18 replies to this topic

[dbcool20]

Hey guys,

So i recently rebuilt a 1380 fast road engine for my SPI mini and i am a bit confused, i have rebuilt a few engines in the past already but this one is really busting my Bal%*s  .

The engine runs pretty good but at idle i start to get a pretty loud knocking sound. the knocking sound seems to be more persistent when the engine is hot. As soon as i rev the engine the sound disappears almost instantly. Another funny thing is the knocking also stops when i press the clutch.

First thing i thought of was the rockers & valve clearance ( i'm using 1:5 rollers) so i re checked again for the 3rd time valve clearance and rocker clearance and interference with the cover... everything looks good. Then i tried to run the engine without the rocker cover and sound still persists but seems like its not coming from the rockers. looks more like its maybe coming from the clutch side but i can't understand why. Could this be a big end failure?

I have been searching for a while but i don't really have any good answers, so before i strip everything down again, maybe someone can help me out or enlighten me on this matter.

Thanks for your help and input guys.

[lsto]

Wouldn't have though it was big end failure as it would be constant, and getting noisier under load. I would suggest its something to do with the clutch, maybe a ropey release bearing?
I'd be inclined to strip off the housing and take a peak.
I know its not the same but on some of the motors at work the drive plates break up and give the same symptoms, knocks on idle then fine when revved.
Could be a loose flywheel perhaps.

[alex-95]

It sounds like the same problem that I've got as seen in this link http://www.theminifo...e/#entry3051321 Which seems like the idle bearing.

[dbcool20]

@ Alex 

i had a look at your thread and the vid.. Thanks for the info. but my knocking is not really similar. Its kinda the opposite as your video. When idling (more when hot) it knocks and rattles, then as soon as you rev it, even slightly it goes away directly.

 

@ Isto

I doubt it could be the release bearing, first of all it was new, and second it would make more of a whiney sound not a knock i think.

Same if it were the flywheel i think you would hear it even when revving. its really kind of a loud metallic knocking sound and not regular. like something knocking around in there. 

 

Well i guess i'll be pulling out the housing tomorrow cause it really looks like the sound comes from around there somewhere.

[Gremlin]

Ignition pinking, I know it doesn't make a knock sound but something to look at before you tear it apart

[dbcool20]

Allright guys so a little update.. 

I was gonna take out the clutch housing with the engine still in the car to see if anything was weird. Managed to get all the screws off but one 

then i was really fed up so before getting the whole engine out of the car i decided to have a last look around. first I re adjusted my rockers, to 15 thou.. they were at 12 thou and witht the 1.5 rollers i heard 15 was the right gap.

then i took out the plugs and looked in the cylinders and realised there was some oil on the dish of the cylinder. So i had a closer look at my crank breather installation and the charcoal recycling unit thingy. and realised, first off that my crank breathers don't have any kind of filtering/separating mesh like they should so maybe i have oil going back in the throttle body.

then second i realised that there are 2 small hoses going back to the throttle body, one is from the charcoal canister (to recycle fuel vapours) and the other from the crank breathing system. Looking closer at those pipes i realised they were swapped around. As read somewhere in the Rover MEMS manual it says that one of these ports in the manifold is a "calibrated orifice" to let in only specific amount of air, and the other one is just a normal port for the fuel vapour recycling. maybe this could have also led to oil in my cylinders? dont really know. anyway had no time to run the engine long enough yet to see if the knocking is gone. Ill try it out later and let you guys know.

[dbcool20]

Hey guys.

Small update but nothing too serious. the car still knocks at idle when hot. now the car seems to be running in limp mode. so i checked (again) all my sensors. As i don't have access to a tester i have to do it the old fashioned way with a multimeter. The lambda sensor seems to be working, i clearly see fluctuating values like i should, the lambda heater is good too. the water temp sensor seems to be okay as i have indication in the car going up, although ( 20 degrees C. outside temp) in the car it indicates a bit lower than half way is this normal or should it be really at the half mark like most normal cars? All vacuum lines are fine, and the map sensor seems to be working (at least responding) as when i disconnect the hose on the ECU the engine idle gets worse. then i checked the resistance and line of the air temp sensor, i have got the volts at the plug, but i found out my air temp sensor must be dead because i get an infinite resistance value.  So maybe i've found the problem. ordered a new one today and ill try again as soon as i get it. keep you guys informed

 

cheers guys 

[dbcool20]

Ignition pinking, I know it doesn't make a knock sound but something to look at before you tear it apart

 

Yeah thought of that too. changed fuel to 100 octane to see but didn't notice any difference.

[A-Cell]

You are describing Classic idler gear rattle. All transverse A series engines exhibit this. Even if you set the clearances in tolerance on the idler gear it can still happen stop worrying and just drove it and enjoy it.
Increasing the revs adds some loading to the transfer gear train taking out the backlash. Likewise pressing the clutch disengages the primary gear.

[MiniGrin]

I have this!! and was getting worried. Just had a new gearbox and it started since then. Nice to know its normal ish and not too critical, just annoying. 

[Gremlin]

If the idler gear was shimmed properly and was fitted with new quality bearings it shouldn't do it, so if it's a new gearbox I'd be telling them to fix it or if you did it your self and it was because of poor shimming you'll know to do it a bit more carefully and bad bearings to spend a but more money

[MiniGrin]

It was by my waste of space local garage ¬_¬ he took 4 months, caused so many issues, i would have took it back, but he is too much of an incompetent idiot, and i dont have any money as he overcharged quite badly, add in all the extra costs to get it running properly again..... im just going to put up with it and when i have some money get it re done again. I know now not to go back to him.

 

[dbcool20]

So you are saying that apart from the annoying noise it is safe to drive like this? i won't be getting any deterioration of the idler gear/ bearings or bearing case? 

[alex-95]

So you are saying that apart from the annoying noise it is safe to drive like this? i won't be getting any deterioration of the idler gear/ bearings or bearing case? 

As seen in my thread by badboytunes, if you leave it it will only get worse, it'll then cost more to fix it. I've taken mine off the road for a few weeks, taken out the engine and now fitting new bearings and am going to give it a good clean and paint.

[dbcool20]

You are describing Classic idler gear rattle. All transverse A series engines exhibit this. Even if you set the clearances in tolerance on the idler gear it can still happen stop worrying and just drove it and enjoy it.
Increasing the revs adds some loading to the transfer gear train taking out the backlash. Likewise pressing the clutch disengages the primary gear.

 

Feeling a bit confused. Just keep driving like this? Humm seeing pics of other users here who had idler gear problems and where the whole case ended up getting chewed up by the gear and spitting metal all over i'm not sure its a great idea. Even though i really don't want to i think the wiser choice is to drop the engine again and have this sorted.