Technical Dead Panda

[DaveMcT]

Lots of folks assume the engine is correctly timed when they fit a new belt. It might be ok but how would you know?

This should help -

https://www.litensaftermarket.com/f...nspanner/en/Installation_Procedure_979778.pdf

Usually, the cam wheel is loosened during tensioning but the cam itself is locked and crank has to remain in position. The cam wheel is locked to the cam after the belt is tensioned.

Fiat's spring loaded timing belt tensioner might affect the detail but in essence it should be the same process.

 

[newbie fiat]

Lots of folks assume the engine is correctly timed when they fit a new belt. It might be ok but how would you know?

This should help -

https://www.litensaftermarket.com/f...nspanner/en/Installation_Procedure_979778.pdf

Usually, the cam wheel is loosened during tensioning but the cam itself is locked and crank has to remain in position. The cam wheel is locked to the cam after the belt is tensioned.

Fiat's spring loaded timing belt tensioner might affect the detail but in essence it should be the same process.

Thanks. I had already seen and read that guide it just says not to let it go out of alignment. Already is so that doesn't help unfortunately

 

[DaveMcT]

Thanks. I had already seen and read that guide it just says not to let it go out of alignment. Already is so that doesn't help unfortunately

The issue with "simply" tensioning the belt is that the crank will always move relative to the cam. The cam wheel should be free turning while the tensioning happens or the cam AND the crank are locked in their correct positions.

With the cam wheel turning free, the belt can be tensioned without anything going awry. Then with the crank checked at TDC, the cam wheel is bolted up tight and the camshaft locking tools removed. Job is done.

On systems where cam wheel AND crank are locked while the belt is fitted, you have to be sure the belt on the side opposite the tensioner is not slack when tension is taken up. The tooth spacing between cogs makes it impossible to get that side too tight but it can be too loose by a few teeth.


In all cases, always check the belt tension after a few (careful) hand turns of the crank and always check the belt has not jumped while it was fitted.

 

[varesecrazy]

I have done belts on SO MANY small 8v FIRE motors..without issue.. just relying on the cast marks.

ALL have the eccentric bearing type tensioner though.

It is a SAFE engine.. so a little 'experimentation' is permissible

Only did the 1 sprung tensioner (1.2 brava)
Still appeared relatively simple though..

Charlie

 

[newbie fiat]

I have done belts on SO MANY small 8v FIRE motors..without issue.. just relying on the cast marks.

ALL have the eccentric bearing type tensioner though.

It is a SAFE engine.. so a little 'experimentation' is permissible

Only did the 1 sprung tensioner (1.2 brava)
Still appeared relatively simple though..

Charlie

(Everything has just fallen into place in my head while typing this. At least I think...)
I have read sooo many guides online and watched animated videos of crankshafts with single OH cam the bottom crank rotates twice for every single revolution of the cam this is what people mean by it can be 180 degrees out as the pistons will be pulling down when the exhaust valves are opened by the cam and be pushing up while the inlet valves are open. I hope that's correct anyway! It makes sense in my head. I'm getting suction on the inlet and black soot out the exhaust when its trying to start so without looking I know I'm not 180 deg out of alignment but I think it may be just a few teeth. Enough that the engine can't self sustain

So as the crankshaft does exactly the same each full revolution if its skipped a few teeth forward I should just be able to set the cam at TDC and release the belt tension. Rotate the crank clockwise till it lines back up and then tighten the belt again? If someone can sanity check that for me?

 

[varesecrazy]

Sounds good to me..
Almost as good ...
as a working FIRE engine

 

[DaveMcT]

So as the crankshaft does exactly the same each full revolution if its skipped a few teeth forward I should just be able to set the cam at TDC and release the belt tension. Rotate the crank clockwise till it lines back up and then tighten the belt again? If someone can sanity check that for me?

As it's a toothed belt you probably wont be able to shunt it along and correct the timing. But there's no harm in trying.

Slacken the belt tensioner, and ideally lift the belt away. Set the cam and crank at their correct points. Refit the belt. Retension and check the timing points are still correct. When you turn the crank 360 degs, the cam will turn 180 degs. Two crank turns will put the cam back at its starting point.


