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Post by djm16 on Oct 14, 2021 23:22:23 GMT
After the huge investment in time and money, it is very disappointing to have failed at the final hurdle.
My 3-litre was subject to a major overhaul: rebore, camshaft bearings, oil pump to name but a few of the expensive items.
After 500 miles of carefully not exceeding 3000 rpm, constantly varying load and speed, I found that oil consumption was extreme, and the spark plugs wet with oil. Plug number 6 was the first to get wet, followed some 100 miles later by the remainder.
The intake valve oil seals are unlikely to be the problem as there is no cloud of smoke after an extended over-run.
The engine was reassembled with JP pistons. I used sticky engine-assembly lube for every moving, and for the rings, a smear of moly grease (as advised by JP). I filled it up with penrite 20W-60 high ZDDP engine oil. Apart from the molydenum grease, this is how I ran-in the P4 engine a few years back, and there were no problems with running-in on that engine.
After much reading on the internet, I came to the conclusion that what I might have done instead was: a) use running-in oil with no friction modifiers b) as soon as the engine was warmed up, then repeat WOT followed by engine deceleration for at least 50 miles.
So I tried the WOT / deceleration technique for the next 100 miles. 4 of the six pots least affected now look oil-dry, still leaving me with a wet 3 and 6.
My next move before tearing the engine down again is to try some Subaru cylinder head cleaning spray (on the assumption that glazing in the bores might be prevented the rings bedding in, and chemically removing the glaze might help) and a third oil change to running-in oil.
Any words of wisdom out there?
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Post by 3litrekiwi on Oct 15, 2021 9:27:31 GMT
Hi David I am embarking on a similar job, my spare block is at the reconditioners and I have been following your job. Given the cost of a major overhaul I understand your disapointment. Also the time to do the work.
If nothing mechanical is damaged I can report that my current engine seems to be finally bedding its rings in after 6000 miles. A reasonable spare perhaps once the refurbed one goes in, cracks in the block not withstanding. I used cheap 20/50 for the first 1000 miles perhaps a genuine running in oil might be required by these old girls and maybe for a bit longer. My new pistons have chromed top compression rings, I don't know whether these will bed in faster or more slowly, the bores will have to wear to the rings I assume.
I will be watching for updates, hopefully that things are coming right as it seemed to me that a lot of care also went into the job.
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Post by enigmas on Oct 15, 2021 13:43:37 GMT
Hi David, that's obviously an upsetting outcome after all the work, time and money you put into refurbishing the engine. As you've literally rebuilt it from top to toe mechanically and have gone to great lengths to ensure all components are well within the prescribed tolerances, my guess is that the problem resides with the cylinder wall finish and perhaps the type of top ring you chose to run.
I don't recall how you finalised the surface finish of the cylinder bores but a smooth or polished surface without any "tooth" to retain an oil film, is a sure way to create poor ring seal.
My preference is to run a silicon-carbide ball hone through the cylinders prior to final assembly as it readily produces an ideal 45° cross hatch pattern. Couple this with a basic set of cast iron rings and an engine will bed itself in very quickly, usually in the first 20 to 30 mins (@1800 rpm) when breaking-in a fresh cam and lifters.
For what it's worth, a simple once over with a ball hone will most likely fix the issue. You could probably even do it with the pistons in situ at the bottom of the stroke. Not ideal, but I can't see that it would harm anything.
* I don't fathom why JP Pistons advise smearing the rings with moly grease, without some friction the rings won't bed into their individual cylinders.
* I used Penrite 20/60W on my P76 project engine for first start-up and had no issues.
* If you use running in oil now in your engine I believe you'll find that it'll smoke excessively.
* Personally I don't believe the 1950s handbook version of incrementally running an engine-in is a valid method anymore.
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Post by Ken Nelson on Oct 15, 2021 14:16:06 GMT
After rebuilding an engine for my MGA many years ago I had similar problems with excessive oil consumption and smoking. I had used chrome rings and after several thousand miles I gave up and re-honed the cylinders (engine in car with pistons out) and used cast iron rings instead and this quickly solved the problem.
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Post by lagain on Oct 15, 2021 15:43:39 GMT
When I had my V8 rebuilt many years ago I was told to start it and run it at 2500 revs for a certain number of minutes that I can no longer remember, perhaps 10 or 20. It was very difficult as the water kept spewing out, but I got there eventually. It seemed, to me, a drastic thing to do with a newly rebuilt engine but was, presumably, to stop any glazing of the bores.
