Cummins 5.9 6BT rebuild?

[Chris Hamilton]

Hi There,

 

I have a 1988 Chris Craft 480. It was re-powered with 5.9 6BT’s in 1993 (engines have 1600 hours on them). Long story but 5 years ago while underway something broke in the starboard engine. It was making a loud repeating banging noise. I immediately shut it down. I tried to restart and it did but same noise so shut it down. We continued on our way as we were headed away on a vacation. Tried to restart again and wouldn’t turn over. Upon return to the marina I had their “mechanic” check it out. First diagnosis was batteries….second was starter…starter checked out fine but they actually lost it. Then they said it was seized.Due to personal circumstances (divorce) I was instructed not to spend money on boat. Fast forward 3 years and I am chatting with an acquaintance who is a diesel mechanic (not marine) and he says he would be blown away if it was seized.  We mess around with the engine and with some force and coaxing we are able to get it to move. It will go through a (cycle?) and then get stuck. We were able to force it past the stuck point and again it would go through a cycle and get stuck. This spring divorce over and I am pumped to get boat back in action. Impossible to find help..no one will even come look at the engine. My girlfriend and I get the engine disconnected and up into the salon. Tranny and oil pan are off among other things. It has great access but I know nothing about engines lol. Finally I get Cummins mechanic to come look at it and he says “seized”….I am beyond frustrated as getting the engine off the boat is a major undertaking. Would anyone hazzard a guess as to what might have happened? My goal was to have it assessed on the boat so I can determine 1. can it be fixed on the boat? 2. Is it beyond repair and need of rebuild? The frustrating part is from what I can figure out..buying a rebuilt is about the same cost as rebuilding.So if it does need a rebuild I would buy a rebuilt and do a swap in one shot and then somewhere down the road rebuild mine as a spare.

 

Any thoughts would be greatly appreciated!!

 

Thanks

 

Topic

[Rob Schepis]

KDP

dmpaterson wrote:

I have read some horror stories about this pin in the Cummins 6BT5.9 diesels.

Where did you read the KDP horrors – on truck forums or on marine forum? – big difference there………

[dmpaterson]

Gidday all on the forum.
My apologies for the late entry.
I was just wondering if you got to the bottom of this problem and I’m curious to know if it was the dowel pin that aligns the timing cover that let go. More affectionately known as the KDP (Killer Dowel Pin).
I am currently in the process of buying a Bayliner 3788 Command Bridge in Australia of which could be the only one in country.
I have read some horror stories about this pin in the Cummins 6BT5.9 diesels.
Look for to anyone’s thoughts on the matter.

Here’s an interesting article

http://www.cumminshub.com/killer-dowel-pin.html

[Chris Hamilton]

oh boy lol..I need a vacation..good thing it starts tomorrow 🙂

Port #44840095

Stbd #44842948

 

 

[Rob Schepis]

They are not siblings, they are identical twins with the same serial number!

You posted the same number twice..

 

[Chris Hamilton]

Sure do

Port is #44842948

The re-power was done in Michigan by a good mechanic. I searched on the internet for info on him when I bought the boat in 2004 and he was even featured in a magazine lol.

Some additional history. Boat was re-powered and taken to salt water and then back to Michigan where it was sold and new owner literally never used the boat ( it sat in the slip for years). The last 3-4 years before I bought it the boat was not in the water (it was part of a litigation). So engines were barely run for years which I read is bad. I used the boat a lot from 2004-2011 never noticed any issues. Boat has been in inside heated winter storage it’s whole life. Right before the engine failed I changed the oil so analysis showed nothing.

 

Thanks

 

[Rob Schepis]

Do you have the port engine serial number?  Would be helpful if Tony could run both, would tell more about the overall history too and if your engines are siblings from day one or not..

[Chris Hamilton]

Hi Guys,

Thanks for the responses! I am headed away for 10 days so won’t have time to post pics until my return. Not sure how pics would help though since the engine is currently disconnected from everything and sitting on blocks up in the salon. I could take pics of the other engine which is still installed though if that would help.

I am not afraid to jump in just have literally no knowledge lol. The jerry rig to get the engine up into the salon worked well haha. I built a wood frame around the engine with 4×4’s and then used a 12v winch as well as heavy duty ratchet straps and went a little at a time adding blocking underneath as I went. I temporarily reinforced the salon floor and once up blocked the engine from the underside with 4×4’s. It’s not going anywhere. I will say I don’t think lowering it back down the same way would be as easy as I am carrying a lot of the weight on the straps and even though the winch can hold the engine it does groan lol.

Tony- that’s exactly what I was looking for! An educated guess as to what could be the issue. At this point I am sure that if I pull the engine off the boat I will be told it needs a rebuild so I am not against more investigation. If it is a valve in your opinion should I investigate more or if it is a valve am I rebuilding anyway? With the winch in place I bet I could pull the head off. If that’s what I would do lol. I think I read somewhere that I can’t sleeve this engine so if there is any internal damage to the cylinder walls it has to be machined and rebuilt.

Engines are Cummins 6 BTA 5.9 @300HP

Starboard Serial # is 44842948

Thanks again!

Chris

 

 

 

 

[Rob Schepis]

“My girlfriend and I get the engine disconnected and up into the salon.”

Well maybe pictures of one engine as installed..and the other leaning against the sofa!

No doubt that was quite the task for the girlfriend and you.  You mentioned you know nothing about engines but you’re certainly not afraid to jump in there – that’s a big plus.  Pictures should be interesting.

[Tony Athens]

Chris,

 

Before I get into the verbal part of trying to sort this out, you need to go down to the boat with a good camera and lift the hatches of floor in the boat…Stand back and take not less that 20 very good pictures of the engines “as installed”  in the boat.. I want to see everything from all angles and perspectives..

 

Send them to me direct ([email protected]) and let me sort thru them.. I’ll attach the applicable ones  you your post. Or you can attached them –your choice.

Your engines are over 25 years old and it sounds like one has a serious mechanical failure at very low hours.. On the surface, with the little you have said, and the way the engine “bars over”, if seems like you may have  “dropped a valve”.. Why?

That’s why I want to start with a good review of the overall installation..

Can you post you engine serial numbers so I can ID your exact 6BT?

Hurry!

Tony

 

 

[Author]

Replies