Bedding in Bottom End Rebuild

[Nick666Akers]

Right then guys,

Some of you are aware I'm currently bedding in my engine after a bottom end rebuild. I've seen many posts on how people have bedded in top end rebuilds such as piston rings etc but I haven't seemed to find anything to do with bedding in the bottom end.

I'm currently running a new crankshaft on this rebuild, 2 new Conrod's & millers running in oil and an OE Filter.

I've being advised to do 1000 miles not spinning any more than 3000rpm.

But I have a theory that the engine needs to used throughout the rev range? Am I correct? I'm terrified that going 100rpm over and boosting is going to cause some serious damage.

Can someone shine some light onto how they have bedded in bottom end rebuilds? Cheers!

[5e colin]

3000 for the 1st 1000km

then start increasing revs slowly

but i hope you revved your engine hard when just build ????? to settle the rings if not bores can be glazed back up !!!!!

[patman]

If this was me I would run it in like a fresh rebuild (just coming to the end of my running in process), others may know more on here about it just being a bottom end but I tell you one thing that someone mentioned and I believe it's right you can't run it a car at 3k revs to 1000miles then red line it you have to build up your revs every so many miles

[patman]

As Colin said but in km

[Nick666Akers]

3000 for the 1st 1000km

then start increasing revs slowly

but i hope you revved your engine hard when just build ????? to settle the rings if not bores can be glazed back up !!!!!

Would you do it for 1000km not miles mate? And I did, I drove it hard through 3,4 gears. What sort of rev range and boost levels would you suggest next after the first 1000km, I need a rough idea on what to do next as I've already covered 400km in the last 5 days....

[patman]

first 500km stick under 3000rpm

500>600 to 3500 sometimes

600>700 to 4000 sometimes

700>800 to 4500 sometimes

800>900 to 5000 sometimes

Up to 1500km don't go over 5000km

Colin is good at this sort of stuff others will tell you other things it really is everyone's own opinion

[5e colin]

Would you do it for 1000km not miles mate? And I did, I drove it hard through 3,4 gears. What sort of rev range and boost levels would you suggest next after the first 1000km, I need a rough idea on what to do next as I've already covered 400km in the last 5 days....

should not do that while driving to much stress on the new parts kid !!! supposed to do it when fresh build on first start wait til hot then rufly 10 hard blips to 5k or so to settle rings

yes 3000rpm for 1st 1000km then slowly start building rpm to 5000rpm to 2000km the next 500km unleash the limiter sometimes if wanted but dont hit the actual limiter

thats the old style of settling engines works very wel indeed :)

[Sefton-EP91]

I finished my running in not so long ago and I just drove normal. Didn't change my driving style or anything. Normal boost conditions etc and the engine is fine! Used millers running in oil. Regular oil changes and she will be fine!

[AdamB]

You don't need to bed in anything other than rings.

If installing new rods/mains bearings just run your normal full synthetic oil and change at 1000 miles to ensure there is no swarf that may have come off the bearing as it gets seated around the journal. There is no need to pay particular attention to loading the engine, just drive it normally.

For bedding in rings follow my post #4 here

http://www.ukstarletowners.com/topic/69965-running-in-fresh-4efte/?hl=mineral#entry991069

[Nick666Akers]

Thank you to all of you!

You all have a slightly different opinion, but everyone seems to be saying around the 1000km mark, I hit 400km today on the way to work! Not long now boys, Japfest is in sight too!

[mikey4410]

just drive it as u normally would.lol.

[mikey4410]

theres always an argument for driving it normally or to pussy foot about.

when I forged my starlet back in 2009 i drove it like I normally did before and it ran fine and perfectly for over 15k miles until my mate bought it and ran it low on oil and it expoloded.

[5e colin]

You don't need to bed in anything other than rings.

If installing new rods/mains bearings just run your normal full synthetic oil and change at 1000 miles to ensure there is no swarf that may have come off the bearing as it gets seated around the journal. There is no need to pay particular attention to loading the engine, just drive it normally.

