on my94 the belt has snapped once with no damage and then when driving at about 30mph it went down to 3 cylinders it turned out one of the belt tensioners had siezed the bearings had broken up the result was both the offside cams jumped about 180 degrees out !!!!! and guess what NO DAMAGE again to the engine (of course might of been different story if was doing 90mph) someone was smiling down on my that day

as far as im aware there is not normally damage on my 94 i read somewhere the engine can still run with no belt ????? get home on 2 cylinders would anyone try it?

[Edited by FamousCoops - 7/5/2002 7:26:10 PM]

 

does anyone know if this causes damage on a 93 WRX?

CHEERS

 

Cambelt snapping on any car is usually serious unless you are very luck. Dont want to worry you but a mate of mine had one go on an Astra GSI and it bent 12 valves cost well over 1K trade to put right, never the same after and he sold it.

Hope you have got away with it,

ChrisP

 

yup i know it bends valves on most cars but some books say that its a safe engine and some dont just wondered if anyone else had a belt snap

cheers anyway

stu

 

Unfortunately,I would be very surprised if you've got away with it,. If you haven't and decide to get it rebuilt, make sure whoever does it checks the rod bearings and pistons on any of the cylinders that have bent valves.
We've just had a rod let go on a company car which had cam tensioner failure 2k previously, the impact had squashed the piston ring lands, causing it to run tight and dry, subsequently overheating, seizing and snapping the rod.
A main dealer did the original head re-work under warranty.

An alternative would be a good second hand unit from a reputable breaker.

 

thanx for that better get engine out then

cheers

stu

 

Re: "yup i know it bends valves on most cars but some books say that its a safe engine and some dont just wondered if anyone else had a belt snap"

Which books (plural?) are these? I ask as the Subaru service manual for the 97 is very clear about there being an interference issue between the intake and exhaust valves. Unless the earlier heads are very much different in design, which i doubt, i would just assume that they also exhibit this interference issue.

Moray
bbs.22b.com

 

94 auto data says its safe

have put a cam bdelt on now anyway and it runs so mine was safe or i was very lucky

stu

 

Some engines are non interferance, meaning they have cut outs the shape of the valves on the piston tops.... however this does not always save the engine from bent valves e.t.c because carbon builds up on the valves and pistons and can mean they both come into contact if the cam belt snaps..!!

Dan

 

Generally a turbo car should be 'safer' than a naturally aspirated one because the lower compression ratio required means that the piston crown stops further away from the valves. However, it is not a theory I would be prepared to test with my engine

 

My timing belt let go, at 7000rpm. The engine was fine. It is possible for damage to occur, but generally I beleive there is a good chance of no damage.

 

It's not just valves hitting pistons, it's inlet valves hitting exhaust valves that can cause damage.
The earlier your car is the less chance of damage as they had less cam lift/duration than the later cars or Sti's

 

Most turbo subarus are no interferring, ie do not bend valves after cam belt snap.

 

The ones we have had in have bent the valves and marked the pistons.

 

According to the workshop manual there can be no more misalignment than 3 teeth on the cambelt before interference can occur. This to me implies that it is an interference design engine, unlike (say) the Toyota 3G-GTE which is a non-interference design engine. What has possibly happened in the cases where no damage has occured is that the cams were in a rest position where all of the cams were (or very quickly became) off-lobe and thus no interference and no damage.

 

A slipped belt, would be a lot more likely to cause damage, than a clean break belt. A clean break should allow the cams to come to rest with the valves closed quite easily. If the belt has jumped teeth, or teeth mising, causing the pulleys etc to be driven in the wrong position, then damage can be expected.

 

I had a cam belt go on a Corsa GSI at carpark speeds and it mullered the engine completely - took a vauxhall dealer 5 months to fix cos they couldn't get parts - vauxhalls... pah