Engine oil use - where's it worn?
Discussion
A deficit of oil (my fault) meant I damaged my engine (toyota unit in an Elise). The net result was an engine sounding like a bag of spanners and a total rebuild. Unfortunately it is now using up quite a lot of oil. I haven't checked the mileage since rebuild but I'd say its used 1.5 litres in under 1000 miles. The engine runs smoothly, doesn't seem to be leaking or blowing much smoke from the back but clearly all is not well.
So, when an engine is rebuilt how does the builder know which bits are worn and so which to replace?
I'm taking it back to the engine rebuilder on Saturday but can't afford another rebuild (and the subsequent divorce!). Should I say 'You fix it, you didn't do the job properly?' (diplomatically of course) or will they say 'Well we can't check everything' etc?
So, when an engine is rebuilt how does the builder know which bits are worn and so which to replace?
I'm taking it back to the engine rebuilder on Saturday but can't afford another rebuild (and the subsequent divorce!). Should I say 'You fix it, you didn't do the job properly?' (diplomatically of course) or will they say 'Well we can't check everything' etc?
It would be quite obvious during a rebuild what needs done, or indeed regardless of what needs done, what should be done.
Of course not all "engine builders" are the same. Some might pass off an oil change as a rebuild lol.
So can you be more specific about what work was carried out ? Was it a case of
1. Take to mechanic, fix my car.
2. Take to mechanic, fully rebuild properly to the highest standard
3. Take it mechanic. fix my car, but I'm broke...can we do it cheaply ?
Clearly 3 different scenarios.
And as you have only done say 1000 miles. You mention nowhere about running in period, or running in oil, or if the builder carried out any work or inspections during the first few hundred miles of use. Or whether any specific driving instructions were given on receipt of the rebuilt engine ?
There are a lot of variables here. But such high oil usage is not normal. But whether it is expected or not depending on work carried out is another matter.
Of course not all "engine builders" are the same. Some might pass off an oil change as a rebuild lol.
So can you be more specific about what work was carried out ? Was it a case of
1. Take to mechanic, fix my car.
2. Take to mechanic, fully rebuild properly to the highest standard
3. Take it mechanic. fix my car, but I'm broke...can we do it cheaply ?
Clearly 3 different scenarios.
And as you have only done say 1000 miles. You mention nowhere about running in period, or running in oil, or if the builder carried out any work or inspections during the first few hundred miles of use. Or whether any specific driving instructions were given on receipt of the rebuilt engine ?
There are a lot of variables here. But such high oil usage is not normal. But whether it is expected or not depending on work carried out is another matter.
Ok, the damage was to the bearings in the conrods (I think) which were slightly oval and this is apparently consistent with oil deficit. The engine runs forged pistons with cylinder liners. The oil is due to be changed about now just as a precaution but it didn't need running in at varying revs, building up over time as it did when I had the pistons/liners fitted. I've been fairly gentle on the engine so far.
The engine was built by an experienced lotus indy and I didn't give a budget as a s/c engine running up to 8500 isn't something you can get away with doing a 'budget build'.
The engine was built by an experienced lotus indy and I didn't give a budget as a s/c engine running up to 8500 isn't something you can get away with doing a 'budget build'.
Well if the engine was rebuilt, using the same pistons and rings in the same bores. Then oil usage should be exactly as it was before.
There would also be no requirement for running in or special ( ie cheap mineral oil )if this was the case, and proper oil could and should have been used right from the start.
As an aside, hopefully a new conrod was fitted anywhere a bearing spun, or it will fail again.
There would also be no requirement for running in or special ( ie cheap mineral oil )if this was the case, and proper oil could and should have been used right from the start.
As an aside, hopefully a new conrod was fitted anywhere a bearing spun, or it will fail again.
Running new rings in the modern way is to load them up quite quickly, it only takes an hour at best not the weeks of slow build up we used to use in the dark ages.
Dave Baker, who posts on here as Pumaracing, has a "How to" which I followed the last time I did an engine.
Here is an extract ( hope you don't mind Dave, if you do let me know)
Now you're ready to take the car out on the road and bed the piston rings in. To do this requires several brief applications of full throttle in a high gear to generate high cylinder pressures and force the rings against the bore walls. Put the car into 4th or 5th at 1500 to 2000 rpm and apply full throttle for about 10 seconds. Coast along for 30 seconds to dissipate any heat generated and repeat. Do this ten times. It should take about 10 minutes and maybe 5 miles if you don't have too many other cars up your chuff trying to get past.
