Running-in

[DamirGTI 327]

Hello !

 

I've ben read a fiev articles of how to run-in a overhauled engine and found a lot different informations abaut that subjet ...

Ones are tellin that engine must be used harder for the first fiev miles with a lots of hard accelerations and deaccelerations , others are sayin that it must be run-in a bit gentle avoiding high speeds and high rmp for the first fiev miles ...

I will soon finish overhaul of my 1.9 8v engine with new set of piston rings , big end bearings , main bearings , reconditioned head , different pistons and liners .. and just wandering what is the best option to do running-in ?

Also what brand and viscosity type oil is best for first fiev miles running-in overhauled engine ?

 

thanks

[veloce200 3]

only an opinion but this is what I would do:

 

Mineral oil - a cheap 10/40 ideal

get it running then get driving asap

revs - keep below 4500 rpm BUT make sure you floor it for short bursts to seal the rings against the bores. then lift off. I'd say 3rd gear would be ideal 2500 rpm up to 4500 rpm full throttle then keep it in gear and lift.

[M_R_205 5 1 Cars]

only an opinion but this is what I would do:

 

Mineral oil - a cheap 10/40 ideal

get it running then get driving asap

revs - keep below 4500 rpm BUT make sure you floor it for short bursts to seal the rings against the bores. then lift off. I'd say 3rd gear would be ideal 2500 rpm up to 4500 rpm full throttle then keep it in gear and lift.

 

iv bin told by my engine builders to drive it very gently for 1500 - 2000 miles keeping it under 3000 revs? i did this with the last engine they built and all seemd good after about 1000 miles it reved alot happier and so on but took aaaaaaages!

[madvalver 0]

When i,ve run diesel engines in on a dyno, there fully loaded within 1.5-2hours of running normally. And the engine manufacture i work with only allow 30 before a 1.5 hour full load run for there production engines(something to do with the peak honed liners they use)

 

My opinion on petrols on the road

 

Mineral Oil

 

And just like Veloce200 said, Make sure you keep opening and snaping shut the throttle at low engine speed in a high gear, to create vacuum in the cylinders opening the rings out against the bores, for the first hundred miles, then slowly up the revs till 800 or so miles and and the jobs done. Vary engine speed and load during run in. Best to do the first hundred miles (or more if possible) in one go, as it will give everything its best chance of bedding in while the engines at a steady working temperture.

[zeolite 0]

I have often wonderd about this. Those mileages are OK for road cars but what about low mileage race engines? My race car does maybe 30 mile a year. How the hell am I ever going to run it in?

[Edd-XS 0]

And a quick question, why mineral oil? Ive just filled mine up with 10/40 castrol magnatec stuff for first 500 miles then was gonna do a filter and oil change then?

bad idea?

Edd

[Beastie 1]

Everyone down the pub has an opinion on this one As you have already discovered it's not easy to sift the wheat from the chaff and come up with a reliable answer unless you are a professional with years of experience building long lasting reliable engines. So my suggestion is that you only take advice seriously if it comes from a professional with a significant number of years of unbroken experience. Even then you are going to get differences of opinion so the person whose advice is most important is the person who built your engine (or if you did it yourself ask the person who did the machining for you).

[madvalver 0]

I build big diesel engine for a living, different beast to a racing engine but heres how i understand things.

 

A race engine would be built with all the clearances towards the top of the acceptable limits. And idealy be run in and set up on an engine dyno or rolling road. This would reduce the time taken to run the engine in because the load and speed factors can be accuratly controlled and the engine closely monitered, including crankcase pressure(amount of piston blow by). So maybe just a few hours of running. Or do what i did with my last 1.9 and hammer it out of the box, didnt have any trouble, built it with plenty of piston to bore clearance, but new it would only be in the car for a couple of thousend miles at the most.

 

A very important part of the running in process is bedding in of piston rings in to the liner walls to help create a gas tight seal, removing tiny peaks in the liner walls left from the honing process. As well as bedding in other components like cams, oil pumps, bushes and bearings etc, but modern production and machining process mean this is not so important and is why the 1000mile(50hrs) run in and service routine has be dropped by alot of engine manufactures.

 

Cheaper Mineral oil does less to slow down the wearing process that the above rely on.

Better oil prolongs the process, and you could glaze(bad) the bores if it doesnt properly run in.

[Edd-XS 0]

Oh ok so the less efficiant oil helps with the bedding in, that makes sense!

I get oil at trade price anyway so another £15 or so for a better running in is worth it. Cheers chaps, sorry for the slight hijack!

Edd

[zeolite 0]

Or do what i did with my last 1.9 and hammer it out of the box, didnt have any trouble, built it with plenty of piston to bore clearance, but new it would only be in the car for a couple of thousend miles at the most.

