Help engine quit when at low RPMs in reverse

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BikerLemur
Posts: 2
Joined: Feb 29th, '20, 23:26

Help engine quit when at low RPMs in reverse

Post by BikerLemur »

Hoping to pick the brain of knowledgeable members. I am a very new owner of a Cape Dory 30 with a Volvo Penta engine. I quickly found out that engine access is virtually non existent, gasp as I blindly tried to find the oil dipstick, but that is another story...
Currently I am having a problem When I throttled back to low RPMs in reverse ONLY. The engine quits. Always. Left us in some interesting situations while trying to dock.
Otherwise it runs fine in forward and idles fine.
We called a mechanic who said the engine needs some forward throttle to start also and there is a diesel leak when running at the injector pump. So he thinks it is either a line at the injector pump or the pump itself. He says he needs to remove the fuel tank to get to the pump.
So I have some pretty novice questions to you experienced “Cape Dorians”:
Anyone experienced the same problem before ? Was it the injector pump? How did you access it?
It sounds so nuts to have to remove the tank to work on the engine. Have you made any mods to your boat to have better engine access?
Thank you all help is appreciated
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Frenchy
Posts: 614
Joined: Mar 14th, '15, 15:08
Location: CD 33 "Grace"

Re: Help engine quit when at low RPMs in reverse

Post by Frenchy »

I'm just an amateur mechanic and not familiar with your engine, but I would suggest that removing the high
pressure pump would be a last resort. Try cleaning all connections with a solvent and drying. Then look for
leaks at those connections. Perhaps a small bit of air is being sucked in too and affecting performance. If you have
those copper banjo washers at the connections, you can make them soft again by annealing. Heat to a dull red
and plunge into water. Then re-connect everything with the right torque. You'll have to bleed at the injectors.
In case you decide to have the mechanic remove the injector pump, get an estimate. It may make more
sense to get a new engine if yours is old.
It's odd that the engine only quits in reverse. Maybe there's extra friction in the drive train or transmission
in reverse? If you put the transmission in neutral and hand-turn the prop shaft forward and reverse,
is there a difference? That's a bit of a mystery. Good luck in any case. - Jean
Jean - 1983 CD 33 "Grace" moored in
Padanaram Harbor
Massachusetts
BikerLemur
Posts: 2
Joined: Feb 29th, '20, 23:26

Re: Help engine quit when at low RPMs in reverse

Post by BikerLemur »

Thanks for your reply. I am very nervous about any work done to the injector pump. The mechanic doesn’t want to give me an estimate. He wants an “open ticket” because he says “he has no idea what he is going to find” or how long it will take to get access. That makes me even more nervous.
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Frenchy
Posts: 614
Joined: Mar 14th, '15, 15:08
Location: CD 33 "Grace"

Re: Help engine quit when at low RPMs in reverse

Post by Frenchy »

Yeah, I understand your concern. That injector pump and the injectors are the most intricate parts of
of your engine, machined to very fine tolerances. If you don't feel comfortable with this mechanic or
cleaning off the piping connections and looking for leaks (maybe with tissue paper dabbing around ), I would get another mechanic to look it over. The chances are high it's nothing serious. Mostly, it's simple stuff.
Your mechanic can't do anything with the injector pump, anyway. It would have to be sent off
to a testing facility ($$). You want to explore all other options first. - Jean
Jean - 1983 CD 33 "Grace" moored in
Padanaram Harbor
Massachusetts
Boyd
Posts: 403
Joined: May 9th, '05, 10:23
Location: CD 30 MkII

Re: Help engine quit when at low RPMs in reverse

Post by Boyd »

Hi:

I have two volvo md2020d's on my catamaran so I am familiar with the volvo line and their issues. I am assuming you have an MD series engine. You didnt mention how many hours on the engine or if the fuel has been setting a long time.

I am not comfortable with what your mechanic is recommending. There are a multiple of things that need checking prior to digging into the injector pump. Its the LAST thing in a long line of items I would touch. its also probably the most expensive to mess with as it will have to have the timing checked when its replaced. A slow and expensive process.

Check the following first. Any of these steps by themselves may cure the problem.

