Fiat/Lancia 2.0 16v turbo interference?

[Yugo_Turbo]

Is there posibility of interference of the valves and pistons in Fiat/Lancia 2.0 16v engines from kappa/coupe?

[Guy Croft]

In normal rotation there is loads of clearance valve-to-valve, but if the belt slips or the cam timing is far out they will hit each other very readily. The photo shows such a head albeit with non-standard cams with more lift esp around tdc (appr 1mm inlet, 0.5mm ex) but if gives an idea of the kind of proximity they can have in operation (cyl 2)

If you're in doubt about this take the head off and inspect the valves for true.

GC

[Yugo_Turbo]

Thanks for the response! A good friend of mine has the following concern. He was changing all the belts (100% stock car), and since he did not have the Fiat factory tool for tension adjustment, he made it himself based on the following photo and factory manual:
http://www.Lancia.co.za//imgarticle/1860745100.jpg
The only thing he was missing was the exact mass of the weight. He used a 750g one, and based on the photo and steel density he estimated the factory one at 900g. He used 120mm for timing and 205mm for balancer belt distances (for the factory tool they are specified at 100mm and 205mm based on the manual). He also replaced both main tensioners, but not the large bearing on the lower balance shaft that the timing belt is touching with it's outer side ("felt" ok) - couldn't remove the pulley.
After reassembling everything, there is a minor squeaking sound (not coming from any of the aux belts) at all rpms, as if the belts are too tight. He did 50 miles like that hoping stuff needs to seat-in, but is concerned about one of the belts snapping. Are they too tight? Do you have the factory tool? After using the home-made tool, the belts did feel tight, but based on sohc experience, nothing too dramatic..
What would be your suggestion for him? Disassemble everything, and loosen them up a bit (like 90mm and 180mm), or just let it be?

[Guy Croft]

Squeeking is not good news, because it can be caused by the cam nose picking-up inside the housing - something that can happen if the belt is too tight. It can also be caused by a worn tensioner bearing..

My advice would be to check or replace the tensioner, then retighten the belt - but adjsut the tool to make it a fraction looser and see if the noise stops. Hopefully it will not have caused enough scuffing damage to be a long-term concern.

The 'acid' test of the belt is tight enough is whether it goes slack when the engine is turned backwards by hand, but of course that doesn't stop overtightening which can of course snap the belt. Remember the belt gets tighter as the engine warms up too.

GC

[bojan]

Thanks for the response here Guy. Sale wrote on my behalf. To follow-up on the issue.

After extensive debugging, I sourced the noise to come from the balance shaft belt (i.e. when balance shaft belt is removed there is no squeeking, so I guess this is good news as I did not ruin the head.

Initially I had hard time removing the pully on the front (lh) balance belt to get to the large bearing (the one timing belt slides over). After a few hours of attempts managed to remove it and replaced the large bearing with a quality SKF one.

The squeeking was still there. Then bought another (different brand, the previous one was new too) balancer belt tensioner bearing. The squeeking was still there.

Finally I gave up assuming the squeeking is coming from one of the shaft bearings that I had no time or interest in replacing at the time...

Are those easy to access with the engine in the car? No manual that I have seen references the disassembly process here..

[Guy Croft]

Well, I do know those balance shafts squeal if the belt is too tight.

I clamp them and don't use the belt at all.

G