300tdi - 2 Broken Valve Springs

LeftFoot · Jun 10, 2018

Greetings,

I have a friend with a 300tdi defender that he just bought "as is" from its previous owner.
We have been trying to start it but with no success. We have confirmed that the starter, injection pump and timing are all ok however, upon removing the rocker cover we discovered not one, but two broken valve springs

.
One on cylinder 1 and the other on cylinder 3.

What can possibly cause these springs to snap? What else should we look for at this point? This doesn't seem to be a regular occurrance as I cannot find much info using the search function.

Wimblowdriver · Jun 11, 2018

LeftFoot said:
What can possibly cause these springs to snap?

Possibilities;
1. Someone fitted second hand parts which had done extremely high mileage.
2. Made from poor quality metal / pattern parts.
3. Ham fisted fitter.
4. Original parts but have done extremely high mileage.

LeftFoot · Jun 11, 2018

Wimblowdriver said:
Possibilities;
1. Someone fitted second hand parts which had done extremely high mileage.
2. Made from poor quality metal / pattern parts.
3. Ham fisted fitter.
4. Original parts but have done extremely high mileage.

I would go with #3 above. Is this something we can get away with by just replacing springs and setting valve clearances?

Kwakerman · Jun 11, 2018

LeftFoot said:
I would go with #3 above. Is this something we can get away with by just replacing springs and setting valve clearances?

As long as the broken spring hasn't allowed the valve to drop low enough to get hit by the piston you may get away with it. You can replace valve springs without removing the head (if the valve will seal correctly). If you can change the springs then do a compression check to see how good the valve sealing is

LeftFoot · Jun 12, 2018

Thanks for the replies. After weighing our options it seems best course is to take the head off for peace of mind.

Oldseadog · Jun 12, 2018

If you're taking the head off, I'd recommend replacing all of the springs and valve oil seals, and whilst you are at it, re-lap the valves into their seats.
Saves a lot of potential problems later on.

Kwakerman · Jun 12, 2018

Oldseadog said:
If you're taking the head off, I'd recommend replacing all of the springs and valve oil seals, and whilst you are at it, re-lap the valves into their seats.
Saves a lot of potential problems later on.

And also check the head is flat, if its not get it skimmed. Also read up on head gasket thicknesses as there are about 4 options for thickness although most seem to use 'the 3 hole' gasket.

Wimblowdriver · Jun 12, 2018

Also check the cam shaft for flat spots, and after fitting new springs check the installed length to avoid coil binding.

300tdi - 2 Broken Valve Springs

LeftFoot

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Wimblowdriver

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LeftFoot

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Kwakerman

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LeftFoot

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Oldseadog

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Kwakerman

Well-Known Member

Wimblowdriver

Well-Known Member

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