 

By plenty you mean how much? are you saying that the lateral movement of the piston in the bore increases the wear on the rings and hence creates the seal quicker?. Is this a form of piston slap?

 

This sounds like the way for me as my engine would only have a couple of hundred miles between rebuilds anyway.

[Dream Weaver 2]

From what I understand, the harder you accelerate the more the piston/ring combo is pushed up against the liner latterally - for a newly honed liner this helps the rings to bed in and seal properly and gets everything running as it should be.

 

I just went straight to full bore on mine, though it had been run after the build by Wayne, who built it.

[Higgy 0]

From what I understand, the harder you accelerate the more the piston/ring combo is pushed up against the liner latterally - for a newly honed liner this helps the rings to bed in and seal properly and gets everything running as it should be.

 

I just went straight to full bore on mine, though it had been run after the build by Wayne, who built it.

 

 

All this agrees with what happened to my mate, who rebuilt a Nissan 200SX engine, and took it too easy after rebuilding and had problems with oil passing by the rings.

 

Second time round he gave it some right foot like previously suggested and the rings seemed to bed-in fine.

[madvalver 0]

By plenty you mean how much? are you saying that the lateral movement of the piston in the bore increases the wear on the rings and hence creates the seal quicker?. Is this a form of piston slap?

 

This sounds like the way for me as my engine would only have a couple of hundred miles between rebuilds anyway.

 

Not so much to do with running in as building a high performance engine.

 

I went for 3thou clearance which is enough to allow for extra expansion and lubrication in an engine used for high performance use. Im sure the piston used in the XU are of the hypereutecic cast type and thus have less expansion when hot which means bore clearance can be run a little tighter than normal cast which you could proberley run up to 4thou clearance for a race engine.

 

But im no expert and someone who builds race engines for a living will be able to tell you more.

[madvalver 0]

From what I understand, the harder you accelerate the more the piston/ring combo is pushed up against the liner latterally - for a newly honed liner this helps the rings to bed in and seal properly and gets everything running as it should be.

 

I just went straight to full bore on mine, though it had been run after the build by Wayne, who built it.

 

After speaking to a colleague today who has 30 more years experance than me, this go's along with what he was saying.

 

Snapping the throttle shut between WOT creates vacuum in the cylinders drawing oil up the liner walls. But you have got to keep the revs down for the first few miles. Otherwise you do run the risk of glazing the bores up.

[DamirGTI 327]

Hi!

 

Again a lots of different informations any way abaut that oil - so is better to use mineral oil but i have read that it must be some metal to metal contact in run-in proces and mileral oil disable that ..

please correct me if i'm wrong , and vhy not to use semi-synthetic oil ?

[Mattsav 1]

Hard and fast is the only way. Keep the rev sensible for the first couple of hundred miles (4.5-5k)

 

Use straight mineral oil - I use 'Motorway' 10/40 - £5/gallon.

The running in process need the parts to wear together so anyadditives that stop this wont allow the engine to bed in.

 

I had to go and look at an engine we'd built that was smoking like a bitch and had oil coming out of the exhaust.

Turned out it had Castrol GTX in it.

The oil was drained and cheapo mineral oil put in and after a couple of days the rings had bedded in and it stopped smoking!

 

As said above, load the engine an then come off the throttle for the first few miles to bed the rings in.

 

If you've built it properly it will be fine. If not then its going to blow up eventually anyway so you might as well get it over with sooner rather than later!!

[zeolite 0]

Hard and fast is the only way. Keep the rev sensible for the first couple of hundred miles (4.5-5k)

 

Use straight mineral oil - I use 'Motorway' 10/40 - £5/gallon.

The running in process need the parts to wear together so anyadditives that stop this wont allow the engine to bed in.

 

I had to go and look at an engine we'd built that was smoking like a bitch and had oil coming out of the exhaust.

Turned out it had Castrol GTX in it.

The oil was drained and cheapo mineral oil put in and after a couple of days the rings had bedded in and it stopped smoking!

 

As said above, load the engine an then come off the throttle for the first few miles to bed the rings in.

 

If you've built it properly it will be fine. If not then its going to blow up eventually anyway so you might as well get it over with sooner rather than later!!

 

Got that Matt. But tell me if you are building a low mileage engine can you just go straight to the limit and speed up the process? I am not bothered if the rings only last 100 miles.

[veloce200 3]

If you've built it properly it will be fine. If not then its going to blow up eventually anyway so you might as well get it over with sooner rather than later!!

 

Thats why those cheapo recon engine merchants say take it easy as they are not confident in their work - probably got such tight bearings that if you went over 3000 rpm it would seize up !