Identifying cavitation with heads off? Now with PICS!

[Thewespaul]

Honestly, you could probably put it back together with the old prechambers and be fine, it would work for as long as it would take to get a new engine, but I’d expect it to eat a lot of oil and blow a headgasket if it ever gets hot.

 

[volvo 4 life]

Even with cracks past the fire ring you think the head gaskets would hold? That's what I'm really concerned about considering the high compression of these engines. I can get all of the pre chambers from diesel cast for around $120 + shipping, but supposedly the heads will have to be skimmed afterward to make sure the pre chambers don't protrude out too much. I don't mind putting a little money into the heads since they could always be removed and installed on another engine but I have a hard time putting money into the block before hearing and seeing it running and knowing for sure that it isn't cavitated. I guess I'm just in a tough spot where either way it's kind of a gamble.

 

[Thewespaul]

If you’re not pushing the headgasket with boost I think it would be fine for some time if you treat it right. I’ve pulled heads off of engines with worse prechambers cracks that never used coolant, remember the fire ring is a multi layered metal o ring for the combustion gasses, cylinder pressure needs to overcome the strength of that material to blow it out, and a cracked precup won’t cause that. It will make a weak point in the fire ring because the separated material in the prechamber generally peels away from itself and isn’t flat, the head not being flat will affect the sealing more than the cracks. Either way, I imagine that head is cracked or at least warped where it would need to be decked anyways, so new prechambers would likely be the way to go.

 

[volvo 4 life]

Ok well I'll think about it a little more and decide in a week or so. Trying to recover from christmas expenses, haha. I'll try and keep the thread updated with my progress and what I decide to do, should be interesting to see the results at least! Thank you for all of the help so far, this has definitely been the best forum I've been on since I built my turbo Volvo with the help of turbobricks.com. Seems like the main stream forums aren't usually as helpful so I'm very grateful to say the least.

 

[IDIBRONCO]

So with cracks like those, how nervous should i be if I run it NA? It seems that these pistons can take a serious amount of abuse and rarely if ever, suffer catastrophic failure.

My honest answer would be a question: how far through the tops of the pistons do the cracks go? If they go all the way through, I wouldn't count on them lasting for a real long time. If they don't, you could be good for even another year or so. Now my estimates may be way off either high or low. You just can't really tell. When you do get it running again, just go easy on it. In theory, a piston could break apart and cause a rod or wrist pin to go through a cylinder wall. I'd recommend getting a replacement engine ready fairly quickly, just in case.

 

[IDIBRONCO]

Ok well I'll think about it a little more and decide in a week or so. Trying to recover from christmas expenses, haha. I'll try and keep the thread updated with my progress and what I decide to do, should be interesting to see the results at least! Thank you for all of the help so far, this has definitely been the best forum I've been on since I built my turbo Volvo with the help of turbobricks.com. Seems like the main stream forums aren't usually as helpful so I'm very grateful to say the least.

The good news here is that you could be the top Volvo expert on this entire forum.

 

[volvo 4 life]

The good news here is that you could be the top Volvo expert on this entire forum.

If you have any questions I'd be happy to help, I even have two of the now rare D24 idi diesel Volvo's.

 

[compressionignitionrules]

If you have any questions I'd be happy to help, I even have two of the now rare D24 idi diesel Volvo's.

aren't they just a 1.6 VW stretched out to a 6 cylinder 2.4?

your cracked cups are just ether starts, common...... if people are to lazy to change glow plugs when they ***** up. test and/or replace all your glow plugs!
put some idi turbo headgaskets in and you're good for years of pleasure. they are different than plain 7.3idi headgaskets. I got them from the Ford dealer but that was years ago., fire ring was much wider. Dads 90 F350 had an aftermarket ats turbo but basically the same as the 93/94idi turbo .

 

[volvo 4 life]

Yes essentially they're just a stretched 1.6d, they share most bottom end parts and valves and such. Very cool little engines, be great and rev over 5k! I will look into the idi turbo gaskets and probably just leave everything stock for now and see if the engine runs without using coolant. If so, then I'll probably do a full rebuild on it in the future. I'd feel better about it knowing the block is good and not spending the time and money on tearing it down and having it magnafluxed.

 

[Macrobb]

Even with cracks past the fire ring you think the head gaskets would hold? That's what I'm really concerned about considering the high compression of these engines. I can get all of the pre chambers from diesel cast for around $120 + shipping, but supposedly the heads will have to be skimmed afterward to make sure the pre chambers don't protrude out too much. I don't mind putting a little money into the heads since they could always be removed and installed on another engine but I have a hard time putting money into the block before hearing and seeing it running and knowing for sure that it isn't cavitated. I guess I'm just in a tough spot where either way it's kind of a gamble.

Slap the heads back on and run it for a while! I'm not seeing anything that would concern me to the point of stopping me.
The precup cracks are bad, but will probably be just fine for quite a while. Worst case, you blow another head gasket.
Cracks look like stress cracks, probably from getting quite hot. I doubt they are going to be a failure point, though.

I'd expect that this engine might use a bit of oil, but probably due to worn rings more than anything to do with the problems shown here.

Run it, then if you decide to do a rebuild, well, you'll end up boring it out and putting new pistons in it anyway.