Okay - this weekend has been a disaster for my family's everyday cars.

1. My mum's Mk4 Astra Turbo diesel snapped the cambelt. I know because i have the belt in my hand - not sure why yet, but that's not the point right now.

Question is - are diesels of this variety significantly low compression that we might have avoided piston to valve contact?

Loathed to take the head off if I can put a new belt on and get away with it...............




2. My Dad's Pajero 2.8TD developed the most unbelievable screech that increased with revs. Sounded very similar to a knackered turbo squealing or a slipping alternator belt noise.

Anyway, exhaust manifold had a stud missing (for missing, see snapped off in the head ), so it was blowing there. Then found the exhaust manifold to be cracked to the point where you can put an airline at the crack and feel the air passing through, and that's on a stone cold manifol -I presume it'll be much worse when warm.

Question is - bearing in mind the turbo looks okay (except for a very small amount of play), and it's not a belt noise (disconnected all belts and engine is chain), could it be the crack in the manifold, and the manifold blow that would cause that noise?

 

I was under the impression that diesels where VERY high compression - although I may be wrong!!!

 

Lee - that's why I'm asking mate - I've so little idea on how a diesel engine works....

 

Rich,

Do a compression test on the diesel (if that's possible), assuming all ok, stick the belt on and give it a few turns by hand.
You should know by then if the head needs to come out or not.

 

I think a diesel engine relys upon very good high compression in order for the explosion to occur. If it were me I'd sling a belt on & keep my fingers crossed - you are hardly going to do anymore damage than has already been done....providing you time it up right of course!!!

 

dont use a std comp tester on a derve, you will blow the fooker 100 foot in the air

dervs are rather high comp i believe

 

Surely you cant do a compression test if there aint a timing belt on it!!!

 

well, no, you cant if no belt on.

 

Can't believe I wrote all that gibberish

Good job the small print in my signature covers me for that kind of stuff

 

The thought was there mate!!!

 

I had a crack in my manifold on a old silvia turbo i had and that made a loud screeching noise when warm and under acceleration.

 

just go for it mate put a belt on and see wat happens but video it so if all gows rong we can all have a good chuckle

 

PMSL.

Right - belt on the Astra it is then.

Still don't know about compression on diesels?

As for the crack in the manifold, that sounds like a good possibility!

 

mine made a high pitched screech whistle kind of noise, sounded awfull lol.

 

RichardPON, borrow a bore-o-scope thingy to stick down a glowplug hole and have a look inside the engine

 

could you not just chemical metal the manifold, just to test if its that or not?

 

Phil - manifold is off, and it was a fucker to take off, so not keen to put it all back on to find out it needs to come off again

 

Rich......article for you.....

http://autorepair.about.com/cs/gener...a102001a_2.htm

With the manifold - why dont you get the crack welded up - have the face skimmed to make sure its flat - clean up the head - and then whack a new gasket in place inbetween and take it from there. I cant see it leaking after that unless you're really unlucky!!! You can sometimes get away with just having one stud missing dependant on whereabout it is in relation to the manifold!!

 

cool, thought it might still be attached to the car! time to source a replacement then!!

 

Up for any other opinions............

 

Good site Lee - cheers

 

pon usually deisel enignes are totally scrap when the belt goes due to the comp ratio

not sure on astras obviously but in a escort deisel engine ya not only bend a few valve but ya actually reseat em in sideways and the other half sits in the piston

might be lucky though , that was what happened on me cousins engine though

diesels also need cambelts doing alot as they wear out quicker and risk fooking the engien so is done at some service times

 

That's what I thought.

 

Older Astra diesels had a cap on top of the valve stem that was designed to snap in half if the valves hit, thus saving the valves.
You could take the rocker cover off and see if they were broken.
I havent worked at Vauxhall for years, so I dont know if the newer ones still have them.
Diesels VERY high compression by the way!!!

 

the same thing has just happened to my mates astra....the water pump siezed and snapped the belt.

His was ok, all it needed was a belt, a water pump and a set of rockers(they all snap when the belt goes on the vx diesels)

Try it out, if it works, it will only cost a hundred quid or so....

 

fook me if thats true then im buying a vauxhall diesel as thats a fooking class idea

 

A Diesel, as said above, is very High Compression. The Reason for this is that the Head has no Combustion Chambers, like a petrol does, a Diesel head is completley Flat. You can Try putting a Belt on it, but.... if the valves are not seating properly where the piston has touched them, the car will never start properly on cold winter mornings, as they rely heavily on Compression to fire em up. But Give it a Try.

 

thats all they do after the glowplugs heat em up