Can someone please explain engine break in period?

[Skyboy8950]

I'm sorry too. Ok, compression check I can do. I don't mind taking it apart to get the cylinders honed. I'm an old hack at taking this thing apart. What I am concerned about is reusing the head gasket. An OEM gasket (which is the only kind that I have read on here that I should use) is $75. I can't imagine mine being used for 50 miles cannot be reused. Hell, I'm taking it off and putting it right back on. That makes sense to me, but obviously, what do I know. As for the valve stem seals, can someone please give me a part number? I doubt anyone has them in stock. I'm still dubious about them being bad as before the rebuild, that didn't happen and I didn't touch the valves.

[tkent02]

If you ran the bike 50 miles without ever letting it get warmed up the gasket might be OK.
The valve stem seals have been hard as a rock on every thirty year old engine I have taken apart. Whether or not they smoke. Some do, some don't.
And,
If it runs well enough for your purposes, leave it alone.

[Nessism]

What he says is that the sharp peaks in the cross hatches wear away that quickly.
They are the part that actually does the cutting.
Once they are smoothed over not much else happens.

Maybe I'm not explaining myself properly...yes, the rough edges on the cross-hatch wear the rings like a file and when the file is dull, the rings should be fully bed in. What I don't understand is that even if you drag a file lightly over the metal surface it will cut...lightly. The file won't dull down as quickly and the rings won't wear in as fast but eventually you will get to the same level. The hone marks won't disappear on their own, they need to be worn away by the rings, and I don't see how the speed of the bedding process will will lead to a better seal.

[tkent02]

Maybe files are made of harder steel than the cylinder walls.
I know the rings are.

If the guy who has built hundreds of winning engines says it is so, and if he's not making money off of me by lying, it is probably so.

I have only built a handful engines, and most of mine were more half assed repairs than true rebuilds.

But running them hard has always sealed the rings quickly and sealed them well, even on engines that were so far out of clearances they should not have run at all.

One Ford truck engine had pistons with about 1/8 inch between the pistons and cylinders, even it ended up with good compression.

(disclaimer, I do not know how long this particular engine lasted) :-)

[OldVet66]

This may be totally bogus, but I have heard some old mechanics talk about running a good puff of Babbo through the carbs at high RPM's to seat the rings quickly. In this day and age I guess it would be Comet or Zud.

[Turtleface]

I'm sorry too. Ok, compression check I can do. I don't mind taking it apart to get the cylinders honed. I'm an old hack at taking this thing apart. What I am concerned about is reusing the head gasket. An OEM gasket (which is the only kind that I have read on here that I should use) is $75. I can't imagine mine being used for 50 miles cannot be reused. Hell, I'm taking it off and putting it right back on. That makes sense to me, but obviously, what do I know. As for the valve stem seals, can someone please give me a part number? I doubt anyone has them in stock. I'm still dubious about them being bad as before the rebuild, that didn't happen and I didn't touch the valves.

As far as the head gasket, here's the skinny. The gasket is designed to be torqued once, and that's it. Once the layers of steel and rubber are compressed, they'll never fully decompress. There stands a fair chance of you getting away with reusing the old gasket, at least initially, but in all likelihood, it'll end up leaking in the long run. I'd second the "run it until it smokes too bad" opinion, and make sure you do your due diligence when it comes time to rebuild/replace.

[chef1366]

I'd ride it this season and tear it apart during the winter.
Chalk it up as one of lifes lessons.

[TheCafeKid]

I'd ride it this season and tear it apart during the winter.
Chalk it up as one of lifes lessons.

+1... Ride it. Worst case scenario, it smokes a bit, and if it gets bad enough to make it worth tearing it down again, it will tell you by fouling a plug or two. Just make sure you carry some spare plugs around with you if it starts smoking bad...

[chef1366]

I wouldn't reuse a head gasket.

[chef1366]

This may be totally bogus, but I have heard some old mechanics talk about running a good puff of Babbo through the carbs at high RPM's to seat the rings quickly. In this day and age I guess it would be Comet or Zud.

Egads!!!

[Turtleface]

Egads indeed. Comet is a terrible idea, load up a cylinder with a bunch of abrasive grit? Seems rather counter-intuitive.

[49er]

Egads indeed. Comet is a terrible idea, load up a cylinder with a bunch of abrasive grit? Seems rather counter-intuitive.

