos/321002609_Lr4DP-M....
In this bore which has had water damage you can see the top ring wear clearly, then below that the seond ring has done less work and the oil ring has barely marked the bore. All cross hatching is still clearly visible.
I've stripped down 100,000 mile engines where all the cross hatching was still visible and the bores had little measureable wear.
However the OP's engine looks like it's completely shagged at 1500 km.
Here's a cylinder that looks a bit like the OP's
http://photos.motoiq.com/photos/689714880_nvswV-M....
No top ring wear marks, more from the second and bad scuff marks from the piston skirt. You can see that the honing marks are almost horizontal like the OP's. Clearly oil control and cylinder lubrication was not working in this engine.
I don't know exactly what the answer is other than if I built this engine it wouldn't happen.
http://www.oldvogue.com/Harley/Front.jpg
You can see the wear from the top ring below the carbon buildup then a fair way below that you can make out the second ring mark and closely below that again you can see the oil ring has hardly marked the bore and not worn through the cross hatching and the piston has not scuffed the bore at all.
http://www.oil-tech.com/croshtch.jpg
Here again you can see the top ring has produced the most wear, less from the second, less again from the third and it actually looks like there were four rings in this engine or maybe the fourth line is the bottom rail of the oil ring.
http://iyork.smugmug.com/photos/321002609_Lr4DP-M....
In this bore which has had water damage you can see the top ring wear clearly, then below that the seond ring has done less work and the oil ring has barely marked the bore. All cross hatching is still clearly visible.
I've stripped down 100,000 mile engines where all the cross hatching was still visible and the bores had little measureable wear.
However the OP's engine looks like it's completely shagged at 1500 km.
Here's a cylinder that looks a bit like the OP's
http://photos.motoiq.com/photos/689714880_nvswV-M....
No top ring wear marks, more from the second and bad scuff marks from the piston skirt. You can see that the honing marks are almost horizontal like the OP's. Clearly oil control and cylinder lubrication was not working in this engine.
I don't know exactly what the answer is other than if I built this engine it wouldn't happen.
stevieturbo said:
This is another newly built engine....
And the marks at the top of the bore above the top ring looks like its from an engine with 100k !!
Why is it so dirty ?? Is the engine running on coal or something ? lol
The answer to why that is happening is already clearly apparent from previous information from the OP. You have a crack at it and then if not I'll tell you why.And the marks at the top of the bore above the top ring looks like its from an engine with 100k !!
Why is it so dirty ?? Is the engine running on coal or something ? lol
Hooli said:
camelotr said:
What if...
the oil gets burned somewhere else - ie at the gearbox, transfer gears, crankshaft etc (for example maybe the gearbox reconditioner did some misstake at the clearances), and the oil heats up more than it should+looses its lubricating ability. Just a wierd idea...
I will fitt a capilary oil temp gauge to see. It should not exceed 80 degrees in normal conditions, am I right?
How would oil burn in a gearbox? that makes no sense to me.the oil gets burned somewhere else - ie at the gearbox, transfer gears, crankshaft etc (for example maybe the gearbox reconditioner did some misstake at the clearances), and the oil heats up more than it should+looses its lubricating ability. Just a wierd idea...
I will fitt a capilary oil temp gauge to see. It should not exceed 80 degrees in normal conditions, am I right?
Edited by camelotr on Saturday 8th May 08:31
I am no telling that this is the problem, but the piston skirt is touching the bore wih 20W50 oil and 0.03-0.04mms piston-bore gap. This should never happen normaly. We may have problem with the piston, ring or lubricant I guess...
Althoug You are quite right about the mysterious wear of the hone - ie it is not even, but it wears out leaving clear spots. This may indicate not round honing.
How can the machinist do bores out of round? Loose honing tool?
Pumaracing said:
I've been trying to find online photos of bore wear without great success but here are a few that warrant viewing.
http://www.oldvogue.com/Harley/Front.jpg
You can see the wear from the top ring below the carbon buildup then a fair way below that you can make out the second ring mark and closely below that again you can see the oil ring has hardly marked the bore and not worn through the cross hatching and the piston has not scuffed the bore at all.
http://www.oil-tech.com/croshtch.jpg
Here again you can see the top ring has produced the most wear, less from the second, less again from the third and it actually looks like there were four rings in this engine or maybe the fourth line is the bottom rail of the oil ring.
http://iyork.smugmug.com/photos/321002609_Lr4DP-M....
In this bore which has had water damage you can see the top ring wear clearly, then below that the seond ring has done less work and the oil ring has barely marked the bore. All cross hatching is still clearly visible.
I've stripped down 100,000 mile engines where all the cross hatching was still visible and the bores had little measureable wear.
However the OP's engine looks like it's completely shagged at 1500 km.
Here's a cylinder that looks a bit like the OP's
http://photos.motoiq.com/photos/689714880_nvswV-M....
