Technical Turbo

[oldskoolmk1unoturbo]

I've taken the head off my UT tonight and it seems the headgasket has gone but not much at all, no blown holes in it or anything as it was caused by it overheating.

Anyway the turbo has been removed and i have taken a look at it and the shaft has hadly any play in it at all which has confused me as there is all oil in the boost hose's and when the boost came on it would puff out oil smoke which indicated to me it was the turbocharger.

could it be an easy fix for the turbo as i always thought that if there is very little or no play in the shaft then its good? the turbo always held boost and there was no problems with it at all apart from the oil smoke and the loss of oil which needed to be topped up every week.

Thanks

Mark

 

[alexGS]

Hmmm. I don't have a lot of knowledge of turbos... I also found oil in all the boost hoses, I think that's 'normal'... I would look at the back of the inlet valves while you have the head off... carbon buildup there? If so, possibly the valve stem seals... but if you have oily sparkplugs and much black carbon buildup on the pistons, maybe you're going to have to think about changing the piston rings and giving the bores a light hone. It can be done with the engine in the car, so it's not too much extra time while you have the head off. It's hard to say for certain if it's necessary - maybe you need the opinion of someone who can see the engine in person.

I would also look at things like the state of the engine oil - does it stay clean or does it become dirty quickly, does it smell excessively of petrol? All these things point to excessive blow-by (worn rings). You would expect some blue smoke even with the engine idling or not on boost. So, if you don't have that, perhaps it is the turbo after all... you'll just have to pay out for new seals I guess.

I always think it's worth giving all the valves a quick lap while you have the head off, and cleaning off the carbon which sometimes cakes up quite thickly. The clearances may need adjusting afterwards, but they don't need doing very often so it will be worth doing once, doing right.

I would also recommend having the head *lightly* skimmed by an engine shop, and using new head bolts for the refitting. It's not worth the risk of further gasket problems IMHO just for the price of a new set of bolts - plus you will find the angle tightening much easier with new bolts than with old, and there's less risk of a bolt shearing off in the block which is a royal PITA...

-Alex

 

[oldskoolmk1unoturbo]

thanks for your reply Alex,

I plan to have a specialist place look at the head and confirm thats its all good, i want to get the head skimmed, new valve oil stem seals and pressure tested, they do clean the head up all nicely so will any carbon buildup will be gone. I'm going to be getting a 2nd hand turbo weekend after next which is said to be in good condition,

The head is going to stay off until i get hold of the other turbo and then it shall all be put back together with cambelt, waterpump, new gaskets and head bolts.

Alex i wanted to ask you with the cambelt tensioner does the engine mount have to be taken off to remove it? as it hits the car body and there doesnt seem to be enough room to remove it.

Mark

 

[alexGS]

Alex i wanted to ask you with the cambelt tensioner does the engine mount have to be taken off to remove it? as it hits the car body and there doesnt seem to be enough room to remove it.

Actually I don't remember taking a cambelt tensioner off an Uno Turbo before, so you may be right. It's basically a pulley with an off-centre mounting - have you tried flopping it over the other way? Or, have you tried removing the stud that goes through the centre? This should give you room to remove the bearing sideways.

The easiest way to remove the stud is with the double-nut technique - i.e. fit two 13mm nuts, and use two spanners to tighten one against the other, then undo the inside nut and it should bring the stud out with it. You may have a coolant leak if the system's not already drained, since the tensioner is fastened into a water passage!

-Alex

 

[SteveNZ]

Or unbolt the engine mounts and jack the engine up.