Yanmar SB8 spare parts?

[PotomacDaysailer]

Anybody have advice on how I go about finding rebuilt parts (specifically fuel lift pump) for a 1976 Yanmar SB8 (or possibly SVE8 ?) engine? [Edit - it is actually a YSE8]

I have the old fuel lift pump, which might be serviceable, however, my son took it off and disassembled it thinking it was broke. He didn't document before disassembling, so not sure how it goes back together. Any advice appreciated.

I will try to get some pictures and post before too long.

 

[garymalmgren]

Hi P daysailer.
This is probably not what you hear because you know it already, but..
A service manual from Yanmar is expensive, but with one almost anyone can do almost any repair of a small Yanmar diesel engine and actually save money.
Look for a second hand one on C####'s L##T or elsewhere. The SB8 is getting rarer these days but maybe someone on here has one to loan. If you can get a parts list as well , it shows the various parts in exploded form.
Laying all of the parts of the lift pump out should give you a basic guide of how it fits together. All the best.

gary

 

[Ken Cross]

I just looked it up in my Yanmar shop manual. It says the fuel lift pump internal parts are not available and to Replace it.
I looked on youtube and didn't quickly find anything useful.
Ken

 

[PotomacDaysailer]

My engine is actually a YSE8. Found a manual for it, my friend and I will attempt to reinstall the fuel pump, reprime the system and get it running this week.

Failing that will try using the old fuel pump body with moving parts removed to plug the hole where it mounts on the engine, and installing an electric fuel pump to bypass it.

I will still try to get some pictures and post.

 

[garymalmgren]

Hi Ponto
I know the YSE/B series quite well. My boat has a 35 year old engine that Purrs.
To clarify, the YSE does not have a fuel pump.
Fuel pumps are for delivering fuel at a constant rate to the fuel injection pump.
Fuel pumps are basically designed to lift the fuel from a lower level than the engine.
The YSE/B have a fuel injection pump.
The injection pump receives the fuel (which is usually gravity fed) , pumps it to a high pressure and sends it down the fuel line to the injector.
The fuel that is sent down the line is timed to arrive at and activate the injector, enter the combustion cylinder and combust..
The amount of fuel that is sent out is controlled by your throttle and limited by the governor.
YSE/B injection pumps are very easy to remove, clean and reinstall. Special attention must be given to the paper gasket between the pump body and the engine crankcase.
This gasket can be reused as long as it is CLEAN and not torn. The gasket is called the "fuel pump body packing" in the diagram on page 19.
The gasket is very thin and this thickness is related to the stroke of the plunger.
No gasket and the stroke will be too long. Too thick a gasket and the stroke will be too short.
If it is damaged you have to buy a new one.
The governor lever needs to be adjusted as per instructions on page 19.
these instruction are a little confusing.
I wrote a clearer description on this page
https://forums.sailboatowners.com/index.php?threads/yanmar-ysb-12-hard-to-start.191563/#post-1461067
The manual for the YSE is on this page
https://www.sailingthanksdad.com/documentation/Yanmar-YSE-YSBServiceManual.pdf
And a basic rundown on this great little engine is on this page
http://www.angelfire.com/rnb/malcsworld/boat/YanmarYSengines.html

I am confused by your suggestion of

Failing that will try using the old fuel pump body with moving parts removed to plug the hole where it mounts on the engine, and installing an electric fuel pump to bypass it.

Are you sure you have a YSE 8?

gary

 

[PotomacDaysailer]

Gary, thanks a ton for all the info.

I am sure it's a YSE8.

It's the fuel injector pump that I need to clean/reinstall. I was under the impression that there was another pump that pressurized the injector and that the one I want to reinstall was to supply low pressure feed. That's why I thought I could just bypass it with an electric pump.
I am afraid I don't have the paper gasket "fuel pump body packing" that you mention. Do you know where I can buy one?

 

[kloudie1]

The diaphragm pump you are talking about is the "lift pump" or "low pressure fuel pump" mounted on the engine.. You can remove it and bypass it with a small electric pump that is rated for use on diesel engines.. Yanmar does not sell rebuild kits for the lift pump but the entire lift pump is still available by ordering from your local Yanmar guy..
https://forums.sailboatowners.com/index.php?threads/experience-with-diesel-fuel-pump-failure.120917/

 

[PotomacDaysailer]

Hi Kloudie, actually Gary is right, it is the injection pump and not a lift pump.

My friend and I were out at the boat today and he got a good look at it. He's a pro engine rebuilder, gas and diesel of all sizes (albeit land-based). So anyway he thinks we (read: he) can get it cleaned up and reinstalled, and find why it's not getting fuel. It looks like it has to be gravity fed although there's a vertical pick-up tube in the tank - so it has to have a siphon going and the system closed to keep fuel flowing. My friend is recommending the addition of a low-pressure electric pump between the primary filter and the injector pump, to bleed/prime the system after working on it and just to more reliably deliver fuel to the injector pump.

Gary, thanks again for the invaluable links. BTW he found the paper gasket, a.k.a. fuel pump body packing, intact and undamaged so that's good.

 

[kloudie1]

Ahh haa .. Interesting... good info, Gary..

