Few problems! Need help! Fuel, Spark, Compression.
Turbo Mini Forums

hi all hope sumone can help!

tried to get starting the engine today,but didnt go so well.
so first of, checked compression on each cylinder 4,3,2 was grand. but on number 1 it read about 15psi. i noticed that the valve clearance wasnt quite rite and looked as if it was holdin the exhaust valve open slightly. sorted that but still no joy. so i squarted abit of oil thru the spark hole and tried again, this time i got upto 40 psi but no higher!

next problem, was the spark. with the dizzy cap off spark was grand, but when back on it only fired every now and again. now the battery has had no charge for about 4 months and was only put on this morning so im thinking maybe it just hasnt got the jucie. no big deal really on this one.

3rd problem, i have alot of fuel *peeing* out of the carb, just above the float bowl. i discovered the pipes were on the wrong way at the tank, so in effect there was no return an thought that it was just the carb overflowing. but when i changed it round it still happens, but takes longer to happen if that makes sence?
just above the lip on the float bowl and about 2cm back were the plenum would meet it, theres a hole where the fuel is coming out. doesnt look broke and doesnt look like there shud be a bolt or a screw in it.

so again any ideas on what ive *melonsed* up this time??

any help would be really appreciated!

thanks
danny

40psi 3bar! you got problems son.

Your getting a spark with the dizzi cap off you got problems son

You got fuel lines crossed and fuel pissing out your carb! Mate sounds like you got major problems.

I know you said you have done it but re check your valve gaps if your still getting isanely low compression you have issues and from the sounds of it it could be a sticky ring.

Is it a turbo or fuel injected motor?

Own the day

its a turbo joshua.
yeah checked everything 3 times over!

From your description that's the float chamber vent line. most people blankit with a bit of pipe with a bolt jammed in the end.

Edited by Mr Joshua on 23rd Apr, 2009.

Own the day

Here I have tapped and plugged mine.

Attachments:

801.64kb

Own the day

from your picture there josh the leak is on the oppisite side.
i have the vent plugged as u discribed with a bolt.

what kind of psi should i have from each chamber??

about 140psi bench mark but not 40. Are ou sure about the fuel leak?

Own the day

99.99% sure mate. starting to think theres maybe a crack in the carb??

Where is it on this pic:





Edit, assuming it is this side of the carb!

Edited by Jay#2 on 23rd Apr, 2009.

He said 15psi dry and 40psi wet so that points to valves/headgasket - a proper cyl leakage test is what is required here!

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know

got the leak sorted. was the float valve causing the problem. thanks!

now, what shout the valve gap be, 12thou, 14, 16??
have a feeling u may be right scruffy!
in terms of the leakage test, how do i go about this??
thanks for tips every1!!

You need one of these
http://www.tooled-up.com/Product.asp?PID=128163

They have gone up a lot in price since I bought mine. You are measuring how much the engine seals the loss of compressed air basically. You set it at 100% then connect it to th the engine ith th appropriate cylinder at tdc & valves shut. Any loss can be measured upto 10% for comp engine or 25% for road. If it is really bad you can hear where it is leaking from.

Edited by Scruffy on 23rd Apr, 2009.

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know

thanks for that scruffy! will inspect the valve first i think and if that doesnt do it will go further!
thanks again!

Back to what scruffy was suggesting I think you have a ring problemthe wetting would have been of the rings not the valves.

Own the day

going to pull the head off, and fill the chambers with thinners to check for leakage. if that holds up, then its looking like the pistion rings!

cheers every1!!!

A Mini 30 was dropped of to the garage a few years back not running after checking the cylinder compressions No1 was way down. Took the head of got it skimmed and the valves re-ground, put it all back together to have found 2,3,&4 had improved but 1 was the same advised either the head was cracked or the rings were shot as the the machine shop had spotted no signs of failure in the head that only leave the block components

Own the day

the head seems quite good, never skimmed it, though re-ground and seated the valves. again was thinking possibly comtamination? peice of grit or something silly not letting a valve close correctly.
the starter motor is struggling to turn the engine over. and its impossible to turn over by hand. god only knows!
so im guessing were into a rebuild!

Edited by dannyg2325 on 25th Apr, 2009.

What were the bores like when you had the head off? Plus what is the history of the engine, has it been rebuilt at all? I hope you don't have to rebuild because you do realise you'll go mad and build a monster don't you?!

We have all have been there.. once its open the wallet tekes a battering :)

That mini is determined to Kill me!!!!

bores were pretty good, pistion were good an clean. bores looked pretty fresh actually. dont have any histroy on the engine jay unfortunatly! does look to have been rebuilt previously, but this may have opened a flood gate for problems too!

Leakage test!

Lets hope none of you lot are Doctors - you'd have your patient cut open before you could say knife only to find they've pulled a muscle!

On 5th Sep, 2011 Vegard said:
I stand corrected. You should know

haha scruffy!

"turns out its a rear wheel bearing fault!"

customer:

"then why the fuck is my engine on the floor?"

Did you fill the bores with oil an see which emptied first?

Own the day