NEED INFO ASAP PLZ HELP
Discussion
please someone help me find out if my engine is an interference engine i have a 1988 944 porsche 2.5liter non turbo....................ive read that some of the non turbo engines are non interference engines does anyone know if mine is or not because if it is an interference engine well i have some pistons and valves to be replacing and im not excited
9za4ck4 said:
i looked it up on google and it gave me FALSE hope and told me that some non turbo engines were non interference but now i have the feeling that there is no hope.....my belt didnt even break it just jumped some teeth but i have the feeling i have to change out the pistons and valves
All doesn't sound lost - jumping a tooth or two need not be deadly, even on an interference engine. Your best bet is to do a compression test before you do the timing belt, which should tell you if the valve train is working roughly as it should. The compression will be down on where it should be due to the timing being wrong, but it will still compress. If valves are bent or broken then the compression test will give a zero on the affected piston.davepoth said:
9za4ck4 said:
i looked it up on google and it gave me FALSE hope and told me that some non turbo engines were non interference but now i have the feeling that there is no hope.....my belt didnt even break it just jumped some teeth but i have the feeling i have to change out the pistons and valves
All doesn't sound lost - jumping a tooth or two need not be deadly, even on an interference engine. Your best bet is to do a compression test before you do the timing belt, which should tell you if the valve train is working roughly as it should. The compression will be down on where it should be due to the timing being wrong, but it will still compress. If valves are bent or broken then the compression test will give a zero on the affected piston.9za4ck4 said:
davepoth said:
9za4ck4 said:
i looked it up on google and it gave me FALSE hope and told me that some non turbo engines were non interference but now i have the feeling that there is no hope.....my belt didnt even break it just jumped some teeth but i have the feeling i have to change out the pistons and valves
All doesn't sound lost - jumping a tooth or two need not be deadly, even on an interference engine. Your best bet is to do a compression test before you do the timing belt, which should tell you if the valve train is working roughly as it should. The compression will be down on where it should be due to the timing being wrong, but it will still compress. If valves are bent or broken then the compression test will give a zero on the affected piston.If it has jumped you need to be looking for the reason why. Don't just re time it & think that it'll be ok because it wont, it jumped teeth for a reason.
Larry Dickman said:
9za4ck4 said:
davepoth said:
9za4ck4 said:
i looked it up on google and it gave me FALSE hope and told me that some non turbo engines were non interference but now i have the feeling that there is no hope.....my belt didnt even break it just jumped some teeth but i have the feeling i have to change out the pistons and valves
All doesn't sound lost - jumping a tooth or two need not be deadly, even on an interference engine. Your best bet is to do a compression test before you do the timing belt, which should tell you if the valve train is working roughly as it should. The compression will be down on where it should be due to the timing being wrong, but it will still compress. If valves are bent or broken then the compression test will give a zero on the affected piston.If it has jumped you need to be looking for the reason why. Don't just re time it & think that it'll be ok because it wont, it jumped teeth for a reason.
If the belt was loose you'll probably find some play in a pulley, there has to be a reason for that slack and you need to find it.
Check how far out the timing is before you remove the belts, that should give a clue as to if the valves are likely to have hit. If you can reset the timing and do a compression test with the old belt still on then it saves fitting the new one just to discover that it's got to come off again to repair any damage (only do this if you are happy that there's no reason it will jump again). If it passes the test you can then stick the new belts on.
Check how far out the timing is before you remove the belts, that should give a clue as to if the valves are likely to have hit. If you can reset the timing and do a compression test with the old belt still on then it saves fitting the new one just to discover that it's got to come off again to repair any damage (only do this if you are happy that there's no reason it will jump again). If it passes the test you can then stick the new belts on.
Edited by Steve H on Saturday 8th January 07:32
Hi
It doesn't take a lot to bend valves on that engine. I rally a 2.5 944 and have bent valves on a couple of occasions.
Causes have been - belt failure, tensioning roller bearing failure and the cam pulley coming loose. With the final one the timmg didn't get far out but all exhaust valves touched pistons. Jumping a tooth on the belt is likely to have caused problems... a compression test will be the best way of confirming.
Replacing valves isn't hard or expensive (I get them from Pelican parts in USA... but then again I am in NZ so you may get them cheaper in the UK). Stick on a new belt and replace guides / tensioner at the same time.
Hoping to get away from all this (or double my trouble) as I'm installing a S2 motor soon
It doesn't take a lot to bend valves on that engine. I rally a 2.5 944 and have bent valves on a couple of occasions.
Causes have been - belt failure, tensioning roller bearing failure and the cam pulley coming loose. With the final one the timmg didn't get far out but all exhaust valves touched pistons. Jumping a tooth on the belt is likely to have caused problems... a compression test will be the best way of confirming.
Replacing valves isn't hard or expensive (I get them from Pelican parts in USA... but then again I am in NZ so you may get them cheaper in the UK). Stick on a new belt and replace guides / tensioner at the same time.
Hoping to get away from all this (or double my trouble) as I'm installing a S2 motor soon
thinfourth2 said:
Okay me confused?
Tight spot?
Did you turn it over with or without plugs in as it might just be compression you are feeling.
Theres a tight spot in the belt like you push on one section of the belt and its super tight and then on the other side of the pulley its loose and floppy, does that makes sense? and i have taken the plugs out so i would be easier to turn the engine by hand but anyways this is where im at il have both the belts on jan 12 (944 isnt all that common in the usa) so do i risk my new belts and putting them back in time or go ahead and take the head off and check the valves or what? Tight spot?
Did you turn it over with or without plugs in as it might just be compression you are feeling.
Set the timing and then do a compression test before you think about pulling the head off.
There is loads of useful info at http://www.clarks-garage.com/
Good luck
There is loads of useful info at http://www.clarks-garage.com/
Good luck
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