CAT 3208 new knock - Page 9

Edelweiss · 08-08-2016, 11:53 PM

Quote:

Originally Posted by robs523

I just talked to the mechanic that did the rebuild . . . .
He also really seemed to remember the job well and had a lot of good info, like cylinders being sleeved, and everything that was done to it to make it as close to new (and stock) as possible for a rebuild.

He also mentioned the exhaust manifold as a possible leak source. What I didn't ask him but should have is, does that mean I need to replace the exhaust manifold gasket? It's a metal gasket that looks in good shape so I wasn't going to replace it.

But what's this business about needing to true the head and block surfaces? Sounds complicated and expensive...

So they actually went so far as to machine the block and sleeving all the cylinders? OK, If that is true and the block isn't cracked that makes rebuilding it much more doable.

As Capt Jon said:
The manifold needs to be tanked and pressure tested. There may be an internal crack or rust through point between the exhaust chamber and the cooling water chamber. Cooling water leaks through the crack, into the exhaust port, through an open valve and into the cylinder.

The valves in the damaged cylinder were probably hammered pretty good by the chunk of piston floating around in the cylinder. The head needs to be taken to a shop or mechanic who does valve grinding, valves dropped and checked for damage. The shop will check and true the heads gasket surface if needed (make sure it's perfectly flat). The matching surface on the top of the engine block also has to be cleaned and checked as well, before you mate the head gasket and head to it. Maybe your mechanic can help you with this. If both head and block surfaces aren't true, the head gasket won't seal properly and eventually will fail.

sdowney717 · 08-09-2016, 08:14 AM

Seeing that expensive earlier rebuilding, got to wonder why it failed?

Due to them increasing the injector pump volume?
Or piston was defective, or did something like trying to compress liquid fracture the piston.

stone beach · 08-10-2016, 03:35 AM

[QUOTE="sdowney717;467848"]Seeing that expensive earlier rebuilding, got to wonder why it failed?

Rebuild was a long time ago...anything could have happened since.

robs523 · 09-14-2016, 09:30 PM

hello everyone, long time, no post. I replaced two injectors- the one on the broken piston was bad and one I managed to tweak trying to get it out of the head and ruined it. Put the new piston on, new rod, new rod bearings, and new rings. I filled it with oil and coolant, made a couple of rookie mistakes (oh yeah, the filter I took off two months ago wasn't ever replaced...) and got it started up. The good news is that I know I shouldn't have a chunk of piston flying around in the #8 cylinder. However, unfortunately, there is a knocking sound that sounds very similar to the knock that started all of this 3 months ago

. If any mechanics want to come visit Sitka and work, I can pay in fresh king salmon and halibut! I guess it's back to the drawing board, starting with the valve lash again and checking the rest of the injectors. It's been a journey to say the least

**Baker** · 09-14-2016, 11:15 PM

Ugghhhhhhhh!!!!!! Sorry to hear that!!!

BruceK · 09-14-2016, 11:50 PM

Oh no! That`s tough. I hope you nail it, somehow.

Busterbrown · 09-15-2016, 12:02 AM

Rob when I saw your post today I was hoping for good news I was a little sick to my stomach after reading it I hope you can find someone to help you out and get everything worked out.

robs523 · 09-15-2016, 12:52 AM

Quote:

Originally Posted by Busterbrown

Rob when I saw your post today I was hoping for good news I was a little sick to my stomach after reading it I hope you can find someone to help you out and get everything worked out.

thanks, it will all work out eventually. Honestly it's becoming a little comical at this point, but I sure do drink a lot more than I used too...(just kidding). I think it was harder the first time because that was prime fishing and boating season and we missed most of it this year, so it's actually a little easier to handle now that summers over, even though it would be a great boat to go hunting for a few days. I can still say I'm learning a lot every time I do something on it, and I'm forever grateful for all the help I've received here! I'll go back tomorrow or Friday and mess around with it again and see what happens.

Ski in NC · 09-15-2016, 08:26 AM

Go back through the valve lash checks. It is easy to get a pushrod out of position when putting the rocker shaft on and that can cause a bent pushrod or other grief. Spin each pushrod to make sure it is straight when valve is closed and rod unloaded.

River Cruiser · 09-17-2016, 07:22 PM

Did you have all the injectors cleaned & tested? I always replaced the injectors anytime I got as deep into one as you did, rebuilt injectors are cheap insurance. Have you cracked the nut on the high pressure lines while it's running to try to locate the cylinder with the problem? Good luck

robs523 · 09-21-2016, 05:34 PM

Quote:

Originally Posted by River Cruiser

Did you have all the injectors cleaned & tested? I always replaced the injectors anytime I got as deep into one as you did, rebuilt injectors are cheap insurance. Have you cracked the nut on the high pressure lines while it's running to try to locate the cylinder with the problem? Good luck

I only tested the injectors on the side I took apart. In hindsight I should have pulled the other 4 but my objective was to get it fixed and back together, I definitely had some tunnel vision after a couple months. But, I took it out Sunday and put a few hours on it and it seems like it's running good. Looks like the knock was valves, now I just a need a couple of oil changes and hopefully it will all be behind me.

A huge thanks again to everyone here, if you're ever in Sitka give me a shout!

Busterbrown · 09-21-2016, 08:07 PM

That's good news. I hope the quick fix works out for you. Keep an eye on your engine temperatures and don't let them over heat.

Hawgwash · 02-22-2017, 10:45 PM

09-21-2016, 03:34 PM----------------22-02-2017, 10:45PM.
What happened in between?

robs523 · 02-24-2017, 01:22 PM

well, I still feel like there's a knock and white smoke but I haven't been out past the fuel station since October. If it's not just my imagination, it's definitely nothing like it was when the piston broke, hopefully valves just still not adjusted right or something easy. And I will be the first to admit that I might just be paranoid. I've been down to the dock a few times and had it running for a while and it seems good, so I am going to go for it once I get the chance and take it slow and easy to start. We've had some unexpected circumstances make it hard to do much of anything over the past 4 months, combined with the winter weather, work, and a vacation and I haven't had much of a chance to try to get out yet.