Help me trouble shoot my engine!

jrowan · Aug 4, 2012

Ps. You also recently offered me "advice" on routing a simple hose running from my crankcase breather to the air filter which is done on most Universal engines without problem. You assumed that my engine needed a complete rebuild because it leaked a few drops of oil. You also stated that my engine could run out of control & explode. You were wrong.

Stu Jackson · Aug 4, 2012

Easy, guys. I've been reading anchorclanker's posts here since he joined, and it took me a while to realize that while he has a non-diesel boat, he knows diesel engines.

Why not "get together" and help weinie out?

The fuel starvation has merits, but he says it starts right up when warm. Hence, a wiring issue. Perhaps I missed suggesting reading our C34 Critical Upgrades, many of which are engine and fuel related (for M25 series engines) but just as applicable to his:

http://c34.org/bbs/index.php/topic,5078.0.html

Bill Roosa · Aug 4, 2012

will not run up to speed, has black soot on the transom, and will not idle in gear.
I'm thinking the injectors are not atomizing the full well resulting in big (big is not really the word but larger than acceptable) drops of fuel which do not burn well. Explains the soot and lack of power at all speeds.
Is there some fuel system injector cleaner for diesels? simple, easy and cheap. you said you had all summer till you would be doing the work, whats to loose?

jrowan · Aug 4, 2012

Hey Weinie,

It's your money mate & I'm really trying to help you out & not waste it.
It my seem cheaper to try & fix it yourself, but when you start buying a bunch of expensive parts, & it still doesn't solve the problem then sometimes getting professional advice from a local marine diesel mechanic is worth it. When my first diesel engine cut out on me many yars ago, I did not realize that a fuel pickup tube could even have a small filter shoved into it that could easily clog, until my mechanic found it & cured the problem in 15 minutes. I was ready to spend $800 on a new injector pump. Your problem is probably relatively simple. Have you also checked the filter screen which is commonly installed inside the fuel injection pump on the fuel intake side? Sometimes partially blocked filters will inhibit full fuel pressure, and will not let an engine get up to full speed & cause stalling, because the engine is being starved for fuel. Also if your fuel is gunked up with bacteria sludge or water molecules, it will continue to clog filters until its polished or replaced. My advice is pump your tank & start with clean fuel (if its dirty)& work your way up to the injectors to find a potential clog. Everytime I've had a engine performance issue on a diesel it was due to a fuel problem. Having a mechanic perform a fuel pressure test at the injector / pump & a compression test are the key to finding your problem. I remember you saying that your mechanic did not have a compression gauge, or something? Maybe you should look for a mechanic who actually owns a full set of tools. Let us know what the culprit turns out to be. Good luck.

anchorclanker · Aug 4, 2012

jrowan said:
Ps. You also recently offered me "advice" on routing a simple hose running from my crankcase breather to the air filter which is done on most Universal engines without problem. You assumed that my engine needed a complete rebuild because it leaked a few drops of oil. You also stated that my engine could run out of control & explode. You were wrong.

Excuse me, but if you would simply read through threads and peoples responses, in their entirety, especially threads you started yourself looking for help and advice, you would have read that I confused your problem with someone else's, and offered you an apology that was never acknowledged and obviously not accepted. Instead of behaving like an adult, you waited for an opportunity to attack me. So thanks, I guess.

And because you brought it up, trying to make a fool of me, I will state this again. A diesel engine that suffers a run away situation, in which the speed is ungoverned, can exceed the safe RPM it is designed to withstand, and can suffer catastrophic failure of reciprocating components. It can occur through failure of the injection pump governor, rack failure, or intake of combustible vapors, through either internal or external means. In short, spun up to high enough speed a diesel engine will come apart.

Here is a good link on the subject, for those with an interest, though there are others as well if you do a search:

http://en.wikipedia.org/wiki/Diesel_engine_runaway

Fly_H23 · Aug 17, 2012

weinie said:
UPDATE:

The good news is that I did the compression test today. Both cylinders are at manufacturers spec.

Bad news is that I still don't know whats wrong! At least I don't think I'm looking at a rebuild!