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Post by harvey on Oct 15, 2021 16:17:37 GMT
When I had my V8 rebuilt many years ago I was told to start it and run it at 2500 revs for a certain number of minutes that I can no longer remember, perhaps 10 or 20. It was very difficult as the water kept spewing out, but I got there eventually. It seemed, to me, a drastic thing to do with a newly rebuilt engine but was, presumably, to stop any glazing of the bores. More likely it was to bed the camshaft in.
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Post by enigmas on Oct 15, 2021 22:34:03 GMT
The only other probable causes that I can think off that may have caused the issue are too tight ring end gap clearances especially the second ring...and perhaps using an old style one piece oil ring rather than a modern 3 piece expander type.
As for chrome top rings these are are very wear resistant but require careful bore prep if you rreference the appropriate tech literature regarding their qualities. I prefer using cast iron rings as they bed-in quickly and are long lived in general use for day to day drivers. The current engine in my P5 coupe, fully rebuilt 28 years ago has over 300,000 kms and still runs very well for a time served engine.
Good luck with your investgations and hopefully the fix is straight forward.
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Post by djm16 on Oct 17, 2021 4:53:04 GMT
Thanks for all the messages of encouragement.
The block was bored by an experienced rebuilder who works out of premises within spitting distance of our local (if retired) Rover specialist. I would be very surprised if the final bore finish was anything other than correct as Pete is quite a perfectionist.
From the look of them, the top two rings are grey iron and the oil ring a four piece shiny (stainless / chrome) assembly.
That leaves the type of lubrication and / or initial running events as the culprit.
2 factors were not helpful initially: 1) the car was unlicensed so I could not just go out and roar up and down hills until it was run-in, I was restricted to direct to and from the inspection place (or place of repair) 2) difficulties with carburation and distributor meant that the engine was not always operating in its best range.
Anyway I will post the results of further thrashing on running-in oil and whether I have to take the head off again.
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Post by enigmas on Oct 17, 2021 8:49:08 GMT
David you don't need to drive the car any distance at all, you don't even need to move it, just start the engine and run it at 1800-2000 rpm for 20 mins straight up and the rings should seat. I still believe your problem stems from the cylinder wall and piston ring seal.
I thought you assembled the engine, if your specialist was responsible I'd be having a word with him.
The second ring isn't fitted upside down?
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Post by djm16 on Oct 18, 2021 5:01:57 GMT
Thanks Vince.
I am sure you are right about the rings / bore. I assembled the engine, so any mistakes with rings would be my fault. I would be very surprised and disappointed if I had put a compression ring in upside down as they are pretty clearly marked.
The state of play after using the cylinder cleaner (strong alkali disolved in an alcohol) and then driving 30 miles with a heavy R foot: 5 of 6 cylinders have virtually identical compressions of 157-160. One cylinder is down a little at 145 but not oily, two cylinders are still a little oily.
Apart from the one cylinder with lower compression (which might be an exhaust valve instead), this suggests that the compression rings are seated fine but the oil rings still are not completely bedded in.
I will probably just run it some more and check again in a few hundred miles. If still not right, then off with its head.
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Post by enigmas on Oct 18, 2021 22:18:56 GMT
From the compression pressures you've posted, they all appear close and uniform...so it's not a total failure as you've stated. If it were mine I would work the engine hard by loading it in taller gears up some hilly terrain if that's an option.
Just out of curiosity David (I'm not au fait with the product/procedure)...what is the cylinder cleaner formula you're using and how does it do its task?
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Post by djm16 on Oct 19, 2021 0:09:12 GMT
This is the stuff: www.carmodsaustralia.com.au/upper-engine-cleaner.html. I sprayed pretty much the whole can a few seconds at a time down each spark plug hole at TDC, then turned the engine 1/3 turn to do the next one. When I been around 3x, I put the plugs back one at a time turning over the engine twice by hand each time to make sure there was no hydrolock. After starting, and warming the engine, I ran it hard up and down hills in top gear for 30 mins. I was very surprised that Subaru did not and would not provide a MSD for this can. Given what I think is in this can, a squirt in the eye would result in blindness.