Personally, I still prefer to use the locking tools. But then I'm used to doing twin cam timing belts.

 

[varesecrazy]

If it has 'wandered'

By 6 teeth..

It should be pretty obvious where the CORRECT marks are.

Hard to see how you could make it to 180degrees out from there.

Im confident we will have a well running panda by the end of the weekend .

Charlie

 

[newbie fiat]

As it's a toothed belt you probably wont be able to shunt it along and correct the timing. But there's no harm in trying.

Slacken the belt tensioner, and ideally lift the belt away. Set the cam and crank at their correct points. Refit the belt. Retension and check the timing points are still correct. When you turn the crank 360 degs, the cam will turn 180 degs. Two crank turns will put the cam back at its starting point.


Personally, I still prefer to use the locking tools. But then I'm used to doing twin cam timing belts.

yep that's what i actually meant, not going to force it along with the belt but will lift the belt away and move the crank manually. i imagine it will be ahead by a number of teeth rather than behind. this being the case if for example it is ahead by 6 teeth i cant move the crank counter clockwise can i? i have head that is bad for an engine... spark plugs will be out to allow the cylinders to dry while i do this so resistance should be minimal. this would be the easiest way, move it back by 6 teeth to bring it in alignment

if i can only move it forward then i will need to move it round till it is back at alignment and then one more full turn wont i? if i just spin it round almost 1 complete turn it will then be 180 deg out of alignment wont it.

seems like an obvious question but i want to get this right first time if i can

 

[newbie fiat]

If it has 'wandered'


Im confident we will have a well running panda by the end of the weekend .

Charlie

yeah not quite but hopefully by the end of tomorrow, im on my last day in work after a full 2 weeks in without a day off, all my tests on the car so far have been straight after work in the dark with a torch. i have a day off tomorrow FINALLY so will get started early morning on it.

 

[DaveMcT]

Set the crank to TDC on #1 (timing mark). The cam should also be at it's timing mark. When you turn the crank with belt fitted, the cam will only go 1/2 a revolution. When you turn them separately they can be quickly lined up.


As you have found, the issue is tensioning the belt without putting the timing out by a tooth (or three).


It is good practice to always turn cam and crank in the correct direction. Fiat are especially firm on this point. If the belt is fitted, the crank has to make two full turns to return the cam to its starting point.

 

[newbie fiat]

ALL FIXED! it was out by 6 teeth forward. Took the tensioner off and there was grease splattered out of the bearing and forward and back movement. obviously failed early its a continental kit and is guaranteed for 5 years so took it back got a refund and then bought a new kit saving £10 as it was reduce for black Friday.

All fitted went very well actually about 1 hour 30 mins in total and purrred into life straight away.

Now to leave it stood on the drive for a year until the missus passes her test! Hopefully nothing else goes wrong!

Cheers for all the help

 

[DaveMcT]

Support it on stands. Leaving it parked risks damage to the tyres.

Pump the tyres up hard and cover with black plastic.

Treat the underside with anti corrosion sprays.

Keep the battery topped up with an Optimate.

Start the engine once a month and run it until fully hot. At least 1/2 hour more if possible.

Even better use the car yourself.

 

[newbie fiat]

Support it on stands. Leaving it parked risks damage to the tyres.

Pump the tyres up hard and cover with black plastic.

Treat the underside with anti corrosion sprays.

Keep the battery topped up with an Optimate.

Start the engine once a month and run it until fully hot. At least 1/2 hour more if possible.

Even better use the car yourself.

Thanks for the tips, I had already read lots about leaving a car stood for extended time. Given it a full wash and wax and thoroughly washed underneath. Tyres are all new but will be taking it round the block once a month to ensure rotation.

Cheers all!

 

[DaveMcT]

It's best to go for a proper drive to get it fully warmed through not just up to coolant temperature. Every litre of petrol makes a litre of water in the exhaust. That will condense in a cold engine and especially in the exhaust.

A good sealing underneath with an oily water dispersing treatment would be good for any car. It's also worth flushing the brakes through with new fluid. Less risk of corrosion in the calipers and wheel cylinders. And the car is probably due a fluid change anyway.