CAT 3208 new knock

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rob;
This won't help with solving anything but will hopefully give moral support.
I like your calm, through this thing; especially your clear and descriptive posts.

Both your posts and ski's are easy to follow and do generate good mental pictures. I sense no frustration at either end.

This thread is bound to help many others.
 
Thanks Hawgwash, I must have you fooled because at this point I'm ready to blow the boat up and buy an old truck. That way, with only 17 miles of roads, if it doesn't run at least I don't feel like I'm missing much.

Old Deckhand- Thanks, I have thought about it but was hoping to fix it before it came to that. I guess I should go ahead and post it on boatdiesel too, I recently joined since buying the boat

Blowby: When replacing the throttle shaft seal, I removed the intake manifold and now I can't get it back on- the bolt holes won't line up (it's not even on backwards). I put a little bit of effort into it but decided to save my energy and frustration since I might just have to pull it right back off and am waiting for the correct replacement gaskets anyway. The ports that the push rods come up through all seem to be smoking equally though, if that matters.

I went to the boat this morning and started it up. When I listen with my ear, it sounds like it's definitely the #8 cylinder. When I try the screwdriver-as-a-stethoscope idea, I can't hear the knock anywhere. I tried all around the valves and exhaust manifold and just couldn't hear it.

After it was warmed up, I revved the engine to my best guess of around 1500 RPMs since that tach isn't working (Aetna thinks I need to use shielded cable, but that's a project that can wait) and turned the key off. The engine stopped almost immediately, no coasting to listen to that I could tell. It might have knocked once, but it stopped so fast I really can't say. I had to get back home and get ready for work, so I'll try again tomorrow.

I have not done the following from this forum: tear apart the oil filters to inspect the media, try to find a camera or boresight, swap injectors to see if the sound moves

The fisherman next to me said he doesn't think it sounds off at all, but that knock was absolutely not there one week ago, and when it started, it was very loud and obvious, so I don't think I've just lost my mind (but it's always a possibility)
 
robs523 said:
The fisherman next to me said he doesn't think it sounds off at all, but that knock was absolutely not there one week ago, and when it started, it was very loud and obvious, so I don't think I've just lost my mind (but it's always a possibility)
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Rob
If you haven't already done so, why don't you send the Youtube video file of the engine running to the Cat shop and get their opinion on the knock.

ps:
I don't want to question you mechanical skills. But every time I listen to your engine video, I come away thinking I'm hearing excess valve lash. Are you absolutely positive that each rocker was off it's cam lobe when you set the lash? Or maybe a broken spring or bent push rod?
 
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I never even thought of trying to send the video to the Cat shop, that's a great idea

By all means, question my mechanical skills. It's the first time I have done valves. Well, the first two times I guess. I did my best to do it exactly as the book explained but I have no reason to believe I still couldn't have done it wrong. I didn't see any broken springs and looked at all the push rods and they all looked straight and in tact. Hopefully I come away from this embarrassed by something cheap and easy, that would be great. And if it happens, sorry for wasting your time and I'll claim my account was hacked and I never wrote any of this...
 
I have had the best luck when using the screwdriver or wood stick trick is to be wearing ear muffs. The muffs shut out the excess noise and by putting the handle on the muff you can her pretty darn good.
I had a 3208NA in a past boat that broke a valve spring. Ended up messing up one cylinder. My local Cat dealer just bored that cylinder and installed an oversized piston. When I asked him about the balance being off he told me Cat makes pistons both 30 and 60 oversized and they weigh the same as the stock ones. He said you could mix and match as needed. I am not a mechanic so take this with a grain of salt. I do know the engine ran very well for the next few years until I sold the boat.
David
 