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Post by enigmas on Oct 19, 2021 4:13:37 GMT
That stuff is obviously nasty, especially as the product is released via an aerosol. Nothing like a bit of blindness to ruin your day. Do you think that the product would do anything in a fresh engine? Perhaps in a well used engine it would release internal carbon, varnish and gum...but a tired engine will often become a smoker when the grunge holding it together is released. I know that the latest direct injection (straight into the combustion chamber) petrol engines heavily grunge up the backs of the inlet valves as there's no longer a stream of fuel vapour cleaning and also cooling them. Apparently its become quite an issue for servicing. Perhaps if you're brave you could try the Bon Ami trick. Here's a snippet of they're blurb for the product... Bon Ami Since 1886, Bon Ami has been committed to offering a nontoxic household cleaner that works. Our exclusive formula uses mild mineral abrasives to gently clean and polish everyday surfaces without the use of harsh chemicals. An ideal all-purpose cleaner. Bon Ami excels at cleaning sinks, countertops, tiles, and more. This PDF article may be worth your while reading. It relates to bigger engines but some of the practical driving solutions seem quite viable. www.engineprofessional.com/articles/EPQ318_82-85.pdf
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Post by 3litrekiwi on Oct 19, 2021 4:51:40 GMT
Slightly off topic and marque.
I used a similar aerosol product in my Navara when I bought it. The engine had at that stage done 320 000 kms or so by 18 careful previous owners. These z24 engines are pretty tough but this one had among other things chewed it's cam chain guides up and deposited them in the sump along with the oil bypass valve for the oil filter ball which had hammered right through the seat due to the filter being totally blocked.
The cam chain had been deflected in the process for a long while and there is a groove in the front of the block that is about 2mm deep. The big end shells were embedded with a huge amount of schrapnel. Surprisingly the journals were still in pretty good shape. I assume the mains are had it too but I've not bothered to look. The plan was to replace the engine.
All cylinders were full of carbon and the plugs had virtually no electrode left. Two cylinders were down at around 100psi.
A lot of debris and smoke blew from the exhaust so the treatment seemed to work at dislodging at least some of it.
New cam chain etc, oil bypass valve and a set of big end shells and we are about to clock 400 000kms and compression is pretty even at 140psi across all four, nearly ten years later.
I'm not sure about glazing but this stuff does seem to remove carbon deposits.
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Post by djm16 on Oct 22, 2021 0:48:01 GMT
1) re Bon Ami. I already had a can of this stuff from years ago when I contemplated doing this to another engine. I decided against. Somehow the idea of sticking abrasive powder into a newly rebuilt engine went against the grain, even if they do do this to 6 litre diesel dozer engines.
2) I am getting more convinced that there is at least "some" valve guide oil leakage. I am now wishing I had gone ahead with having the valve guides machined for top hat seals. The reason I didn't is that there was little / no smoke on overrun with the 50 year old O rings before the rebuild. Obviously I replaced them and was ultra careful not to damage them during insertion. However, I can tell driving at night with a car headlights behind me that after idling a few seconds at traffic lights, there is exhaust smoke for a few seconds on take off. I still can't see any smoke on a long downhill coast, but then the rear view mirror is perhaps to tiny for this to be visible.
Note, the replacement O-rings came in the standard engine rebuild package from the usual purveyors. I can recommend not using them now!
3) re Subaru head cleaner. I tried it out first on the plugs. I sprayed some into a glass jar and placed all 6 plugs point down in it. I was not convinced that much carbon came off, however anything remotely oily looking did come off. Sure the cleaner was black after a few minutes, but so were the ends of the plugs that were black before.
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Post by djm16 on Nov 30, 2021 11:36:48 GMT
An update.
I pulled the head off again.
My memory is not what it was! Several years before the engine rebuild, I had some work done on the head that included skimming, and also K-lining the inlet valve guides. I now remember that the specialist who did the K-liners used a set of O-rings that he had in stock for the hundreds of other old heads that he works on. So my memory of no exhaust smoke relates to whatever O-rings he used. My previous advice re the contents of the engine rebuild gasket set stands: under no circumstances use the O-rings that come with the set!
When I removed the inlet valve springs, the valves pretty much fell out of their own accord: there was no springiness left in them after only about 2 thousand miles.
The bores looked OK, the rings seemed intact, and the two pistons I removed had clean skirts with no scuffing.
An interesting observation though, the bore was clearly more polished on the side nearest the exhaust valves. I took photos, but it is really hard to see without moving your head around.
The inlet guides have now been machined to take top-hat seals, and the head is back on and waiting for a test run.
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Post by Phil Nottingham on Nov 30, 2021 12:29:09 GMT
The O rings are a very poor idea - they quickly harden and wear and may even make matters worse and pump oil assisted by vacuum into the cylinders
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Post by 3litrekiwi on Feb 6, 2022 19:48:33 GMT
Hi David Any news on how your engine is performing?
