Technical Post Camshaft change problems

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Technical Post Camshaft change problems

dvewls

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Hi All, new here looking for help and getting deparate.

1.4 12v Bravo 1996. Drizzle bar dried up and rounded all 4 cam lobes on the exhaust valves by about 5mm or more. Have changed for a new camshaft (new secondhand) and now the little darling won't start. I have followed tdc by the flywheel and also a screwdriver down the 1st spark plug hole. I have set the cam according to haynes with cam on pot one just above horizontal and on pot 4 exhaust just off and inlet just on. Oringinally belching fire out of carb every fourth or fifth rotation, now nothing, theres fuel, and spark but it justy sounds like a big starter moter with a light chugging sound coming from the exhaust. i am trying the ECU reset, again. Any other thoughts.

I did do a compression text and 1 and 3 came up nothing 2 at 150 4 at 50 but I wasn;t sure if this was due to miss timing?

Many thanks

Dave
 
Hello welcome to the forum.

Obviously the problem is a lack of compresion. Hopefully it is not valve damage or gasket failure. Have you checked the camshaft followers for damage? They have problably worn badly aswell. Is there a chance you have gotten the timing 180 degrees out?

you can see the crank alignment mark here, between the lower belt cover and the auxiliary pully.


The camshaft mark is on the right side of the rear top camshaf cover, its at 3'oclock from memory (obvious once spotted). It lines up with the white mark on the camshaft. Just out of shot on this pic.


The white marks on the cambelt should line up perfectly with both pullys, when you install the belt. Obviously the timing tools are the best option
3470.jpg
 
I had the same problem as you.
i fixed mine by swaping the entire head.
i set the timing belt my self ( after i saw a mecanic do it)
the marks I used were the white mark on the cam shaft, witch aligned with a plastic arrow at the mark i made in adrian's picture

and the other marks i used where on the flywheel( opposite side of the engine) you have to remove the coil pack and the thermostat to see it.
There are 3 marks on the flywheel ( very close to each other about 10 mm apart) and one mark on the flywheel housing. I aligned the center mark withe the one on the housing.

after aligning the marks i put the timing belt on, adjusted the belt tensioner, and then i turned the crank shaft 2 times (with the spark plugs out)
As i got closer to the marks i moved the crank shaft slower and stopped exactly on the marks.
Checked the marks lined up, aand that was it.
 

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Hi, I only have one clear notch on the flywheel which is aligned to a mark on the housing with a 0 on it. (to the front of the rectangle hole on the housing) ther are two other marks centre of the rectangle hole and to the rear. Your camshaft marks show pointing to the rear, Haynes indicates it pointing to the front. As I said cam lobes on pot 1 are both pointing just above horizontal at aroud ten to 2, with the camshaft mark lining up with a plastic arrow which forms part of hte cambelt cover bolted into the head. is this 180 out, I did try it the other way and had no joy also.

Another theory, which I am prepared to have quashed, could the new camshaft be holding the valves slightly open even in the closed position so not getting a gas tight seal, the valve seating is used to worn lobes and the unworn ones don't ever allow it to close properly?

I'm going to do a few hours on it later and will maybe take some pictures which might help.

Many thanks, and growing more frustrated.

Dave
 
bellhmark.jpg
As promised tdc mark on bellhousing,
camlob.jpg
how Haynes tells you to do it, cam lobes above horizontal
campull.jpg
where the camshaft pulley ends up.

Query on 180 out on camshaft, I have done this but it didn't work either way.
TDC on the crank happens twice as 1 and 4 move together, how does the car know weather to fire on 1 or 4? I have pulled the crank sensor out of an old engine and the gap in the teeth comes round each time 1 and 4 are at tdc. So theoretically it doesn't matter if the cam marks are 180 degree backwards? Or does it?

Can the ECU stop the car starting even when showing a spark and giving fuel?

I am close to throwing the engine in the bin!!

ta

Dave
 
the engine is fine. just don't give up.
the timing marks on the cam are the ones i mean.
the thing is:
those 3 marks on the flywheel ... they might have been on the housing.. don't realy remember.
the point is : one has 3 and the other has 1.
the one with 1 has to line up to the middle one on the one with 3.

If the engine is 180 out, then the coil will give spark to the cylinder that is not compressed, i.e.
-if cylinder 1 is compressed( with fuel ) a spark should ignite this cylinder, but if it's 180 out then it will spark on cylinder 4.

I think you could just change the ht leads between the cylinders to see if it fires up. change 1 with 4 and 2 with 3.



on the other hand..
If the hydraulic tappers ( or whatever they are called) are keeping the valves opened( due to the fact that your old cam was so much smaller ) . you could try to discharge them (they are full of oil) .
To do this you just hit them, use something like a metal rod and a hammer... just be sure where you do the hitting.
the tappers are at the opposite end of the metal thing that is under each cam lolbe and is resting on one end on the valve stem and the other on the tapper.
give 1-2 hits on top of each tapper, they will fill up with oil afther the engine starts up.
 
Thanks for all the help, no progress. Tappets were seized so took them out and cleaned them and gave them a press with a vice nice and springy again now but still no compression. I am going to take the head off and see what the problem is none on 1, 150 on 2, none on 3 and 50 on 4, somthing is amiss, I'm hoping the valves are being held open by gunk. Had experienced help tonight also and I was so wishing he would laugh and call me stupid and have the car running in 2 mins but no such luck

This winters project now lined up I think, complete strip down and re-build of engine/s (two old ones into one).

Cheers

Dave
 
if the car was running before the cam belt change
and it will not start after it, your best bet is bent valves after a bad timing.

What i would do is take the head off and check to see if any of the valves are visibly bent, and if so.. replace them ( with valves from your other heat.. or replace the head completly. If you go to the trouble of removing the head make sure you spend some time on lapping the valves.

It makes it very easy to see valves that don't close properly.
Use some gasoline, to see if any of the valves are still leaking after replacing any visibly bent valves.
When i did mi valves i used some rubber hose and a electric drill, some polishing cream and oil.. lots of oil.
 
Its well worth lapping the valves. I did mine by hand

If you remove the valves from the head you will need replacement valve stem oil seals. When you refit the valves its really important to protect the steam seal from the sharp edges on the valve steam. Thats what went wrong with my 1.4 a machine shop damaged all of the steam seals, I paid them to check the guides and they offered to fit the steam seals for free.

It is good practice to change the seals when the head is off anyway.
 
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thanks, the plan is to strip the head down on the one in the car, the other dropped a valve into pot 4 and damaged the head and valve tube. then strip the block on the one with a damaged piston, i know that block works really well, at least pre broken valve. will check cylinder first though. like i say i have all winter and lots to learn, then combine with new seals and wearing parts. should be interesting.

cheers

dave
 
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