Nanni 3.90 HE crank no start

[Alapa1964]

Thanks for your reply. Skipperpete
Ok that's good news ,, those tester can be expensive ..Im back on the boat next week, so I will do the leak down test and tell you what the results are..Thanks so much for your help..PS I'll also do a test on the schraeder valve,,to make sure its not leaking..

[jerryf609]

I wonder if possibly the compression test is giving you false readings. Itis a new diagnostic tool to you so it's possible that you are not using it right or that it is faulty. Not being critical of you but you certainly dont want to chase that down if itsnot the problem. If it were me I would want a mechanic to verify compression test. If he confirms then proceed based on that. It should not cost much to get the testing done.

Because there is another possible cause to no start. Even after checking good battery voltage there could be a problem in the wire harness that causes voltage drop. If you could bypass the longish wire harness and send starting voltage directly to the starter and glow plugs you may be able to rule in or rule out wiring harness / starting voltage.

[jerryf609]

I had hard start on my C30 diesel engine. There was significant voltage drop in the harness. I resolved it by using solenoid. The wiring harness only had to energize the solenoid located near the starter with heavier guage shorter wires running from battery primary to starter. I alsoadded a similar solenoid setup to the glow plugs.

[ColIn Ferguson]

It is really strange that you have no compression in all 3 cylinders. I cant think of any conditions that would cause that other than the whole head being loose on the holding down studs.
If that was the case i would expect the engine would spin at high revs when cranking and diesel would be seen leaking at the gasket.
I suspect your compression test is wrong.
I had a Volvo that became difficult over months to start due to low (but not absent) compression. Regrinding the exhaust valve seats sorted it.
Also have you tested that you are getting fuel all the way to the injectors.

[Horst65]

The problem may be the stop solenoid or the mechanical stup cable.
If you have a stop solenoid, first check the function. When turning the start key to on position the solenoid must move the leaver on the injection pump.
If not check the cable on the solenoid or if you get voltage there.
Try to move the stop leaver by hand sveral times in both directions.
I had a similar problem with a Nanni 4.38 (4 years old, about 150 hours)

On first start after 11 month the motor gets to high revolution and was not able to stop with the key. In panic i jumped down and try to move the stop leaver to ctop position by hand. I was able the stop it but break the leaver.
After repair this the motor do not start, every other parameter were ok.
Then I deinstalled the injection pump and carefully opened it.
I have knowledge how to do that. The internal stop lever cling to the stop position due to my panic emergency stop (to much force on the outer leaver). After fixing this every thing works well.
I have now about 450 hours on the engine (8 years old).
Fazit: The inner and outer leaver of these injection pumps are not fix connected together. There is a kind of spring load between them, so the inner leaver may cling in one position. If this is the stop side, the motor would not start.

[Jopinot]

“Replaced injector pump”…
Is it timed correctly?
Diesel only need compression air and fuel At The Right Time to fire up
‘Spill time’ it, but put the beer on ice first��

[Shaneesprit]

Ok everyone missed the absolute basics!
Fuel Air Compression yes but first Easy start, takes fuel and compression out of the Math.
First if your engine won’t run but it’s turning,
Then Easy Start - Simples Long before taking the head head off / Compression test / even checking the fuel at the injector all these come after the Easy Start, on a mechanical injection engine.
just squirt a little in the air filter while cranking and report back.
If it fires then you have compression somewhere.

[bazan]

Please excuse my ignorance; I'm not familiar with this particular engine.
Does it have decompression levers?
Could they be jammed open (even partially )?
To be suddenly getting such low compression test results seems very odd...

[skipperpete]

Originally Posted by Shaneesprit

Ok everyone missed the absolute basics!
Fuel Air Compression yes but first Easy start, takes fuel and compression out of the Math.
First if your engine won’t run but it’s turning,
Then Easy Start - Simples Long before taking the head head off / Compression test / even checking the fuel at the injector all these come after the Easy Start, on a mechanical injection engine.
just squirt a little in the air filter while cranking and report back.
If it fires then you have compression somewhere.

No one missed the basics and certainly not the OP...... and the 3 basics are FUEL , OXYGEN and HEAT.
He replaced the injector pump, primed the system, checked the valve clearances, replaced the glow plugs and tested em in situ , removed the manifold ( intake and exhaust)did a (failed) compression test and finally removed the head to inspect the gasket and cylinders. Using products like “Easy start” is a really bad choice unless you’re in subzero conditions, particularly with high compression indirect combustion diesel engines like Kubota and precom yanmars. The briefest of internet searches will provide more than enough photographs of broken pistons. Yeah , I know ....Cummins and Caterpillar both had ether canisters but were arranged in a way that ether could only be injected after cranking commenced.... even then it was a destructive accessory and is dis continued. Sure , on a gasoline engine ... go for it, but on a 24:1 compression diesel beware, it WILL damage the engine (and possibly the human if they spray a volatile liquid into an engine with hot glow plugs)

[Alapa1964]

Some great suggestions. Thanks to all,,
Yes I did think it strange that Im not getting any reading on the compression test.
Im going to test the gauge and try again.
My kubota D850/Nanni 3.90 has a pull stop lever,No compression lever, Ive been told that in cuts of fuel to the injectors I will check this... Someone thought it might open the compression to stop engine?
Im going to do a leak down test to hear if cylinders are leaking..
But first I will bypass the longish wire harness and send starting voltage directly to the starter and glow plug to rule this out. I did replace the injector pump , as for timing it ?