There is more so don't take this as the full " How to"
There are similar descriptions if you Google " Running an engine in"
You may need the bores honed and new rings as oil consumption is indicative of worn rings usually
Dave Baker, who posts on here as Pumaracing, has a "How to" which I followed the last time I did an engine.
Here is an extract ( hope you don't mind Dave, if you do let me know)
Now you're ready to take the car out on the road and bed the piston rings in. To do this requires several brief applications of full throttle in a high gear to generate high cylinder pressures and force the rings against the bore walls. Put the car into 4th or 5th at 1500 to 2000 rpm and apply full throttle for about 10 seconds. Coast along for 30 seconds to dissipate any heat generated and repeat. Do this ten times. It should take about 10 minutes and maybe 5 miles if you don't have too many other cars up your chuff trying to get past.
There is more so don't take this as the full " How to"
There are similar descriptions if you Google " Running an engine in"
You may need the bores honed and new rings as oil consumption is indicative of worn rings usually
Edited by PaulKemp on Saturday 27th October 08:10
The only way oil can get out of an engine is via the rings or to a lesser extent the valve stem oil seals, this will be burned and you will see smoke.
Oil can leak from seals and gaskets or get blown out of breathers but this is not in great volumes and makes a lot of mess
Oil out of the breathers, gaskets and seals again points to presure caused by blow back past the rings
A compression test and leak down test will show how the rings are
Oil can leak from seals and gaskets or get blown out of breathers but this is not in great volumes and makes a lot of mess
Oil out of the breathers, gaskets and seals again points to presure caused by blow back past the rings
A compression test and leak down test will show how the rings are
PaulKemp said:
The only way oil can get out of an engine is via the rings or to a lesser extent the valve stem oil seals, this will be burned and you will see smoke.
Oil can leak from seals and gaskets or get blown out of breathers but this is not in great volumes and makes a lot of mess
Oil out of the breathers, gaskets and seals again points to presure caused by blow back past the rings
A compression test and leak down test will show how the rings are
Plenty of engines burn lots of oil and emit no visible smoke at all.Oil can leak from seals and gaskets or get blown out of breathers but this is not in great volumes and makes a lot of mess
Oil out of the breathers, gaskets and seals again points to presure caused by blow back past the rings
A compression test and leak down test will show how the rings are
Just look at a lot of modern engine's that go through oil at a shocking rate.
A lot of the VW TSi/FSi engines or whatever they're called, and some EJ25 Subarus
Quick update on this from the builder. Apparently forged pistons and liners do use more oil than the std ones and its not uncommon in toyotay engined cars. Not sure if this is the same for all car engines. Wished they'd have bloody told me this before fitting them. It would have saved me about £4.5K!! 
Frimley111R said:
Quick update on this from the builder. Apparently forged pistons and liners do use more oil than the std ones and its not uncommon in toyotay engined cars. Not sure if this is the same for all car engines. Wished they'd have bloody told me this before fitting them. It would have saved me about £4.5K!!
I suggest you find a new engine builder.No engine should consume so much oil during normal or even enthusiastic usage that it should empty the sump in 1000 miles.
My experience:
Westfield with Vauxhall 2.0 XE engine.
When I first fitted the engine it was standard with approx 70k miles on it. It used very little oil - not enough to notice and measure. Then I decided to rebuild it with solid lifter cams and deeply pocketed pistons. The block was bored/honed for the new pistons and the advice was to "give it death" straight away to bed the rings in, especially in such a light car. My running in regime was similar to that described above. Once run in, I noticed the oil usage was horrendous. It would use 2.5 to 3 litres of oil on a ~1100 mile trip to Le Mans and back (high speeds, lots of hard acceleration), although there was no visible smoke.
I concluded that I hadn't bedded the rings properly, so re-ringed the pistons and had the bores rehoned. After fixing a couple of leaks and ensuring the valve guides/seals were OK, I filled the sump with running in oil and went out and did lots of 30-80 third gear full throttle acceleration runs seperated by off throttle decelerations for cooling. Result: similarly high oil use.