For bedding in rings follow my post #4 here

http://www.ukstarletowners.com/topic/69965-running-in-fresh-4efte/?hl=mineral#entry991069

your right but the hard fast way is for modern engines ONLY !!!!!!

so guys on our old engines nice and slow ha ha

[AdamB]

your right but the hard fast way is for modern engines ONLY !!!!!!

so guys on our old engines nice and slow ha ha

Makes no difference how old the motor is.

Piston rings have used the same theory for years, piston rings themselves don't seal against the bore because they have very little spring tension. I'm sure you're aware of this as its far from an elastic band, stretch it too far and it snaps.

It's the gas that gets behind the ring that seals it. If you don't load the engine very little gas gets behind the ring to force it out against the wall and the rest of it goes flying past the ring into the crankcase.

Besides, no one says you have to stick to the manufacturers honing tolerences and bearing tolerences etc. Over the last 26 years since the first 4E was released machining tolerences, oils etc have come along way.

Everyone has their own way of "running in" an engine, and more often than not it's dictated by the person who built it. Don't listen to them and you can void any warranty given, as well as if anything goes wrong you got no leg to stand on.

[5e colin]

did you read the link you posted ??? it clearly states it there its got to do with the honing of the blocks its way finer honed on the new engines so have to be bed in fast and hardto settle rings

our blocks are course honed so low and slow ha ha

think im getting something going ere ha ha

[Rob H@RCH Engineering]

But this is about bearings only not the bores isn't it? In that case there is no running in required!

[5e colin]

so you think conrod and mains dont need running in ????

[AdamB]

The bearings don't require running in, they "should" run on a film of oil, there's very little friction there, and what friction there is comes from the viscosity of the oil being sheared.

Edited April 22, 2015 by AdamB

[5e colin]

i personally doubt that

so next time a bottom end goes just fit new crank and bearings and rev the shit out of it ???? it would seize for sure the bearings will fail

[Rob H@RCH Engineering]

There a non friction part, hence building to a oil clearance, rings on the other hand are a friction part that makes direct contact with the bores so needs bedding in. The bearings float on oil thats why you loose oil pressure when they fail/ wear out because the clearance is to big so the oil escapes. There really is no need to bed in the bearings.

[Rob H@RCH Engineering]

The only reason a new built bottom end would fail is if the bearings are too tight or too loose.

[5e colin]

hmmmmmm must try that on a old 4efe engine see how that goes just replace bearings and test it

to me the oil isnt always there because if it was bearings would not wear down ??? and they do over time for sure friction wear

im always more woried to damage a bearing then my rings when bedding in a engine ha ha

[Rob H@RCH Engineering]

When do they wear down? I build engines at work on with one at the mo out of a 7 ltr bus its got 750,000km on the clocks the rings have worn through the liners before the bearings have worn out lol ive have 2 cars with over 250,000 miles on the clocks thats never had bearing problems. The bigest problem with bearings in our cars is the emence battering they get and bad tuning is also a cause of bearing failure. You fined a car that has WORN out the bearings from normal road use. 9 times out of 10 there will be a reason!

[5e colin]

i have only rebuild around 35 of them over the years and on a good few i deffo see the friction wear marks on them as discoloration

so was curious and checked them with my digital gauge and it was fractionally thinner where the discoloration is compared to the edge where the 2 bearings cup half meet so me thinking wear down ?

thats great that tha is your job next time i have a tehnical Q i can pm u :) i only learned it by doing it at home

Edited April 23, 2015 by 5e colin

[AdamB]

Bearings will wear when there is no oil there. This can happen for a number of reasons, incorrect clearances, lack of oil pressure or simply too much pressure put on them.

Think when your running a relatively high performance engine, that piston and rod weight as well as the force exerted above it is squashing the rod into the bearing, and the crank into the mains. Very little oil clearance and it will wear through the bearing to the backplate in no time at all when pushing some hefty boost or rev's.