MD7a Newbe

[Badsanta]

Be sure to turn the raw water intake off and then quickly turn it on as the engine starts. When doing alot of cranking you can fill up the exaust line with water and it will back up into the engine. Not a good thing. Something to watch for.

[MollyJo]

Guys I owe you an apology, I didn't properly look at the manual you linked to and assumed it was the same as the one I have. Sorry, having looked it properly it describes my issues exactly. (as you know), what a freaking goose!
Anyhow, my boat is now on the hard so battery/power for cranking shouldn't be a problem.

Interesting and lucky, I changed the impeller and did a lot of cranking before reading in other threads that flooding can occur as just pointed out on this thread.
I guess I did a poor job of that too as there was no such flooding. At the time I didn't know to use silicone grease and also used gasket goo (very thin smear though) but perhaps enough to spoil the seal of impeller against the pump cover. Learning heaps here thanks to everyone and I guess this is just the very basic stuff, hope you are all still around when things become involved.

[Badsanta]

Dont feel bad. Just read read read. You sound sharp enough to figure it out. Just give yourself some time.

[SkiprJohn]

Don't feel bad at all. I'll speak for myself here but I've learned most the stuff I know about diesels through making mistakes rather than reading manuals. Now I advise reading manuals and asking trusted experienced engine users.

I've done the cranking enough to flood an engine before but luckily there was no permanent damage. Strange I didn't mention it.

Good luck in your research and repair.

kind regards,

[Cheechako]

I think the filler cap is typical of low temp raw water cooled engines.

[Acushla]

You are getting great info on the requirements for bleeding the system here obviously from many hours of trying to get reticent engines to fire up. One point for you on the lift pump performance is that they operate off a cam driving a cranked lever to the diaphragm. If the engine stops with the high point of the cam against the crank and diaphragm then the manual operation is resrticted. Just turn the engine on the flywheel by hand to move the cam so the heel of the cam is adjacent the crank and you will get considerably more movement of the diaphragm when you pump by hand.

Cheers

[Badsanta]

Yeh, I tried the trick of using a garden hose stuck in the intake while on the hard. Tried to start it and hydrolocked it in 3 seconds. Thankfully I had read that could happen but hoped it wouldnt but did. Loosened the injector. Replaced the washers and had it going in 10 minuets. But the pucker factor was high.

[MollyJo]

Originally Posted by Badsanta

Yeh, I tried the trick of using a garden hose stuck in the intake while on the hard. Tried to start it and hydrolocked it in 3 seconds. Thankfully I had read that could happen but hoped it wouldnt but did. Loosened the injector. Replaced the washers and had it going in 10 minuets. But the pucker factor was high.

I think I'll wait until I hear some signs of life then hook up a hose through a ball valve so hopefully I can avoid that particular nightmare. Impressive that you had it running so soon after.

[Badsanta]

The best way is to put your intake hose in a bucket and fill the bucket with the garden hose.

[MollyJo]

Hi All
Another day at the boat yard and still nothing exciting to report.
Having tried several positions on the flywheel to get the manual pump to feel more positive and failing, I figured it needs overhauling so went about pulling it off the motor.
The first thing I noticed was how loose one of the two mounting bolts was and now suspect that was at least part of the problem. No gasket either.
Anyway, I'll replace the diaphragm and seals as per the manual and see where that leads.
Before taking it off, I did try pumping fuel and did have it at the bleed nut on top the fuel filter. But then nothing at the injectors. Cranking produced a squirt at one ejector rather than a flow, but nothing on the other. Not sure if the delivery should be a timed squirt or a flow before the injector but I imagined the latter. Any thoughts?
Spent half the day today a the yacht club AGM. Bit of a farce a must say!! And in hindsight a waste of an otherwise beautiful day.
Cheers Dave

[Cheechako]

If the volvo pump is quite expensive, get an electric from NAPA and put it in line. Not a bad idea to have the electric to prime your fuel filters etc anyway. If the electric solves the problem then you can dcide whether to spend the big bucks on the Volvo pump!

[barnakiel]

When we get fuel to the hp pump then we ease one of the injector nuts and crank till it weeps. Then we lock it. Then we undo the other injector nut and we crank some more till this one weeps too. Then we close this one. Then we try to start the engine.

I am not certain but maybe when one injector gets fuel while the other does not this may (?) imply the hp pump has still some air in it. I would take one step back and bleed the hp pump again. The order of the bleeding nuts is very important on our pump (I thin we have a CAV pump). I know this is not the only hp pump found on MD7 (I think the other is a Bosch).

b.

[Badsanta]

You are not cranking enough. Crank it till you have fuel to all injectors. It may seem like alot but you have alot of air in it

[Acushla]

The lift pump or manual pump will only supply a positive pressure to the fuel filter and injection pump. This to remove air from that part of the delivery system. The injection pump is a constant displacement pump that supplies a measured amount of fuel at a given timing. Therefore the manual pump can't deliver past this point. To get the fuel to the injectors you need to crank the engine over on the starter. If you suspect alot of air in the system then disconnect the fuel supply at the injectors and let them discharge into a container (glass or plastic jar) until you get an airless flow. This could take a little time Then connect up to the injectors with some confidence that the air has been removed.

Cheers
Jim

[MollyJo]

Thanks again for your suggestions and experience. The hardest thing is not knowing what is normal. The second hardest thing is finding dropped screws in the almost inaccessible confined space around the engine Hopefully I fully understand the process now and will have her going next visit.
Cheers
Dave