Stuck! Need advice ASAP 7.4 motor knock- need to get home!

Russ Calasant

Russ Calasant

Active Member
Dec 9, 2009
2,128
East Greenwich, RI
Boat Info
2001 480 DB
Engines
CAT 3196
Not a good trip, cruised obout 19 miles to destination as I was pulling into the harbor my port motor quit. Starting it up she will run but sounds like not firing all cylinders and a loud knocking or rapping noise coming from what sounds like top of motor. I need to limp back home on one motor in a couple days and I am told I should "lock" the shaft on the non running motor. I have V drives, anyone have any advice? How do I lock it?
A little history- I replaced the manifolds beginning of last season and noticed a little moisture in the center outside manifold of this motor. This spring when starting it rumbled like it was skipping a cylinder, puffed what looked like a little oil smoke and gas sheen on the water top out of the exhaust. When warmed up it was fine. It has done the same a couple times when not run for extended periods since that time. Obviously it has finally given in and something is broken. The temp was and is good as is oil pressure and condition.
I am stuck on an island with out mechanics or service of any kind, any help is appreciated!
 
The moisture is an indicator of something going wrong.Could have broken a rocker arm, pushrod, or bent a valve that got stuck from the water getting in a cylinder.Could pull the valve cover and look .
 
I never heard of "locking a shaft". Where did you hear that? If that advice is legitimate, then somebody on CSR will chime in soon. Be patient & good luck on your return trip Russ.

~Ken
 
Russ,

Sorry to hear about your issue, but it does sound like it is in the top end (this is good as opposed to the bottom end). As mentioned above I would start by pulling the valve covers and just see if all the rockers look the same. Hopefully a valve did not break and drop into the cylinder... You may not see anything by looking but you have nothing to loose at this point. Your not going to find a mechanic that works on gas motors in Block unless you have him come over by ferry, just went through this with a buddy of mine. At least you don't have a long ride back, if you have drip less seals you should lock the shaft by putting a pair of vise grips on the shaft and brace it against the stringer or transmission.
Again sorry for your trouble but it was good meeting you this weekend in Montauk...
 
Bt Doctur said:
The moisture is an indicator of something going wrong.Could have broken a rocker arm, pushrod, or bent a valve that got stuck from the water getting in a cylinder.Could pull the valve cover and look .
Click to expand...
Thanks,
That's what I was thinking but I don't know a lot about motors, worth a look when I get back home. Are any of the above mentioned issues expensive/major fixes?
Any input on the shaft and traveling back?
 
electricaldoctor said:
I never heard of "locking a shaft". Where did you hear that? If that advice is legitimate, then somebody on CSR will chime in soon. Be patient & good luck on your return trip Russ.

~Ken
Click to expand...

Thanks Ken, yes , I was told the shaft lube is an issue and the transmission on the free spinning side that's not running will cause damage.
 
Just a thought, I'm assuming that the reason locking the shaft was suggested was to prevent the prop from turning the motor. I know absolutely nothing about V-drives, if the throttle lever is not engaged and the prop is turned manually will it try to turn the motor? I would not think so but if it does maybe it would be just as easy to remove the prop.
Sorry for the problems your having.
 
Larry said:
Russ,

Sorry to hear about your issue, but it does sound like it is in the top end (this is good as opposed to the bottom end). As mentioned above I would start by pulling the valve covers and just see if all the rockers look the same. Hopefully a valve did not break and drop into the cylinder... You may not see anything by looking but you have nothing to loose at this point. Your not going to find a mechanic that works on gas motors in Block unless you have him come over by ferry, just went through this with a buddy of mine. At least you don't have a long ride back, if you have drip less seals you should lock the shaft by putting a pair of vise grips on the shaft and brace it against the stringer or transmission.
Again sorry for your trouble but it was good meeting you this weekend in Montauk...
Click to expand...

thanks Larry, pleasure meeting you also. If a valve dropped in the cylinder would it still run? Because she will run- just didn't think it was a good idea. How did your buddy make out? What was it and was it expensive? I do have dripless seals, really vice grips? I don't think I have any big enough- I will have to get in there, I assume there is a place to lock on? Any other way to lock the tranny?
 