1. Is the prop clean? Barnacles? Damaged. If you suspect damage have it checked by a prop shop. Also check the cutlass bearing for excess slop. As mentioned by an earlier post the problem might be in the tranny but I would go thru all the engine checks first.

1a. Verify the fuel in the tank has no water or other contamination. Drain and replace if you have suspicions. Change all filters. Add Centane booster to your fuel. Verify the air cleaner is clean and not restricted.

2 Check the idle rpm with a optical tach. is it correct. The boat tach may not be correct. The transmission uses a different gear ratio in reverse and typically will put a slightly greater load on the engine in reverse. Low idle may be the problem.

3. Check that the engine revs to full WOT in neutral. Mine is 3400 rpm. Use an optical tach unless you have proved the boat tach is right. If not not able to make WOT you have either a clogged filter, weak fuel pump, or an air leak on the suction side of the fuel pump. If you have an air leak on the suction side of the injection pump then it will manifest itself in forward as well as reverse. I would just replace all fuel hoses and hose clamps as a matter of course. The stuff is cheap. Its possible the fuel pump (not the injector pump) is not working. Volvo no longer sells a rebuild kit for this pump. You have to buy a new pump.

3a. Bleed the complete injection system if you have a rough idle. If the idle is rough after bleeding, Crack open the nuts on each injector in turn and the idle should drop. Tighten and go to the next. If it doesnt drop on one cylinder then that cylinder is basically not functioning. Possibly you need to adjust valves or the injector is not working well.

4. If you have fuel leaks on the pressure side of the pump or at the injectors, fix that immediately its a fire hazard.

5. Any chance the water injector elbo on the end of the manifold is clogged. Those are famous for clogging and then ruining the manifold. The manifold is brutally expensive to replace. Take the exhaust water injection elbo off and if its not pristine get a new one. These dont last long. There are SS aftermarket versions much cheaper and better than genuine ripoff Volvo parts.

6. If all the above doesnt cure the problem, pull the injectors and take them to a diesel shop for rebuild. These generally need service at 1000 hours. I assume your exhaust is essentially clear or slightly grey. No other color in the smoke?

7. The normal maintenance interval for the injector pump is 1500 hours, but its not likely to need anything for a very long time. I totally doubt this is the problem. My engines have 3000 hours on each and I have never needed these pumps worked on.

Boyd
s/v Cat-a-Tonic
Prout 34 Catamaran
Fort Lauderdale, Fla.
sgbernd
Posts: 265
Joined: Mar 3rd, '06, 11:53
Location: Valhalla
CD-28 #359
Ventura, CA

Re: Help engine quit when at low RPMs in reverse

Post by sgbernd »

Having owned many diesel engines, including the MD7, the only reason to dig into pump is that it is leaking and needs to be resealed. The other problems (out of calibration, etc) are mostly things that can be put off if a bit of smoke can be tolerated. The usual failure mode is that it leaks and your garage or boat stinks of fuel.

My inclinations are as follows;

1) is the idle perhaps too low? Check the spec and against the tach and adjust if necessary. Maybe even adjust it towards the high side of the tolerance.

2) I assume you have a single level control. If so, there is a way to dis-engage the transmission from the throttle, typically a lever or button. Do so and move the lever to reverse. Does it still stall? If so, there is something wrong with linkage and/or idle adjustment because the engine does not know which way the propeller is turning and can go no slower than the idle setting. If it stalls, I'd suspect the idle screw is set way to low (or maybe fell out) and the pump control is resting on the cable rather than the idle stop. In this case, there is more slack in reverse which allows it to stall. But the real problem is that it is not resting on the idle adjust stop where it should be.

3) If it won't stall with the transmission disengaged but set to reverse, but will when the transmission is engaged, that hints the problem is in the drive line. As mentioned earlier, make sure the prop is clean, no lines, wire, etc. are fouling the shaft or propeller which might be free to turn one way but start unwrapping when spun the other way. While you are at it, and in the water, set the transmission to neutral (engine off) and turn the prop by hand a couple of turns both ways. It should spin fairly easily either way. If you are in gear, the clutch will engage one way but slip the other way so make sure you are in neutral.

Those would be my ideas to start with.

Good luck,
Steve Bernd
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