Cylinder wall scoring. How much is too much?

[Jedidiahwiebe]

I figured I'd start a new thread as there isn't one on this topic yet that I could find.

I have the head off currently to assess the damage of a slipped timing belt. Broken rocker and cam hold downs. I think I've got that sorted out now. Was just about to reassemble, and noticed vertical scoring on the cylinder wall. This I believe dates back to two years ago when two glow plugs failed. There are numerous impressions on the pistons and bottom of head left behind while the fractured bits of glow plug bounced around and got crunched. Seems it scratched the cyl wall. Several scratches on one cylinder, and lots on the other. Very fine, can not feel with fingertip, but can with fingertip. Only one is deep enough to just barely catch fingernail.
I've been running it for two years with no problems, maybe an insignificant increase in oil consumption, but that could be leaks. No smoke. Compression on other cylinders reads 475 on my gauge, and 450 on the worse scratched one.

Is this something that will get worse? Or is it just the way my engine is now and it will just keep running as is?

How hard is it to hone the cylinder? Would I need new rings then too?

I don't want to do unnecessary work. I'm not a hot-rod guy, but I also want the van to last! Thanks!

[FalcoColumbarius]

Just a thought: Did you know that the motor comes with replaceable cylinder sleeves? Not that you need to do this, nor am I a mechanic, but it is a common practice in the diesel world to overhaul from time to time, which is what I will do when time comes. I don't like new style computer vehicles and I really dig my wagon. There is this guy I met recently who bought a Starwagon that had a recent T-belt change. The people who did the change did not change the oil seal because it looked fine. This is very poor economics. One day buddy parked in a hill and when he came back to his wagon there was a massive oil spill underneath. The oil seal had burst and oil was everywhere, including on the 20K old T-belt, which of course compromises the belt's integrity ~ so it's a new belt.

The reason I relate this story to you is, well you're in there, sounds as though you are already part way through an overhaul anyway, you want your wagon to last ~ what does your gut tell you? Having said that I believe a new set of sleeves is a G note. How was she performing prior to taking her apart?

Falco.

[Jedidiahwiebe]

I know! I just found out last night reading the manual about the replaceable sleeves so sweet! Too bad they didn't also supply it with replaceable cast iron heads!

My neighbour is gonna take a look at it, and if he says so I'll do the re-hone.

The thing was running amazingly until the second it broke down. I've only had really good performance out of this engine. Very pleased.

[TieMyShoe]

If you're already in there, whats a little more time and money. If the scoring is minor a hone will sometimes take it out, more severe will require boring or new sleeves.
If you pistons are badly damaged I have a set from my old motor sitting in the garage.

Just an FYI part number for for 4d56 and 4d55 rings are the same, it also appears the updated rings for the turbo motor are the same as the old non turbo rings. The manual will states the rings should look different.. however this is no longer the case.

[Jedidiahwiebe]

Oil pan off, first piston out. Honing away with one of those hones with the three stones. Only problem is I have no idea when to stop! I cant find any size mentions in my manual for max size before I need new rings. So far the hole is 91.05mm.

I also have no idea how to tell if the piston needs replacing. To tell the truth a big part of me doesnt really want to know...

[Jedidiahwiebe]

Also: tiemyshoe: If I need new pistons I'd be stoked to take you up on your offer

[TieMyShoe]

don't reuse old rings, if the piston is out replace the rings. They are going to run you about 200 bucks for a full set. The hone is actually designed to put a cross hatch pattern back into the cylinders. Don't let the hone sit still in one spot or you will be replacing those sleeves whether you like it or not. Basically the hone has done its job when the cylinders are no longer shiny and there is a good cross hatch put back into the bore. There's lots of good how to on you tube. Make sure you remove the oil squirters as well, if you catch one with the hone you are apt to snap it off.

The manual has cylinder specs in it. As for the pistons if they have notable dents/damage they should be replaced. Sharp edges can cause hot spots on the piston.

[FalcoColumbarius]

Jed, where are you?

[Jedidiahwiebe]

I'm in Salmon Arm brotha! Sorry it took so long to reply. Guess what? This repair didn't take. Evidence of blown head gasket/cracked/warped head. gonna teardown again. Feel free to stop by if you are in the area.