No top ring wear marks, more from the second and bad scuff marks from the piston skirt. You can see that the honing marks are almost horizontal like the OP's. Clearly oil control and cylinder lubrication was not working in this engine.
I don't know exactly what the answer is other than if I built this engine it wouldn't happen.
Very intresting photos there. Thanks. Especialy the last one. It realy resembles mine.http://www.oldvogue.com/Harley/Front.jpg
You can see the wear from the top ring below the carbon buildup then a fair way below that you can make out the second ring mark and closely below that again you can see the oil ring has hardly marked the bore and not worn through the cross hatching and the piston has not scuffed the bore at all.
http://www.oil-tech.com/croshtch.jpg
Here again you can see the top ring has produced the most wear, less from the second, less again from the third and it actually looks like there were four rings in this engine or maybe the fourth line is the bottom rail of the oil ring.
http://iyork.smugmug.com/photos/321002609_Lr4DP-M....
In this bore which has had water damage you can see the top ring wear clearly, then below that the seond ring has done less work and the oil ring has barely marked the bore. All cross hatching is still clearly visible.
I've stripped down 100,000 mile engines where all the cross hatching was still visible and the bores had little measureable wear.
However the OP's engine looks like it's completely shagged at 1500 km.
Here's a cylinder that looks a bit like the OP's
http://photos.motoiq.com/photos/689714880_nvswV-M....
No top ring wear marks, more from the second and bad scuff marks from the piston skirt. You can see that the honing marks are almost horizontal like the OP's. Clearly oil control and cylinder lubrication was not working in this engine.
I don't know exactly what the answer is other than if I built this engine it wouldn't happen.
camelotr said:
Hooli said:
camelotr said:
What if...
the oil gets burned somewhere else - ie at the gearbox, transfer gears, crankshaft etc (for example maybe the gearbox reconditioner did some misstake at the clearances), and the oil heats up more than it should+looses its lubricating ability. Just a wierd idea...
I will fitt a capilary oil temp gauge to see. It should not exceed 80 degrees in normal conditions, am I right?
How would oil burn in a gearbox? that makes no sense to me.the oil gets burned somewhere else - ie at the gearbox, transfer gears, crankshaft etc (for example maybe the gearbox reconditioner did some misstake at the clearances), and the oil heats up more than it should+looses its lubricating ability. Just a wierd idea...
I will fitt a capilary oil temp gauge to see. It should not exceed 80 degrees in normal conditions, am I right?
Edited by camelotr on Saturday 8th May 08:31
I am no telling that this is the problem, but the piston skirt is touching the bore wih 20W50 oil and 0.03-0.04mms piston-bore gap. This should never happen normaly. We may have problem with the piston, ring or lubricant I guess...
Althoug You are quite right about the mysterious wear of the hone - ie it is not even, but it wears out leaving clear spots. This may indicate not round honing.
How can the machinist do bores out of round? Loose honing tool?
stevieturbo said:
I guess because of the crap bore finish...and subsequent crap ring sealing.....oil from both the bore and crankcase pressure is caking up there ?
No. The diameter of the ring land area of the piston is so much smaller than bore size that carbon is building up rapidly in the gap. Normally the top of the piston is sized to expand almost to match the bore when it's hot leaving very little crevice volume for carbon build up. At 0.75mm under bore size the top of these pistons have about twice the gap they really require for thermal expansion.Other than a few final thoughts I'm going to call it a day on this topic as there's not much left to be said.
I don't like engines reclaimed with liners especially if the parent bore material is not very sturdy anyway as with the A series block. Having a separate liner sat inside the thin remnants of the parent bore leaves a much weaker structure than the original block. I suspect that poor fitting of the liners may be a factor here in how round they stay after being be bored and honed and how much they move about under load. I also find it hard to understand why anyone would go to the expense of linering an old A series engine in the first place instead of just finding another block.
I don't like the piston crown diameter which is far too small although it's debateable whether it's affecting the ring sealing much. I also have my doubts about the skirt design with so much scuffing taking place and the amount of oil ring wear on the bores is very unusual. However it might all be down to the boring and honing or poor/dirty assembly but without doing another block properly and trying the same pistons again we'll never know.
My own view would be to start with a fresh unlinered block, a different machine shop and ideally different pistons and rings. I've already given the dimensions for ring land diameter and pin offset for an ideal design.
I'm unsure whether piston/bore clearances previously quoted are just what the machine shop said or whether the OP has his own bore gauge which in my view is essential. Whatever work I've had to farm out in the past I've always at least had my own equipment for checking what's been done as at the end of the day the responsibility for getting everything right rests with the person who assembles the engine.
That means being tooled up and competent to check EVERY single tolerance on the engine before assembling it. Ring gaps, bearing shell clearances, bore size and finish, valve to guide clearance etc and then doing all work with scrupulous cleanliness which very few people get right. Cleaning a block properly takes hours and I've seen far too many engines in my time that are ruined by the grit and crap left in them by the engine builder before they've even had a chance to run in.