Have you taken your boat out and run the motor hard for a couple hours? Diesels do tend to load up with soot if run infrequently at low rpm for short periods of time as we often do motoring in and out of marinas. Have you verified your prop size in determining what max rpm should be?

anchorclanker · Sep 24, 2012

You should still check/adjust the valves, which would conclude your maintenance. Outside of that and with everything else looking good, you may have an injection pump failing.

Just for the sake of discussion, what did you see for psi on the compression test?

anchorclanker · Sep 25, 2012

The compression is excellent, but of course cannot speak to the condition of the oil rings. The pump would need to be removed and tested on special equipment that measures fuel flow rates and other factors.

You havnt said, but have you checked valve clearance or injection timing yet? I know your having a hard time with the limited access, but its something that needs to be done regularly just as the other things are. I would not even look at the pump until I checked the valve clearance and injector timing, in that order.

If you get all of that done and still have trouble, then consider the pump. The labor to have the pump tested will be as much or more as the cost of a replacement, so its kind of a no brainer. If youve done everything yourself up to now, swapping out the pump shouldnt prove too difficult. Read the manual and look at the parts diagrams and youll see how it comes apart.

You will need to set pump timing again on a new pump, but with everything else done the motor wont require anything major for another 500 hours. If the oil rings are fouled, it could be the result of running the the engine in a poor state of tune. Once you get the engine running right, a few short period (10 hour) oil changes coupled with some good long hard runs will likely defoul the rings. It should then be okay until the next 500 hour service and if regularly maintained could run another lifetime.

leftbrainstuff · Sep 25, 2012

Valve clearance can't be checked visually. The manufacturer's procedure and specification should be followed exactly. For an older engine wear can occur in the valve gear including camshaft lobes, rocker arms and valve ends and stems. Valves are designed to rotate to even out wear and worn components can effect this.

Once the valve clearances are adjusted correctly then it is relatively simple but tedious procedure to assess actual wear.

I'd be more inclined to further asses your injection pump. It also sounds like you have some excess blowby past the oil control rings. This can often occur after the engine has run hot and hard. Other than a tear down and rebuild or using some engine oils designed for a worn engine you'll probably have to live with it.

anchorclanker · Sep 25, 2012

To accomplish a valve clearance check and adjustment, the main objective is turn the engine to get the valve lifter or cam follower on the base circle of the cam. On a two cylinder four stroke, when one cylinders valve reaches full open, the opposite cylinders corresponding valve will be on its base circle. IOW, if #1 intake is open, you can measure #2 intake, and vice versa. When #1 exhaust is open, you can measure #2, and vice versa. You need not see any marks on the flywheel to accomplish it.

The same can be done on 4 cylinder inline engines, as the end cyinders are paired, and the center cylinders are paired 180 degrees opposed. In this case you would measure #1 intake when #4 intake is open, and vice versa, #2 when #3 is open etc..

You will need to get the flywheel marks aligned correctly to check injection timing however.

If you have the injectors out you can turn it quite easily during valve adjustment.

kloudie1 · Sep 26, 2012

Pull out the kill knob and make sure it stays out.. Ya don't want to have one cylinder fire while you are playing with it.. Ideally, use a ratchet wrench to turn the crankshaft so if it does fire, the wrench will freewheel instead of breaking your hand.. Be VERY careful with this and make all crankshaft moves very slowly.do not try on a hot or warm engine.. Remove the valve cover .. determine which valve is intake and which is exhaust.. roll the engine slowly forward and watch the intake valve.. when it goes fully open (and the exhaust valve is loose) you will be on intake stroke.. continue to rotate slowly forward until that valve is fully closed .. continue to rotate the crank another 3/8 turn.. a little less than 1/2. At that point, you should feel both valves on that cylinder fully loose .. there, you'll be very close to top dead center on compression stroke.. That is where you set the valve clearance.. Do the same for the other cylinder and you are done..
Side note.. at one point, both valves will be tight and slightly open.. That is tdc on exhaust stroke and the beginning of intake stroke.. One full crankshaft turn from that point is TDC compression and where you set the valves..
I can't emphasize enough that ya need to go slowly when turning the crank.. and have the fuel kiil engaged.. We were messing with an old Kubota tractor like that and it fired .. no one hurt but our laundry folks knew there had been an event!