Cam belt tension spring almost claims an engine.

[GTiMini]

Here's a warning for all the GTi engined minis out there. Get rid of the cam belt tensioner spring. Its is only necessary when setting up the cam belt tension but once its all locked in place take the spring out and leave it out.

Last weekend I was enjoying my ride when suddenly the engine tone changed and sounded like an old A series with a Webber (oohhh shudder) and it was reduced to just about as much power. I limped home and everything looked okay so I took it for another run which resulted in it getting worse and the engine shut down after a brief rattle. :shock:

Turns out the cam gears were adjusted forward about 4 teeth. WTF?? How did the gear move forward against the rotation of the crank and why is it rattling so much? Stripped the engine down and found a stretched cam belt as a result of the tensioner spring coming loose and going between the belt and crank gear getting mangled in the process.

Yuk!!! Head off to assess the damage. :lol: Phewww. Inlet valves kissed the pistons but not bent and only a tiny mark on the pistons.

So, as I changed gears and the engine RPM was dropping the spring let go which resulted the cams continuing to rotate while the crank was slowing. A few post on the GTi forums confirmed that little spring has claimed a few engines and mine was almost one of them.

On the bright side. :D Engine is apart so time to port and polish the head, fit some oversize valves and some bigger cams and shave it some. WooHoo, every cloud has a silver lining. :lol:

[GTi_Clubby]

oh con your very lucky mate! i was wondering about that little culprit when i changed the belt.. looks like ill be taking it out asap!

looks like ill be at the muster this year 8)

[GTiMini]

I hope I'll be there. I've stripped down the engine, bought a set of billet Tighe cams, done lots of head work, intake work and upgraded the ECU. I had a set of adjustable cam gears made locally and they are rubbish. Don't adjust properly and adjustment slots are out of phase. :cry: Wasted money, and it looks like I'll have to modify them myself to make them work. I hope I get enough time to finish it before the show.

Maybe we should have a separate section for 16V mini's. Up until now I've been the only one there apart from Don Vidlers race car and Matts V8 project car so they probably won't go for it yet. Its only a matter of time before more and more will appear.

Will yours be finished and registered by then?

[Whitestriped63]

Its only a matter of time before more and more will appear.

Yes, yes it is.

[GTi_Clubby]

hey con, im hoping for it.. well honestly, all i have to do cosmeticly.. is paint the bonnet and bootlid.. mechanicly.. just make an intake pipe up for my air filter..

12th june.. thats what a month away now?

planning on having it on the road within probably 2-3 weeks.. so ill most definatly will be there.. hope we can park side by side...

get to work! hehehe ive been getting home from work at 5:30 this week, and have been spending till at least 10 the last 2 nights.. and planning on having the paint stuff prepped to spray on the weekend.. oh and my bloody indicator stalk to, still have to get that connected, but ive organised a local mobile guy to do it on sunday so all is well.. 8)

[GTiMini]

I think I've counted 5 people in Brisbane currently building. If the Clubby is there then this will be the first year that I won't feel like a GTi-nofriends. :lol:

I think I've inspired a lot of people to do this conversion because they can see it and it works, but so far not many have finished. As you guys know, its not easy and there are no kits to work from.

JC are you coming? Bring that cr@ppy old front cut with the engine sitting in it on a trailer. 8)

I hope I can get my engine reassembled okay before the meet because its in a thousand pieces right now after the timing belt problem. :roll:

[Whitestriped63]

certainly am coming

[GTi_Clubby]

woot 1 month tomorow..

should most likly be there..

as said earlier con, get to work my friend :)

[sean]

Hi all,

I looked at the spring when I replaced the belt and thought to myself that it look a bit light and could come off but stupid me put it back in. I don't think I can get my cover off in place so if the engine has to come out for what ever reason, I will certainally remove the offending item. But hey Con, what an opportunity to throw in a few extra ponies.

Oh, by the way, if I could drive on water I too would be at the muster.

[GTiMini]

To get the lower cover off now means you will have to remove the alternator belt and the crank pulley. Its tricky in a swift so worse in a mini. With luck they seem to stay put. I've just discovered that top piece of the spring snapped probably from heat/age fatigue. Keep your fingers crossed.

On a brighter note I've got my engine back together with the new cams, adjustable cam gears and ported and shaved head. Now it sounds like a cross between an A series and a Rotor. Honest!! Really awesome! It will tame down a bit once I tune it but I'm tempted to leave it as it is just for the sound. Big improvement in power especially above 5000rpm so it was worth the exercise.

[GTi_Clubby]

haha awesome.. looks like the muster will be very interesting.. might have to line em up :P

cant wait.. :)

[miniswift]

Hey Con,

What CAM are you using?
Is it BD14 type or something like that?
Will you take it to Rolling road for the tune up?
If you do let us know the result.

I will be welding under gearbox subframe in this weekend so...nearly there.

Cheers
Atchi

[GTiMini]

Atchi, I'm using BD10's. I'm trying to keep the car civilised and drivable. However, even the BD10's make the car sound like a rotary and they are supposed to be mild cams. Idle is around 1200rpm so for my purposes I wouldn't go bigger.

I haven't had the car on a dyno (rolling road) yet. I do all my tuning using an onboard Wide Band O2 system and a Gtech. Most settings are tried and proven by many other people, I copy them then road test and adjust to suit.

The Gtech is telling me I am over 100Hp at the wheels now and there is still a lot of tuning left to be done. 130-135 engine horsepower is my target, nothing more. Weight is in the low 600Kg range. It is nimble, light, tractable and drivable. Power is on tap anywhere between 2000-8000rpm so its nice to drive, forgiving of mistakes, and very economical. Its bringing home figures like 45mpg regularily.

Eventually I'll get it to a dyno, maybe on a club dyno day.