Engine Running In Techniques

[wracing 19]

Im sure this may have been covered before, but im looking for a few opinions on running in the XU series engine. while i know there are going to be some variations between the alloy block and steel block it would be nice to know what has been working for everyone else.

 

there seams to be two trains of thought softly and hard, both have logic behind them. has anybody done any back to back testing.

 

im more interested in steel block running in, on t16 bearings and 87mm forged pistons, but any info would be great!

 

Thanks James

[SurGie 54]

Iv not done any back to back testin my self however, i would not like to go hiking 20 miles with new shoes, would you ?

[wracing 19]

agreed, but how quickly should you bead the rings in, what's the key to getting them done before the bores glaze?

[DamirGTI 342]

Try this :

http://www.guy-croft.com/viewtopic.php?f=8&t=78

 

.. i did mine as per this instructions after overhaul , and it's turned up all nicely bedded in been measuring compression just few days ago after some odd 60.000km's , and it's bullet proof on all the 4 cylinders same strong value without any oscillation ..

 

If it's on a dyno could be done in just a few hours , but i would do it slowly/gentle on the road .. step by step , you'll even feel that the engine "open's up" with the gradually increase of mileage ..

 

Damir

[SurGie 54]

I agree ^

 

Its similar to when the car is cold after its first start, it then opens up when its warmer.

[DamirGTI 342]

Though , the above description lacks rings/bores bedding in procedure which is vital and most important factor of the whole running in job .. did that like this :

 

- el' cheapo mineral oil and OE oil filter for the first few miles of running in (replaced later on again ..)

- warm up the engine up to operating temp (water/oil)

-> and do this as soon as possible (providing that the fueling/ignition is spot on .. do not do it if it detonates or runs lean until you sort things out ..) :

- pick some quiet straight road, stick it in 4-th or 5-th gear @ say 3000rmps and step on the throttle all the way holding it like that for a few seconds , then snap it shut and coast down for a few seconds -> repeat the process at least 15 times ... this creates pressure to force the piston rings against the cylinder walls and by snap loosing the throttle vacuum which sucks inside additional amount of oil ..

 

Afterwards you've done this say 15 times , drive by constant varying with speed , avoid at all costs driving at steady speed in one gear - use all gears as much as you can (up hill/down hill road configuration helps !) and periodically do this the same snap on/off throttle stuff ..

 

Damir

Edited February 4, 2010 by DamirGTI

[wracing 19]

one thing i didnt mention this is on a turbo charged engine? very quick spool low compression engine should a force the waste gates open?

 

thanks

[Tom Fenton 1,542]

Any news on Pot box James??

[wracing 19]

PM'ed

[opticaltrigger 52]

Runing in.......The scariest part of it all.

Somthing like 90% of all camshaft failures occur in the first ten minutes of an engines life James.

It's a super critical phase and must be conducted with super critical attention to the valve train above all else.If the cam and followers are new it's even more so.

The case hardening on the cam lobes and follower faces is very thin and the contact areas are tiny so the applied pressure is very high at the point of maximum lift.

When the motor is fired up there is an appreciable time delay before oil is supplied in sufficient quantities to offset the temprature rise at the camshaft lobe apexes.Dont be fooled here,the temprature at the lobe apex will rise at a stagering speed and the window of tollerance for it is quite narrow,if it gets to hot to quick you loose the case hardening and in turn the valve train associated with it.(like in the bat of an eye).

Provided that all tollerances are correct the bores,rings and shells will look after themselves.It really is mostly about valve train.

 

Fill it with cheap oil and a fillter.

 

Fire it up and instantly bring it to about 2000 RPM,this will serve two purposes firstly it will deliver oil to the camshaft quickly but most importantly,because the engine is spining quite quickly the amount of time that the lobe apex of the cam spends in contact with the follower is less,which gives less chance for hot spots to form.

 

Run it like this for aproximatley ten minutes varying engine speed ocationaly and casually between 2000 and 2500 RPM.(it's best to get some help here as you need to monitor pressures and tempratures very closely during this phase).

This part is the most important of all as it is where the cam and followers are burnished together as a matching pair forever.

 

Switch off and dump the oil and fillter.

 

Replace with more cheap oil and fillter.

 

Fire it back up and do exactly what you just did again for another ten minutes.Thiss will simply back up the process you have just performed on the valve train.

 

Switch off and dump the oil and fillter again.

 

Replace with final cheap oil and fillter.

 

Fire it up again and this time for about five minutes move it around slowly between 2000 and 1500 RPM.After about five minutes gradualy move the engine down towards idle speed and check that it will idle happily.Once happy with your idle keep varying your speed between idle and 2500 RPM from time to time for around another twenty minutes.Just dont let it sit there chuging away to itself for to long.

 

Switch off and dump the oil and fillter one last time.

 

Replace with a reasonable semi synthetic oil and clean fillter and run it around for 500 miles or so.

 

Finaly dump that oil and fillter and replace with your chosen final running oil and fillter.(see Oilmans post on that).

 

Many people think three oil and fillter changes in 30 minutes or so is excessive but it's cheap in the long run and is the only way to make sure you remove as much particulate contaminants as possible during the initiall breakin period.

For the 500 miles part just dont let it labour to hard in the wrong gear and not to heavy on the revs.As you get towards the 500 mark gradualy start to move the motor up towards it's maximum revs point from time to time and steadily start to increase load also but not to heavy on the load at first though.

 

All the very best

O.T.

[Sandy 191]

It depends massively on how it's built. The cam issue is critical in all cases, the bearing clearances should be right from the off and the rings/bores depend on the standard of preparation. With the right rings on the right bores, an hour and a half of normal running will be sufficient, but if the rings are poorly matched to the bores then it could well take hundreds of miles.

[welshpug 1,661]

how about when an engine is only partly refreshed?

 

I.e new rings and big ends, same components elsewhere

[kyepan 291]

doesn't it depend on the type of rings you have, ie chrome coated, or moly or steel? as they bed in at different rates?

[Cameron 16]

If an engine is only partly refreshed then you should just warm it up as normal, then run the rings in, then run the bearings in.

 

A nice little video to demonstrate running in piston rings:

 

 

Floor it in 4th (or 5th on a 6-speed) from about 3K and let it rev up to 3/4 maximum rpm (around 5K), then snap the throttle closed and let it coast down to about 3K, then repeat. The first time it will feel gutless and slow as hell, but each time you rev it up you will feel it become more powerful and more urgent.

 

But make sure you have your breathers routed properly, otherwise this happens!

 

 

And after you've bedded the rings in, revert to the old-fashioned running in procedure to run in the bearings. So 500 miles at varying throttle and load, avoiding low rpm loading (sub 2K) and building up to normal use over that period.

Edited February 5, 2010 by Cameron