PS my engine does not have a solenoid to stop engine. Access to the exhaust vetus water lock is difficult but I will check and I dont have a Transom exhaust flapper valve.
One thing I noticed when rotating the crank shaft by hand is it is relatively easy to turn with a long wrench but a one point it becomes harder.. dont know if this is normal..Im back on the boat tomorrow,, I will let you know how I go ..
Thanks so much for all suggestions.

[Icarus]

Originally Posted by Alapa1964

Hi Guys
My problem is Ive got a Nanni diesel 3 cylinder 3.90 HE that cranks but will not start. Ive replaced all fuel filters, bleed the lines systematically from tank to top of injectors, fuel is coming out no bubbles. Then checked new glow plugs with 12volt and replaced old ones. Then checked glow plugs while in the engine all good. Engine was running the day before but was getting harder to start over the last few months. I never had to prime with a hand pump, which is located just after the tank but lately, I have. Not sure if this helps or is a problem..Checked lift pump seems ok, replaced injector pump. Any help would be appreciated. Thanks

You replaced the injector pump? Did you time it correctly? Sounds a drastic step to take..
Lift pump SEEMS ok? how did you check it?
Close the raw water intake, empty the water trap check the exhaust for blockage.
Checked the valves and settings first, crank the engine and loosen an injector pipe connection and see what comes out. Next I'll remove the injectors and test for blockage.
Compression test?

[sinnerman]

the Nanni manual I found on line says the base engine is a Kubota.

The base engine on my 3 cylinder Universal M-25 is also a Kubota (model d-850).

It will NOT start without first using the glow plugs to heat the pre-combustion chambers.

Make sure the glow plugs are not burned out (measure with a ohmmeter), and that they are receiving power. You can tell if at least one of them is working by monitoring the voltmeter (if you have one). THe volts will dip significantly when you energize the glow plugs.

I cannot think (as others have expressed) how you can get zero pressure across all three cylinders unless the decompression lever is depressed. Either that or (most likely) the compression tester was leaking / not working...
Even with a blown head gasket you still get some pressure...

Remove the three injectors, tape plastic cups to the injector lines, put the throttle at max power, turn on the elec power to the engine, and crank the engine (turn off raw water beforehand so as not to flood the muffler/engine).

After a few rotations, check the cups to see how much fuel they have collected. All three cups should have approx. the same amount of fuel. If NO fuel - troubleshoot this issue.

Note: If there is ANY air in the injector lines the engine will most likely not start as the air acts as a shock absorber and prevents the build up of enough pressure to "fire" the injectors.. You have to bleed the fuel system especially from the injection pump to the injectors

My two cents

cheers

[skipperpete]

Originally Posted by Alapa1964

Some great suggestions. Thanks to all,,
Yes I did think it strange that Im not getting any reading on the compression test.
Im going to test the gauge and try again.
My kubota D850/Nanni 3.90 has a pull stop lever,No compression lever, Ive been told that in cuts of fuel to the injectors I will check this... Someone thought it might open the compression to stop engine?
Im going to do a leak down test to hear if cylinders are leaking..
But first I will bypass the longish wire harness and send starting voltage directly to the starter and glow plug to rule this out. I did replace the injector pump , as for timing it ?

PS my engine does not have a solenoid to stop engine. Access to the exhaust vetus water lock is difficult but I will check and I dont have a Transom exhaust flapper valve.
One thing I noticed when rotating the crank shaft by hand is it is relatively easy to turn with a long wrench but a one point it becomes harder.. dont know if this is normal..Im back on the boat tomorrow,, I will let you know how I go ..
Thanks so much for all suggestions.

Its encouraging that the engine gets harder to rotate “ at one point”, possibly this is at 3 points and suggests that there’s compression. Did you use a new head gasket? did the valves and seats get an inspection while you had the head off?
Timing the injection pump in your case basically means re using the shim pack that was originally under the cassette pump. If you lost these shims the timing will need re setting, its not difficult ... just time consuming.

[Alapa1964]

No I didnt use a new head gasket as the head had been hownd and cleaned recently,, valves and seats had been checked and cleaned 6months ago by a pro at the same time the injectors were inspected and cleaned diesel shop. The shimes were replaced the same this was before trouble started..
thanks for reply

[skipperpete]

Sheesh! We might need an exorcist. I’d love to be the guy you hired to solve this problem. Are you sure there’s no water in your fuel? Are you sure you properly connected the rack to governor link? I’d never re use a head gasket but for the moment it should be ok, a customer of mine put his headgasket on upside down and had an overheating problem, re did the job and crossed the Indian ocean with no leaks. I look forward to the results of the leakage test cos I’m out of sensible ideas knowing how much work you’ve done on the engine and I’m curious to know how many hours you have on er SINCE the head/valves/injectors/timing shims work? And why was the work done? Did you have a hydro lock that hasn’t been mentioned. Is it sub zero where you are, It’s 38°C here in Brisbane today, hot enough to start an engine with 200psi compression but if you’re in a blizzard ?????my next move would be to try starting it with the exhaust disconnected…. I know you said the mixer elbow was ok when you had the manifold off but I’m getting very suspicious that this is a plugged exhaust….. one of the very few straws we have left to grasp at.