After a few years (and lots of oil) I decided to tackle the problem - increasing cold weather piston slap forced my hand. I had the block rebored and honed to take slightly bigger pistons (same make/design) but, this time, the bores were plateau honed. Freshly done, they looked far more "run in" than they did even after a heavy duty bedding process and several thousand miles of running. Having now bedded the new pistons/rings into the plateau honed bore, the engine uses very little oil at all.
Conclusion: I had to ask at three different engine remanufacturers before I found one that did (or admitted to) plateau honing. I think that the orginal and interim honing jobs were done on old fashioned equipment and I didn't know enough at the time to recognise this. What I suspect was happening was on each upstroke of each piston, oil was splashing/spraying onto the cylinder walls and getting trapped in the honing "grooves". On the downstroke, the excess oil was scraped off by the oil control ring, but quite a lot of oil was left behind to be burnt on the power stroke. This constant burning of tiny amounts of oil (relatively speaking) lead to monster oil use. The plateau honing leaves much shallower honing marks so less oil is left on the cylinder walls and the oil control rings are much more effective at their job. So, if your fresh bores look like they've been attacked with 60 grit sand paper, your oil use may be eye watering; if they look like they've been polished after the 60 grit attack then you've more chance of not having to top up between oil changes.
As ever, YMMV - mine has.
Westfield with Vauxhall 2.0 XE engine.
When I first fitted the engine it was standard with approx 70k miles on it. It used very little oil - not enough to notice and measure. Then I decided to rebuild it with solid lifter cams and deeply pocketed pistons. The block was bored/honed for the new pistons and the advice was to "give it death" straight away to bed the rings in, especially in such a light car. My running in regime was similar to that described above. Once run in, I noticed the oil usage was horrendous. It would use 2.5 to 3 litres of oil on a ~1100 mile trip to Le Mans and back (high speeds, lots of hard acceleration), although there was no visible smoke.
I concluded that I hadn't bedded the rings properly, so re-ringed the pistons and had the bores rehoned. After fixing a couple of leaks and ensuring the valve guides/seals were OK, I filled the sump with running in oil and went out and did lots of 30-80 third gear full throttle acceleration runs seperated by off throttle decelerations for cooling. Result: similarly high oil use.
After a few years (and lots of oil) I decided to tackle the problem - increasing cold weather piston slap forced my hand. I had the block rebored and honed to take slightly bigger pistons (same make/design) but, this time, the bores were plateau honed. Freshly done, they looked far more "run in" than they did even after a heavy duty bedding process and several thousand miles of running. Having now bedded the new pistons/rings into the plateau honed bore, the engine uses very little oil at all.
Conclusion: I had to ask at three different engine remanufacturers before I found one that did (or admitted to) plateau honing. I think that the orginal and interim honing jobs were done on old fashioned equipment and I didn't know enough at the time to recognise this. What I suspect was happening was on each upstroke of each piston, oil was splashing/spraying onto the cylinder walls and getting trapped in the honing "grooves". On the downstroke, the excess oil was scraped off by the oil control ring, but quite a lot of oil was left behind to be burnt on the power stroke. This constant burning of tiny amounts of oil (relatively speaking) lead to monster oil use. The plateau honing leaves much shallower honing marks so less oil is left on the cylinder walls and the oil control rings are much more effective at their job. So, if your fresh bores look like they've been attacked with 60 grit sand paper, your oil use may be eye watering; if they look like they've been polished after the 60 grit attack then you've more chance of not having to top up between oil changes.
As ever, YMMV - mine has.
I was wondering if it was honing related. When ever I've built an engine and run a flex hone up and down the bores, the oil consumption has always been massively higher than the factory honing. The factory honing seems to be 45 degrees-ish, compared to the much more horizontal scores flex-hones leave behind.
Honing is extremely important to avoid oil consumption but also piston scuffing.
The piston manufacturer should provide specifications for the hone angle and cut, which the machining company that the builder uses can work to. The terms will be specified as Rk, Rvk, Cv, angle. They are all important. If the machining company is using a ball hone and not a 'nodding donkey' then they'll probably get something wrong.