 

[garymalmgren]

Hi Ponto
You mentioned "find why it's not getting fuel."
And also "It looks like it has to be gravity fed although there's a vertical pick-up tube in the tank - so it has to have a siphon going and the system closed to keep fuel flowing."

I can't envision any system that has a vertical pick up in the tank and no pump to suck the fuel out.
A passive siphon system would bleed back and need to be primed somehow every time the engine stops. So I suspect you have a supply line from the bottom of the tank that is hidden from view.
Are you aware that there is a fuel return line that goes from the injector back to the tank? This will feed into the top of the tank and could be what you are looking at. Easy way to check is find the line at the injector ( it will be rubber or some more flexible material) and trace it back.
The function of this line is that more fuel than is needed is sent to the injector by the "fuel injector pump" The injector opens and squirts fuel into the cylinder, When the injector closes, the excess high pressure fuel is sent back to the tank via this line.

As for why you are not getting fuel.
Is this the reason why you originally removed and disassembled the fuel injector pump?
How do you know it wasn't getting fuel?
And at what stage of the system was fuel absent?
Fuel lines are usually ample size for supplying fuel though the system. Your Yanmar is extremely frugal and uses a tiny amount of fuel each firing.

The system will be,
1. in tank filter (connected to the inside of the fuel cock)
2, fuel cock
3, in line fuel filter
4. injector pump.
5, pump to injector fuel line (metal)
6. injector
To confirm fuel flow, start from tank and undo each fitting.
If fuel doesn't run out, you have found your blockage.or restriction

Gary

 

[PotomacDaysailer]

Hi Gary,
I assumed the vertical tube in the tank is the fuel pickup since it has a quarter-turn shut off valve on it which I thought would be the fuel shut off; I figured that once the system is primed it wouldn't lose siphon as long as no air was introduced.
You asked,

As for why you are not getting fuel.
Is this the reason why you originally removed and disassembled the fuel injector pump?
How do you know it wasn't getting fuel?

Yes I have been working on the theory that the reason my engine wouldn't start was fuel starvation and that was the reason for removing/disassembling the fuel pump. I'm aware that it was foolish to do so without eliminating more mundane causes first and without keeping a record of how it went back together. However that's water under the keel now so to speak.

1. in tank filter (connected to the inside of the fuel cock)
2, fuel cock
3, in line fuel filter
4. injector pump.
5, pump to injector fuel line (metal)
6. injector
To confirm fuel flow, start from tank and undo each fitting.
If fuel doesn't run out, you have found your blockage.or restriction

That's the plan after reinstalling the injector pump.
My friend Steve found that the primary fuel filter was in very bad shape, he has ordered a replacement which he will be installing.
Also he will add a priming bulb to the system between the tank and fuel filter instead of the earlier idea to add an electric pump.

 

[garymalmgren]

Hi Ponto
Priming bulb is a good move (cheap and low tech).
Make sure you leave enough line so you can reconnect the fuel line if you have trouble with the bulb in the future.
A couple of plastic of brass fuel line barbs would do the job if you ever need to.

Keep us informed of progress please.
As my dad used to say.
"I love work.. I could watch someone else doing it all day"
ary

 

[PotomacDaysailer]

We made progress but the problem is not solved.

Installed new fuel filter and priming bulb and are getting fuel all the way to the pump. But after reinstalling the pump it just won't push fuel up to the injector. You can operate the plunger by hand, and it will squirt fuel without the delivery valve spring (red arrow) installed, but not when the spring is in there. So Steve believes that replacing the plunger assembly and the delivery valve assembly should be our next move. He found them online for relatively cheap (under $100). We also found out from the marina guys that the only place in NE Oklahoma that will rebuild the pump for me is Thompson Diesel in Broken Arrow, $150 for labor (ballpark) plus parts, which is the backup plan at this point.

 

[garymalmgren]

Hi Ponto
I take it you have the pump fitted and are rotating the engine by hand or with the starter motor and fuel is not emitting the pump on the outlet side.
My first thought is that an airlock in the pump would do this. Steve is on site and I am along way away, but I still have a couple of ideas before buying a pump plunger assembly (BTW $100 is a great price, so maybe worth buying and sticking in the spares box)
Give the following a try. Using your exploded parts list as a guide.
Use lots of paper towels or rags to catch fuel.
1. Screw in regulator spindle (with fingers) until it seats. This will give max fuel delivery.
2.Unscrew delivery valve holder 4 or 5 turns. Under normal conditions fuel will dribble or pour out from around this outlet without the pump actually pumping. Let a liberal amount of fuel run out. (10 or 15 seconds or so). Tighten valve holder.
Actually a worn or damaged plunger, plunger barrel or delivery assembly will allow MORE fuel to pass in this situation.
3, Fit fuel delivery pipe to fuel delivery valve. Don't fit it into the injector. Tighten at valve end.
4, Place rag over outlet at injector end.
5.. Crank over engine. (using the decompressor lever helps)
This process should give you pure fuel at the injector and eliminate an airlock in the pump itself .

