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| Too much fuel locking cylinder(s)?... |
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hightide
New member
Username: hightide
Post Number: 1
Registered: 11-2008
| | Posted on Wednesday, November 26, 2008 - 08:27 pm: | 
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I have twin Cat 3208s that have been sitting for a while with start batteries removed and I have been hand pumping the fuel primer pump to keep fuel in the cylinders to keep them lubricated.
I found out later that the engine can be hand turned with a large rachet wrench applied to the large nut on the crank pulley wheel... however, the stbd eng turns 270 degrees and then stops suddenly and I can't get it to turn the last 90 degrees... afraid of forcing it. When turning it slowly through the 270 degrees I can feel the engine go through compression on some cylinders and can hear the valves breathing, especially if I have the oil filler caps open on the valve covers. The Port engine I can only turn 90 degrees and then it stops suddenly, feels like the stbd eng does. Oil in both engines is clean... no water in the oil... shining a light down the oil filler tubes on the valve covers shows the rocker arms and lifters that I can see through this opening, to be pristine and sparkling and appears to have an oil coating on the parts... no corrosion at all. I can't imagine that there would be stuck valves or lifting rods... both engines were running perfectly before removing the batteries so, the only thing I can think of is that I pumped too much fuel (every time I visited the boat)into one or some of the cylinders and as the pistons come up and push the fuel to the top in the compression stroke with both intake and exhaust valves closed that the compressed fuel causes sort of a hydraulic lock preventing the piston(s) going through the compression stroke. I suppose the next step is to remove the valve covers and inspect all the rocker arms and lifting rods and turn the engine by hand to see which cylinder(s)are not going through the compression step. If I can identify the cylinder containing the excess fuel, maybe I can make a tool that would depress the valve springs just to open the valve enough so the piston can push the excess fuel out without hitting the open valve. What do you think? Does this sound reasonable? Has anyone had a similar problem? If this doesn't remedy the problem, then I suppose I will have to remove the head assembly to hunt for the source of the problem... something I would like to avoid if possible. Any ideas or feedback would greatly be appreciated and I'll keep you all posted on this problem. Thanks. |
Hy Stat
Advanced Member
Username: hystat
Post Number: 981
Registered: 05-2007
| | Posted on Monday, December 01, 2008 - 09:38 am: |
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the fuel priming pump only builds about 40 psi. It takes about 800 psi to get the injector nozzles to begin opening. So the priming pump thing did not lock the cylinders with fuel. The injectors don't let fuel in until the actual high pressure fuel injection plunger for each cylinder reaches it's VOP (valve opening pressure)
It could be water in the cylinder from a failing riser or exhaust manifold. You'd have to pull nozzles and turn engine to verify. It could be the transmission or raw water pump etc you are feeling too..
btw, 3208 fuel systems hate water- they are fuel lubricated. maintain your water separator religiously. Water can make the fuel injection sleeves stick in full fuel and make those engines run away. |
hightide
New member
Username: hightide
Post Number: 2
Registered: 11-2008
| | Posted on Monday, December 01, 2008 - 06:26 pm: |
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Ok... Thanks Hy Stat. That is good information. The Engines are in neutral and I can roll the couplings over with my foot. Also, the raw water pump on the stbd eng has been removed to rebuild. On the port eng the raw water pump turns ok. Thanks for the tips on run away... just in case... how do you stop a run away engine... cut off the fuel?
Also, anybody know where I can get a shop (service) manual for the 3208? I wrote Caterpillar and they did not reply. |
hightide
New member
Username: hightide
Post Number: 3
Registered: 11-2008
| | Posted on Monday, December 01, 2008 - 06:29 pm: |
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If there is corrosion in the cylinder(s) I'm thinking of using a product call "Engine Release" that is supposed to dissolve the corrosion and free up the engine. Has anyone used this product or technique? |
Hy Stat
Advanced Member
Username: hystat
Post Number: 987
Registered: 05-2007
| | Posted on Saturday, December 06, 2008 - 01:52 am: |
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you stop a runaway diesel with a steel plate over the intake. Always remove air intake piping and have a blocking plate ready if starting a diesel after working on the injection pump.
If there is corrosion in the cylinders, you need to find the source of the problem.
You can't dissolve corrosion. Corrosion is a verb, not a noun.
Corroded iron is the noun.
Corrosion is an already completed reaction to oxidization. the metal has rotted away. You can't reverse the process and put the metal back. |
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