I cant hear a knock on your video..just valve "tappet" noise?
If none of the valves are sticking , ski already told you to check this and this is very important to be sure about, then I don't see this rattle is too much to worry about..... insufficient valve clearance leads to problems, too much clearance (within reason) results in nothing more than a slightly irritating noise just like this one.
If you have wear on the rocker arms, which you will have unless they have been replaced, then it is somewhere between difficult and impossible to set the valve clearance correctly.
You can try to waggle each rocker arm or the push rod ends up and down and see if they are all equally "loose" at the setting point, you might be able to find one that moves more than the rest ?? tighten this one up slightly ignoring the feeler gauges but ensuring you keep the push rod movement similar to the rest and hopefully the noise will go away...alternatively, if it was mine, I would just ignore it and get on using the boat. If it is something more serious it will soon let you know !!
I am assuming there is no connection between the noise and the original smoke...that's another thing it is easy to become obsessed with, its an old boat after all and some smoking on start up is to be expected, smoking under load is a different story.
 
Thanks Stone Beach, the knock is brand new and pretty loud while operating the boat but harder to hear on my video. I sent the video to the nearest CAT shop and they said it's not fuel, it's metal on metal and I need to send them an oil filter and have them test an oil sample but they think it's in the bottom end based on the videos. I removed one filter and cut it open and there are some very small flakes, but not much. Then I realized that I might need to inspect both filters in case the other was the first filter and catching the larger stuff, if it's there, before the oil goes to the next filter. Or maybe I created the flakes while cutting the canister open.

So, How much metal in the oil is too much? I might cut the other filter open along with both on the port side just to look at all of them. They weren't due for a change yet but maybe I'll just go ahead and change it all anyway. Of course I might just have to do that again if there are new shavings made every time I run it and work on it until it's fixed.
 
robs523 said:
Thanks Stone Beach, the knock is brand new and pretty loud while operating the boat but harder to hear on my video. I sent the video to the nearest CAT shop and they said it's not fuel, it's metal on metal and I need to send them an oil filter and have them test an oil sample but they think it's in the bottom end based on the videos. I removed one filter and cut it open and there are some very small flakes, but not much. Then I realized that I might need to inspect both filters in case the other was the first filter and catching the larger stuff, if it's there, before the oil goes to the next filter. Or maybe I created the flakes while cutting the canister open.

So, How much metal in the oil is too much? I might cut the other filter open along with both on the port side just to look at all of them. They weren't due for a change yet but maybe I'll just go ahead and change it all anyway. Of course I might just have to do that again if there are new shavings made every time I run it and work on it until it's fixed.
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I am thinking any metal that you can see with your naked eye is way too much. That is my very ignorant opinion.
 
here are a couple pics. Doesn't seem to stick to the magnet, but they're so small I'm having a hard time keeping track of them when I try.
 

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Never dealt with the 3208na if I had a cats that's the ones I'd want. I've rebuilt 2ea 6bt and 1ea 4bt. Sounds like a rod knock to me.
 
Well the metal in the filter tells the story it is not an injector. That much metal in the filter is almost certainly a serious internal problem. Where it mine I would be removing the pan and having a look.
 
robs523 said:
here are a couple pics. Doesn't seem to stick to the magnet, but they're so small I'm having a hard time keeping track of them when I try.
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It may be bearing metal and not ferromagnetic. Testing the oil samples will prove that one way or the other.
 
if you had a failed bearing I would expect to see more white metal particles in the filter, having said that there shouldn't be any in the filter so something is wrong.

I can't hear a knock on the video, as previously explained, however if you can hear one then continuing to run the engine (with a knock) brings a serious risk of possibly major damage.

As you have just bought the boat you don't know how long it is since the oil filter was changed....all the failed bearing material might be in a previous one so the lack of material in the filter now doesn't mean there isn't much wrong.

Similarly an oil sample analysis may not tell you that much, the oil might have been changed the day before you bought the boat ???

I am afraid you need specialist help at the boat not this internet guessing game before you end up with a wrecked engine !!
 
Thanks everyone, you all have been a great help! At this point I'm going to look at getting a CAT mechanic over here from Juneau. I'll let you know what the final verdict ends up being.
 
Did you ever check the blowby for "puffing" as suggested way back??
 
