'84 FJ restoration about to be started - looking for break-in procedure

[tboy]

FJ Oakville Ontario - had the engine rebuilt with new rings and the head cleaned up.  The builder gave me the run-in procedure, then I promptly forgot it.  Any suggestions on breaking in the new rings up to standard running? 

Thanks very much

Tim

[fj1289]

There are lots of thoughts and opinions on this..

I believe in a "harder" break-in to a point.  I think it is bad to "baby" one too much during break-in.  The theory being the rings need to be "loaded" to properly make a seal. 

I'd suggest a good warm up and easy ride around the block and check everything is functioning properly and no leaks.  Then restart and get the oil up to temp.  Then accelerate thru the gears at 1/2 to 3/4 throttle up to maybe 5,000 RPM and let it coast down.  Then repeat to maybe 6,000 RPM thru the gears and coast down.  Cruise for a bit, but constantly vary your load and speed.  Maybe one more romp thru the gears to 6,000 PRPM and take it home and let it cool down.  Change the oil.  And repeat.  Taking it a bit higher in the rev range and making sure to coast down and cruise easy between pulls to allow the engine to cool a bit and "normalize" the temperature.  A couple more heat cycles like this, another oil change and call it good.  Thorough warmups are important to the FJ.  A lot of your clamping force for the head gasket comes from the expansion of the cylinder block when warmed up vice high torque numbers on the cylinder head nuts. 

Bottom line, ride in a sensible manner and constantly vary the load and speed somewhere between "babying" and "abusing"...

[ribbert]

FJ Oakville Ontario - had the engine rebuilt with new rings and the head cleaned up.  The builder gave me the run-in procedure, then I promptly forgot it.  Any suggestions on breaking in the new rings up to standard running? 

Thanks very much

Tim

Don't baby it, don't thrash it, don't run it in with Synth oil, minimise cold starts.

I start a fresh motor on the old oil I drained out of it, or something else, run it for 5 mins then drain it off and refill with new oil.

Then, go for an all day ride (500km) ride, accelerating and decelerating, varying load and speeds, gradually increasing both.

Change oil and filter again at 1000km.

As 1289 said, there are endless opinions on the subject and you can make it as complicated as you like but unless you do something stupid, you can't really stuff it up.

IMO

Noel

[CutterBill]

You seat the rings by forcing them out against the cylinder walls.  This is done by the high-pressure combustion gases getting behind the rings and forcing them out. This won't happen at small throttle openings...

From a stop, accelerate at wide open throttle thru the gears, but short-shift at about 5 or 6000 RPM.  Important... Wide Open Throttle but not Redline.  Got that?  Once you are going as fast as you dare, slow down to the legal limit and cruise for just a minute... cooling the engine.  Then do the whole thing again.  Do this 3 or 4 times and you should be good to go.

Ideally, you would run very hard up a very long uphill road... allowing you to use WOT but only 5-6K RPM.  Hard to find such a road, I know.  But that's the idea. And even then, I would be leery of such an extended WOT run without a temp gauge, so that I didn't overheat the engine.  Lots of friction from the rings in those first few miles.

But absolutely do not baby the engine, else the rings will never seat and you will have an oil-burner.

Just my opinion: first oil change isn't needed until about 400-500 miles. The filter will catch any loose particles, and the oil isn't going to break down from heat.  That comes from the very old days of engines with no filters and very poor cooling systems that couldn't handle the extra heat generated by the friction of new rings.

Fun fact: It has been proven in a lab by installing thermocouple around the cylinders of (air-cooled) airplane engines that the rings do indeed rotate. Slowly. About 1 rpm. So don't get real crazy about the "perfect" ring gap spacing when you put the engine together.

Interesting data point:  one of the more oft-repeated Old Wives' Tales is that you should never break-in an engine on synthetic oil.  When I rebuilt my first FJ motor about 25 years ago, I didn't know this. (no internet back then.) So I filled the new engine with synthetic and rode off into the sunset. Probably put 10,000 miles on that engine and it ran great. Never burned any oil. What does that prove? Nothing. It's just one sample. But interesting, nonetheless. 
Bill

[ribbert]

Interesting data point:  one of the more oft-repeated Old Wives' Tales is that you should never break-in an engine on synthetic oil.  When I rebuilt my first FJ motor about 25 years ago, I didn't know this. (no internet back then.) So I filled the new engine with synthetic and rode off into the sunset. Probably put 10,000 miles on that engine and it ran great. Never burned any oil. What does that prove? Nothing. It's just one sample. But interesting, nonetheless. 
Bill

It proves my point.....

...... unless you do something stupid, you can't really stuff it up.

IMO

Noel

I agree with you about loading up the engine without excessive revs.

As for the fuel tank drain bung, the absence of them appears to be exclusively an American thing, I was unaware of that and don't know why. My 3 yo Lexus has one and I recently drained an X5 tank with one.

Noel

[tboy]

Thanks to all the responses for my break-in question.   About to start the process - lots of great suggestions.

tboy

[aviationfred]

I would recommend the use of 'Break in oil'.

I used this oil in my Big Bore build last year.

http://www.royalpurpleconsumer.com/products/royal-purple-break-in-oil/


Fred