Technical How does the oil feed to the camshaft work?

[intelceleronman]

Hey guys

I have a South African +-1100cc Uno Fire with a overhead camshaft.

Removed the head at 325,000km because the carbon builtup was so bad it started to get crunched between the valves and pistons.

Anyway send the head in so they can cut the valves,put new shims in for the valve clearances and to skim it. (0.1mm)

After fitting everything back including a new water pump, cambelt, cambelt tensioner it starts and runs no problem. BUT theres a noise like a bush/bearing that is whining. The car had a very faint whine to it before but now it is very bad as soon as the engine starts to get abit hot (60c).

The noise is on the cam belt side at the top part of the engine. (Not waterpump, cam tensioner or alternator)

I removed the cam cover and the oil feed pipe is dripping alot of oil onto each cam lobe while turning over. And I did check the headgasket to fit the right way. What I want to know is how is the outer two camshaft bearings lubricated? Is it done with the oil feed pipe that drips oil on the lobes or is there a channel inside the head that feeds them from the bottom of the bearing?

Thanks

 

[alexGS]

Hey guys

I have a South African +-1100cc Uno Fire with a overhead camshaft.

Removed the head at 325,000km because the carbon builtup was so bad it started to get crunched between the valves and pistons.

Anyway send the head in so they can cut the valves,put new shims in for the valve clearances and to skim it. (0.1mm)

After fitting everything back including a new water pump, cambelt, cambelt tensioner it starts and runs no problem. BUT theres a noise like a bush/bearing that is whining. The car had a very faint whine to it before but now it is very bad as soon as the engine starts to get abit hot (60c).

The noise is on the cam belt side at the top part of the engine. (Not waterpump, cam tensioner or alternator)

I removed the cam cover and the oil feed pipe is dripping alot of oil onto each cam lobe while turning over. And I did check the headgasket to fit the right way. What I want to know is how is the outer two camshaft bearings lubricated? Is it done with the oil feed pipe that drips oil on the lobes or is there a channel inside the head that feeds them from the bottom of the bearing?

Thanks

I would say the noise is from the cambelt being too tight. It gets worse as the engine warms up because the engine 'grows' and makes the belt tighter still.

As far as I remember, the camshaft bearings have holes that are linked to the cylinder head oil gallery which in turn is fed through a crucial hole in the head gasket.

If in doubt, you should probably take the camshaft caps off and check that the bearing material is not showing signs of scoring, heat damage, etc. If not, then you can probably assume they're getting oil and then make sure that cambelt's not too tight.

Cheers,
-Alex

 

[Chas Uno]

Removed the head at 325,000km because the carbon builtup was so bad it started to get crunched between the valves and pistons.

That's an impressively high mileage, and you must be using dodgy oil/ petrol to get that much carbon build up!

 

[UnoMia]

Hi,
I've also got an SA Uno 1100 and I had exactly the same problem as you describe after I changed the head gasket a few months back. However in my case I'd fitted the new head gasket the wrong way round and had covered the cam oil feed hole!
I changed the gasket a second time and all became quiet again. I can tell you though through checking my own engine at the time, that the pipe that carries the oil up from the block and runs across the top of the cam lubricates the three cam brearings from above.
I'd pull the cam out and check for damage to the bearing surfaces and make sure that the top half of the beaings are fitted in the correct order, as there is a groove inside them that allows oil to flow around the bearing. Maybe these are in the wrong order and the groove doesn't line up?

 

[intelceleronman]

That's an impressively high mileage, and you must be using dodgy oil/ petrol to get that much carbon build up!

My dad's 1994 Mazda 626 2Lt did 520k with no major work done. Heck its first clutch still had 40% life over. But then it had a water leak by one of the radihator pipes and overheated. They redid the engine and its standing at 545k atm.

We have another uno 1100cc thats got 385k on without any major issues. (One distributor, a few ign moduals, suspention ball joints). Had to take the top of at around 350k because the head gasket had a leak between one piston and a water jacket. That baffled me for a while because there was no normal signs of headgasket failure (oil in the coolant, compression loss, coolant loss). What happend is when the engine got to operating temp the water pressure was high enough to force a little coolant into one of the pistons and then you just see a lot of steam out of the exhust. Ill never forget when it first happened, I was standing at a robot waiting for it to change, when I pull off I counldend see the car behind me of all the steam.. hehe.

But anyway only did the headgasket on that egnine because you could still see the honing marks

On the dirty petrol/oil issue I use shell oil in the car and 93 octane unleaded petrol but I suspect its the petrol thats not upto standerd in SA.

Hi,
I've also got an SA Uno 1100 and I had exactly the same problem as you describe after I changed the head gasket a few months back. However in my case I'd fitted the new head gasket the wrong way round and had covered the cam oil feed hole!
I changed the gasket a second time and all became quiet again. I can tell you though through checking my own engine at the time, that the pipe that carries the oil up from the block and runs across the top of the cam lubricates the three cam brearings from above.
I'd pull the cam out and check for damage to the bearing surfaces and make sure that the top half of the beaings are fitted in the correct order, as there is a groove inside them that allows oil to flow around the bearing. Maybe these are in the wrong order and the groove doesn't line up?

Now what I want to know is, are the bearings getting enough oil because it looks that most of the oil will exit the pipe by the two holes ontop of the cam lobes. Also I presume that the bearings are not pressure fed like the crankshaft bearings?

Thanks for you help so far.

 

[UnoMia]

Hi,
The oil feed pipe gets oil to the camshaft bearings via the three banjo bolts ontop of the cam bearings. It also has a few holes in the pipe that dribble oil onto the cam lobes. Check that the bearing caps have been refitted in the correct order, as the groove inside must match up with the other half in order to feed oil around the camshaft bearing.