I will soon be putting bits back on to my engine, the only thing I'm really not sure on, which I have just never bothered to learn.

Fitting cambelts and timing up etc.

I dont understand it really, the new cambelt has marks on which you line up with the marks on the pulleys? Whats hard about that?

Or am I missing something? Lol

Any help on here would be great, as I could get someone to do it, but going this far by myself, I'd rather be able to do it myself.

 

Not missinng anything, it really is that simple.


Line up the marks on the belt with the single lines on the sprockets, and the notches on the covers
check the cam sprocket double lines agree with each other.
refit the bottom roller on the longest run
pull the pin on the tensioner.
rotate the crankshaft two full turns in the direction of rotation (clockwise from the front).
check the sprocket timing marks still line up (belt timing marks are for fitting only and will not line up again for al lot of rotations, think it is 72 rotations but can't remember the exact figure and it is not important)

Simples

 

I'm gonna be doing this myself soon, what about getting the correct tension on the belt

 

It's exactly like H&H says. Refitting the belt properly is dead simple. One thing to do that'll remove hassle is to line the engine up before taking the old one off. In particular if the crank pulley is in its "safe" position, the pistons are all halfway up the bores and so there's no chance of piston-valve interference. The 2-4 bank pulleys will be under pressure at this point so they'll probably release when you pull the belt, but it's easy to get them back where they need to be with a wrench on the pulley bolt

Also get hold of a couple of 1mm drills to space out the belt guides properly. If you take them off it can be difficult to judge the correct clearance in the car (impossible with the radiator on).

There's a reason it's called an automatic belt tensioner.

 

The tension is set by hydraulic tensioner. When the belt is off remove the tensioner, push the plunger back in and fit a retaining pin (suggest small allan key). When the tensioner and belt has been refitted and timed the pin is pulled and the hydraulic plunger sets the tension.

Care must be taken compressing the plunger. There are two types of tensioner. The older pencil type is more resiliant and can be compressed SLOWLY in a vice. The nodding type is prone to internal damage and/or leaking if compressed too quickly, and must be compressed VERTICALLY over 5 minutes.

Download the manuals here https://www.scoobynet.com/technical-...w-updated.html for full details.

 

Just thinking out loud (so don't flame me)...

Why does the cambelt have to line up? Is it 'handed' or something? Or are the teeth on the pullies (therefore, also on a certain section/s of the belt) non-uniform, or something?

Surely, so long as the pullies are all lined up as in the pic (i.e. the correct position of the camshafts/valves relative to the pistons) - and before the belt's slipped on - then why does it matter that the belt's marks have to line up too? I don't get it, lol.

 

the line are there so you can make sure that its all correct lined up, you dont have to line up the lines on the belt as long as you dont miss any tooth or leave the bel loose, i have done several times and i never use the marks on the belt it is very easy to do it. just use the diagrame

 

Sure.

If I was to do it myself, I WOULD also line up the marks on the belt as a matter of course... But just wondered if it was necessary.

 

No, the belt marks not necessary, just a confidence booster on a new belt.

Have used old belts where the marks have been worn off several times in the past. Just line up the relevent sprocket timing marks, no issues.

That said there is a direction arrow mark on the belt which may just be to get the timing marks on the belt the right way round but I try to get the direction right at least. My understanding is that these belts may be direction sensitive. Quite what the problem with running the wrong direction is I don't know, and I don't want to find out the hard way LOL.

As a precaution I tippex all the marks on any belt I remove now, just to make sure ;-)

 

As above, confidence booster. The primary value is in allowing you to be certain you have the correct number of belt teeth between the different parts of the system before fitting the tensioners and pulling the pin. Without the marks, you can get the relationship between the timing pulleys on each side correct, but, if you're unlucky, upon releasing the belt tensioner, suddenly find you're a tooth out at the crank.

Re. the "direction sensitivity" of the belt, it shouldn't be an issue, given that the belt has to carry loads in "both ways" during normal operation. That said, genuine Subaru/STi belts have a rotation direction printed on them, although whether this is because the kevlar reinforcement is asymmetrical, or simply to get the timing marks to line up, is an open question. I'd suspect the latter.

 

Yeah noticed the arrow - sound advice/tips.

 

Ahhh, that would make sense. Now I know.

 

Big thankyou to you all, very helpful thread!

I'm **** about checking things, so hopefully I'll get it right! Lol

 

I stuck some pictures on my website of an engine I had here at home in the garage maybe of help.

JollyGreenMonster.co.uk

Simon

 

mines due.. really making me wanna do it meself!! gonna save a few £££.

why do people charge so much??

 

it does take a reasonable length of time to do and the belt is not cheap

 

Awesome! That will be very useful for when I come to do it!

Thanks very much Simon

 

surley that dont warrent 300+ tho!

 

Belt change should be done as part of a major service, so if that £300 includes oil change, filter, labour etc etc it's not too bad. If it includes new belt tensioner and a complete set of idlers then it's pretty good.

Also the least problematic way to do it is to take the radiator out, which obviously means draining, and probably a coolant change, plus the time taken to do it all.

But you're right, there is quite a degree of profit built into having it done commercially, and provided you know what you're doing, nothing lost replacing it yourself. Then you can make the judgment calls about the tensioner, idler wheels and replace as necessary. Like most things on these cars it isn't actually a difficult job.

 

stitimingbelt.pdf