15 replies to this topic

[Slav]

My engine blows smoke on start up, when under excelleration, and down shifting, engine builder says it will come good in another 1000km, I'm concerned

[Fast Ivan]

is it blue smoke? I would be supprised if it will sort itself out, sounds like the rings may not have bedded in properly. I would rule out it being a head issue first though.

Was the block bored and honed and new rings fitted? Was the fueling set up to run lean?

[Slav]

Yes it is blue smoke, and is using half litre of oil every 1000 km, engine was full rebore, new rings and was tuned on dyno

[Fast Ivan]

full rebore, but was it honed? and was it tuned to run lean? these are questions for your engine builder/dyno man

[mike.]

As above, if the engine is run rich during its first running, the bores can be 'washed' with fuel and reduce the friction required to bed the rings in properly. 

[Badboytunes]

Take it back. It should not smoke after 1000 km !!

[Vipernoir]

Not going to get better.

 

Raise concerns with the engine builder and get him to confirm in writing that the smoke will go away if you follow a course of treatment as laid down by him - and that he will rectify all faults if nothing changes within x-miles.

[KernowCooper]

Was the head and valve guides done at the same time just a thought.

[ACDodd]

Hang on here, this could be a perfect build ruined by over fueling, remove the head and check bore wear. And lip indicates bore wash and is nothing to do with the builder!!

Just to add, the wear may also not show up in milder cases. It will however show up when the cylinder are lightly honed. This is evident as more wear around the oil control rings (top of stroke) on the bore walls.

 

AC

Edited by ACDodd, 30 April 2013 - 08:14 PM.

[Slav]

Thanks all, I now have more question for engine builder.

[Earwax]

Interesting question brought up, engine builder responsibilities in regard to jetting-  i t would seem reasonable that an engine builder for an in car situation would oversee the jetting and running in procedures to avoid pinking, bore wash etc - would it be reasonable for the builder of a bench motor to advise on these things?? Not trying to start anything, just interested in perspectives - slav i do hope this can be solved for you

 

Edit to clarify

 

just to add further info, i am sure good engine builders do (this and more)- after all it is in everyones best interest for the build to go well -  but given the number of 'prebuilt' engines i see advertised maybe these are important questions to ask  to avoid things going pearshaped

Edited by Earwax, 01 May 2013 - 07:48 AM.

[Captain Mainwaring]

Hang on here, this could be a perfect build ruined by over fueling, remove the head and check bore wear. And lip indicates bore wash and is nothing to do with the builder!!

Just to add, the wear may also not show up in milder cases. It will however show up when the cylinder are lightly honed. This is evident as more wear around the oil control rings (top of stroke) on the bore walls.

 

AC

 

 

I reckon that would have to be running hellishly rich to wear the bore in a 1000km's - I'd guess the oil would stink of fuel. 

My guess would be a real mess up of the block honing or a problem with the head - but if the head wasn't touched and was OK before the rebore, then i'd be surprised if it developed such a problem in 1000km's.

 

I'm far from being an engine builder, but I would leave the mixture as standard during the run in, neither rich nor lean. The only thing I was advised to do with a lotus twink was to back off the timing just a few degrees while the engine loosened up - but block boring was a lot different then. One comment that stuck in my mind was that a tight engine doesn't get loose as it runs in, you just end up with a worn out tight engine.....

Edited by Captain Mainwaring, 01 May 2013 - 10:12 AM.

[ACDodd]

No, engines can be wrecked in as little as 20 revolotions thats 0 miles! It is yoour responsibility as an owner to ensure that the fueling is corrrect. Sure the engine build can advise on needle choice, and where this info is given it is best to go with this info. However the engine builder has no control over the engine after it leaves his property for you to fit. You are then responsible to ensure that the ignition timing and carburetter is set correctly during the first start. First start is where 90% of the problems arise. It is for this reason thsat MLMotorsport do not sell engines without being able to do the first start and initial settings. It is always best where guarantees are concerned to allow the user to supply and fit to ensure that yoou have any chance of a comeback should it be needed.

 

The point with this thread is that you need to determine the cause of the fault using a competent engine builder before you start pointing fingers at who built it originally. As I said a perfect engine can be wrecked in minutes if its over fueled, and that is even before its turned a wheel.

 

AC

[Cooperman]

Initial start-up is always an issue with new engines as the settings are not correctly established and it is a bit of a 'chicken & egg' situation. After all, if a rolling road session is needed to correctly set the engine up the inference is that until that is done the settings are not accurate.

A dyno set up is ideal, but not everyone can do this, so it's a bit of guess work at the beginning and it's a good idea to ask the experts where to begin.

 

However, 1000 km per 0.5 litre represents about 1000 miles/per pint of oil. I wish my rally Cooper 'S' used only this much! It was not unusual for a 1275 'S' to do 250 miles/pint.

 

Presumably you are using a top-quality 20w50 oil.

 

I think I would drive it for more miles before going back to the builder to see if it beds in a bit more. Hopefully it has not 'over fuelled', but get the mixture and timing set up properly and measure the oil consumption accurately. Minis do burn a bit of oil due to their long stroke and old design.

[Captain Mainwaring]

No, engines can be wrecked in as little as 20 revolotions thats 0 miles! It is yoour responsibility as an owner to ensure that the fueling is corrrect. Sure the engine build can advise on needle choice, and where this info is given it is best to go with this info. However the engine builder has no control over the engine after it leaves his property for you to fit. You are then responsible to ensure that the ignition timing and carburetter is set correctly during the first start. First start is where 90% of the problems arise. It is for this reason thsat MLMotorsport do not sell engines without being able to do the first start and initial settings. It is always best where guarantees are concerned to allow the user to supply and fit to ensure that yoou have any chance of a comeback should it be needed.

 

The point with this thread is that you need to determine the cause of the fault using a competent engine builder before you start pointing fingers at who built it originally. As I said a perfect engine can be wrecked in minutes if its over fueled, and that is even before its turned a wheel.

 

AC

That would be the result of a catastrophic failure or fundamentally wrong build. Not as a result of over fueling. 

In this case we are assuming that the OP refitted his original carb, and that it had been running OK'ish before hand. To see bores knackered in less than 500 miles of running, i'd expect to see the choke out for most of them.

I'd have to disagree with you that such damage could be done in such a short space of time unless something else was out of kilter. Bearing in mind the weather the UK has had, it wouldn't be unusual to have to use the choke to get going and for the first couple of miles or so, particularly if encountering traffic.
I've started up plenty of rebuilt engines with a bit of choke used with care and never had an issue. Cold morning starts every day of the week are unavoidable.
I agree that it isn't necessarily fair to blame the engine builder until an analysis is carried out, but rich mixture could be eliminated from the investigation in two minutes flat. 

My best guess would be cylinders mucked up during boring or not properly honed/head gasket/valve guides.......I wonder how the OP got on with the engine builder?