Ski in NC said:
Did you ever check the blowby for "puffing" as suggested way back??
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When replacing the throttle shaft seal, I removed the intake manifold and now I can't get it back on- the bolt holes won't line up (it's not even on backwards). I put a little bit of effort into it but didn't try very hard since I'll just have to pull it right back off. The ports that the push rods come up through all seem to be smoking equally though. Is that the same, or should I get the manifold back on and check it?
 
Bolt holes should line up, unless cylinder heads are not in the same spots!!! One thing that is tricky is one bolt on the right head next to inj pump has to be backed off, but not removed as it hits the inj pump. Manifold is slotted so this is not a big deal. Mani takes a bit of wiggling to get it right, and get all bolts in loose before snugging any up.

And you want to put the intake on before putting the injector hard pipes on, at least I think they are in the way? So you did shaft seal, then put inj lines on, then cranked engine with intake off and rocker covers off? Nothing wrong with having intake ports open, but dang it if anything gets in there you have a problem.

Any chance something dropped into head intake ports while all this is opened up? That will make for a heck of a noise!!
 
My advice as a marine engineer is to stop touching this engine and ask for a diesel specialist to come. You can do severe harm without knowledge. For me the sound points to a piston or piston-rod.... Every time you start this engine you possible worsen the situation..
 
Reiziger said:
My advice as a marine engineer is to stop touching this engine and ask for a diesel specialist to come. You can do severe harm without knowledge. For me the sound points to a piston or piston-rod.... Every time you start this engine you possible worsen the situation..
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I still can't get a local mechanic to look at it since I'm a pleasure vessel and not a fishing vessel, which I understand but it's very frustrating. The CAT shop in Juneau thinks the engine needs an overhaul which would probably cost $35000, based on the youtube video and oil filter pic I emailed them. But they said the good news is that there's a long block available in Germany...

Since I don't have a spare $35000 and these engines supposedly only have 1700 hours since being rebuilt, my next plan of action is to send in an oil sample and start tearing everything apart myself. The biggest thing I am lacking, which is definitely a very big thing, is the ability to diagnose the problem in the first place to know what to fix. But I guess a little On the Job Training will do me some good. What's the worst that happens, I can't use the boat that I'm paying for and, well, not able to use now anyway? Then I'll change oil and filters every few hours for a couple times and hope to get enough metal out that it won't do more damage, but at least I can use the boat I just bought.
 
I'd say wait and figure out for sure what is going on. And you should be able to find a replacement or rebuild for a helluva lot cheaper than $35k I would think....
 
robs523 said:
I still can't get a local mechanic to look at it since I'm a pleasure vessel and not a fishing vessel, which I understand but it's very frustrating. The CAT shop in Juneau thinks the engine needs an overhaul which would probably cost $35000, based on the youtube video and oil filter pic I emailed them. But they said the good news is that there's a long block available in Germany...

Since I don't have a spare $35000 and these engines supposedly only have 1700 hours since being rebuilt, my next plan of action is to send in an oil sample and start tearing everything apart myself. The biggest thing I am lacking, which is definitely a very big thing, is the ability to diagnose the problem in the first place to know what to fix. But I guess a little On the Job Training will do me some good. What's the worst that happens, I can't use the boat that I'm paying for and, well, not able to use now anyway? Then I'll change oil and filters every few hours for a couple times and hope to get enough metal out that it won't do more damage, but at least I can use the boat I just bought.
Click to expand...

Knowing what is wrong is only part of the big picture. You need to havea proper failure analysis done so you know why it failed at such a low hr and how to make sure it doesn't happen again.
 
You have probably visited these thoughts.

You said earlier those engines were rebuilt in 2004.

Then...

When you sea trialed the boat in May, you said the owner and surveyor commented it was a good thing there was no smoke. Right after the cheque was cashed you had smoke.

Coincidence?
Did you have the engine surveyed?
Oil analysis?
Who found the boat and/or engine surveyor?

Probably a close boating community there; you think there is something you don't know?
 