Kolbenschmidt Pierburg and Federal Mogul provide good honing guidance for those in the engine building business. It might be worth ascertaining what method was used to hone the bores and to run a leakdown check & borescope. Based on that the rebuilder may have to repeat his work at his expense.
Edited for typos.
The piston manufacturer should provide specifications for the hone angle and cut, which the machining company that the builder uses can work to. The terms will be specified as Rk, Rvk, Cv, angle. They are all important. If the machining company is using a ball hone and not a 'nodding donkey' then they'll probably get something wrong.
Kolbenschmidt Pierburg and Federal Mogul provide good honing guidance for those in the engine building business. It might be worth ascertaining what method was used to hone the bores and to run a leakdown check & borescope. Based on that the rebuilder may have to repeat his work at his expense.
Edited for typos.
Edited by GavinPearson on Friday 16th November 20:54
cmsapms said:
My experience:
Westfield with Vauxhall 2.0 XE engine.
Your experience, or at least your conclusions are eye wateringly wrong. The deep (relatively) 45 degree crosshatch on properly honed bores does not in any way contribute to excessive oil consumption. In fact it's essential to maintain an oil film on the bore surface to properly lubricate the piston rings. Any bore without a substantial crosshatch pattern will not operate correctly.Westfield with Vauxhall 2.0 XE engine.
Plateau honing just removes the jagged tops of the honing marks, which the piston rings will do quickly anyway, to provide a faster bedding in process with less initial ring wear but it's the crosshatch that remains underneath that which gives the bore its ideal oil retention and long life properties.
I see many rebuilt engines that use excessive oil and in almost every case it's down to incorrect boring and honing technique. We went into that in great detail here a couple of years ago with an A series engine in Hungary. I'll try and find the thread later. My advice eventually resulted in a complete cure for the problems being experienced.
The most common problem is boring too close to finished size and then not being able to create a deep enough crosshatch pattern without making the bores oversize. This is easily spotted by anyone with sufficient experience because the boring marks are still visible underneath the shallow honing marks. I'm consulting on just such an engine at present which smoked and used excessive oil from the get go. The owner had the head rebuilt thinking it was valve guides and valve stem wear but my examination indicated poorly honed bores with substantial boring marks under the honing that had never worked properly from the start.
SuperchargedVR6 said:
I was wondering if it was honing related. When ever I've built an engine and run a flex hone up and down the bores, the oil consumption has always been massively higher than the factory honing. The factory honing seems to be 45 degrees-ish, compared to the much more horizontal scores flex-hones leave behind.
The ONLY useful purpose of a flex hone in engine cylinder bores is to remove just the uppermost bit of the jagged tops of the underlying cross hatch to speed up ring bedding in. This takes only a few strokes of the flex hone, maybe five seconds worth. The same thing can be achieved with a very fine grit stone (600 grit) in a normal honing system, again for just a few strokes of the hone.If you flex hone or fine stone hone for long enough to remove the underlying cross hatch created by the coarse stones then the bore will cease to operate properly and oil consumption will go through the roof.
A flex hone can't recondition a worn bore, it will just destroy its oil retention properties. Nor can a very fine honing stone for the same reasons. Glaze busting flapwheels are similarly pointless. The only way to treat a worn bore that's not quite worth reboring oversize is to use a coarse honing stone for just a few strokes under high pressure to create new 45 degree cross hatch scratches without removing any significant surface material. Then a very fast flash over with a very fine stone will remove the jagged or torn tops of those to minimise ring wear on bedding in.
It's almost impossible to create cross hatching in a bore that's too deep or coarse for the engine to work properly. You MUST be able to see a deep cross hatch pattern in any bore if it's to work properly. The upper surface finish is another matter. That's created by the final medium and/or fine stone honing which doesn't remove the underlying coarse cross hatch but ameliorates it to remove smeared and jagged material that might hurt the rings initially.
Olde worlde honing was with grit stones that cut relatively cleanly and didn't require much fine honing over the top. Modern OE equipment uses diamond grit hones which cut really fast and don't wear out quickly but create quite a jagged, torn top surface to the peaks of the honing marks. That's why a quick flex hone or a fine grit stone hone over the top of those removes the jagged smeared material and prolongs ring life somewhat. However once an engine has run in it's the underlying coarse cross hatch that determines its oil consumption and ring seal.
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