If fuel doesn't dribble from the loosened delivery valve, my guess is the the pump has not been assembled correctly.
I know it seems a hassle, but remove the pump, disassemble and reassemble.
If it dribbles from the valve but doesn't spray out of the injector supply pipe, it would seem to be a worn plunger assembly.
If it sprays out of the pipe, just fit the pipe into the injector. Set governor arm assembly as I mentioned before and you should be on your way.
Finicky? Yes , but the hit you get when she starts is worth it.

gary

 

[PotomacDaysailer]

Success! Last night we reinstalled the rebuilt fuel pump (parts obtained from Yanmar via Toad Marine). Had to adjust the governor lever and eliminate air as in Gary's posts above. Eventually we got it to catch and run.
I say "we" - my part was limited to turning the key when instructed (a small but absolutely essential role).
Hope to get out for a bit on Sunday, forecast currently calls for 45 to 52 deg during the day with 8-14 kt winds. I will have to change the oil before running the engine again.

 

[garymalmgren]

Change the oil? What's that?
Turn the T handle on the oil filter on the front of the engine 2 or 3 times before you start and when you shut down.
That can be removed easily by the three bolts. Washed in diesel fuel and blown out with compressed air, once a year. Clean the inside of the housing with a clean rag.
Oil change once a year. The cheapest diesel oil that you can get your hands on.
Glad to hear that you have her running.
She should start first pop, so if she doesn't reset the governor arm again.
All the best

gary

 

[PotomacDaysailer]

I changed the oil but wasn't able to get it to start, again. So my pal Steve (who is beginning to feel a bit proprietary of the engine by now!) met me at the boat Wednesday (12/12/18). Another friend who has taken an interest in this project, Gareth, came out too.
Steve had ordered a replacement regulator needle and installed that (found that the old one was quite worn) and also removed and checked the exhaust elbow for clogs. Then he repeated the governor arm adjustment. We managed to get it started, but after shutting down it was still very balky about starting again; he repeated the adjustment procedure several times and finally were able to start it fairly reliably.
There are three bolts holding the exhaust elbow to the engine, one of which broke; and the old gasket is no good. So it currently leaks exhaust fumes into the cabin. We plan to go back out and replace that gasket; hopefully the two good bolts will be sufficient to hold the elbow tight with a new gasket and sealant to prevent exhaust leakage. Otherwise we might need to drill out and replace the broken bolt.
Steve wants to also check and clean the injector at some point, make sure we're getting a good spray pattern.
The motor makes a loud hammering noise when first starting before it smooths out. I hope that is not a symptom of impending failure.
If the engine does fail catastrophically then I'll probably have to repower with an outboard, it would be very tricky to say the least to extract the engine for a rebuild or replacement.
Meanwhile, the next test will be to see if I can get it to start OK when Steve's not around!

 

[garymalmgren]

Hi Ponty
You are on your way
Time for a bit of Zen and the Art of Yanmar Maintanance.

You have an engine that starts and runs.
You are dissatisfied with:
1. the starting ( not reliable yet)
2. the knocking noise on startup.
3. a broken bolt in exhaust side of the head.
That is not such a long list.

In the back of your mind you are thinking, "Oh, screw it. I will just get an outboard. Put the Yammy to bed and save myself a lot of trouble."

Relax, take it easy. Do the job the right way and save yourself a lot of pain in the long run.
That is lesson 1 from Zen and the Art of Yanmar Maintanance.

To fix the broken bolt, the head will have to come off eventually. Two bolts will probably hold but with the way those little buggers vibrate you will eventually end up with another broken bolt and will then have to take the head off. So do it now.

Head off = drain cooling water from head by the small cock under it.
Remove air inlet (drop parts and bolts for each part into a separate small cardboard box)
Remove Exhaust.
Remove rocker cover,
Remove valve rocker arms etc.
Remove 4 head nuts.
Remove head.

Parts needed are. head gasket, exhaust gasket, rocker cover gasket, (you can reuse inlet gasket or make one from a cornflakes box) 3 new exhaust flange bolts.

Note : Steve's idea of testing the injector nozzle is a good one and with the head off you can do the nozzle, remove the broken stud and check the condition of the valves.
If you are removing the injector it is easier to undo the injector retaining nuts before you remove the head.
Get a quote on the nozzle test before having the work done, it could be the same or more expensive than a new nozzle.

Once the head is off you can check the bore out too.
Of course if there is no room on the starboard side of the engine room to remove the head, ,this whole explanation is pretty useless.

Now to replacing the diesel with an outboard.
You will need to buy the motor and the transom motor mount. As well as a fuel tank and hose. The motor will need to be a long shaft which are rarer and more expensive to pick up second hand.You will still have the weight of the diesel as well as the drag of the prop. Then when you get around to selling, it will be a real turnerofferer.

So I would suggest sticking to the yanmar.
Once you get it sorted out, you will know it well and even with the horrible knocking, come to love it.
Remember lesson one
Relax, take it easy. Do the job the right way and save yourself a lot of pain in the long run.


gary

 

[PotomacDaysailer]

In the back of your mind you are thinking, "Oh, screw it. I will just get an outboard. Put the Yammy to bed and save myself a lot of trouble."

Perish the thought! Only as a last resort.