Your frustration is understandable but hang in there, better days ahead.
Your engine is extremely common in non-marine applications. We ran lots of them on dry land in trucks and loaders and scrapers and such. CAT shops are notoriously expensive though also notoriously well qualified. We avoid them when we can and we have been able to find some real talented people that work on these things outside of CAT shops. Some of them are retired CAT folks and have all or most of the tricky little gadgets that you might need to work on them like the captive timing tool among others. At one point there was just a bunch of these guys that came out of the oilfields in Alaska and some of them even made their way down here and have been helpful.

Try going inland a ways and asking small construction companies who they are using for independent mobile mechanics. You may run into some options like a moonlighter that can at least give you some good advice and point you in the right direction. We would take the heads off and take them to a good machine shop and sometimes we could find a short block take out and hang the old auxiliaries on the new block. Once in awhile we would rework one hole but if we could find a short block for a few grand, usually went that way. Could be as simple as a rebuild kit and/or a crank and you can get the kit aftermarket and find or machine the crank.

Good luck with this. The diagnosis is the key and if you haven't lived around these things, you should really find some help with that to keep you from going down a rat hole that is unnecessary. Missing a torque spec or some other little thing could make a small project into a big expensive one. Take breath!
 
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Rob- At this point I am a bit confused as to what exactly has been done to the engine. I understand you bought it running ok, then pulled the intake to change governor shaft seal, then intake would not go on, and then you ran it with no intake and also you can not check blowby because the rocker covers are off? And somewhere in this process you got a "tick".

To help us out in putting all the pieces together, and to keep you busy while waiting on a mechanic, take some time and develop a complete timeline of exactly what was done to the engine, what symptoms showed and when, and the engine running details such as rpm and noise in between steps of work. Be concise, but leave out no details. Piecing it together from thread posts leaves gaps.
 
The Cat dealer in Kansas City would roll in new bearings at 90,000 miles in 3208 truck engines because they would start flaking bearing material at 100,000 miles according to oil samples. With the metal you found in the filter media I would not run the engine at all until it's been repaired, any running could drastically increase the cost of repair.
 
"To help us out in putting all the pieces together, and to keep you busy while waiting on a mechanic, take some time and develop a complete timeline of exactly what was done to the engine, what symptoms showed and when, and the engine running details such as rpm and noise in between steps of work. Be concise, but leave out no details. Piecing it together from thread posts leaves gaps."

Here you go-

3208 Timeline

May 5- The boat became mine a couple days ago so I decide to change the oil and all filters, along with all the fuel filters and engine zincs. My goal was to change everything (belts, water impellers, coolant, tranny fluid, whatever else I could get my hands on but no main bearings or rods!). At this point there was 1605 hours on starboard engine.

Mid May, a CAT mechanic that was in town came and took a look at the motors because I was a little concerned about a fuel leak from the throttle shaft seal on both engines. He confirmed what several others have told me- it’s something that should be fixed sooner than later but nothing catastrophic will happen, just wasting fuel from the leak

Over the first 6 weeks or so after we bought it, we put about 110 hours on the engines. Going long distances, short distances, trolling, sightseeing, fast slow, etc...No knocks, no unusual noises, but I do have to prime the fuel and purge the air from the bad seals. Otherwise, everything seemed good. I pay very close attention to the gauges I have (oil pressure, fuel, and water temp) every time we go out and they never go out of range. I always check the oil and coolant levels before going out. Every once in a while I have to add some oil but not huge amounts. The oil pressure is always good, according to the gauges, so I was hoping to make it a winter project.