They used to do that here too on re-ringed engines, without a hone. The stuff used was a powdered kitchen cleaner called "Jiff". I'm told it did work, but the stuff would be quite abrasive on the carb internals, valve stems and seats, as well. I doubt that the roller bearings would appreciate the abrasion either

Easy to do on an auto after the air cleaner has been removed.

I wouldn't subject my engines to this treatment.

[paco13]

another vote to just run it as is unless it burns enogh oil to create other probs. fix it next winter.

[Footy.]

From the "Engine Reconditioner"

Footy.



THE DEFINITIVE GUIDE TO RUNNING-IN


Nowhere in our industry is there such a hotch potch of bunk, bull and old wives’ tales as in the running-in department. “Don’t exceed 50 mph for the first 1,000 miles” – in a Jaguar XJ6 4.2! “Let it tick over for a couple of hours to loosen off”. “Having spent a lot of money on having the engine reconditioned, it makes sense to put a high quality service oil in it” – and so on. One day, I might just write a small book, listing as many of these sayings as I can remember, calling it “HOW TO WRECK YOUR ENGINE” and awarding each saying points out of a hundred for stupidity.

Let’s try and blow away the myths and cobwebs and come up with some sensible methods for running in both petrol and diesel engines. First though, let’s look at and define what we are trying to achieve in running in.

Any engine which has undergone a major rebuild needs to be run in for best results. The running in process is the means by which new components are bedded together for long term performance. The principal areas of consideration are cylinder bores/ piston rings, crankshaft journals/bearings and camshaft/followers.

Good as any machining operation is, the old engineering saying that nothing is perfectly round, flat or square is very true. Because of this, components which are brought together for the first time and then move against each other will have asperities (peaks and troughs) which are removed in the initial running.

New piston rings do not seal – first they have to create a compatible bedding surface with the cylinder bore. Then, and not before, they will seal.

If I have said it once, I have said it ten thousand times – if a piston ring does not bed in, it will not work.

Piston rings are not seals – they make seals in conjunction with the cylinder bores. It’s like flour and bread – first use the flour to make the bread and then put your butter and jam on it. You do not put the butter and jam onto the flour.

The running-in process includes, therefore, the making of the seal which will ultimately contain the power of the expanding gas and also the lubricating oil – arguably the most important facet of the newly reconditioned engine.

ENGINE RUNNING-IN SCHEDULE

Note: Do not run the engine at low or high idle speeds for long periods after installing new rings or liners, since the rings will not bed in during idle operation.

Start
Prior to starting, make sure that:

