Hino EH700 (175 hp) Idle RPM and Lope/Hunting Issue-gctid824657

[Cool_Beans]

If anyone here recalls all the videos I posted before I bought my boat, the rough idle or "hunting or loping" at idle bothered me. Honestly it hasn't affected my ability to dock nor has the engine ever quit on me so I'm not crazy worried about it...but I've gotten to this part of my list, lol.

I checked the idle RPM on my starboard engine as it is the worse sounding of the 2. The only clean RPM reading I could get via laser tach was off the water pump pulley. I found in a post that the crank pulley is 6" and the WP pulley is 7"? So with a little math I came up with:

~700 RPM dead idle, cold.

~805 RPM the hunting/loping is barely noticable

~866 RPM the hunting is gone, but the engine is idling pretty fast to my ear.

Interesting note, at these speeds, my tach is off about 200 rpm.

It looks like my engine is idling at the low end of spec? To try and adjust out the hunting now, how do I tweak the governor? I read a post on a marine diesel forum that there is a cap at the back of the fuel pump that I can remove to turn a screw that tensions the governor spring? I see a long hex cap or bolt with safety wire. Is this it?

Is there a procedure to adjust this or has anyone here made this adjustment and could share with me how to do it?

thanks!

[Pcpete]

There should be a rubber boot near the starter. If your engine paint is in nice shape it can be hard to find, mine is sorta shaped like a blotted B.

I have my engines idling at 760 & 790. I used the stop on the throttle lever to adjust the rpms. I've never heard of messing with the governor for idle, only maximum rpm. Then again, I've lived a sheltered life. My engines still lope, it the nature of the beast and is completely okay. Then, with the Hurth transmissions and their built in lash, idling sounds like it's full of rocks because of the lope.

Those super smooth idling engines you hear are usually Detoits, I'll take my Hinos personally.

[smitty477]

I would not hesitate to adjust the low idle and high idle (WOT no load) setting via the screws and stop nuts that are not wired or capped.

Set you low idle to whatever you like but they are normally set for 800-850 where your lope will not really occur.

Please do not mess with the governor settings unless you have someone with you that is experienced with them.

Yes - I have all the diagrams and setting around here somewhere but the engines are running well and I have seen well intentioned owners really cause problems here.

No one setting on the governor is independent of the rest - mess with one and you open up a set of adjustments that will often bring you right back to the initial settings.

[Cool_Beans]

Hmmmm. I hope I'm talking about the right thing. Not too many references online of what I think I'm talking about. One was on boat diesel (which my membership expired about 2 weeks ago) that mentioned fixing my exact issue by pulling off a cover and tweaking a screw and idle governor spring to eliminate loping idle up to 1200 rpm? The other was a few mentions on here that Earl had fixed this issue the same way and it only takes a few minutes. Nothing went into detail though

I just kind of imagined this would be the equivalent of me tweaking the idle screw in a carburetor inch:

There should be a rubber boot near the starter. If your engine paint is in nice shape it can be hard to find, mine is sorta shaped like a blotted B.

What is this and why am I looking for it?

Loping then and the tin pan full of rocks sound isn't too out of the normal, I guess I will adjust my idle speed up some and see how she reacts. Pcpete, how does your boat react when put in gear at those rpms? What's your prop pitch like?

Thanks!

[smitty477]

" Loping then and the tin pan full of rocks sound isn't too out of the normal"

The rattling sound is typical of the transmission at very low speeds. On a 6 cyl diesel that is well tuned the rattle should completely stop by 900 rpm or very close to that.

Loping and rattling that continue at higher rpm are suspect to other issues such as a poor injector or the like.

Many times I had been asked by someone to look at their engines that were causing 'rattling' above 900 rpm only to find that their real rpm was closer to 700 and the tachs were way out on the bottom end. It is somewhat amazing that the Hinos will run so low and rpm - I have seen them running really low on some boats as they had never been checked and adjusted over 25+ years.

[Pcpete]

I would call the reaction "gentle". It shifts with a slight delay without feeling sudden. My props are either the 20x22 or 22x20 whichever was stock. I'll look next time I go to the boat.

[Sunbird]

Cool Beans-

I have the same issue on my port motor. It goes away as soon as I increase idle a small amount. The idle speed and hex nuts on the back of the injection pump are still safety wired so nothing has ever been adjusted. I struggled getting an accurate reading with a laser tach as the pump pulleys are not spinning at crank rpm.

However- discussing this with Earl he said if you remove the large hex nut (17mm- it's actually a cap. )

The nut behind it locks the position of the screw that adjusts the spring and changes the pump response to eliminate the hunting.

I ran out of summer before I could try this so it's on my list for spring. Caution! That screw should only be turned a small amount 1/4 to 1/2 turn. If it does not make a change put it back where it was, then tighten the lock nut.

I hope this helps- I did not want to do this until I have verified what my true idle rpm is.

[Cool_Beans]

Awesome Sunbird!

That sounds exactly what I had read about. I do think though, I will save any governor adjustments till after I adjust the idle RPM (I'm going to bump it up this weekend) and check valve lash, tighten head bolts, time the injector pump, etc. If there is a lope still after all that, I'll tweak the governor screw.

Thanks all!