June 21- The boat is loaded up and we’re ready to start the family vacation. Engines have been running in the harbor and are warmed up. We go a few hundred yards to fuel up and after getting fuel, I restart the motors and notice more white smoke than I remember seeing before coming from the starboard side and make a mental note to pay closer attention. About 20 or 30 minutes later, I was going a little faster than cruising speed to make up for lost time but nothing extreme. Then all of a sudden I hear a very loud knocking sound. I immediately pulled back on both throttles and put both engines in neutral. I turn off the port motor, knock continues. I turn off the starboard motor and knock goes away. I ask my wife to restart the starboard motor while I go to the ER to see if I can find anything obvious. There was a lot of smoke and the fuel leak was pretty excessive, worse than it’s been, and the knock started right away and was loud enough to make me very nervous so I signaled to my wife to turn it off right away. I think the fuel was on the exhaust manifold, so maybe this is a blessing in disguise- I don’t know if it would get hot enough to ignite or not?? I didn't think so, but maybe I was wrong

We limped out on the port motor to a nearby cove and anchored up for the night in order to try to make the trip not be a complete loss. I started the motor the next morning and the knock was still there so I turned it right off. On the way back in, I talked to my friends wifes uncle (ever see Ferris Bueller? Anyone? Anyone?) who is not a mechanic but a fisherman that has had CATs for years. His recommendation is to fix the fuel leak first since I know that problem exists. Unfortunately fishing season is here so all of the people that know about these things are either booked solid or out fishing. The great news is that after I put in the new seal, it doesn’t leak or need priming anymore, so the seal fix worked for that. But the knock is still there. This brings me to June 24th when I came to the forum I have learned to trust and love, and hopefully contribute to someday instead of just leach info from all of you...

I got directions on how to replace the throttle shaft seal from boatdiesel, and it didn’t mention removing any fuel lines, so I didn’t. It wasn’t easy to get the air intake manifold off that way but it worked. Thats how I’ve been able to crack open injector bolts and try to do other diagnostics you all have mentioned since I originally posted. I have kept the intakes covered up when not on the boat and I am confident that nothing has fallen in, but this all started before any of that was ever removed anyway. I tried listening with a screwdriver, cracking injector lines, and correcting valve lash (twice). I have posted here, boat diesel, and paid for an opinion on justanswer.com, been on the phone and email with the CAT shop, had a couple of pseudo-mechanics offer opinions, talked to experienced boaters at work, and anything else I can do. I am in the process of looking for a lab to get oil analyses but ran out of time before I head out of town tomorrow morning. To be honest, I don't have a lot of faith in the shop that says I need to spend 35k without even seeing the motor. This is the same shop that said the motors were fine 7 weeks ago. I'm not saying they're crooked, but I'll probably get a 2nd opinion before going back to them. After everything lead to dead ends, I pulled the oil filter and found the flakes. I have not started it since then, nor do I plan to. Tonight I tried to drop the oil pan only to learn that the forward motor mount bracket is in the way. I have to go down to Klawock for work for the next 10 days and when I get back there’s a mechanic that wants me to give him a call so he can try to come take a look. Hopefully while I’m gone I can learn how to jack up my motor enough to remove those bolts without sending a jack through the bottom of the boat!

I don't know the RPMs because my tachs don't usually work. I try keep it around 7-9 knots and adjust the throttle so it sounds even. This is what I have seen from the PO, the surveyor, and the broker from another vessel I had surveyed in WA. When the knock started, I was probably closer to 12 knots. WOT gets me to about 17-18. The knock knocks at all RPMs, whether in neutral or in gear. If you would like any other info, let me know and I'll do my best.
 
35k for a 3208 rebuild is crazy high. 3208 is hugely popular truck engine, and short blocks are everywhere. Possible 35K for cutting hole in boat to remove, patching hole, re paint, complete installation with sea trial, turn key out the door...?

Once you figure out the exact failure...upper end or lower end you'll know which direction to head.

My experience with those engines is that if piston bore is scored, you're better off to short block it vs re bore over sized. As others have said, some consider them throw away blocks.

I'd go for an oil sample even though you don't have a base line sample to compare it against. OS will be able to tell where the metal came from.

As others have said I wouldn't run it any more as a catastrophic failure could cost you big time in core charges. The problem could be in the lower end, and unnecessary running the engine could cause the problem to spread to the upper end.

I feel you're pain as I've been down this road a time or two with some of my heavy equipment. We had fairly good luck with 3208, but not so much with his little brother 3204.

Thanks for keeping this thread updated.

Conall
 
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