1 All bearings are pre-lubricated
2 The crank case is filled with specified engine oil
3 The cooling system is filled to the correct level
Running in
1 Start and run the engine at ¾ rated engine speed with no load until operating temperature (80 85ºC) is reached – covering the radiator if necessary. DO NOT run for over 10 minutes.
2
At this point it may be helpful to deal with the question of lubricating oils. Under no circumstances should normal service oils be used during the running-in process. The high level of protection offered by these oils would prevent the correct bedding-in procedure to take place, ie the wearing down of asperities and the consequent establishing of a correct bore to piston relationship. Secondly, bore glazing could easily occur. This is the deposition of combustion by-products on the cylinder bores. The honing pattern can still be seen beneath these by-products but, since the piston rings would not be touching the actual bore – they would be running over the glaze – this would prevent the creation of a compatible bedding surface and, as previously stated, if a piston ring does not bed in, it will not work.
Service oils offered by the various lubricant manufacturers are now so good that the use of an initial fill or running-in oil can be classed as obligatory and it is a clever man who profits while at the same time making sure that he gets no “come-backs” and so it is recommended that all engine reconditioners stock and sell initial fill or running-in oils. If a newly reconditioned engine needs them, the engine reconditioner may as well sell them and make the profit on the sale, whilst at the same time preventing “come-backs” under warranty.
The best type of running-in oil is one that provides mechanical protection yet, at the same time, permits bedding-in to take place. Wide span multigrades use a base oil in line with the cold temperature viscosity that is then thickened with polymers. Ideal running-in oils are monogrades with only moderate levels of performance additives.
Monograde oils have the disadvantage of relatively poor cold flow properties which hinder cranking speed and lubrication of remote engine components. With the advent of hydraulic valve lifters, heavy monogrades would be unsuitable. An ideal initial fill oil is one with a viscosity equating to SAE 20W/30 by using high viscosity index (HVI) base oils. This provides high film strength for maximum component protection, yet with reasonable flow properties to overcome other problems, plus additives which provide protection but do not inhibit the bedding-in process.
For those customers who complain they didn’t have to go through this procedure when the car was new, it can be explained that new engines are usually run in by the manufacturer during a carefully controlled bench procedure whilst reconditioned engines in the field are run in during the first 500 1,000 miles of road work. Further, it is essential that the driver of the vehicle being run in is aware that he also has a part to play. The main criteria are:-
1 Do not over-rev the engine
2 Do not be too gentle – moderation is the key issue
3 The running-in oil must be drained after no more than 1,000 miles and the engine re-filled with the correct grade of service oil.
Anyone wanting further information or guidance on the subject of lubricants is invited to telephone Millers Oils in Brighouse, West Yorkshire, and speak to their Technical Adviser, Mr Mike Fenton, on 01484 713201.
Apart from operating this superb back-up service, Millers also offer “Glazebuster Oils”. Should any reconditioner get into trouble with arrested ring bedding due to cylinder bore glazing, the use of glazebuster oil is infinitely preferable and far cheaper than stripping the engine and physically de-glazing the cylinder bores but for precise directions on how to use the oils, please telephone Graham Lord at Millers on the number given.
With diesels, the main points are the use of a specially formulated running-in oil and making the engine work almost from square one. The problems will occur when the engine is put onto low load stop/start operation or – perish the thought – where the driver sits with the engine ticking over so that he can keep warm!
Petrol engines are not just as critical but, again, it is strongly recommended that an initial fill, running-in oil is used in preference to normal service oil during the running-in period, which should be between 500 and 1,000 miles. The message is do not be too gentle. Whilst the engine should not be raced from one end of a motorway to the other, it should be given a reasonable amount of work to do and my advice is to forget that the engine has been reconditioned and drive it as normal. No one has yet come back to me having seized an engine but hundreds of drivers have complained of oil consumption through incorrect running-in procedures, so the moral is clear. It’s not a question of high speed, rather it is a question of making the engine work and it is in this area that most of the problems come to light.
There is in fact a select little group of engines that includes Jaguar XJ6 4.2, Rover 3.5 V8, MGB 1800 and several more high performance engines which can exceed the national speed limits in second gear and never, never work hard enough to “get a sweat on” – and therein lies the problem. Unless the engine works reasonably hard there is the ever present danger of bore glazing and, once the bores are glazed, the piston rings can never bed in. Fortunately, because we are looking at load and not speed, it is possible fit a caravan on the back of the car or, in the absence of a tow ball, to fill the car with passengers – preferably fat ones – and take it on a fairly long trip. As a last resort, the car can be ballasted with, for example, bags of sand, which should ensure that the engine is given some work to do during the running-in period.
I remember saying this to a caller from Boston, Massachusetts, whose MGB was allegedly using more oil than fuel and, to make matters worse, this was his third engine where oil consumption had been a problem. He thought it was a “leg pull” when he was told to load the car up with bags of sand and then go out there and get the rings to bed in but, when he ‘phoned back three weeks later, he said, “This is the best MG I have ever broken in but I really did think you were joking.” It was nice of him to pay for a transatlantic call to express his thanks and I do hope that the garden centre took the “ballast” back for credit but I suppose he could always hire out the ballast kit to other owners!
In summary, therefore, always use a specially formulated running-in oil and never a normal service oil when the engine is put back to work. Following this, give the engine some work to do and do not let it tick over for any period or use it on stop/start light duty operation. Once an engine has been run in properly, you can use it for whatever purpose you want but until then strict formalities have to be observed if you are to avoid all the pitfalls.

11 April 2000

[Turtleface]

This is turning into a very informative thread. I was a car geek in high school (pretty decent automechanics program), and between me and my friends, we rebuilt about thirty or so engines, mostly small block Chevys and Fords, as well as the odd motorcycle, boat, or ATV. Even a lawnmower or two. Being high school kids, we were pretty liberal with the throttle. Not full on racing or anything, but probably about 3/4 of the rpm range was used in initial break-in. Most of us had manual transmissions, kept the vehicle in lower gears, and drove in a "spirited" fashion. Any problems with compression or oil consumption were always traced back to an improperly installed part, or a service that was performed incorrectly, such as a bad valve job or rings installed improperly.