However if the cranking pressures are ok and the oil consumption is now minimal the easiest thing might be to just drive the bloody thing and stop trying to make a silk purse out of a sow's ear. It has at least been a valuable learning experience for both the OP and hopefully other people reading the thread.
I don't like engines reclaimed with liners especially if the parent bore material is not very sturdy anyway as with the A series block. Having a separate liner sat inside the thin remnants of the parent bore leaves a much weaker structure than the original block. I suspect that poor fitting of the liners may be a factor here in how round they stay after being be bored and honed and how much they move about under load. I also find it hard to understand why anyone would go to the expense of linering an old A series engine in the first place instead of just finding another block.
I don't like the piston crown diameter which is far too small although it's debateable whether it's affecting the ring sealing much. I also have my doubts about the skirt design with so much scuffing taking place and the amount of oil ring wear on the bores is very unusual. However it might all be down to the boring and honing or poor/dirty assembly but without doing another block properly and trying the same pistons again we'll never know.
My own view would be to start with a fresh unlinered block, a different machine shop and ideally different pistons and rings. I've already given the dimensions for ring land diameter and pin offset for an ideal design.
I'm unsure whether piston/bore clearances previously quoted are just what the machine shop said or whether the OP has his own bore gauge which in my view is essential. Whatever work I've had to farm out in the past I've always at least had my own equipment for checking what's been done as at the end of the day the responsibility for getting everything right rests with the person who assembles the engine.
That means being tooled up and competent to check EVERY single tolerance on the engine before assembling it. Ring gaps, bearing shell clearances, bore size and finish, valve to guide clearance etc and then doing all work with scrupulous cleanliness which very few people get right. Cleaning a block properly takes hours and I've seen far too many engines in my time that are ruined by the grit and crap left in them by the engine builder before they've even had a chance to run in.
However if the cranking pressures are ok and the oil consumption is now minimal the easiest thing might be to just drive the bloody thing and stop trying to make a silk purse out of a sow's ear. It has at least been a valuable learning experience for both the OP and hopefully other people reading the thread.
I would like to say thanks for all Your help and advices. Though I am not an all-out perfectionist, I am allways after an honestly good job. And as this engine is no yet good enough, I will go on searching the problem. Especialy as the final lesson will be leaned after I have found the problem.
I will now try the following.
Step1: I will dismantle the engine again
.
I have another block which is std size (unfortunatly A+). I will put the pistons in it and assemble it to run with the rest of my engine components. This may help to find out if boreing/honing gives the problem.
If this fails, I will order a set of pistons from a piston manufacturer with the dimensions stated here (crown diameter, pin offset etc). And I will try to exemine every part THROUGLY.
I will now try the following.
Step1: I will dismantle the engine again
.I have another block which is std size (unfortunatly A+). I will put the pistons in it and assemble it to run with the rest of my engine components. This may help to find out if boreing/honing gives the problem.
If this fails, I will order a set of pistons from a piston manufacturer with the dimensions stated here (crown diameter, pin offset etc). And I will try to exemine every part THROUGLY.
For cleaning bores a toothbrush is too small and with little reach. I use a dishwashing brush like this
http://www.leisureshopdirect.com/homeandgarden/kit...
I lash that to a wooden extension handle about 12" long with tape or wire and then you can really scrub everything hard and reach right down the bores without hitting your hands on the block.
For oilways and valve guides I use nylon test tube and burette brushes from scientific equipment suppliers. Just a couple of quid for a pack of ten. 18 inch long burette brushes are good for the oilways that run all the way down the block and shorter test tube brushes about 6 inches long for everything else.
http://www.leisureshopdirect.com/homeandgarden/kit...
I lash that to a wooden extension handle about 12" long with tape or wire and then you can really scrub everything hard and reach right down the bores without hitting your hands on the block.
For oilways and valve guides I use nylon test tube and burette brushes from scientific equipment suppliers. Just a couple of quid for a pack of ten. 18 inch long burette brushes are good for the oilways that run all the way down the block and shorter test tube brushes about 6 inches long for everything else.
Here is my plan for the week:
- 1st remove the engine and rebuild it with an old A+ block. Put it in and test it.
- 2nd meanwhile have the original block rehoned at another machine shop and rebuild the engine with this block
- 3rd if the above tests fails, I will rebuild the engine with using a set of old pistons to see if it makes any difference.
4th - pour some gasoline around...
- 1st remove the engine and rebuild it with an old A+ block. Put it in and test it.
- 2nd meanwhile have the original block rehoned at another machine shop and rebuild the engine with this block
- 3rd if the above tests fails, I will rebuild the engine with using a set of old pistons to see if it makes any difference.
4th - pour some gasoline around...
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