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Post by djm16 on Feb 24, 2022 4:53:26 GMT
It has taken a long time to get to the point where I can give an update.
If you recall, the problem was excessive oil consumption immediately after an engine rebuild, and getting worse. Eventually it became apparent that most of the exhaust oil smoke was being generated on the overrun and at idle.
When I had driven far enough (5,000 miles) to be convinced that the rings were as bedded in as they were ever going to get, I pulled the head off and took out number 6 piston (the oiliest) to inspect the rings. The bores and the rings on number 6 looked fine.
The next place to look was the head. When I took off the inlet valve springs, the valves all pretty much fell out. That was when I remembered that 6 year ago, when I had the guides K-lined, the engineer (A) gave me a set of modern O-rings to fit rather than the crap that comes with a typical engine gasket set. Of course I had forgotten all this when I came to rebuild the whole engine, and I had carefully fitted the O-rings supplied with the kit. They were probably fine for a hundred or two miles before smoking on the overrun again.
I took the head to the engineer B who did the rebore on the block, and he machined the tops of the valve guides for a set of top hat seals. I should probably have gone back to engineer A that did the K-lining, but that is 20:20 hindsight.
"Problem solved", I confidently assumed.
Of course it wasn't. The was still blue smoke after going downhill. It was at least 95% better, but that is still not good enough. Over the next 5,000 miles, I suffered increasing quantities of blue smoke on the overrun and idle, and on inspecting the plugs (dozens of times at frequent intervals), it was apparent that number 6 was burning all the oil: eventually the plug was dripping with oil, including the central electrode.
I really did not want to pull the head off again - time, money, no spare head gaskets, so I made a valve spring compressor to lever on the top of the valve spring, using a rocker cover stud as a pivot. You have to have the relevant piston at TDC to stop the valve dropping into bore.
What I found then was first the the top hat seal was sitting slightly off the base of the machined section, and second, that there is virtually no clearance between the top of the seal and the underside of the valve spring cup. My theory was that at every stroke, the valve spring cup was bashing the top of the seal and causing it to leak.
After consulting with engineer A, I fitted a spare top hat seal that he had lying around. It was very slightly shorter than the one that came out.
Again, a dramatic reduction in the quantity of blue smoke, but only 95%. Still smoking on downhill and at idle.
WTF?
A look at the plugs again, this time 1 to 5 are all dry, and there is just a trace of oil around the base of number 6.
Something else I had noticed when setting the inlet valve tappet clearance was that the head fills up very rapidly with oil, to fast for it to drain down the pushrod holes back into the block before spilling over the head and down the back of the engine onto the floor.
So my current working theory is that the head is filling up with oil that is coming over the tops of the top hat seals. It is also possible that oil is creeping up between the metal casing of the top hat seal and the valve guide. My solution is to look at the rocker shaft to see why there is excessive oil flow.
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Post by djm16 on Feb 24, 2022 4:57:07 GMT
Here we see the load bearing area of the inlet rocker shaft. Conspicuously missing is a lubrication hole. Now we see the lubrication hole, and it looks like little / no lubrication is getting to the rocker.
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Post by djm16 on Feb 24, 2022 5:00:55 GMT
The first step was to re-drill the lubrication hole and the locating hole. I have done this before on my P3, and found the steel too hard to drill with HSS bits. This rocker shaft however was barely tougher than mild steel. New oil supply hole: New locating hole: Plugging the old oil supply hole
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Post by Phil Nottingham on Feb 24, 2022 6:29:22 GMT
Pleased to see you are getting there! The O ring valve seals are poor but not that bad normally. There was the head oil pooling problem though which is why on Mk2c engines the head was modified to allow a drain at the rear.
Have you fitted the correct head gasket with the oil drain hole?
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Post by djm16 on Feb 24, 2022 8:48:48 GMT
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Post by djm16 on Feb 24, 2022 8:50:22 GMT
Hi Phil, thanks for your reply. Mine is a MkIIb. I am not aware of any other drains except the pushrod openings. Where would one be if it existed?
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Post by Phil Nottingham on Feb 24, 2022 12:24:07 GMT
Hi Phil, thanks for your reply. Mine is a MkIIb. I am not aware of any other drains except the pushrod openings. Where would one be if it existed? It is at the rear end. It came at the same time the big crank did in March 1964. What is the engine number?
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