CAT 3208 new knock

[Busterbrown]

Rob are the other pistons okay? What do they look like? Is that cylinder furthest away from the water pump? Hopefully the bottom end is still okay. The experts will chime in soon. Good job pulling the head off. Good luck on the repair.

[robs523]

Originally Posted by Busterbrown

Rob are the other pistons okay? What do they look like? Is that cylinder furthest away from the water pump? Hopefully the bottom end is still okay. The experts will chime in soon. Good job pulling the head off. Good luck on the repair.

Thanks. I only pulled one side, and this was the #8 cylinder. The other three cylinders looked fine as far as I could tell. When we were tearing it apart, we did notice the valve to the dripless bearings was pretty clogged up, I wonder how much water could even get in there. Maybe the cooling system has too much crud built up and it over-heated? I dropped the pan a couple days ago and everything appeared normal from a quick look but I also don't really know what I'm looking at, so take that for what it's worth. If the

Maybe a dumb question, but could the piston be replaced without boring the cylinder?

[Ski in NC]

Take the rod cap bolts out and pull that piston. You already have the pan dropped so that works well. If lucky, the cylinder bore can be cleaned up with a light honing and fit a new piston.

How does cylinder bore look? Any deep grooves?

[BruceK]

Fingers crossed robs523, hope it`s the easy fix. Sure explains the knock.

[FF]

For a very common engine it is sometimes possible to order an oversized ring set.

If honed a bit to replace the required lubrication hone marks the slightly larger ring can be fitted , just use the stock ring end gap..

[bayview]

fibers and dust get me thinking about swallowing an air filter

[Ski in NC]

Looks like debris got in cylinder or a big chunk of carbon got loose. Looks like a lot of carbon in there, but photos not real clear.

Get another piston and ringset. Make sure you get the right piston as there are several different ones for different models of 3208.

Plan on pulling the other head and cleaning things up there. Old motor will be glad it got two fresh head gaskets.

Clean all sealing surfaces with a steel scraper, use care to avoid gouging any metal.

Do NOT use scotch brite or similar silicon carbide pads or sandpaper to clean!! Abrasive particles are shed and it gets everywhere and makes havoc.

Figure out what is going on with that rod cap bolt you partially loosened- That needs to be resolved before pan goes back on.

Clean up all head bolts and replace any that are corroded or stretched. To check for stretched bolt, hold two together with threads meshed, any light coming through means one or both are stretched.

Clean bolt holes in block by hand screwing a bolt in each hole with something like wd40. Blow out hole with comp air, repeat until hole is clean and bolt threads in like butttaaahhh.

I usually check the valves by taking a few or all of them out and inspecting sealing surfaces. Sometimes a quick lapping job to verify good contact. Almost always the valves are in really good shape.

[robs523]

thanks everyone. We had the mechanic come take a look today and got some pointers on pulling the engine out. I think I'm going to build a cradle and get the engine in my garage, basically overhaul it over the fall/winter, and put it back in with the goal of fishing next April or May. If I'm really ambitious maybe I'll get to both of them by then. I'm sure I'll be posting a lot more questions via new threads as that process goes on, then who knows, maybe I'll be helping the next person in my shoes. Thanks!

[BruceK]

Originally Posted by robs523

thanks everyone. We had the mechanic come take a look today and got some pointers on pulling the engine out. I think I'm going to build a cradle and get the engine in my garage, basically overhaul it over the fall/winter, and put it back in with the goal of fishing next April or May. If I'm really ambitious maybe I'll get to both of them by then. I'm sure I'll be posting a lot more questions via new threads as that process goes on, then who knows, maybe I'll be helping the next person in my shoes. Thanks!

For the second engine I`d subscribe to "if it`s not broken don`t try to fix it". But for the defective engine you do need to establish why it failed, ? cooling system.

[Ski in NC]

Is cylinder bore in good shape? If so with a piston and some gaskets you could be running in a week.

[Busterbrown]

Had my engine bored in the salon If the bottom end looks good you might get lucky with a quick fix.

[FF]

"get the engine in my garage, basically overhaul it over the fall/winter"

If you do overhaul it , take the reciprocating goodies to a "speed shop" machinist. .

For very modest cost they will balance the crank, match the rod ends and the piston weights.

Take the crank damper (your new one) and the flywheel too.

The factory has "specs" but a machinist doing the work will make the engine smoother than you can believe.

You will need to watch the tach to see if its operating.

[robs523]

Originally Posted by Ski in NC

Is cylinder bore in good shape? If so with a piston and some gaskets you could be running in a week.

you guys are killing me. I had myself convinced I'd make it if I didn't get it fixed anytime soon but now I'm looking at every scenario and trying to figure out how I'm going to be fishing in 2 weeks when we have friends in town. The hardest part is that lousy "job" thing that always gets in the way, but now you've motivated me- Quit toying with my emotions!

So an in-the-boat honing seems appropriate, at least it does for a guy that's never actually done it (and should I just get a flexhone???), with a new piston and rings for that cylinder only. Clean up the rest of them along with the heads, put it back together, and see what happens. Then I'll just pray that both motors don't blow up on the same day and I should be good to go.

Hopefully the next pics are of fish!

[Ski in NC]

There is no one difficult step in doing this job, just a lot of steps and each must be done carefully.

Removing piston, honing bore and fitting piston would be best to do with someone experienced helping.

Try to make an arrangement with a local mechanic where he stops by periodically and mentors you. Maybe have him fit the piston.

90% of the work in this job is cleaning things and lugging things around.

[123]

I most certainly would not advice to hone out of hand, you end up with an elliptical bore. Find a magnetic drill-stand (rent) to keep it centered and to keep the honing pressure centered in the bore..

[sdowney717]

Being a diesel, how much piston to head clearance exists? Something will give, maybe the piston just collapsed.
You need to see if the rod is bent and if the crank journal got scuffed - cooked.

[Busterbrown]

Rob get that piston out and post some good photos of the cylinder walls, piston top and sides, rod, crank journal and journal bearings. Let the trawler forum army help guide you through this.

[robs523]

Originally Posted by Busterbrown

Rob get that piston out and post some good photos of the cylinder walls, piston top and sides, rod, crank journal and journal bearings. Let the trawler forum army help guide you through this.

Here's the piston. Makes me wonder if maybe an oil home was blocked? Looking at where it appears to have been hot. I'll try to get cylinder pics this weekend. Can't really get pics of the journal very well.

[robs523]

Oil hole, not home

[robs523]

Here's the connecting rod