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Discussion Starter #1
I've got a Volvo Penta MD7A with a failed CAV fuel injector pump. I'm removing it but want to make sure it is timed properly when I re-install it. The timing marks on the flywheel and block are rusted/painted over and I can't find them. I have no idea where to even start looking for them since the manual doesn't say where they are. What does the manual mean when it says "Rotate the flywheel until the valves on No. 2 cylinder "rock". Also, which is the #2 cylinder?
 

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Mechsmith
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Valves rocking is the term used for the position of the pistons at valve overlap. At a very short time in the cycle both valves are moving. This is on the top of the stroke on the cylinder opposite of the one that is firing. This is a handy way of getting the motor in position so you can find timing marks. (or even make some)_ Some Volvos don't have timing marks at all. Also some Ferraris. This works well on motors with an even number of cylinders. Three cylinders or five---not so much.
 

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Discussion Starter #4
I have a total of four manuals:
White 8.5”x11” (22cmX28cm) Workshop Manual Publ. 3023 May 1975
Green 8.25”x11.5” (21cmX30cm)Workshop Manual A 2(0) June 1998
Blue and White 6”x8.25” (15cmX21cm) Instruction Book Volvo Penta Marine Diesel Engine 2562 March 1972
Blue and White 6”x8.25” (15cmX21cm) Instruction Book Owner’s Manual Publ.3249B August 1980
None of them show which is #1 or #2 Cylinder, nor show where to look for timing marks.
 

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Mechsmith
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Basic timing.
To find or make your own timing marks.
First put the piston up.(either one) Then put a cellophane drinking straw through the (removed) injector hole. Back the crankshaft pulley until the straw goes down a bit. Mark the straw and the crankshaft pulley. Turn turn crankshaft pulley forward. Straw will go up. Keep turning till the mark on the straw is back down to the mark. Mark the pulley again. Top dead center will be 1/2 way between between the marks you made on the crankshaft pulley. Mark it.

Pump timing. Some pumps have an inspection cover. Usually held by 2 screws with marks underneath. If so there will be marks under it. If not turn crankshaft one complete turn and look for marks.

If no inspection cover then look for a bolt near the drive end that is doing nothing. Pull the bolt and look for a dimple in the shaft that the bolt will enter. If so turn the motor until the bolt enters the dimple and locks the shaft. If so this will give you factory injection pump timing.

If neither method works then you must set up a system that allows fuel to flow through the pump. Use an electric pump or a gravity set up. Through most of the cycle fuel will flow through the pump and out the return valve and hose. Back motor up a little, let fuel run through the return line and turn motor till fuel stops running. That is the moment of injection. It should be near the mark you made at TDC. This will vary from one to about 8 degrees depending on engine type. All diesels will run safely at zero. Most are set to start at that but not all by any means.

To look for marks. Crankshaft pulley ; Flywheel, either under starter or inspection cover or a slot in flywheel that lines up with a pointer. A dot on the flywheel that lines up with a hole usually near the starter. An inspection cover atop the flywheel housing with marks on flywheel.

Again some Volvos do not have marks period. Then you must do it the hard way.
 

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Logically #1 cyl would be that closest to the front of the engine??
 
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Mechsmith
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Unfortunetly logic may have little to do with it. At least one major manufacturer of inlines numbers motors from the flywheel (output) end. All three US auto manufacters use a different method of numbering their V8 engines.

Thats why you have to match the pump (or distributer in a gas job) to the motor. Yes, at times without a good book, I have torn out some hair.
 

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Another great unknown in this mixed world of ours. The great unknown? Which cylinder on a Volvo MD17B is number two. Volvo sure make it difficult for those of us trying to keep their marine engines going. Timing not right,buy a new engine. God forbid that the Volvo company should even attempt to help us keep their engines going.

Happy Harry
 

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Hi, several years later. 2021 And I had the same problem on my MD7a too. I also did not find a timing mark on my flywheel!
In this video the CAV DPA injection pump (which is fitted on a MD7a) is overhauled, at 05.00min in this video the man shows you where you can find your timing mark!

It may be handy for the people who are also interested!

Good luck.

P.s: If the video is deleted in the future, try to search on YouTube for "CAV DPA pump" !
 
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