Engine suddenly quit.

[thedjjack]

piston hit a valve.... might have bent itself so it no longer hits...

You can skip the leak test... you could just fix the timing marks, fix the rocker, turn the key... worst case you will have a cylinder or two down and your pulling the head again...

Balance shaft turn.... Delica group should pool some money for a compression tester/leak down tester to share... just saying...

[yojimbo]

Occams razor. Balance belt snapped. Timing jumped a valve got smacked and it gave up. This more common than youd like to think lol. Also I think all diesels are interference. Only on the 'low'compression of a petrol do you have the luxury of leaving room! Fix it and drive it.

[Big-Bird]

[Big-Bird]

You are right to ask why didn't other valves get hit. Pure luck perhaps.

If you are removing the head anyway save your money (leak down tester) and get the head checked. Its obvious something is wrong when a rocker is bent. In your case the timing belt didn't break....it was the silent shaft belt correct?

A moment of slack on the timing belt would allow a valve to stay open longer than normal and the piston comes back up and hits the edge of the open valve. The belt regains tension again and the motor spins to a stop and not a sudden thud. All other valves are saved certain doom.

[Jedidiahwiebe]

I'm actually building a cheap/basic leakdown tester just for fun. I'm taking pics too. Will post it to the site.

I noticed you mentioned that I should get the head checked when it's off. I was thinking of replacing the valve myself with the help of a neighbour who is wicked skilled at keeping his engines running. And I was kind of thinking about skipping the hundreds of dollars the head shop charges for anything. What would he be able to check for that us redneck farmers will miss with our homebrewed mechanic-ing skills? (I am always eager to do it right) If you say I should really take it in to get looked at I will do that.

[Big-Bird]

Lets assume the individual valve is potentially bent due to the damaged rocker arm you spotted.



There is a spring, a heavy spring washer and pair of valve keeper locks on each valve.

You will need a valve spring compressor to compress the spring fully so that the keeper locks can be removed. The keeper locks hold the valve pin tightly at the washer and the washer exerts upward pressure on the valve stem via the spring. Don't lose the valve seal as it might pop out and go flying. It usually has a small tension spring that keeps the seal tight on the valve stem.

Pull the valve out and check for obvious damage. If there no obvious bend then roll the valve stem on a flat surface and check for bends in the stem.

Bent valves almost always leave a nasty dent behind on the valve seat which will prevent proper compression in the affected cylinder. (sound familiar???) A dent gives a perfect path for pressure to escape and a possible ignition fire to flow through the dent...and if its the intake valve that was damaged the flame will flow back through the intake system and cause more trouble.

If a new valve needs to be installed it may require a resurfacing of the existing valve seat or a new valve seat entirely. The old valve guide might also need to be changed due the new valve. Changing these pressed parts is not something you can do at home, it requires an engine shop.

[Jedidiahwiebe]

Fingers crossed for the valve guide to be okay!

[Jedidiahwiebe]

Well, for some reason none of the valves showed any sign of bend. I even had an experienced cylinder head rebuilder who I trust check it out. 3 of the 5 camshaft hold downs were broken however. So I've replaced those, new valve seals, lapped the valves. Cleaned it up and ready to put it back together.

When I noticed a good handful of scratches on the sides of cyl3 and a few on 4. At the very least 20 thousand km ago I had TWO glow plug tips shatter, and the bits of ultra hard metal naturally bounced around in there for a while whilst pounding neat looking impressions in the tops of the pistons and the bottom of the head before finding their way out the exhaust valve (one tiny piece even seems to have lodged in the top of the piston! But I picked it out.) Soooo I guess they also took their opportunity to make a few scratches on the side of the cyls. Just enough to feel with your fingernail but not your fingertip. These scratches have been there for a couple years and I haven't noticed a thing. I use a teeeeeeny bit of oil, but maybe that's because of a leak? Compression on that cylinder is about 450 according to my new gauge.... the other two read 475. So I guess that's good.
What to do? These scratches are presumably polished out as much as the rings are going polish them. Will it develop into some worse issue? Or is it just going to be the way it is from now on?
Thanks!

[TieMyShoe]

DIY test for cracks you can flip the head upside down and fill each of the precombustion chambers with solvent (I used mineral spirits). If moister starts to appear in any of the ports the head has cracked between the combustion chamber and port.

This isn't as good as having the head xray.... but it works as a cheap DIY test.