Universal 5432 starting issue....

[rwthomas1]

Hello All,
I replaced the engine in my E38 with a used 5432 this winter and although the "new" engine runs great there is one small problem. It starts instantly when cold, or even hot if I just shutdown and restart in a few minutes. If I go for a 2-4 hour sail and then try to start the engine to motor back into the harbor it doesn't want to stay running. It will almost catch, as if running on two cylinders, but not quite, and die 2-4 times before it will stay running. Once running, its fine and seems completely normal, but it takes a few seconds to clear out from the attempted starts.

-Fuel filters are clean, and new.
-Plenty of fuel
-New fuel tank 4 years ago.
-Electric fuel pump, new, functioning perfectly

I have tried starting with and without glowplugs, with and without fuel pump, etc. Nothing seems to make a difference. More annoying is that once I have returned to the dock and shutdown for 15-20 minutes it will restart instantly. I cannot duplicate the issue without a long shutdown period.

The engine does not smoke, make any strange noises, etc. I have a decent amount of experience with diesels but I can't figure this one out. The next step is to start swapping parts like injectors, delivery valves, etc.

Any ideas would be appreciated, TIA, RT

 

[Emerald]

Hi Rob,

I know you've got a pretty good gearhead, so I'm probably gonna start with what you already did, but is there any way you are loosing prime on the critter? Some small air leak, vent blockage etc.? Somehow something affected by heeling? Thinking of the heeling makes me think of another long shot, but not to rule out. Any chance that with actual sailing and wave action you're bouncing water back in via exhaust and having a really minor hydro-lock occurring that is doing this? Can't help but think to some similar starting issues I've experienced where it was hydro-lock - kinda makes ya wish it was a converted Chevy V-8 and you could pull a plug in a second or two....

 

[rwthomas1]

David,
I did install a new exhaust with the new engine. The Vernalift is in the same location as the old unit and it is a bit smaller in volume even though the hose is much larger. I doubt that this is a hydrolock issue for a few reasons: The boat would have to heel VERY far to allow water to get that far up into and over the exhaust elbow. A hydrolock "should" stop the engine from rotating, yes? The engine cranks easily, no hesitation. I would assume that if I was getting seawater in a piston bore that it would also leak past the rings and show up in the crankcase oil. Water in crankcase oil usually turns it milky and its pretty obvious.

I suppose I could go for a sail on starboard tack and go below, pull the exhaust hose off the elbow and know for sure!

I was thinking that somehow the engine may be loosing prime while under sail but I'm not sure how to check for that. I would also think that the electric pump would take care of that as it runs for 20 seconds or so while the glowplugs are going.... I was thinking of adding a check valve to the fuel line for a test.

Good ideas though, thanks! RT

 

[Emerald]

Hi,

on the water lock, yes, if the water sat any length of time in the cylinder, it should leak past the rings and make a milk shake. Also, you should have some hesitation on cranking with a minor hydro-lock (and no cranking with a complete hydro-lock). I've had engines where it would almost act like the battery was low on juice, and then once it got spinning and kicked it would seem to run OK, until you shut it down and the water drained back and locked it again (one was a cracked riser with a slow leak).

Here's a thought on checking the prime. I'm assuming that you can turn your key to run and the electric pump starts up regardless of the engine actually running/being cranked. So, after you've been sailing awhile, and before cranking, crack a fuel line as close to the injection pump as you can and have someone activate the fuel pump and as soon as fuel appears, tighten up the line and then give it a cranking start and see what happens.

When can you test again? - I wanna know what fixes this!

 

[bayhoss]

I'm leaning in the direction of the fuel pump losing the prime. But, does the engine start rite up when its cold and you first come to the boat to go sailing? If so, then the prime should have been lost during the time that the boat sat.
If I'm getting this correct, the engine starts cold, and will start warm, its when its been off for a couple of hours that the problem presents itself. Correct? Also a good place to check is the psi delivery of the lift pump. I realize that it is new and running but try removing the bleeding plug and insterting a small gauge. Then bring power to the pump and see what you read.
Best,
Frank

 

[Tom Metzger]

On a previous boat I had a Yanmar 2QM15 which had a closed fuel system. This engine had a similar problem you described which was air that required bleeding. It occurred after short shut downs, not long. I kept a wrench in the engine compartment for bleeding at the injector return lines which cured the symptom. I never found a leak, and I could never figure out what happened to the air after cool down. People laughed when I suggested it was dissolved gas that recombined after cooling.

Returning the fuel to the tank rather than the secondary filter eliminated the problem.

 

[rwthomas1]

Thanks for the input so far. I have had little luck locating a Kubota injector socket online. They are slotted for the return nipple clearance. I think I have a Kubota part number for the socket so I will have to call around. Can't hurt to check the injectors.

Its possible that the check valve in the Facet pump is faulty and allowing fuel to siphon back to the tank. Its also possible that there is a very small leak in a return line that only opens under vacuum and allows air to be pulled into the system. Tried to find an inline check valve today or one that will fit the inlet of the Racor, I know I've heard of them....

I will likely replace the return lines from the injectors back to the tank. Test the Facet pump for pressure, I already tested flow, easy to do with a T inline.

The fight goes on.....

RT

 

[rwthomas1]

Hello All,
I believe I have the problem solved. There is a bleed valve at the fuel inlet on the injection pump. This bleed valve is connected to the first injectors return fitting, and if I'm understanding the setup correctly, you open the valve to bleed the injector pump and the fuel/air just runs back to the tank via the return lines. THAT VALVE WAS LEAKING AIR! The boat would move about under sail and the fuel would create a little vacuum in the line, suck some air and then not want to start. I found this be accident when troubleshooting the problem. I bumped the valve and it started leaking fuel! If it leaks fuel, it will leak air! I have tightened up the valve packing nut and very firmly seated the valve and the engine starts easily. Now the valve is still leaking fuel but that is from the packing and I'm doing away with the valve entirely anyway. Never had a diesel with a valve like this and never needed one. Thanks for all the help! RT