Velvets like V`s need oil circulating .free wheeling dosent circ any oil. We blew a motor and tried everything ,including trying to pull the prop. Ended coming home at 5 Kts
 
If I understand correctly your saying that freewheeling without oil circulating can damage the V drive. I that's the case perhaps you can take a simpler approach and loop a line around the dead prop and tie it to an aft cleat. That would keep the prop from free wheeling.
 
Hey Russ.... Steve here "Retreat".... It was nice to meet you this weekend at the MYC. Sorry to hear about your engine trouble. I would pull the spark plugs to see if there is any water or metal deposits on the plug. Although the shaft seal manufacturer states that its is very important to maintain water flow to the shaft seal, I would think that is based on normal operating conditions. I don't know if the shaft would be spinning enough RPM's to do anything to the seal. It may be worth a call to the company and get their suggestion. I'm not keen on the idea of the prop be dragged thru the water rather than naturally spinning but may not be a big deal, I just don't know.....

BTW..... as you know I had my share of problems.... I was able to get the starter to engage an start the stbd engine... I figured I had nothing to lose , so I pulled the solenoid from the starter, messed with it by taking it half apart and it must of been just enough to allow the starter to engage.... I made sure the ignition key was on so if it did engage the engine would start which it did. Thank god! I think we left the dock before you awoke....
I was able to get a new solenoid yesterday, installed it and all is good again..... Fortunately a local starter rebuilding shop had one on a starter that he was willling to sell me.... Would you believe they don't sell the solenoid separately... you have to buy the whole starter... How crazy is that...
 
Go under boat and rap a rope around prop and strut and tie it off also put big vice gripe on shaft with rag on it. If you ran with prop spining you will burn out shalt and sceal $ 2000.00 mure damage or get tow boat to tow you back.
 
Dripless shaft seals are cooled with water that is pumped to them from the engines raw water circuit. If the engine is not running, then you are not cooling the shaft seal and will burn it out. Check to see if by chance your seals are "cross connected". It's simply a line with T fittings between both shaft seals. If you have this, then both seals will get water from either one running engine. My boat was not cross connected and my surveyor pointed that out. I had them cross connected for just this reason. From what I have learned, DON'T allow that prop to free spin unless you want to replace the dripless seal. This would require removing the shaft to do so and will get expensive with haul out etc. etc. If your's aren't cross connected, then yes, the vice grip, or a pipe wrench tightened against the shaft and held against the stringer is in order.
 
Last edited:
Russ, Sorry to hear of your problem. If you have a ZF hurth 630 v drive, allowing the shaft to "freewheel" should not damage the transmission. If you do not have cooling/lubricating water crossover from the running engine, you may do damage to the shaft and /or seal by allowing it to freewheel. In that case you have to tie it off to prevent the shaft from turning. You may be able to get an adjustable wrench on the coupling nut and secure it against a stringer with a good amount of duct tape or what ever you have handy.
I would also close the seacock to that motor before towing or running on one engine, to eliminate the possibility of forcing water through the sea water side of your cooling system and flooding the manifolds. (leave a note to that effect next to your ignition switch)
Hope your up and running soon.
Good luck
 
There are 2 potential problems with a free-wheeling shaft: One is the dripless seal gets no lubrication at all and the seal design used on Sea Rays is a Delrin collar or seal body that requires water as a cooling agent and lubricant. You might run a few miles at idle, but 19 miles probably will mean replacing the shaft seal. The only exception here is if your boat has cross-over cooling and you can tell that by checking to see if there are one or 2 hose barbs on the seal.....2 means you have cross-over cooling and you can run home on one engine. However, the second problem is a little more dire in the consequences department: SOME transmissions develop internal hydraulic pressure when the shafts free-wheel and turns the output shaft in the transmission. That will partially but not completely engage the clutch pack and can burn up the transmission clutches, so the problem isn't no oil flow or a lack of lubrication, but too much oil flow. Some transmission design can free-wheel without damage and I think the ZF-Hurth 600 and 800 series later replaced by the 60-80 or 65-85 series identifiers are ok to run free-wheeling. I don't know about other brands and Sea Ray has used Hurth, ZF, Borg Warner, Velvet Drive and Twin Disc brands at different times.

The safest thing to do is to tie off the shaft and go slow. Vice grips aren't going to have the holding power to do it. You need either a pipe wrench on the shaft/coupler resting against a stringer or a large adjustable wrench on the shaft nut and resting against a stringer or tied off in some manner. You can also tie off the dead shaft/prop with a line.

Also, from your description of your engine problem, you most likely have a broken rocker arm, bent push rod or a bent valve.

Good luck with it..............
 
Russ, that's a bit of bad luck. When planning your trip back home from Block, try to leave about an hour after low tide. Then you can ride the tide back into the Sound. I made that trip in my old boat on one engine and it was a long, long trip. You have less far to go, but still...

Let me know how you make out.

Gene
 
"locking the shaft" is for a few reasons. 1-if you do not have a crossover cooling line on your liqued cooled shaft seals, the rotation onf the shaft on the non-running motor while underway will most likley cause your seal to be ruined. if your shaft seals have cross over cooling lines-cooled from both motors, not just one, then you can run without locking the shaft. 2-the other reason which I know less about would be potential damage to the transmission from having the shaft 'freewheeling ' while underway. As long as your in nuetral on the bad engine, I don't think that would cause an issue but I am not a tranny expert. The shaft seal issue I am certian of since I just had mine upgraded to a dual cooling 'strong' seal . An easy way to lock the shaft is to clamp a pair of large pliers to the shaft and then lash it to someting stationary in the engine room. At slow speeds, this will work just fine.

Good luck!
 
Hey Russ........How did you make out? Did you make it back to Mystic ok? Any determination of what went wrong? Hopefully nothing to serious..... Best of luck and hopefully you will be back on the water soon.


Steve
 
Russ,
I'm sorry to hear that man. That really sucks! I wish I could be of more help but you've probably forgotten more about these set-ups than I know. All I can do is comisserate with you buddy and wish you well on the way home. I hope you get better conditions than we did coming from Montauk. Meanwhile my advise to you is to drink.............HEAVILY!!! Good Luck buddy!
 
cod said:
Hey Russ.... Steve here "Retreat".... It was nice to meet you this weekend at the MYC. Sorry to hear about your engine trouble. I would pull the spark plugs to see if there is any water or metal deposits on the plug. Although the shaft seal manufacturer states that its is very important to maintain water flow to the shaft seal, I would think that is based on normal operating conditions. I don't know if the shaft would be spinning enough RPM's to do anything to the seal. It may be worth a call to the company and get their suggestion. I'm not keen on the idea of the prop be dragged thru the water rather than naturally spinning but may not be a big deal, I just don't know.....

BTW..... as you know I had my share of problems.... I was able to get the starter to engage an start the stbd engine... I figured I had nothing to lose , so I pulled the solenoid from the starter, messed with it by taking it half apart and it must of been just enough to allow the starter to engage.... I made sure the ignition key was on so if it did engage the engine would start which it did. Thank god! I think we left the dock before you awoke....
I was able to get a new solenoid yesterday, installed it and all is good again..... Fortunately a local starter rebuilding shop had one on a starter that he was willling to sell me.... Would you believe they don't sell the solenoid separately... you have to buy the whole starter... How crazy is that...
Click to expand...

Hi Steve, thanks, I'm glad to hear you got her running and solved the starter problem- that is crazy but it is a boat, why buy a $20 part when they can make you buy the whole thing?!
 
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